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How is climate change impacting the world’s ocean

The ocean has long taken the brunt of the impacts of human-made global warming, says UN Climate Change . As the planet’s greatest carbon sink, the ocean absorbs excess heat and energy released from rising greenhouse gas emissions trapped in the Earth’s system. Today, the ocean has absorbed about 90 percent of the heat generated by rising emissions. 

As the excessive heat and energy warms the ocean, the change in temperature leads to unparalleled cascading effects, including ice-melting, sea-level rise, marine heatwaves, and ocean acidification. 

These changes ultimately cause a lasting impact on marine biodiversity, and the lives and livelihoods of coastal communities and beyond - including around 680 million people living in low-lying coastal areas, almost 2 billion who live in half of the world’s megacities that are coastal, nearly half of the world’s population (3.3 billion) that depends on fish for protein, and almost 60 million people who work in fisheries and the aquaculture sector worldwide. 

Here are some of the major consequences of the impacts of climate change on the ocean.

Sea-level rise

Sea-level rise has accelerated in recent decades due to increasing ice loss in the world’s polar regions. Latest data from the World Meteorological Organization shows that global mean sea-level reached a new record high in 2021, rising an average of 4.5 millimeter per year over the period 2013 to 2021. 

Together with intensifying tropical cyclones, sea-level rise has exacerbated extreme events such as deadly storm surges and coastal hazards such as flooding, erosion and landslides, which are now projected to occur at least once a year in many locations. Such events occurred once per century historically.

Moreover, the Intergovernmental Panel on Climate Change (IPCC) says that several regions, such as the western Tropical Pacific, the South-west Pacific, the North Pacific, the South-west Indian Ocean and the South Atlantic, face substantially faster sea-level rise.  

Marine heatwaves

Marine heatwaves have doubled in frequency, and have become longer-lasting, more intense and extensive. The IPCC says that human influence has been the main driver of the ocean heat increase observed since the 1970s. 

The majority of heatwaves took place between 2006 and 2015, causing widespread coral bleaching and reef degradation. In 2021, nearly 60 percent of the world’s ocean surface experienced at least one spell of marine heatwaves. The UN Environment Programme says that every one of the world’s coral reefs could bleach by the end of the century if the water continues to warm. 

Coral bleaching occurs as reefs lose their life-sustaining microscopic algae when under stress. The last global bleaching event started in 2014 and extended well into 2017 - spreading across the Pacific, Indian and Atlantic oceans.   

Loss of marine biodiversity

Rising temperatures increase the risk of irreversible loss of marine and coastal ecosystems . Today, widespread changes have been observed, including damage to coral reefs and mangroves that support ocean life, and migration of species to higher latitudes and altitudes where the water could be cooler.  Latest estimates from the UN Educational, Scientific and Cultural Organization warn that more than half of the world’s marine species may stand on the brink of extinction by 2100. At a 1.1°C  increase in temperature today, an estimated 60 percent of the world's marine ecosystems have already been degraded or are being used unsustainably. A warming of 1.5°C threatens to destroy 70 to 90 percent of coral reefs , and a 2°C increase means a nearly 100 percent loss - a point of no return.

The ocean – the world’s greatest ally against climate change

The ocean is central to reducing global greenhouse gas emissions. Here are a few reasons we need to safeguard the ocean as our best ally for climate solutions.

Peter Thomson: Moving the needle on the sustainable blue economy

Ambassador Peter Thomson of Fiji, UN Special Envoy for the Ocean, mobilizes global action to conserve and sustainably use the ocean. Read the full interview.

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Why is the ocean so important for climate change, the ocean acts as a “buffer” that protects our atmosphere from seeing the full effects of climate change..

September 22, 2020

Since the 1700s, humans have raised the amount of greenhouse gases in the atmosphere by almost 50%, trapping a huge amount of heat on Earth. But only a tiny fraction of that heat has actually stayed in the air. “The ocean has taken up about 90% of the heat that’s been trapped in our atmosphere,” says Dr. Stephanie Dutkiewicz, senior research scientist at the MIT Center for Global Change Science, whose research focuses on phytoplankton in oceans. Without the ocean absorbing heat, our planet’s air temperature would be changing much faster.

Why does the ocean absorb so much heat? It’s because water molecules can take in much more heat than the molecules in the air. “Think about the fact that if you stay in the water too long, you get very cold because the water is taking your heat,” says Dutkiewicz. “But if you stay in the air, you don’t really feel that different.”

Not only has the ocean absorbed heat, but it is also estimated that it has absorbed one third of the carbon dioxide humans have emitted since the industrial revolution. Carbon dioxide, or CO 2 , is the most important greenhouse gas driving climate change. As we’ve added extra CO 2 to the atmosphere, much of it has dissolved in the ocean’s surface waters, in an attempt to bring the atmosphere and ocean CO 2 back into equilibrium.

Tiny organisms called phytoplankton are also very important in the Earth’s carbon cycle. They take up CO 2 and sunlight through photosynthesis to grow and reproduce. When phytoplankton die, a small portion of the carbon they have taken in sinks to the deep ocean, forming a large “carbon reservoir.” “If you were to kill off all the phytoplankton, about 200 PPM (parts-per-million) of CO 2 would be released into the atmosphere,” says Dutkiewicz. “To put this in perspective, the amount of pre-industrial atmospheric carbon dioxide is about 280 PPM.”

Although oceans have helped slow climate change by absorbing heat and carbon, these changes are also hurting ocean life. The added heat changes the currents of the ocean and how the surface mixes with deeper water. This in turn affects how well nutrients move, which affects phytoplankton and all the life that depends on it. Since phytoplankton are the base of the marine food web—a crucial food source for animals from shrimp to whales—this is a big change for almost everything that lives in the sea. Heating the ocean also makes the water expand, which is the main cause of sea level rise . Finally, the absorption of CO 2 is making the ocean more acidic , which is especially dangerous to shellfish and corals.

Read more Ask MIT Climate

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What You Need to Know About Oceans and Climate Change

#ShowYourStripes graphic by Professor Ed Hawkins (University of Reading) https://showyourstripes.info/

How does climate change affect oceans?

Climate change is a major threat to ocean health globally, and one that adds to other ongoing anthropogenic threats – in other words, environmental changes caused by human activity. We are starting to understand these impacts better and learning more about the extent and scope of the problem. First, climate change is causing some serious changes in oceans, including temperature increase, sea level rise, and acidification. Significant changes in ocean current patterns are also occurring. All these factors impact ocean health and marine species. For instance, coral reefs, which are critical marine ecosystems, are threatened by a trifecta of acidification, increasing sea temperatures and sea level rise. But acidification is also a much broader issue since it disrupts carbon sequestration by other species including mollusks and crustaceans. Changing ocean current patterns threaten recruitment of fish stocks – the number of fish born in a given time frame that reach the juvenile stage – with very real and direct impacts on coastal communities that depend on these resources. The impacts of climate change on oceans are therefore myriad, complex, and interrelated.

What role do oceans play in mitigating climate change?

Oceans are the largest heat sink on the planet. They absorb 90% of the excess heat caused by climate change. Oceans are also a very efficient carbon sink, absorbing 23% of human-caused CO2 emissions. Ecosystems such as mangroves, which grow in coastal areas but with roots in sea water, as well as tidal marshes and seagrass meadows, all sequester and store more carbon per unit area than forests. We also know that some carbon particles have been sequestered in seabed sediment over millennia, though that phenomenon is not as well understood or even measured.

But the role of oceans as a carbon sink is directly affected by the impacts of climate change on ocean health, creating a vicious cycle. As it is, we are only just beginning to understand the importance of the ecological functions of oceans, yet climate change is already impacting them.

What role do oceans play in climate change adaptation?

 Coastal zones are very high energy areas -- think about tides or wave action – and to protect coastal communities, these incessant forces must be managed. You can manage them by building gray infrastructure such as jetties or seawalls, or you can use green infrastructure such as mangroves, or a combination of green and gray infrastructure.  New research in  Bangladesh  estimates that, in a powerful cyclone, mangroves would reduce the rise in seawater levels between 4 and 16.5 centimeters and bring down water inflow speed to between 29% - 92%. So, communities can really benefit from the protection of mangroves.  

What is the World Bank doing to support ocean health?

The World Bank has developed the  Blue Economy approach,  which focuses on the sustainable and integrated management of coastal and marine areas in healthy oceans. Our multi-donor trust fund,  PROBLUE , supports governments in their efforts to improve fisheries, address marine pollution, manage coastal resources, and limit the impacts of key sectors such as tourism, maritime transport and offshore renewable energy on ocean health. This is a critical agenda for the Bank. ,  and this number is expected to double to $3 trillion by 2030 . . For instance, we are helping our client countries develop new, more sustainable approaches to coastal tourism linked to marine protected areas.  We also support more than 105 million hectares of marine protected areas  where human activities are managed in a significant way, including core areas where all activities are restricted.

We are also focused on the decarbonization of shipping. Many ships run on bunker fuel – the dirtiest form of fossil fuel used today.  And as oceans recover, we work to develop alternative livelihoods for the impacted communities as they adapt to current and future changes driven by climate.

And last but not least, we focus much of our efforts on reducing and managing marine plastic pollution. Plastics are yet another threat to ocean health and one of the most visible. Plastic pollution is caused in part by poor solid waste management, but we are tackling the problem throughout the plastic value chain, from production to switching to a circular economy and, if all else fails, beach clean-ups. Because the task is daunting, many parts of the World Bank Group need to be involved and we have much more to do, but if marine plastics are not tackled in earnest, oceans will simply not be able to play their vital role in mitigating climate change.

What will it take to ensure oceans are healthy and can help us fight climate change in the future?

 The Bank is not alone in this endeavor and we can see a growing global commitment around the effort. A few countries have set ocean health targets as part of their nationally determined contributions to the Paris Agreement – and many more should do so. Some countries are adopting integrated ocean planning that looks at the development of various oceanic sectors in an integrated and sustainable way. This is the break from business as usual that needs to take place: we simply cannot continue on the path that has brought us to this point. At COP26 in Glasgow, negotiators approved new rules for carbon markets that could help better value ocean-based carbon sinks such as mangroves and coral reefs and create incentives for their preservation. There is no silver bullet, but we can and must continue working together to restore ocean health.

• Website: Climate Explainer Series
• Website: PROBLUE
• Learn more: Blue Economy
• Blog: Protecting oceans from climate change impacts

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• Published: 13 July 2020

Warming trends increasingly dominate global ocean

• Gregory C. Johnson   ORCID: orcid.org/0000-0002-8023-4020 1 &
• John M. Lyman 1 , 2  

Nature Climate Change volume  10 ,  pages 757–761 ( 2020 ) Cite this article

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The ocean takes up about 93% of the global warming heat entering Earth’s climate system. In addition, the associated thermal expansion contributes substantially to sea-level rise. Hence, quantifying the oceanic heat uptake rate and its statistical significance has been a research focus. Here we use gridded ocean heat content maps to examine regional trends in ocean warming for 0–700 m depth from 1993–2019 and 1968–2019, periods based on sampling distributions. The maps are from four research groups, three based on ocean temperature alone and one combining ocean temperature with satellite altimeter sea-level anomalies. We show that use of longer periods results in larger percentages of ocean area with statistically significant warming trends and less ocean area covered by statistically significant cooling trends. We discuss relations of these patterns to climate phenomena, including the Pacific Decadal Oscillation, the Atlantic Meridional Overturning Circulation and global warming.

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Past and future ocean warming

Acceleration of the ocean warming from 1961 to 2022 unveiled by large-ensemble reanalyses

Projected ocean warming constrained by the ocean observational record

Data availability.

The Ssalto/Duacs global maps of satellite-altimeter-derived sea-surface height anomalies used for the PMEL maps were downloaded in January 2019 and can be accessed at https://www.aviso.altimetry.fr/en/data/products/sea-surface-height-products/global.html . The in situ Argo data used for the PMEL maps ( https://doi.org/10.17882/42182#61117 ) were downloaded from the US Argo Global Data Assembly Center in January 2019 and can be accessed at https://www.usgodae.org//argo/argo.html . The historical in situ temperature data other than Argo used for the PMEL maps were EN3 v2a from www.metoffice.gov.uk/hadobs . This version has been superseded, but historical non-Argo data in later versions are very similar. The ocean heat content maps from JMA can be accessed at https://www.data.jma.go.jp/gmd/kaiyou/english/ohc/ohc_global_en.html , those from IAP at http://159.226.119.60/cheng/ and those from NCEI at https://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/ .

IPCC Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) (Cambridge Univ. Press, 2013).

Cazenave, A. et al. Global sea-level budget 1993–present. Earth Syst. Sci. Data 10 , 1551–1590 (2018).

Article   Google Scholar  

Meyssignac, B. et al. Measuring global ocean heat content to estimate the Earth energy imbalance. Front. Mar. Sci. 6 , 432 (2019).

Johnson, G. C., Lyman, J. M. & Loeb, N. G. Improving estimates of Earth’s energy imbalance. Nat. Clim. Change 6 , 639–640 (2016).

Roemmich, D. et al. Unabated planetary warming and its ocean structure since 2006. Nat. Clim. Change 5 , 240–245 (2015).

Wijffels, S., Roemmich, D., Monselesan, D., Church, J. & Gilson, J. Ocean temperatures chronicle the ongoing warming of Earth. Nat. Clim. Change 6 , 116–118 (2016).

Abraham, J. P. et al. A review of global ocean temperature observations: implications for ocean heat content estimates and climate change. Rev. Geophys. 51 , 450–483 (2013).

Lyman, J. M. & Johnson, G. C. Estimating global ocean heat content changes in the upper 1800 m since 1950 and the influence of climatology choice. J. Clim. 27 , 1945–1957 (2014).

Roemmich, D. et al. On the future of Argo: a global, full-depth, multi-disciplinary array. Front. Mar. Sci. 6 , 439 (2019).

Johnson, G. C. & Birnbaum, A. N. As El Niño builds, Pacific Warm Pool expands, ocean gains more heat. Geophys. Res. Lett. 44 , 438–445 (2017).

Roemmich, D. & Gilson, J. The global ocean imprint of ENSO. Geophys. Res. Lett. 38 , L13606 (2011).

Palanisamy, H., Meyssignac, B., Cazenave, A. & Delcroix, T. Is anthropogenic sea level fingerprint already detectable in the Pacific Ocean? Environ. Res. Lett. 10 , 084024 (2015).

Wills, R. C. J. et al. Ocean circulation signatures of North Pacific decadal variability. Geophys. Res. Lett. 46 , 1690–1701 (2019).

Kenigson, J. S., Han, W. Q., Rajagopalan, B., Yanto & Jasinsk, M. Decadal shift of NAO-linked interannual sea level variability along the US northeast coast. J. Clim. 31 , 4981–4989 (2018).

Roemmich, D., Gilson, J., Sutton, P. & Zilberman, N. Multidecadal change of the South Pacific Gyre circulation. J. Phys. Oceanogr. 46 , 1871–1883 (2016).

Carson, M. & Harrison, D. E. Regional interdecadal variability in bias-corrected ocean temperature data. J. Clim. 23 , 2847–2855 (2010).

Richter, K. & Marzeion, B. Earliest local emergence of forced dynamic and steric sea-level trends in climate models. Environ. Res. Lett. 9 , 114009 (2014).

Blunden, J. & Arndt, D. S. State of the climate in 2018. Bull. Am. Meteorol. Soc. 100 , Si–S305 (2019).

Johnson, G. C. et al. in State of the Climate in 2019 (Ed. Lumpkin, R.) S74–S77 (American Meteorological Society, 2019).

Ishii, M. et al. Accuracy of global upper ocean heat content estimation expected from present observational data sets. Sola 13 , 163–167 (2017).

Cheng, L. J. et al. Improved estimates of ocean heat content from 1960 to 2015. Sci. Adv. 3 , e1601545 (2017).

Levitus, S. et al. World ocean heat content and thermosteric sea level change (0-2000 m), 1955-2010. Geophys. Res. Lett. 39 , L10603 (2012).

Wu, L. X. et al. Enhanced warming over the global subtropical western boundary currents. Nat. Clim. Change 2 , 161–166 (2012).

Article   CAS   Google Scholar  

McCarthy, G. D., Joyce, T. M. & Josey, S. A. Gulf Stream variability in the context of quasi-decadal and multidecadal Atlantic climate variability. Geophys. Res. Lett. 45 , 11257–11264 (2018).

Wang, Y. L. & Wu, C. R. Discordant multi-decadal trend in the intensity of the Kuroshio along its path during 1993-2013. Sci. Rep. 8 , 14633 (2018).

Chen, X. Y. & Tung, K. K. Varying planetary heat sink led to global-warming slowdown and acceleration. Science 345 , 897–903 (2014).

Liu, W., Xie, S. P. & Lu, J. Tracking ocean heat uptake during the surface warming hiatus. Nat. Commun. 7 , 10926 (2016).

He, C. F., Liu, Z. Y. & Hu, A. X. The transient response of atmospheric and oceanic heat transports to anthropogenic warming. Nat. Clim. Change 9 , 222–226 (2019).

Armour, K. C., Marshall, J., Scott, J. R., Donohoe, A. & Newsom, E. R. Southern Ocean warming delayed by circumpolar upwelling and equatorward transport. Nat. Geosci. 9 , 549 (2016).

Mantua, N. J., Hare, S. R., Zhang, Y., Wallace, J. M. & Francis, R. C. A Pacific interdecadal climate oscillation with impacts on salmon production. Bull. Am. Meteorol. Soc. 78 , 1069–1079 (1997).

Salinger, M. J., Renwick, J. A. & Mullan, A. B. Interdecadal Pacific Oscillation and South Pacific climate. Int. J. Climatol. 21 , 1705–1721 (2001).

Merrifield, M. A. & Maltrud, M. E. Regional sea level trends due to a Pacific trade wind intensification. Geophys. Res. Lett. 38 , L21605 (2011).

Hamlington, B. D. et al. An ongoing shift in Pacific Ocean sea level. J. Geophys. Res. Oceans 121 , 5084–5097 (2016).

Roxy, M. K., Ritika, K., Terray, P. & Masson, S. The curious case of Indian Ocean warming. J. Clim. 27 , 8501–8509 (2014).

Caesar, L., Rahmstorf, S., Robinson, A., Feulner, G. & Saba, V. Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature 556 , 191 (2018).

Smeed, D. A. et al. The North Atlantic Ocean Is in a state of reduced overturning. Geophys. Res. Lett. 45 , 1527–1533 (2018).

Josey, S. A. et al. The recent Atlantic cold anomaly: causes, consequences, and related phenomena. Annu. Rev. Mar. Sci. 10 , 475–501 (2018).

Durack, P. J. et al. Quantifying underestimates of long-term upper-ocean warming. Nat. Clim. Change 4 , 999–1005 (2014).

Durack, P. J. et al. Ocean warming: from the surface to the deep in observations and models. Oceanography 31 , 41–51 (2018).

Ingleby, B. & Huddleston, M. Quality control of ocean temperature and salinity profiles—historical and real-time data. J. Mar. Syst. 65 , 158–175 (2007).

Locarnini, R. A. et al. World Ocean Atlas 2009, Volume 1: Temperature (US Government Printing Office, 2010).

Ishii, M. & Kimoto, M. Reevaluation of historical ocean heat content variations with time-varying XBT and MBT depth bias corrections. J. Oceanogr. 65 , 287–299 (2009).

Smith, W. H. F. & Sandwell, D. T. Global sea floor topography from satellite altimetry and ship depth soundings. Science 277 , 1956–1962 (1997).

Wunsch, C. The Ocean Circulation Inverse Problem (Cambridge Univ. Press, 1996).

von Storch, H. & Zwiers, F. W. Statistical Analysis in Climate Research (Cambridge Univ. Press, 1999).

Download references

Acknowledgements

G.C.J. and J.M.L. are supported by the Global Ocean Monitoring and Observing programme, National Oceanic and Atmospheric Administration (NOAA), US Department of Commerce and NOAA Research. The Argo data used here were collected and made freely available by the International Argo Program and the national programmes that contribute to it ( http://www.argo.ucsd.edu , http://argo.jcommops.org ). The Argo Program is part of the Global Ocean Observing System. The Ssalto/Duacs altimeter products were produced and distributed by the Copernicus Marine and Environment Monitoring Service (CMEMS) ( http://www.marine.copernicus.eu ). We thank chief editor B. Wake for helpful comments and suggestions. The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the authors and do not necessarily reflect the views of NOAA or the Department of Commerce. PMEL Contribution number 4968.

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G.C.J and J.M.L designed the study. J.M.L. made the calculations and analysed the trends. G.C.J. wrote the manuscript. Both authors contributed to interpreting the results and improving the manuscript.

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Correspondence to Gregory C. Johnson .

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Extended data

Extended data fig. 1 maps of means, standard deviations, and ratios of their magnitudes for the different 0–700 m ocean heat content trend estimates used..

Means of trends for ( a ) 1993–2019 are contoured over twice the range used for ( b ) 1968–2019. Similarly, the standard deviations for ( c ) 1993–2019 trends are contoured over twice the range used for ( d ) 1968–2019. The ratio of the mean trend magnitudes to their standard deviations are contoured on the same scale for ( e ) 1993–2019 and ( f ) 1968–2019. Latitudes are gridded at 30° intervals, and longitudes, centered on 150 °W, at 60° intervals (dotted lines).

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Johnson, G.C., Lyman, J.M. Warming trends increasingly dominate global ocean. Nat. Clim. Chang. 10 , 757–761 (2020). https://doi.org/10.1038/s41558-020-0822-0

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DOI : https://doi.org/10.1038/s41558-020-0822-0

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How Does Climate Change Affect the Ocean?

Why is the ocean important for life on earth.

The Bahamas seen from the Space Shuttle STS-52 in November 1992. Credit: NASA

The ocean is important because it is a very large part of our planet. In fact, it covers 70% of Earth’s surface. The ocean is a home and food source for countless fish, mammals, plants, birds, and more.

The ocean plays an important role in whatever happens in our environment on Earth. Even if you live on land – like humans do – you wouldn’t survive without the ocean!

One example: without the ocean, Earth would be much hotter than it is right now. That’s because the ocean absorbs heat from the Sun and spreads it more evenly around our planet.

How does the ocean soak up heat from the Sun?

Earth’s oceans help to absorb extra heat from the atmosphere because water is good at storing heat. How do you think a balloon filled with water would react to a flame differently than a balloon filled with air? Credit: NASA/JPL-Caltech

Water is excellent at storing heat. Water has a high heat capacity—it absorbs a lot of heat before it begins to get hot. Air, on the other hand, is not so great at storing heat.

Earth’s climate is warming due to human activities. As Earth experiences a warming climate, we experience hotter air temperatures. The ocean does an excellent job of absorbing the extra heat from the atmosphere, delaying the full impact of global warming.

The top few meters of the ocean store as much heat as Earth's entire atmosphere. So, as the planet warms, it's the ocean that gets most of the extra energy. More than 90% of the global warming is going into the ocean.

But if the ocean gets too warm, then the plants and animals that live there can get sick or even die.

How can a water balloon teach us about climate change? Watch this video and find out!

How are coral reefs affected by climate change?

Coral reefs are created by living creatures. Warming oceans caused by climate change are putting coral reefs in danger. Coral reefs are made by very fragile colonies of organisms that build skeletons around themselves.

Coral lives together with a certain kind of colorful algae. The algae make food using sunlight ¬– a process called photosynthesis. The algae share the food with the coral, and in turn, the coral gives the algae a safe and comfortable place to live.

The two of them get along fine, living in clean, clear, shallow waters where the Sun shines through brightly. Fish and other sea creatures love coral too, because there are lots of nooks and crannies for them to hide in.

But the algae cannot carry out photosynthesis in water that is too warm. The algae either die, or the coral spits it out. It's bad for the algae, the coral and the fish, because the coral lose their food sources and become weak and can die. This event is called coral bleaching , and it is a very serious problem in many ocean ecosystems around the world.

Read about what it’s like to be an ocean scientist studying coral reefs .

A bleached coral next to an unbleached coral. Credit: Carolina Rogers/USGS

How does the ocean soak up CO 2 ?

Fish and other animals in the ocean breathe oxygen and give off carbon dioxide (CO 2 ), just like land animals. Ocean plants take in the carbon dioxide and produce oxygen, just like land plants. The ocean is great at absorbing CO 2 from the air.

However, a lot of CO 2 comes from human activities, too. For example, exhaust from cars, planes, and factories put extra carbon dioxide into our air. Too much carbon dioxide in the air is a problem, as it causes the Earth to trap more heat. The ocean absorbs about one-quarter of the CO 2 that humans create when we burn fossil fuels (oil, coal, and natural gas).

Too much carbon dioxide in the ocean causes a problem called ocean acidification. You can read this article to learn all about ocean acidification and its effects .

How does the ocean affect the climate?

The ocean absorbs heat from the Sun and ocean currents move that warm water all around the planet. Ocean currents are like highways that carry water around the world. Heat (along with salt) is a major source of power for ocean currents.

Cold water near the North and South Poles sinks deeper into the ocean. Water near the equator is warmed by the Sun. Then, the warm surface water moves closer to the poles where it cools and sinks.

The "great ocean conveyor belt" refers to the major ocean currents that move warm water from the equator to the poles and cold water from the poles back toward the equator. Credit: NASA/JPL-Caltech

As Earth’s climate warms, the water also warms melting sea ice. This warming could make the water less cold and less likely to sink. Without sinking cold water, the ocean currents could slow down or stop in some places. This could change the climate in places like Europe that have milder climates thanks to the warm currents in the oceans around them.

Does the salt in the ocean do anything?

Fresh water has lower salinity (saltiness) than estuary water, where the ocean water mixes with river water. The ocean itself is the most salty of all. Credit: NASA/JPL-Caltech

The amount of salt in the ocean also affects currents. Saltier water is heavier than less salty water. When salty ocean water freezes, the ice can no longer hold on to the salt. Instead, the salt mixes with the water below making it saltier and heavier. Glaciers, land ice and icebergs are made of fresh water, so what happens when this ice melts? Good question!

The water in the North Atlantic sinks because it's cold, but also because it's salty. Being both cold and salty makes it really dense and heavy, so it can sink very far. But if too much ice melts in the North Atlantic, the water could become less salty and affect ocean currents. NASA satellites are keeping a close eye on the melting ice, the ocean currents, and ocean life to better understand this complicated system.

Play Go With the Flow to use temperature, salinity, and ocean currents to find treasure!

How does climate change impact sea level?

As Earth warms, sea levels are rising. Credit: NASA/JPL-Caltech

As Earth warms, NASA has observed that sea levels are rising. Water expands as it gets warmer. So, warm water takes up more room in our oceans, and this leads to higher sea levels. Another reason that oceans are rising is due to melting ice on land. Glaciers and ice sheets are large masses of ice that sit on the land. As our planet warms, this ice melts and flows into the oceans. More water in the oceans makes sea level higher.

NASA satellites are constantly measuring sea level around the globe. Learn more about how we measure sea level with satellites .

Related NASA Missions

OSTM (Jason-2)

Sentinel-6 Michael Freilich

Conservation News

News, views and stories from the front lines of conservation

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5 ways that climate change affects the ocean.

© Andre Seale/Marine Photobank

This post was updated on December 3, 2021

For an ecosystem that covers 70 percent of the planet, oceans get no respect .

They feed us, provide most of the oxygen we breathe and protect us from the worst effects of global warming. Were it not for the oceans, climate change would have already made Earth uninhabitable.

The oceans have absorbed more than 90 percent of the global warming created by humans since the 1970s. Had that heat gone into the atmosphere, global average temperatures would have jumped by almost 56 degrees Celsius (100 degrees Fahrenheit).

But as vast as the seas are, there is a limit to how much heat they can absorb — and they are beginning to reach it. Conservation News examines some of the ways that climate change affects life in the oceans — and what that means for humanity.

1. Higher temperatures are bad for fish — and for us

Persistently rising temperatures are having cascading effects on marine life. Consider:

• Warmer waters cause coral bleaching, which in turn impacts coral reef ecosystems that are home to a dizzying array of marine biodiversity — and provide crucial sources of food for people.
• Warmer waters threaten to cause mass migration of marine species in search of the right conditions for feeding and spawning. For example, Conservation International research revealed that ocean warming is altering the habitats of tuna, causing them to move significantly to the east of the Pacific Islands. This mass exodus could be catastrophic for the economies of many Pacific Island countries such as Fiji and the Cook Islands.
• Change in water temperatures can directly affect the development and growth of most fish and cephalopods (such as octopus and squid).

For the 3 billion people who rely on fish as their chief source of protein, the prospect of fewer and smaller fish in the sea is bad news.

2. Polar ice is melting

In what has become a dismal annual pattern, wintertime Arctic sea ice continues to dip to new lows as the oceans warm.

Meanwhile, Antarctica is shrinking underwater, as submerged ice is rapidly melting, according to recent studies .

The effects of this warming on iconic species such as polar bears are well-documented . Under the surface, though, the problem is no less urgent. Consider:

• The production of algae — the foundation of the Arctic food web — depends on the presence of sea ice. As sea ice diminishes, algae does too, causing a ripple effect on species from Arctic cod to seals, whales and polar bears.
• Dwindling sea ice results in the loss of vital habitat for seals, walruses, penguins, whales and other megafauna.
• Sea ice is a critical habitat for Antarctic krill, the food source for many seabirds and mammals in the Southern Ocean. As sea ice has receded in recent years, Antarctic krill populations have dropped , resulting in declines in the species that depend on the krill.

What does this mean for us? Impacts to Arctic cod fisheries are having cascading effects, culminating in human-wildlife conflict and food insecurity. A dramatic decrease in sea ice — and seafood — pushes polar bears toward coastal communities and hunting camps to find food, bringing them into closer contact and potential conflict with people.

3. Rising sea levels represent a slow, seemingly unstoppable threat

Climate change poses a dual threat for sea levels.

For one, when land-based polar ice melts, it finds its way to the sea. (Ice that forms in polar seas, on the other hand, doesn’t affect sea levels when it melts.) Second, when water warms, it expands to take up more space — a major yet unheralded cause of sea-level rise.

With sea-level rise accelerating at a rate of about one-eighth of an inch per year , the effects on humanity are plain:

• Higher ocean temperatures are melting polar ice and glaciers from the Greenland and Antarctic sheets at a rapid rate, resulting in an unprecedented rise of sea levels that has the potential to displace more than 680 million people living across low-lying coastal communities, according to a 2019 UN report .
• Recent research revealed that several major coastal cities could be almost entirely underwater due to sea level rise by the middle of the century, including Ho Chi Minh City, Vietnam; Shanghai, China; and Mumbai, India.

The effects of sea-level rise on wildlife are less explored but no less important:

• The survival of coral reefs, mangroves, seagrasses and other critical habitat-forming species hinges on their ability to move into shallower waters. Slow-growing species are most unlikely to be able to keep pace with the rising sea level.
• Critical coastal habitats — for instance, sea turtle nesting beaches — are lost as the sea level rises. Natural and man-made barriers such as cliffs, mangrove forests, sea walls and coastal developments stand in the way of them migrating further inland.

4. Warming oceans alter currents

Climate change affects ocean temperatures as well as wind patterns — taken together, these can alter oceanic currents.

How does this affect wildlife?

As mentioned earlier, many marine species’ migratory patterns can change as the currents they follow are altered. And many species that depend on ocean currents for reproduction and nutrients will be affected. For example, reef-building coral and reef fish species rely on dispersal of their larvae by currents .

The impacts of changes in ocean currents on humanity could be severe, as currents play a major role in maintaining Earth’s climate. For example, Europe’s relatively mild climate is maintained in part by the large Atlantic current called the Gulf Stream, which is experiencing an “ unprecedented slowdown .” Changing these currents will have major implications worldwide for the climate, including changes in rainfall — with more rain in some areas and much less in others — and fluctuating air temperatures. These changes have drastic implications for countless species, including humans.

5. Climate change is affecting the chemistry of seawater

The same burning of fossil fuels that increases greenhouse gas levels in the atmosphere, is also altering the chemical composition of seawater by making it more acidic. The ocean absorbs 30 percent of the carbon dioxide in the atmosphere — and when that carbon dissolves into the water, it forms carbonic acid.

How much does this affect marine life? A lot.

Acidification can dissolve the calcium carbonate shells of marine species such as corals, scallops, lobsters and crabs, and some microscopic plankton that are a foundation of the food web throughout the ocean. These shell-forming organisms provide critical habitats and food sources for other marine life. Increased acidification can also limit the ability of certain fish to detect predators, disrupting the entire marine food chain.

The disruption and destruction of coral reefs and shellfish will have profound effects on humanity, chiefly in the form of less food for people who rely on the ocean for it.

Jessica Pink was an editorial intern for Conservation International.

Want to read more stories like this? Sign up for email updates. Donate to Conservation International.

Further reading:

• Climate crisis pushing oceans to the brink, report warns
• The oceans are on the brink. Here are 3 ways to save them

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Climate Change Impacts on the Ocean and Marine Resources

The ocean is an essential part of the global environment. It influences climate and weather around the world and is home to millions of different forms of life. 1 Thriving marine ecosystems provide Americans with food, medicines, jobs, and recreation. The ocean also connects people to nature and is critical to some Native cultures.

Coral bleaching. Coral reefs are home to many sea creatures. When water is too warm or too cold, coral becomes damaged in a process called bleaching . If bleaching goes on for too long, it can kill the coral. 39

Dead Zones. Harmful algal blooms (HABs), sometimes called red tides, have been linked to increasing temperatures in the Atlantic and Pacific Oceans. Some species of HABs can produce excessive amounts of biomass that can prevent light from getting below the ocean surface. As these organisms die and decompose, oxygen levels go down, making it harder for other organisms to survive. Other species of HABs can produce toxins that are hazardous to marine life and humans .

Threats to subsistence fishing. Salmon and other types of fish are an essential part of subsistence fishing in Alaska. Climate change is making it difficult for Indigenous people to practice fishing traditions.

Wildlife impacts. A 2014 marine heatwave caused the death of many sea lions. 35 The warm water caused the fish that the sea lions eat to move elsewhere. As a result, thousands of sea lion pups starved.

Decreases in commercial fishing harvests. America’s East Coast is projected to see a 20% to 30% decrease in fish harvests by 2060. 36 Climate change will drive fish further north as waters heat up.

Increasing emissions of greenhouse gases into the atmosphere from the burning of fossil fuels are causing changes in the ocean (see box). These changes can alter which species of marine life thrive best in certain areas. For example, many fish have shifted their typical range as water temperatures rise. 2 However, other species are expected to decline in number or leave areas that are no longer favorable for them. 3 These shifts can have significant impacts on marine ecosystems and on fishing communities. 4

Many climate change impacts will only be avoided by reducing carbon dioxide emissions. 5 Climate-driven changes in the ocean are motivating people to find solutions to the new challenges. For example, new forecast tools are helping predict changes in ocean conditions that can help the fishing industry adapt. Many organizations are working together to protect coral reefs , which face hazards such as bleaching, infectious diseases, smothering from sediment, collapses in fish stocks, and other issues. Such strategies can help preserve and protect marine resources. Even with these efforts, however, it will take decades or longer for the ocean to recover.

Explore the sections on this page to learn more about climate impacts on the ocean and marine resources :

Top Climate Impacts on the Ocean and Marine Resources

The marine environment and the economy, environmental justice and equity, what we can do, related resources, climate change impacts on the ocean .

Human-caused carbon dioxide emissions are affecting the ocean in three main ways:

• Warming. Greenhouse gases in the atmosphere trap energy from the sun. The ocean absorbs much of this energy, causing ocean waters to warm. Warmer waters also contribute to sea level rise.
• Acidification. The ocean’s absorption of carbon dioxide from the atmosphere is changing the pH of the ocean, making seawater more acidic.
• Low oxygen levels. Warm water cannot hold as much oxygen as cold water. 

Climate change affects the ocean in many ways. Three key impacts are described in this section.

1. Changes in Ocean Ecosystems

Climate changes to the physical and chemical makeup of the ocean have significant impacts on marine ecosystems. For example, water temperature influences which species can live in an area. Acidification affects many animals’ ability to make shells or skeletons, while low oxygen levels can contribute to hypoxia , or dead zones . Warm temperatures can exacerbate the effects of both acidification and hypoxia. 6

Impacts on one species can ripple across an entire ecosystem. For example, plankton—tiny organisms at the bottoms of many marine food chains —are sensitive to water temperatures and oxygen concentrations. They can die off if the water gets too warm. Animals farther up the food chain, like whales, can suffer food shortages when this happens. 

Climate changes to the marine environment will come in many forms. For instance, the diversity of some temperate ecosystems is expected to increase. 7 But overall, climate change is projected to disrupt marine ecosystems in ways that reduce the services they provide and their diversity of life. 8

2. More Common and Severe Extreme Marine Events

Rising water temperatures, acidification, and low oxygen levels can combine with natural ocean cycles to create extreme marine events. Marine heat waves, dead zones, and coral bleaching are just a few examples of these events, which are projected to become more common and severe. 10 Extreme events can harm marine ecosystems and communities connected to these systems. For example, a large heat wave off the West Coast in 2014 shut down crab fisheries and starved baby sea lions. 11

3. Impacts on Marine Fisheries

Commercial and recreational marine fisheries in some regions are at high risk from climate-driven changes in the size and distribution of fish populations. 12 Some fish species have already altered their geographic range in response to climate change. For example, pollock and cod are moving north to colder water as local ocean temperatures rise. 13

The movement of fish into new areas disrupts the ecosystems that they move into. It can also cause confusion about what fishing regulations apply. 14 Changes in where fish live may also mean boats have to travel further from ports, potentially increasing costs. 15

Climate change is also affecting the timing of seasonal events, which can affect fisheries. For example, some species, such as striped bass, are spawning earlier in the year. 16 This means that catches can peak earlier than normal. Fisheries will need to adapt to such changes or risk reduced catches and lost revenues, which can also increase prices for consumers. 17

Changes in the locations and number of fish species in the ocean can present new opportunities in some cases. For example, scientists predict that some areas, such as the Bering Sea, will see more kinds of fish as warming waters drive populations north. 18 This could lead to new fishing opportunities and economic growth in that region.

For more specific examples of climate change impacts in your region, please see the National Climate Assessment .

Many U.S. industries depend on the ocean. The marine economy generated over $665 billion in sales in 2019, with tourism and recreation, including recreational fishing, making up more than one-third of that total. 20 The marine economy also generated $397 billion in gross domestic product (GDP), which was 1.9% of the national GDP. 21

Commercial fisheries are an important contributor to the economy. In 2019, they produced 9.3 billion pounds of seafood valued at $5.5 billion. 22 Other businesses, such as grocery stores, tackle shops, and restaurants, also benefit from fishery-related products and services.

As of 2019, almost 2.4 million Americans had jobs related to the ocean in fields including fisheries, construction, tourism, real estate, food service, and transportation. 23 The Atlantic and Pacific Oceans are both key trade channels for importing and exporting goods. 24 The United States also extracts oil, gas, sand, and gravel from the ocean.

The ocean also provides many benefits that are harder to measure in economic terms. These are called ecosystem services . Carbon storage, water filtration, and shoreline protection are just a few of the many ecosystem services that the ocean provides.    

Healthy oceans provide Americans with food and employment and are important to cultural traditions. Climate change leaves communities that depend on the ocean vulnerable to hardship. Many fishing communities already experience high rates of poverty. 25 Unstable fish populations and market pricing can hurt fishing communities’ earnings. 26 This is especially true if a community depends on a single species for their livelihoods.

Ocean health is a cornerstone of many Indigenous cultures . Native American, Pacific Islander, and Alaska Native communities often practice subsistence fishing. 27 , 28 Fluctuating fish populations can lead to food insecurity for rural Alaskan villages, where many people depend on locally caught fish for a large portion of their diet. 29 For example, populations of Chinook and chum salmon hit record lows in 2021, leading to the closure of subsistence salmon fishing for much of the year. 30 The number of shellfish, another important part of subsistence diets, has also been declining due to ocean acidification. 31

Climate change also affects Indigenous people culturally. Gathering and preparing food provide social, spiritual, and economic benefits for Indigenous communities. 32 , 33 Disruptions to subsistence practices have negative health outcomes such as anxiety disorders and feelings of isolation. 34  

We can help reduce the impact of climate change on the marine environment in many ways, including the following: 

• Adapt fishery management. Fishing professionals and government officials can help people adapt to climate change by changing policies and practices to avoid overfishing and maintain healthy marine ecosystems. 
• Diversify fisheries. Aquaculture , or seafood farming, helps build resilience against climate change. 
• Reduce energy use. Everyone can take steps to lower carbon emissions , which can help reduce ocean warming and acidification. 
• Shop sustainably. Plan your meals with sustainably harvested seafood to keep ocean ecosystems healthy. These are fish and shellfish that have been caught using sustainable techniques and management practices. 
• Recreate responsibly. Help protect coral reefs . When boating, be careful not to let anchors damage coral reefs or seagrass beds. Never touch coral reefs when diving or snorkeling. Also avoid using sunscreens containing chemicals that can harm marine life.

See additional actions you can take, as well as steps that companies can take, on EPA’s What You Can Do About Climate Change page.

Related Climate Indicators

Learn more about some of the key indicators of climate change related to this sector from EPA’s Climate Change Indicators in the United States :

• Ocean Acidity
• Sea Surface Temperatures
• Marine Species Distribution
• Atmospheric Concentrations of Greenhouse Gases
• Climate Change Indicators in the United States: Oceans.
• National Oceanic and Atmospheric Administration (NOAA) Fisheries . Manages fisheries around the nation and provides resources to professional and recreational fishers.
• National Estuary Program . Provides information about the location and function of U.S. estuaries, where freshwaters mix with saltwater from the sea.
• Ocean and Coastal Acidification . Explains the causes and effects of acidification.
• Fish and Shellfish Advisories . Provides information on safe eating guidelines and explains how advisories are formed.
• NOAA: Gulf of Mexico Hypoxia Watch . Monitors levels of dissolved oxygen in the waters of the Gulf of Mexico. 

1  National Oceanic and Atmospheric Administration (NOAA). (2017). Marine life counts: The U.S. marine biodiversity observation network . National Ocean Service. NOAA Ocean Podcast: Episode 35. Retrieved 3/7/2022.

2  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 369.

3  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 358.

4  Moore, C., et al. (2021). Estimating the economic impacts of climate change on 16 major U.S. fisheries . Climate Change Economics, 12(1).

5  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 367.

6  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 362.

7  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 357.

8  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 360.

9  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 355.

10  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 372.

11  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 366.

12  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 361.

13  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 355.

14  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 362.

15  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 362.

16  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 366.

17  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 366.

18  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 362.

19  NOAA. (N.D.). Northeast fish and shellfish climate vulnerability assessment . NOAA Fisheries. Retrieved 3/18/2022.

20  U.S. Department of Commerce. (2021). Marine economy satellite account, 2014–2019 . Bureau of Economic Analysis. Retrieved 3/7/2022. 

21  U.S. Department of Commerce. (2021). Marine economy satellite account, 2014–2019 . Bureau of Economic Analysis. Retrieved 3/7/2022. 

22  NOAA Fisheries. (2019). Fisheries of the United States . Retrieved 5/11/2022. 

23  U.S. Department of Commerce. (2021). Marine economy satellite account, 2014–2019 . Bureau of Economic Analysis. Retrieved 2/7/2022. 

24  U.S. Department of Commerce. (N.D.). Maritime services . International Trade Administration. Retrieved 3/18/2022. 

25  NOAA. (2021). Social indicators for coastal communities . NOAA Fisheries. Retrieved 3/18/2022.

26  NOAA. (2021). Social indicators for coastal communities . NOAA Fisheries. Retrieved 3/18/2022.

27  U.S. Environmental Protection Agency (EPA). (2016). Guidance for conducting fish consumption surveys . Retrieved 3/7/2022.

28   EPA. (2016). Technical guidance for assessing environmental justice in regulatory analysis . Retrieved 3/7/2022.

29  Markon, C., et al. (2018). Ch. 26: Alaska . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 1205.

30  Alaska Department of Fish and Game. (2021). 2021 Yukon River summer season summary . Retrieved 3/18/2022. 

31  Markon, C., et al. (2018). Ch. 26: Alaska . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 1205.

32  Jantarasami, L.C., et al. (2018). Ch. 15: Tribes and indigenous peoples . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 582. 

33  Markon, C., et al. (2018). Ch. 26: Alaska . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 1205.

34  Jantarasami, L.C., et al. (2018). Ch. 15: Tribes and indigenous peoples . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 582. 

35  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 366.

36  Pershing, A.J., et al. (2018). Ch. 9: Oceans and marine resources . In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II . U.S. Global Change Research Program, Washington, DC, p. 363.

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Protecting the ocean is key to fighting climate change

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Stay up to date:, restoring ocean life.

• Currently, about 7% of the ocean is protected and CO2 emissions from bottom trawlers are akin to global aviation industry.
• New study reveals that to preserve marine life, increase food supplies and reduce CO2 emissions we must save at least 30% of the ocean.
• We outline four key areas that could help prevent the collapse of this ecosystem and avert a climate disaster.

2021 ought to be the “super year” for nature, where we collectively agree on how to deal with the greatest risk to humanity: we have become totally out of balance with nature. But there is a solution that is scientifically proven and cost-effective, and new research has found a way forward.

We’ve already lost 60% of terrestrial wildlife and 90% of the big ocean fish. Approximately 96% of all mammals on earth are humans and our domesticated livestock. Only 4% is everything else, from bears to elephants to tigers. We now risk the extinction of 1 million species during this century. Losing these species and all the goods and services they give us would mean the collapse of our life support system and everything we care about and need to survive: our food, our health, our economy, our security – everything .

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5 critical things we need to do to protect our ocean , the ocean is changing faster than ever. investing in nature can help protect it.

The good news is that we can still avert this catastrophe. In October this year, the world’s countries will meet at the UN Biodiversity Conference in Kunming, China, to agree on how much space we humans are willing to give up to all the rest of the species with whom we share this planet. The ocean must become a more central character in this change. It is a victim of climate change – due to ocean warming and acidification – but it can also be a big part of the solution. However, despite the serious threats to our ocean life support system, presently only 7% of the global ocean is under some kind of protection. How much more do we need to protect?

Some argue that we cannot protect more ocean because soon we will need to feed 10 billion people – they recommend we need to develop a new “blue economy”. But this is a myth. We cannot take more fish out of the ocean by fishing more. And we cannot have a blue economy from a dead ocean. Already over three-quarters of fish stocks are fished beyond sustainable limits, and The World Bank suggests that we can only catch more fish if we cut almost in half the effort the world spends fishing.

Our ocean covers 70% of the world’s surface and accounts for 80% of the planet’s biodiversity. We can't have a healthy future without a healthy ocean - but it's more vulnerable than ever because of climate change and pollution.

Tackling the grave threats to our ocean means working with leaders across sectors, from business to government to academia.

The World Economic Forum convenes the Friends of Ocean Action , a coalition of global leaders from a wide range of sectors who are working together to protect the seas. From a programme to scale blue carbon benefits through coordinated action with governments to unlock finance, strengthen and empower local communities, to a global partnership to catalyze science-based actions towards healthy and sustainable blue food value chains, the Forum’s Ocean Action Agenda is pushing for new solutions and aiming to support 1000 Ocean Startups by 2030 that are creating a wave of innovation to address global challenges.

The Forum's Ocean Action Agenda also works closely with our industry partners, such as offshore wind developers and ports, to support them in their transitions towards a nature positive and net zero future. Climate change is an inextricable part of the threat to our ocean, with rising temperatures and acidification disrupting fragile ecosystems. The Forum runs a number of initiatives to support the shift to a low-carbon economy , including hosting the Alliance of CEO Climate Leaders, who have cut emissions in their companies by 9%.

Is your organization interested in working with the World Economic Forum? Find out more here .

This perceived trade-off between extraction and protection is what prompted me to assemble a team of colleagues a couple years ago, to calculate how much of the ocean we need to protect, and which areas should be protected to maximize benefits for people and planet. The science is clear: the more biodiversity there is, the more benefits the natural world gives us. So, we need to protect whatever wild is left, and restore what we have degraded.

On land, restoration can be accelerated by replanting native vegetation or reintroducing large animals, but in the ocean, the fastest way to restore balance is to let the ocean do it itself. When we close areas to fishing and other damaging activities, the biomass of fish increases on average six-fold within a decade. Thus, our team developed a new mapping tool to identify the areas that, if fully protected from damaging activities, would give us the greatest gains. Our main findings are the following:

1) More protection = more food

If we protect the right areas in the ocean, they would help replenish the surrounding areas so that the global fishing catch would increase globally up to over 8 million metric tonnes (or 10% of the global catch in 2018). So there goes the myth that we cannot protect more because we need to catch more fish. It is, in fact, conservation that will result in more fish.

2) More protection = less ocean carbon emissions

Our research found that the seafloor, which we thought was the largest carbon store on our planet, has been turned into a source of carbon emissions. Bottom trawlers plow around 5 million km 2 of the seafloor (an area over twice the size of Greenland) every year with huge and heavy nets, disturbing the sediment and the carbon in it. Some of that carbon, when disturbed and resuspended in the water, turns into carbon dioxide – a greenhouse house that can stay in the air for 1,000 years.

The most shocking finding was that CO2 emissions from bottom trawling are similar to those of global aviation. There is a huge opportunity here, to protect the seafloor and precious ecosystems from bottom trawling, and at the same time reduce massive carbon emissions. The carbon that would not be emitted year after year could be sold by countries as carbon credits, and that capital could then be used to finance ocean protection.

3) We must protect at least 30% of the ocean

Our research found that, no matter how we value marine life vs food vs climate, we must protect at least 30% of the global ocean. We would protect less than that only if humanity decided that marine biodiversity was something we did not want – which we know is suicidal. Identifying which areas to protect depends on how countries value each of biodiversity, fisheries and climate change mitigation. Our new mapping tool allows stakeholders to give different values to the different objectives and calculate multiple benefits. Every option yields a different map. But no matter how one values these three areas, the vast majority of the priorities for ocean conservation are located within countries’ 200 mile exclusive economic zones.

4) Global collaboration is more efficient

Importantly, our new research shows that if countries protect areas based on global priorities, it would take less than half of ocean area to achieve the desired benefits than if every country only cares about their national priorities. Going alone would take more effort and be costlier.

Our results support the global target of at least 30% of the ocean to be protected by 2030 that is being proposed by over 50 nations and the European Commission as one of the main targets for the Kunming nature agreement later this year. If we give the ocean the space it needs, it will feed us, boost food security and help us avert climate catastrophe. That is the blue economy we need, the economy of a living ocean.

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The Science of Climate Change Explained: Facts, Evidence and Proof

Definitive answers to the big questions.

Credit... Photo Illustration by Andrea D'Aquino

Supported by

By Julia Rosen

Ms. Rosen is a journalist with a Ph.D. in geology. Her research involved studying ice cores from Greenland and Antarctica to understand past climate changes.

• Published April 19, 2021 Updated Nov. 6, 2021

The science of climate change is more solid and widely agreed upon than you might think. But the scope of the topic, as well as rampant disinformation, can make it hard to separate fact from fiction. Here, we’ve done our best to present you with not only the most accurate scientific information, but also an explanation of how we know it.

How do we know climate change is really happening?

How much agreement is there among scientists about climate change, do we really only have 150 years of climate data how is that enough to tell us about centuries of change, how do we know climate change is caused by humans, since greenhouse gases occur naturally, how do we know they’re causing earth’s temperature to rise, why should we be worried that the planet has warmed 2°f since the 1800s, is climate change a part of the planet’s natural warming and cooling cycles, how do we know global warming is not because of the sun or volcanoes, how can winters and certain places be getting colder if the planet is warming, wildfires and bad weather have always happened. how do we know there’s a connection to climate change, how bad are the effects of climate change going to be, what will it cost to do something about climate change, versus doing nothing.

Climate change is often cast as a prediction made by complicated computer models. But the scientific basis for climate change is much broader, and models are actually only one part of it (and, for what it’s worth, they’re surprisingly accurate ).

For more than a century , scientists have understood the basic physics behind why greenhouse gases like carbon dioxide cause warming. These gases make up just a small fraction of the atmosphere but exert outsized control on Earth’s climate by trapping some of the planet’s heat before it escapes into space. This greenhouse effect is important: It’s why a planet so far from the sun has liquid water and life!

However, during the Industrial Revolution, people started burning coal and other fossil fuels to power factories, smelters and steam engines, which added more greenhouse gases to the atmosphere. Ever since, human activities have been heating the planet.

We know this is true thanks to an overwhelming body of evidence that begins with temperature measurements taken at weather stations and on ships starting in the mid-1800s. Later, scientists began tracking surface temperatures with satellites and looking for clues about climate change in geologic records. Together, these data all tell the same story: Earth is getting hotter.

Average global temperatures have increased by 2.2 degrees Fahrenheit, or 1.2 degrees Celsius, since 1880, with the greatest changes happening in the late 20th century. Land areas have warmed more than the sea surface and the Arctic has warmed the most — by more than 4 degrees Fahrenheit just since the 1960s. Temperature extremes have also shifted. In the United States, daily record highs now outnumber record lows two-to-one.

Where it was cooler or warmer in 2020 compared with the middle of the 20th century

This warming is unprecedented in recent geologic history. A famous illustration, first published in 1998 and often called the hockey-stick graph, shows how temperatures remained fairly flat for centuries (the shaft of the stick) before turning sharply upward (the blade). It’s based on data from tree rings, ice cores and other natural indicators. And the basic picture , which has withstood decades of scrutiny from climate scientists and contrarians alike, shows that Earth is hotter today than it’s been in at least 1,000 years, and probably much longer.

In fact, surface temperatures actually mask the true scale of climate change, because the ocean has absorbed 90 percent of the heat trapped by greenhouse gases . Measurements collected over the last six decades by oceanographic expeditions and networks of floating instruments show that every layer of the ocean is warming up. According to one study , the ocean has absorbed as much heat between 1997 and 2015 as it did in the previous 130 years.

We also know that climate change is happening because we see the effects everywhere. Ice sheets and glaciers are shrinking while sea levels are rising. Arctic sea ice is disappearing. In the spring, snow melts sooner and plants flower earlier. Animals are moving to higher elevations and latitudes to find cooler conditions. And droughts, floods and wildfires have all gotten more extreme. Models predicted many of these changes, but observations show they are now coming to pass.

Back to top .

There’s no denying that scientists love a good, old-fashioned argument. But when it comes to climate change, there is virtually no debate: Numerous studies have found that more than 90 percent of scientists who study Earth’s climate agree that the planet is warming and that humans are the primary cause. Most major scientific bodies, from NASA to the World Meteorological Organization , endorse this view. That’s an astounding level of consensus given the contrarian, competitive nature of the scientific enterprise, where questions like what killed the dinosaurs remain bitterly contested .

Scientific agreement about climate change started to emerge in the late 1980s, when the influence of human-caused warming began to rise above natural climate variability. By 1991, two-thirds of earth and atmospheric scientists surveyed for an early consensus study said that they accepted the idea of anthropogenic global warming. And by 1995, the Intergovernmental Panel on Climate Change, a famously conservative body that periodically takes stock of the state of scientific knowledge, concluded that “the balance of evidence suggests that there is a discernible human influence on global climate.” Currently, more than 97 percent of publishing climate scientists agree on the existence and cause of climate change (as does nearly 60 percent of the general population of the United States).

So where did we get the idea that there’s still debate about climate change? A lot of it came from coordinated messaging campaigns by companies and politicians that opposed climate action. Many pushed the narrative that scientists still hadn’t made up their minds about climate change, even though that was misleading. Frank Luntz, a Republican consultant, explained the rationale in an infamous 2002 memo to conservative lawmakers: “Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly,” he wrote. Questioning consensus remains a common talking point today, and the 97 percent figure has become something of a lightning rod .

To bolster the falsehood of lingering scientific doubt, some people have pointed to things like the Global Warming Petition Project, which urged the United States government to reject the Kyoto Protocol of 1997, an early international climate agreement. The petition proclaimed that climate change wasn’t happening, and even if it were, it wouldn’t be bad for humanity. Since 1998, more than 30,000 people with science degrees have signed it. However, nearly 90 percent of them studied something other than Earth, atmospheric or environmental science, and the signatories included just 39 climatologists. Most were engineers, doctors, and others whose training had little to do with the physics of the climate system.

A few well-known researchers remain opposed to the scientific consensus. Some, like Willie Soon, a researcher affiliated with the Harvard-Smithsonian Center for Astrophysics, have ties to the fossil fuel industry . Others do not, but their assertions have not held up under the weight of evidence. At least one prominent skeptic, the physicist Richard Muller, changed his mind after reassessing historical temperature data as part of the Berkeley Earth project. His team’s findings essentially confirmed the results he had set out to investigate, and he came away firmly convinced that human activities were warming the planet. “Call me a converted skeptic,” he wrote in an Op-Ed for the Times in 2012.

Mr. Luntz, the Republican pollster, has also reversed his position on climate change and now advises politicians on how to motivate climate action.

A final note on uncertainty: Denialists often use it as evidence that climate science isn’t settled. However, in science, uncertainty doesn’t imply a lack of knowledge. Rather, it’s a measure of how well something is known. In the case of climate change, scientists have found a range of possible future changes in temperature, precipitation and other important variables — which will depend largely on how quickly we reduce emissions. But uncertainty does not undermine their confidence that climate change is real and that people are causing it.

Earth’s climate is inherently variable. Some years are hot and others are cold, some decades bring more hurricanes than others, some ancient droughts spanned the better part of centuries. Glacial cycles operate over many millenniums. So how can scientists look at data collected over a relatively short period of time and conclude that humans are warming the planet? The answer is that the instrumental temperature data that we have tells us a lot, but it’s not all we have to go on.

Historical records stretch back to the 1880s (and often before), when people began to regularly measure temperatures at weather stations and on ships as they traversed the world’s oceans. These data show a clear warming trend during the 20th century.

Global average temperature compared with the middle of the 20th century

+0.75°C

–0.25°

Some have questioned whether these records could be skewed, for instance, by the fact that a disproportionate number of weather stations are near cities, which tend to be hotter than surrounding areas as a result of the so-called urban heat island effect. However, researchers regularly correct for these potential biases when reconstructing global temperatures. In addition, warming is corroborated by independent data like satellite observations, which cover the whole planet, and other ways of measuring temperature changes.

Much has also been made of the small dips and pauses that punctuate the rising temperature trend of the last 150 years. But these are just the result of natural climate variability or other human activities that temporarily counteract greenhouse warming. For instance, in the mid-1900s, internal climate dynamics and light-blocking pollution from coal-fired power plants halted global warming for a few decades. (Eventually, rising greenhouse gases and pollution-control laws caused the planet to start heating up again.) Likewise, the so-called warming hiatus of the 2000s was partly a result of natural climate variability that allowed more heat to enter the ocean rather than warm the atmosphere. The years since have been the hottest on record .

Still, could the entire 20th century just be one big natural climate wiggle? To address that question, we can look at other kinds of data that give a longer perspective. Researchers have used geologic records like tree rings, ice cores, corals and sediments that preserve information about prehistoric climates to extend the climate record. The resulting picture of global temperature change is basically flat for centuries, then turns sharply upward over the last 150 years. It has been a target of climate denialists for decades. However, study after study has confirmed the results , which show that the planet hasn’t been this hot in at least 1,000 years, and probably longer.

Scientists have studied past climate changes to understand the factors that can cause the planet to warm or cool. The big ones are changes in solar energy, ocean circulation, volcanic activity and the amount of greenhouse gases in the atmosphere. And they have each played a role at times.

For example, 300 years ago, a combination of reduced solar output and increased volcanic activity cooled parts of the planet enough that Londoners regularly ice skated on the Thames . About 12,000 years ago, major changes in Atlantic circulation plunged the Northern Hemisphere into a frigid state. And 56 million years ago, a giant burst of greenhouse gases, from volcanic activity or vast deposits of methane (or both), abruptly warmed the planet by at least 9 degrees Fahrenheit, scrambling the climate, choking the oceans and triggering mass extinctions.

In trying to determine the cause of current climate changes, scientists have looked at all of these factors . The first three have varied a bit over the last few centuries and they have quite likely had modest effects on climate , particularly before 1950. But they cannot account for the planet’s rapidly rising temperature, especially in the second half of the 20th century, when solar output actually declined and volcanic eruptions exerted a cooling effect.

That warming is best explained by rising greenhouse gas concentrations . Greenhouse gases have a powerful effect on climate (see the next question for why). And since the Industrial Revolution, humans have been adding more of them to the atmosphere, primarily by extracting and burning fossil fuels like coal, oil and gas, which releases carbon dioxide.

Bubbles of ancient air trapped in ice show that, before about 1750, the concentration of carbon dioxide in the atmosphere was roughly 280 parts per million. It began to rise slowly and crossed the 300 p.p.m. threshold around 1900. CO2 levels then accelerated as cars and electricity became big parts of modern life, recently topping 420 p.p.m . The concentration of methane, the second most important greenhouse gas, has more than doubled. We’re now emitting carbon much faster than it was released 56 million years ago .

30 billion metric tons

Carbon dioxide emitted worldwide 1850-2017

Rest of world

Other developed

European Union

Developed economies

Other countries

United States

E.U. and U.K.

These rapid increases in greenhouse gases have caused the climate to warm abruptly. In fact, climate models suggest that greenhouse warming can explain virtually all of the temperature change since 1950. According to the most recent report by the Intergovernmental Panel on Climate Change, which assesses published scientific literature, natural drivers and internal climate variability can only explain a small fraction of late-20th century warming.

Another study put it this way: The odds of current warming occurring without anthropogenic greenhouse gas emissions are less than 1 in 100,000 .

But greenhouse gases aren’t the only climate-altering compounds people put into the air. Burning fossil fuels also produces particulate pollution that reflects sunlight and cools the planet. Scientists estimate that this pollution has masked up to half of the greenhouse warming we would have otherwise experienced.

Greenhouse gases like water vapor and carbon dioxide serve an important role in the climate. Without them, Earth would be far too cold to maintain liquid water and humans would not exist!

Here’s how it works: the planet’s temperature is basically a function of the energy the Earth absorbs from the sun (which heats it up) and the energy Earth emits to space as infrared radiation (which cools it down). Because of their molecular structure, greenhouse gases temporarily absorb some of that outgoing infrared radiation and then re-emit it in all directions, sending some of that energy back toward the surface and heating the planet . Scientists have understood this process since the 1850s .

Greenhouse gas concentrations have varied naturally in the past. Over millions of years, atmospheric CO2 levels have changed depending on how much of the gas volcanoes belched into the air and how much got removed through geologic processes. On time scales of hundreds to thousands of years, concentrations have changed as carbon has cycled between the ocean, soil and air.

Today, however, we are the ones causing CO2 levels to increase at an unprecedented pace by taking ancient carbon from geologic deposits of fossil fuels and putting it into the atmosphere when we burn them. Since 1750, carbon dioxide concentrations have increased by almost 50 percent. Methane and nitrous oxide, other important anthropogenic greenhouse gases that are released mainly by agricultural activities, have also spiked over the last 250 years.

We know based on the physics described above that this should cause the climate to warm. We also see certain telltale “fingerprints” of greenhouse warming. For example, nights are warming even faster than days because greenhouse gases don’t go away when the sun sets. And upper layers of the atmosphere have actually cooled, because more energy is being trapped by greenhouse gases in the lower atmosphere.

We also know that we are the cause of rising greenhouse gas concentrations — and not just because we can measure the CO2 coming out of tailpipes and smokestacks. We can see it in the chemical signature of the carbon in CO2.

Carbon comes in three different masses: 12, 13 and 14. Things made of organic matter (including fossil fuels) tend to have relatively less carbon-13. Volcanoes tend to produce CO2 with relatively more carbon-13. And over the last century, the carbon in atmospheric CO2 has gotten lighter, pointing to an organic source.

We can tell it’s old organic matter by looking for carbon-14, which is radioactive and decays over time. Fossil fuels are too ancient to have any carbon-14 left in them, so if they were behind rising CO2 levels, you would expect the amount of carbon-14 in the atmosphere to drop, which is exactly what the data show .

It’s important to note that water vapor is the most abundant greenhouse gas in the atmosphere. However, it does not cause warming; instead it responds to it . That’s because warmer air holds more moisture, which creates a snowball effect in which human-caused warming allows the atmosphere to hold more water vapor and further amplifies climate change. This so-called feedback cycle has doubled the warming caused by anthropogenic greenhouse gas emissions.

A common source of confusion when it comes to climate change is the difference between weather and climate. Weather is the constantly changing set of meteorological conditions that we experience when we step outside, whereas climate is the long-term average of those conditions, usually calculated over a 30-year period. Or, as some say: Weather is your mood and climate is your personality.

So while 2 degrees Fahrenheit doesn’t represent a big change in the weather, it’s a huge change in climate. As we’ve already seen, it’s enough to melt ice and raise sea levels, to shift rainfall patterns around the world and to reorganize ecosystems, sending animals scurrying toward cooler habitats and killing trees by the millions.

It’s also important to remember that two degrees represents the global average, and many parts of the world have already warmed by more than that. For example, land areas have warmed about twice as much as the sea surface. And the Arctic has warmed by about 5 degrees. That’s because the loss of snow and ice at high latitudes allows the ground to absorb more energy, causing additional heating on top of greenhouse warming.

Relatively small long-term changes in climate averages also shift extremes in significant ways. For instance, heat waves have always happened, but they have shattered records in recent years. In June of 2020, a town in Siberia registered temperatures of 100 degrees . And in Australia, meteorologists have added a new color to their weather maps to show areas where temperatures exceed 125 degrees. Rising sea levels have also increased the risk of flooding because of storm surges and high tides. These are the foreshocks of climate change.

And we are in for more changes in the future — up to 9 degrees Fahrenheit of average global warming by the end of the century, in the worst-case scenario . For reference, the difference in global average temperatures between now and the peak of the last ice age, when ice sheets covered large parts of North America and Europe, is about 11 degrees Fahrenheit.

Under the Paris Climate Agreement, which President Biden recently rejoined, countries have agreed to try to limit total warming to between 1.5 and 2 degrees Celsius, or 2.7 and 3.6 degrees Fahrenheit, since preindustrial times. And even this narrow range has huge implications . According to scientific studies, the difference between 2.7 and 3.6 degrees Fahrenheit will very likely mean the difference between coral reefs hanging on or going extinct, and between summer sea ice persisting in the Arctic or disappearing completely. It will also determine how many millions of people suffer from water scarcity and crop failures, and how many are driven from their homes by rising seas. In other words, one degree Fahrenheit makes a world of difference.

Earth’s climate has always changed. Hundreds of millions of years ago, the entire planet froze . Fifty million years ago, alligators lived in what we now call the Arctic . And for the last 2.6 million years, the planet has cycled between ice ages when the planet was up to 11 degrees cooler and ice sheets covered much of North America and Europe, and milder interglacial periods like the one we’re in now.

Climate denialists often point to these natural climate changes as a way to cast doubt on the idea that humans are causing climate to change today. However, that argument rests on a logical fallacy. It’s like “seeing a murdered body and concluding that people have died of natural causes in the past, so the murder victim must also have died of natural causes,” a team of social scientists wrote in The Debunking Handbook , which explains the misinformation strategies behind many climate myths.

Indeed, we know that different mechanisms caused the climate to change in the past. Glacial cycles, for example, were triggered by periodic variations in Earth’s orbit , which take place over tens of thousands of years and change how solar energy gets distributed around the globe and across the seasons.

These orbital variations don’t affect the planet’s temperature much on their own. But they set off a cascade of other changes in the climate system; for instance, growing or melting vast Northern Hemisphere ice sheets and altering ocean circulation. These changes, in turn, affect climate by altering the amount of snow and ice, which reflect sunlight, and by changing greenhouse gas concentrations. This is actually part of how we know that greenhouse gases have the ability to significantly affect Earth’s temperature.

For at least the last 800,000 years , atmospheric CO2 concentrations oscillated between about 180 parts per million during ice ages and about 280 p.p.m. during warmer periods, as carbon moved between oceans, forests, soils and the atmosphere. These changes occurred in lock step with global temperatures, and are a major reason the entire planet warmed and cooled during glacial cycles, not just the frozen poles.

Today, however, CO2 levels have soared to 420 p.p.m. — the highest they’ve been in at least three million years . The concentration of CO2 is also increasing about 100 times faster than it did at the end of the last ice age. This suggests something else is going on, and we know what it is: Since the Industrial Revolution, humans have been burning fossil fuels and releasing greenhouse gases that are heating the planet now (see Question 5 for more details on how we know this, and Questions 4 and 8 for how we know that other natural forces aren’t to blame).

Over the next century or two, societies and ecosystems will experience the consequences of this climate change. But our emissions will have even more lasting geologic impacts: According to some studies, greenhouse gas levels may have already warmed the planet enough to delay the onset of the next glacial cycle for at least an additional 50,000 years.

The sun is the ultimate source of energy in Earth’s climate system, so it’s a natural candidate for causing climate change. And solar activity has certainly changed over time. We know from satellite measurements and other astronomical observations that the sun’s output changes on 11-year cycles. Geologic records and sunspot numbers, which astronomers have tracked for centuries, also show long-term variations in the sun’s activity, including some exceptionally quiet periods in the late 1600s and early 1800s.

We know that, from 1900 until the 1950s, solar irradiance increased. And studies suggest that this had a modest effect on early 20th century climate, explaining up to 10 percent of the warming that’s occurred since the late 1800s. However, in the second half of the century, when the most warming occurred, solar activity actually declined . This disparity is one of the main reasons we know that the sun is not the driving force behind climate change.

Another reason we know that solar activity hasn’t caused recent warming is that, if it had, all the layers of the atmosphere should be heating up. Instead, data show that the upper atmosphere has actually cooled in recent decades — a hallmark of greenhouse warming .

So how about volcanoes? Eruptions cool the planet by injecting ash and aerosol particles into the atmosphere that reflect sunlight. We’ve observed this effect in the years following large eruptions. There are also some notable historical examples, like when Iceland’s Laki volcano erupted in 1783, causing widespread crop failures in Europe and beyond, and the “ year without a summer ,” which followed the 1815 eruption of Mount Tambora in Indonesia.

Since volcanoes mainly act as climate coolers, they can’t really explain recent warming. However, scientists say that they may also have contributed slightly to rising temperatures in the early 20th century. That’s because there were several large eruptions in the late 1800s that cooled the planet, followed by a few decades with no major volcanic events when warming caught up. During the second half of the 20th century, though, several big eruptions occurred as the planet was heating up fast. If anything, they temporarily masked some amount of human-caused warming.

The second way volcanoes can impact climate is by emitting carbon dioxide. This is important on time scales of millions of years — it’s what keeps the planet habitable (see Question 5 for more on the greenhouse effect). But by comparison to modern anthropogenic emissions, even big eruptions like Krakatoa and Mount St. Helens are just a drop in the bucket. After all, they last only a few hours or days, while we burn fossil fuels 24-7. Studies suggest that, today, volcanoes account for 1 to 2 percent of total CO2 emissions.

When a big snowstorm hits the United States, climate denialists can try to cite it as proof that climate change isn’t happening. In 2015, Senator James Inhofe, an Oklahoma Republican, famously lobbed a snowball in the Senate as he denounced climate science. But these events don’t actually disprove climate change.

While there have been some memorable storms in recent years, winters are actually warming across the world. In the United States, average temperatures in December, January and February have increased by about 2.5 degrees this century.

On the flip side, record cold days are becoming less common than record warm days. In the United States, record highs now outnumber record lows two-to-one . And ever-smaller areas of the country experience extremely cold winter temperatures . (The same trends are happening globally.)

So what’s with the blizzards? Weather always varies, so it’s no surprise that we still have severe winter storms even as average temperatures rise. However, some studies suggest that climate change may be to blame. One possibility is that rapid Arctic warming has affected atmospheric circulation, including the fast-flowing, high-altitude air that usually swirls over the North Pole (a.k.a. the Polar Vortex ). Some studies suggest that these changes are bringing more frigid temperatures to lower latitudes and causing weather systems to stall , allowing storms to produce more snowfall. This may explain what we’ve experienced in the U.S. over the past few decades, as well as a wintertime cooling trend in Siberia , although exactly how the Arctic affects global weather remains a topic of ongoing scientific debate .

Climate change may also explain the apparent paradox behind some of the other places on Earth that haven’t warmed much. For instance, a splotch of water in the North Atlantic has cooled in recent years, and scientists say they suspect that may be because ocean circulation is slowing as a result of freshwater streaming off a melting Greenland . If this circulation grinds almost to a halt, as it’s done in the geologic past, it would alter weather patterns around the world.

Not all cold weather stems from some counterintuitive consequence of climate change. But it’s a good reminder that Earth’s climate system is complex and chaotic, so the effects of human-caused changes will play out differently in different places. That’s why “global warming” is a bit of an oversimplification. Instead, some scientists have suggested that the phenomenon of human-caused climate change would more aptly be called “ global weirding .”

Extreme weather and natural disasters are part of life on Earth — just ask the dinosaurs. But there is good evidence that climate change has increased the frequency and severity of certain phenomena like heat waves, droughts and floods. Recent research has also allowed scientists to identify the influence of climate change on specific events.

Let’s start with heat waves . Studies show that stretches of abnormally high temperatures now happen about five times more often than they would without climate change, and they last longer, too. Climate models project that, by the 2040s, heat waves will be about 12 times more frequent. And that’s concerning since extreme heat often causes increased hospitalizations and deaths, particularly among older people and those with underlying health conditions. In the summer of 2003, for example, a heat wave caused an estimated 70,000 excess deaths across Europe. (Human-caused warming amplified the death toll .)

Climate change has also exacerbated droughts , primarily by increasing evaporation. Droughts occur naturally because of random climate variability and factors like whether El Niño or La Niña conditions prevail in the tropical Pacific. But some researchers have found evidence that greenhouse warming has been affecting droughts since even before the Dust Bowl . And it continues to do so today. According to one analysis , the drought that afflicted the American Southwest from 2000 to 2018 was almost 50 percent more severe because of climate change. It was the worst drought the region had experienced in more than 1,000 years.

Rising temperatures have also increased the intensity of heavy precipitation events and the flooding that often follows. For example, studies have found that, because warmer air holds more moisture, Hurricane Harvey, which struck Houston in 2017, dropped between 15 and 40 percent more rainfall than it would have without climate change.

It’s still unclear whether climate change is changing the overall frequency of hurricanes, but it is making them stronger . And warming appears to favor certain kinds of weather patterns, like the “ Midwest Water Hose ” events that caused devastating flooding across the Midwest in 2019 .

It’s important to remember that in most natural disasters, there are multiple factors at play. For instance, the 2019 Midwest floods occurred after a recent cold snap had frozen the ground solid, preventing the soil from absorbing rainwater and increasing runoff into the Missouri and Mississippi Rivers. These waterways have also been reshaped by levees and other forms of river engineering, some of which failed in the floods.

Wildfires are another phenomenon with multiple causes. In many places, fire risk has increased because humans have aggressively fought natural fires and prevented Indigenous peoples from carrying out traditional burning practices. This has allowed fuel to accumulate that makes current fires worse .

However, climate change still plays a major role by heating and drying forests, turning them into tinderboxes. Studies show that warming is the driving factor behind the recent increases in wildfires; one analysis found that climate change is responsible for doubling the area burned across the American West between 1984 and 2015. And researchers say that warming will only make fires bigger and more dangerous in the future.

It depends on how aggressively we act to address climate change. If we continue with business as usual, by the end of the century, it will be too hot to go outside during heat waves in the Middle East and South Asia . Droughts will grip Central America, the Mediterranean and southern Africa. And many island nations and low-lying areas, from Texas to Bangladesh, will be overtaken by rising seas. Conversely, climate change could bring welcome warming and extended growing seasons to the upper Midwest , Canada, the Nordic countries and Russia . Farther north, however, the loss of snow, ice and permafrost will upend the traditions of Indigenous peoples and threaten infrastructure.

It’s complicated, but the underlying message is simple: unchecked climate change will likely exacerbate existing inequalities . At a national level, poorer countries will be hit hardest, even though they have historically emitted only a fraction of the greenhouse gases that cause warming. That’s because many less developed countries tend to be in tropical regions where additional warming will make the climate increasingly intolerable for humans and crops. These nations also often have greater vulnerabilities, like large coastal populations and people living in improvised housing that is easily damaged in storms. And they have fewer resources to adapt, which will require expensive measures like redesigning cities, engineering coastlines and changing how people grow food.

Already, between 1961 and 2000, climate change appears to have harmed the economies of the poorest countries while boosting the fortunes of the wealthiest nations that have done the most to cause the problem, making the global wealth gap 25 percent bigger than it would otherwise have been. Similarly, the Global Climate Risk Index found that lower income countries — like Myanmar, Haiti and Nepal — rank high on the list of nations most affected by extreme weather between 1999 and 2018. Climate change has also contributed to increased human migration, which is expected to increase significantly .

Even within wealthy countries, the poor and marginalized will suffer the most. People with more resources have greater buffers, like air-conditioners to keep their houses cool during dangerous heat waves, and the means to pay the resulting energy bills. They also have an easier time evacuating their homes before disasters, and recovering afterward. Lower income people have fewer of these advantages, and they are also more likely to live in hotter neighborhoods and work outdoors, where they face the brunt of climate change.

These inequalities will play out on an individual, community, and regional level. A 2017 analysis of the U.S. found that, under business as usual, the poorest one-third of counties, which are concentrated in the South, will experience damages totaling as much as 20 percent of gross domestic product, while others, mostly in the northern part of the country, will see modest economic gains. Solomon Hsiang, an economist at University of California, Berkeley, and the lead author of the study, has said that climate change “may result in the largest transfer of wealth from the poor to the rich in the country’s history.”

Even the climate “winners” will not be immune from all climate impacts, though. Desirable locations will face an influx of migrants. And as the coronavirus pandemic has demonstrated, disasters in one place quickly ripple across our globalized economy. For instance, scientists expect climate change to increase the odds of multiple crop failures occurring at the same time in different places, throwing the world into a food crisis .

On top of that, warmer weather is aiding the spread of infectious diseases and the vectors that transmit them, like ticks and mosquitoes . Research has also identified troubling correlations between rising temperatures and increased interpersonal violence , and climate change is widely recognized as a “threat multiplier” that increases the odds of larger conflicts within and between countries. In other words, climate change will bring many changes that no amount of money can stop. What could help is taking action to limit warming.

One of the most common arguments against taking aggressive action to combat climate change is that doing so will kill jobs and cripple the economy. But this implies that there’s an alternative in which we pay nothing for climate change. And unfortunately, there isn’t. In reality, not tackling climate change will cost a lot , and cause enormous human suffering and ecological damage, while transitioning to a greener economy would benefit many people and ecosystems around the world.

Let’s start with how much it will cost to address climate change. To keep warming well below 2 degrees Celsius, the goal of the Paris Climate Agreement, society will have to reach net zero greenhouse gas emissions by the middle of this century. That will require significant investments in things like renewable energy, electric cars and charging infrastructure, not to mention efforts to adapt to hotter temperatures, rising sea-levels and other unavoidable effects of current climate changes. And we’ll have to make changes fast.

Estimates of the cost vary widely. One recent study found that keeping warming to 2 degrees Celsius would require a total investment of between $4 trillion and $60 trillion, with a median estimate of $16 trillion, while keeping warming to 1.5 degrees Celsius could cost between $10 trillion and $100 trillion, with a median estimate of $30 trillion. (For reference, the entire world economy was about $88 trillion in 2019.) Other studies have found that reaching net zero will require annual investments ranging from less than 1.5 percent of global gross domestic product to as much as 4 percent . That’s a lot, but within the range of historical energy investments in countries like the U.S.

Now, let’s consider the costs of unchecked climate change, which will fall hardest on the most vulnerable. These include damage to property and infrastructure from sea-level rise and extreme weather, death and sickness linked to natural disasters, pollution and infectious disease, reduced agricultural yields and lost labor productivity because of rising temperatures, decreased water availability and increased energy costs, and species extinction and habitat destruction. Dr. Hsiang, the U.C. Berkeley economist, describes it as “death by a thousand cuts.”

As a result, climate damages are hard to quantify. Moody’s Analytics estimates that even 2 degrees Celsius of warming will cost the world $69 trillion by 2100, and economists expect the toll to keep rising with the temperature. In a recent survey , economists estimated the cost would equal 5 percent of global G.D.P. at 3 degrees Celsius of warming (our trajectory under current policies) and 10 percent for 5 degrees Celsius. Other research indicates that, if current warming trends continue, global G.D.P. per capita will decrease between 7 percent and 23 percent by the end of the century — an economic blow equivalent to multiple coronavirus pandemics every year. And some fear these are vast underestimates .

Already, studies suggest that climate change has slashed incomes in the poorest countries by as much as 30 percent and reduced global agricultural productivity by 21 percent since 1961. Extreme weather events have also racked up a large bill. In 2020, in the United States alone, climate-related disasters like hurricanes, droughts, and wildfires caused nearly $100 billion in damages to businesses, property and infrastructure, compared to an average of $18 billion per year in the 1980s.

Given the steep price of inaction, many economists say that addressing climate change is a better deal . It’s like that old saying: an ounce of prevention is worth a pound of cure. In this case, limiting warming will greatly reduce future damage and inequality caused by climate change. It will also produce so-called co-benefits, like saving one million lives every year by reducing air pollution, and millions more from eating healthier, climate-friendly diets. Some studies even find that meeting the Paris Agreement goals could create jobs and increase global G.D.P . And, of course, reining in climate change will spare many species and ecosystems upon which humans depend — and which many people believe to have their own innate value.

The challenge is that we need to reduce emissions now to avoid damages later, which requires big investments over the next few decades. And the longer we delay, the more we will pay to meet the Paris goals. One recent analysis found that reaching net-zero by 2050 would cost the U.S. almost twice as much if we waited until 2030 instead of acting now. But even if we miss the Paris target, the economics still make a strong case for climate action, because every additional degree of warming will cost us more — in dollars, and in lives.

Veronica Penney contributed reporting.

Illustration photographs by Esther Horvath, Max Whittaker, David Maurice Smith and Talia Herman for The New York Times; Esther Horvath/Alfred-Wegener-Institut

An earlier version of this article misidentified the authors of The Debunking Handbook. It was written by social scientists who study climate communication, not a team of climate scientists.

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What Is Climate Change?

Climate change is a long-term change in the average weather patterns that have come to define Earth’s local, regional and global climates. These changes have a broad range of observed effects that are synonymous with the term.

Changes observed in Earth’s climate since the mid-20th century are driven by human activities, particularly fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere, raising Earth’s average surface temperature. Natural processes, which have been overwhelmed by human activities, can also contribute to climate change, including internal variability (e.g., cyclical ocean patterns like El Niño, La Niña and the Pacific Decadal Oscillation) and external forcings (e.g., volcanic activity, changes in the Sun’s energy output , variations in Earth’s orbit ).

Scientists use observations from the ground, air, and space, along with computer models , to monitor and study past, present, and future climate change. Climate data records provide evidence of climate change key indicators, such as global land and ocean temperature increases; rising sea levels; ice loss at Earth’s poles and in mountain glaciers; frequency and severity changes in extreme weather such as hurricanes, heatwaves, wildfires, droughts, floods, and precipitation; and cloud and vegetation cover changes.

“Climate change” and “global warming” are often used interchangeably but have distinct meanings. Similarly, the terms "weather" and "climate" are sometimes confused, though they refer to events with broadly different spatial- and timescales.

What Is Global Warming?

Global warming is the long-term heating of Earth’s surface observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere. This term is not interchangeable with the term "climate change."

Since the pre-industrial period, human activities are estimated to have increased Earth’s global average temperature by about 1 degree Celsius (1.8 degrees Fahrenheit), a number that is currently increasing by more than 0.2 degrees Celsius (0.36 degrees Fahrenheit) per decade. The current warming trend is unequivocally the result of human activity since the 1950s and is proceeding at an unprecedented rate over millennia.

Weather vs. Climate

“if you don’t like the weather in new england, just wait a few minutes.” - mark twain.

Weather refers to atmospheric conditions that occur locally over short periods of time—from minutes to hours or days. Familiar examples include rain, snow, clouds, winds, floods, or thunderstorms.

Climate, on the other hand, refers to the long-term (usually at least 30 years) regional or even global average of temperature, humidity, and rainfall patterns over seasons, years, or decades.

Find Out More: A Guide to NASA’s Global Climate Change Website

This website provides a high-level overview of some of the known causes, effects and indications of global climate change:

Evidence. Brief descriptions of some of the key scientific observations that our planet is undergoing abrupt climate change.

Causes. A concise discussion of the primary climate change causes on our planet.

Effects. A look at some of the likely future effects of climate change, including U.S. regional effects.

Vital Signs. Graphs and animated time series showing real-time climate change data, including atmospheric carbon dioxide, global temperature, sea ice extent, and ice sheet volume.

Earth Minute. This fun video series explains various Earth science topics, including some climate change topics.

Other NASA Resources

Goddard Scientific Visualization Studio. An extensive collection of animated climate change and Earth science visualizations.

Sea Level Change Portal. NASA's portal for an in-depth look at the science behind sea level change.

NASA’s Earth Observatory. Satellite imagery, feature articles and scientific information about our home planet, with a focus on Earth’s climate and environmental change.

Header image is of Apusiaajik Glacier, and was taken near Kulusuk, Greenland, on Aug. 26, 2018, during NASA's Oceans Melting Greenland (OMG) field operations. Learn more here . Credit: NASA/JPL-Caltech

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Climate change.

Climate change is a long-term shift in global or regional climate patterns. Often climate change refers specifically to the rise in global temperatures from the mid-20th century to present.

Earth Science, Climatology

Fracking tower

Fracking is a controversial form of drilling that uses high-pressure liquid to create cracks in underground shale to extract natural gas and petroleum. Carbon emissions from fossils fuels like these have been linked to global warming and climate change.

Photograph by Mark Thiessen / National Geographic

Climate is sometimes mistaken for weather. But climate is different from weather because it is measured over a long period of time, whereas weather can change from day to day, or from year to year. The climate of an area includes seasonal temperature and rainfall averages, and wind patterns. Different places have different climates. A desert, for example, is referred to as an arid climate because little water falls, as rain or snow, during the year. Other types of climate include tropical climates, which are hot and humid , and temperate climates, which have warm summers and cooler winters.

Climate change is the long-term alteration of temperature and typical weather patterns in a place. Climate change could refer to a particular location or the planet as a whole. Climate change may cause weather patterns to be less predictable. These unexpected weather patterns can make it difficult to maintain and grow crops in regions that rely on farming because expected temperature and rainfall levels can no longer be relied on. Climate change has also been connected with other damaging weather events such as more frequent and more intense hurricanes, floods, downpours, and winter storms.

In polar regions, the warming global temperatures associated with climate change have meant ice sheets and glaciers are melting at an accelerated rate from season to season. This contributes to sea levels rising in different regions of the planet. Together with expanding ocean waters due to rising temperatures, the resulting rise in sea level has begun to damage coastlines as a result of increased flooding and erosion.

The cause of current climate change is largely human activity, like burning fossil fuels , like natural gas, oil, and coal. Burning these materials releases what are called greenhouse gases into Earth’s atmosphere . There, these gases trap heat from the sun’s rays inside the atmosphere causing Earth’s average temperature to rise. This rise in the planet's temperature is called global warming. The warming of the planet impacts local and regional climates. Throughout Earth's history, climate has continually changed. When occuring naturally, this is a slow process that has taken place over hundreds and thousands of years. The human influenced climate change that is happening now is occuring at a much faster rate.

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New proposals to help nasa advance knowledge of our changing climate.

Tiernan P. Doyle

Nasa headquarters.

NASA has selected four proposals for concept studies of missions to help us better understand Earth science key focus areas for the benefit of all including greenhouse gases, the ozone layer, ocean surface currents, and changes in ice and glaciers around the world.

These four investigations are part of the agency’s new Earth System Explorers Program – which conducts principal investigator-led space science missions as recommended by the National Academies of Sciences, Engineering, and Medicine 2017 Decadal Survey for Earth Science and Applications from Space. The program is designed to enable high-quality Earth system science investigations to focus on previously identified key targets. For this set of missions, NASA is prioritizing greenhouse gases as one of its target observables.

“The proposals represent another example of NASA’s holistic approach to studying our home planet,” said Nicky Fox, associate administrator, Science Mission Directorate at NASA Headquarters in Washington. “As we continue to confront our changing climate, and its impacts on humans and our environment, the need for data and scientific research could not be greater. These proposals will help us better prepare for the challenges we face today, and tomorrow.”

As the first step of a two-step selection process, each of these proposals will receive $5 million to conduct a one-year mission concept study. After the study period, NASA will choose two proposals to go forward to launch with readiness dates expected in 2030 and 2032. The total mission cost cap is $310 million for each chosen investigation, excluding the rocket and access to space, which will be provided by NASA. 

Most of what we know about our changing planet is rooted in more than 60 years of NASA’s Earth observations. NASA currently has more than two dozen Earth-observing satellites and instruments in orbit. The missions ultimately selected from this set of proposals will make their own unique contributions to this great Earth observatory – which works together to provide layers of complementary information on Earth’s oceans, land, ice, and atmosphere.

The four proposals selected for concept studies are: 

• The Stratosphere Troposphere Response using Infrared Vertically-Resolved Light Explorer (STRIVE) This mission would provide daily, near-global, high-resolution measurements of temperature, a variety of atmospheric elements, and aerosol properties from the upper troposphere to the mesosphere – at a much higher spatial density than any previous mission. It would also measure vertical profiles of ozone and trace gasses needed to monitor and understand the recovery of the ozone layer – another identified NASA Earth sciences target. The proposal is led by Lyatt Jaegle at the University of Washington in Seattle.
• The Ocean Dynamics and Surface Exchange with the Atmosphere (ODYSEA) This satellite would simultaneously measure ocean surface currents and winds to improve our understanding of air-sea interactions and surface current processes that impact weather, climate, marine ecosystems, and human wellbeing. It aims to provide updated ocean wind data in less than three hours and ocean current data in less than six hours. The proposal is led by Sarah Gille at the University of California in San Diego.
• Earth Dynamics Geodetic Explorer (EDGE) This mission would observe the three-dimensional structure of terrestrial ecosystems and the surface topography of glaciers, ice sheets, and sea ice as they are changing in response to climate and human activity. The mission would provide a continuation of such measurements that are currently measured from space by ICESat-2 and GEDI (Global Ecosystem Dynamics Investigation). The proposal is led by Helen Amanda Fricker at the University of California in San Diego.
• The Carbon Investigation (Carbon-I) This investigation would enable simultaneous, multi-species measurements of critical greenhouse gases and potential quantification of ethane – which could help study processes that drive natural and anthropogenic emissions. The mission would provide unprecedented spatial resolution and global coverage that would help us better understand the carbon cycle and the global methane budget. The proposal is led by Christian Frankenberg at the California Institute of Technology in Pasadena.

For more information about the Earth System Explorers Program, visit:

https://explorers.larc.nasa.gov/2023ESE/

Liz Vlock Headquarters, Washington 202-358-1600 [email protected]

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Climate change: World's oceans suffer from record-breaking year of heat

Fuelled by climate change, the world's oceans have broken temperature records every single day over the past year, a BBC analysis finds.

Nearly 50 days have smashed existing highs for the time of year by the largest margin in the satellite era.

Planet-warming gasses are mostly to blame, but the natural weather event El Niño has also helped warm the seas.

The super-heated oceans have hit marine life hard and driven a new wave of coral bleaching.

The analysis is based on data from the EU's Copernicus Climate Service.

Copernicus also confirmed that last month was the warmest April on record in terms of air temperatures, extending that sequence of month-specific records to 11 in a row.

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For many decades, the world's oceans have been the Earth's 'get-out-of-jail card' when it comes to climate change.

Not only do they absorb around a quarter of the carbon dioxide that humans produce, they also soak up around 90% of the excess heat.

But over the past year, the oceans have displayed the most concerning evidence yet that they are struggling to cope, with the sea surface particularly feeling the heat.

From March 2023, the average surface temperature of the global oceans started to shoot further and further above the long-term norm, hitting a new record high in August .

Recent months have brought no respite, with the sea surface reaching a new global average daily high of 21.09C in February and March this year, according to Copernicus data.

As the graph below shows, not only has every single day since 4 May 2023 broken the daily record for the time of year, but on some days the margin has been huge.

Around 47 days smashed the record for that day of the year by at least 0.3C, according to BBC analysis of Copernicus data.

Never before in the satellite era had the margin of record been this big.

The biggest record-breaking days were 23 August 2023, 3 January 2024 and 5 January 2024, when the previous high was beaten by around 0.34C.

"The fact that all this heat is going into the ocean, and in fact, it's warming in some respects even more rapidly than we thought it would, is a cause for great concern," says Prof Mike Meredith from the British Antarctic Survey.

"These are real signs of the environment moving into areas where we really don't want it to be and if it carries on in that direction the consequences will be severe."

Huge impact on sea life

This human-driven ocean warming is having considerable impacts on global sea life and may even be shifting the seasonal cycle of sea temperatures, according to according to a recent study .

Perhaps the most significant consequence of the recent warmth has been the mass bleaching of coral globally.

These key ocean nurseries turn white and die because the waters they live in grow too hot. They are a critical element in the ocean ecosystem, home to around a quarter of all marine species.

Unusually warm seas may also have taken a direct toll on one of the most beloved ocean-going creatures in the coldest continent, the emperor penguin.

"There have been examples of the sea-ice collapsing before emperor chicks have properly fledged, and there have been mass drowning events," says Prof Meredith.

"The emperor penguin is a threatened species because of climate change, and the sea-ice and the ocean temperatures are strongly implicated in that."

In the UK, rising sea temperatures are having an impact, with a number of creatures having vanished completely from coastal locations - some barnacle species, for example.

"The problem of climate change is that it's happening too quickly for evolution to catch up with it," says marine biologist Dr Nova Mieszkowska from the University of Liverpool.

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On the Welsh coast, a team from Aberystwyth University use the same technology the police use at a crime scene to track changes in the marine population of Cardigan Bay.

Collecting DNA traces from water samples, they show some invasive species are thriving, including a sea squirt that is believed to have originated in Japan and which grows like a carpet over the sea floor.

"They prevent the growth of native organisms in the areas that they colonise," says Prof Iain Barber, head of Life Sciences at Aberystwyth University. "Because they do so well in our environment, they can potentially take over huge areas of the seabed."

Species that are more invasive appear to be responding more strongly to global warming and the increasing water temperatures, Prof Barber says.

The El Niño effect

One important factor that's made the last year more impactful in seas all over the world has been the El Niño weather phenomenon, adding to human-driven emissions of warming gases.

El Niño sees warmer waters come to the surface of the Pacific. As a result, it tends to push up the global average.

A simple guide to climate change

What are El Niño and La Niña?

El Niño kicked into gear in June 2023 - after a prolonged period of cooler La Niña conditions - and reached a peak in December, although it has since been fading away .

But other ocean basins that aren't usually affected by El Niño have also experienced record marine heatwaves - leaving scientists trying to work out exactly what is going on.

"The Atlantic has been warmer than usual, and this is not a pattern you normally associate with El Niño - so it's something somehow different," explains Carlo Buontempo, director of Copernicus.

This heat is still persisting in many ocean basins, including the tropical Atlantic.

Warmer seas give tropical storms extra energy , and this could help to fuel a potentially damaging hurricane season.

"There is still a large patch of warmer than usual water in the tropical Atlantic [and] this is the main development region for tropical cyclones," explains Dr Buontempo.

"We are almost a month ahead in the sea surface temperature in the Atlantic with respect to the annual cycle [...] so this is an area that has to be watched."

As well as these short-term impacts, researchers warn there will be long-term consequences that society will have to adapt to.

For example, ice-sheet melting and deep-ocean warming are likely to continue to fuel sea-level rise in the centuries to come.

"When we talk about climate change, we tend to reduce that to changes on the surface because we live there," said Angélique Melet, a researcher with Mercator Ocean International.

"However, the deep ocean is one of the aspects [of global warming] that is committing us to centuries and millennia of [climate] change."

But Dr Melet stresses that is not a reason to give up on cutting emissions.

"Depending on our actions, we can reduce the speed of that warming, and we can decrease the overall amplitude of that warming and sea-level rise."

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The Ocean Has Never Been Hotter

I mean that literally. This might be the ball game for us, species-wise.

Fueled by climate change, the world's oceans have broken temperature records every single day over the past year, a BBC analysis finds. Nearly 50 days have smashed existing highs for the time of year by the largest margin in the satellite era. Planet-warming gases are mostly to blame, but the natural weather event El Niño has also helped warm the seas. The super-heated oceans have hit marine life hard and driven a new wave of coral bleaching. The analysis is based on data from the EU's Copernicus Climate Service. Copernicus also confirmed that last month was the warmest April on record in terms of global air temperatures, extending that sequence of month-specific records to 11 in a row.

This is decidedly not a good thing. If we manage to screw up the oceans beyond all recall—and, between fossil fuels and plastic containers and sewage, we're well on our way to doing just that—then that's the ball game for us, species-wise.

For many decades, the world's oceans have been the Earth's 'get-out-of-jail card' when it comes to climate change. Not only do they absorb around a quarter of the carbon dioxide that humans produce, they also soak up around 90% of the excess heat. But over the past year, the oceans have displayed the most concerning evidence yet that they are struggling to cope, with the sea surface particularly feeling the heat. From March 2023, the average surface temperature of the global oceans started to shoot further and further above the long-term norm, hitting a new record high in August. Recent months have brought no respite, with the sea surface reaching a new global average daily high of 21.09C in February and March this year, according to Copernicus data.

And there already is massive collateral damage going on. Undersea coral is being "bleached" at an alarming rate, ruining its ability to sustain the lives of the other species that depend on it. (Coral is home to 25 percent of all marine species.) And then there are the penguins.

Unusually warm seas may also have taken a direct toll on one of the most beloved ocean-going creatures in the coldest continent, the emperor penguin. "There have been examples of the sea-ice collapsing before emperor chicks have properly fledged, and there have been mass drowning events," says Prof Meredith. "The emperor penguin is a threatened species because of climate change, and the sea-ice and the ocean temperatures are strongly implicated in that."

In addition, the warming seas are causing an influx of invasive species all over the world. For example, the waters around Great Britain are now home to a huge population of sea squirts, which are native to Japan but have now commandeered the ocean floor off Wales to the detriment of native species.

"They prevent the growth of native organisms in the areas that they colonise," says Prof Iain Barber, head of Life Sciences at Aberystwyth University. "Because they do so well in our environment, they can potentially take over huge areas of the seabed." Species that are more invasive appear to be responding more strongly to global warming and the increasing water temperatures, Prof Barber says.

Ah, but you say, nature is always in flux. Evolution is a constant churn. Nova Mieszkowska, a marine biologist at the University of Liverpool who appears in a video accompanying the BBC story, grants all that, but she also explains that the changes wrought by the climate crisis are happening too fast for evolution to keep up. She says:

The thing that I've seen is that species are not all moving at the same rate, so things are moving north but not at the same speed. So all the community compositions are changing everywhere because different species are moving at different rates.

I find it all quite sad. I mean, nature is never static. The environment is always changing, and species respond. The problem with climate change is that it's happening too quickly for evolution to catch up with it, which is why we're seeing all these shifts because species can't evolutionarily adapt to it. I think if I were a barnacle, I'd be quite worried."

I'm worried that, in certain important ways, we're all becoming barnacles here.

Charles P Pierce is the author of four books, most recently Idiot America , and has been a working journalist since 1976. He lives near Boston and has three children. 

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Study: Heavy snowfall and rain may contribute to some earthquakes

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When scientists look for an earthquake’s cause, their search often starts underground. As centuries of seismic studies have made clear, it’s the collision of tectonic plates and the movement of subsurface faults and fissures that primarily trigger a temblor.

But MIT scientists have now found that certain weather events may also play a role in setting off some quakes.

In a study appearing today in Science Advances , the researchers report that episodes of heavy snowfall and rain likely contributed to a swarm of earthquakes over the past several years in northern Japan. The study is the first to show that climate conditions could initiate some quakes.

“We see that snowfall and other environmental loading at the surface impacts the stress state underground, and the timing of intense precipitation events is well-correlated with the start of this earthquake swarm,” says study author William Frank, an assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “So, climate obviously has an impact on the response of the solid earth, and part of that response is earthquakes.”

The new study focuses on a series of ongoing earthquakes in Japan’s Noto Peninsula. The team discovered that seismic activity in the region is surprisingly synchronized with certain changes in underground pressure, and that those changes are influenced by seasonal patterns of snowfall and precipitation. The scientists suspect that this new connection between quakes and climate may not be unique to Japan and could play a role in shaking up other parts of the world.

Looking to the future, they predict that the climate’s influence on earthquakes could be more pronounced with global warming.

“If we’re going into a climate that’s changing, with more extreme precipitation events, and we expect a redistribution of water in the atmosphere, oceans, and continents, that will change how the Earth’s crust is loaded,” Frank adds. “That will have an impact for sure, and it’s a link we could further explore.”

The study’s lead author is former MIT research associate Qing-Yu Wang (now at Grenoble Alpes University), and also includes EAPS postdoc Xin Cui, Yang Lu of the University of Vienna, Takashi Hirose of Tohoku University, and Kazushige Obara of the University of Tokyo.

Seismic speed

Since late 2020, hundreds of small earthquakes have shaken up Japan’s Noto Peninsula — a finger of land that curves north from the country’s main island into the Sea of Japan. Unlike a typical earthquake sequence, which begins as a main shock that gives way to a series of aftershocks before dying out, Noto’s seismic activity is an “earthquake swarm” — a pattern of multiple, ongoing quakes with no obvious main shock, or seismic trigger.

The MIT team, along with their colleagues in Japan, aimed to spot any patterns in the swarm that would explain the persistent quakes. They started by looking through the Japanese Meteorological Agency’s catalog of earthquakes that provides data on seismic activity throughout the country over time. They focused on quakes in the Noto Peninsula over the last 11 years, during which the region has experienced episodic earthquake activity, including the most recent swarm.

With seismic data from the catalog, the team counted the number of seismic events that occurred in the region over time, and found that the timing of quakes prior to 2020 appeared sporadic and unrelated, compared to late 2020, when earthquakes grew more intense and clustered in time, signaling the start of the swarm, with quakes that are correlated in some way.

The scientists then looked to a second dataset of seismic measurements taken by monitoring stations over the same 11-year period. Each station continuously records any displacement, or local shaking that occurs. The shaking from one station to another can give scientists an idea of how fast a seismic wave travels between stations. This “seismic velocity” is related to the structure of the Earth through which the seismic wave is traveling. Wang used the station measurements to calculate the seismic velocity between every station in and around Noto over the last 11 years.

The researchers generated an evolving picture of seismic velocity beneath the Noto Peninsula and observed a surprising pattern: In 2020, around when the earthquake swarm is thought to have begun, changes in seismic velocity appeared to be synchronized with the seasons.

“We then had to explain why we were observing this seasonal variation,” Frank says.

Snow pressure

The team wondered whether environmental changes from season to season could influence the underlying structure of the Earth in a way that would set off an earthquake swarm. Specifically, they looked at how seasonal precipitation would affect the underground “pore fluid pressure” — the amount of pressure that fluids in the Earth’s cracks and fissures exert within the bedrock.

“When it rains or snows, that adds weight, which increases pore pressure, which allows seismic waves to travel through slower,” Frank explains. “When all that weight is removed, through evaporation or runoff, all of a sudden, that pore pressure decreases and seismic waves are faster.”

Wang and Cui developed a hydromechanical model of the Noto Peninsula to simulate the underlying pore pressure over the last 11 years in response to seasonal changes in precipitation. They fed into the model meteorological data from this same period, including measurements of daily snow, rainfall, and sea-level changes. From their model, they were able to track changes in excess pore pressure beneath the Noto Peninsula, before and during the earthquake swarm. They then compared this timeline of evolving pore pressure with their evolving picture of seismic velocity.

“We had seismic velocity observations, and we had the model of excess pore pressure, and when we overlapped them, we saw they just fit extremely well,” Frank says.

In particular, they found that when they included snowfall data, and especially, extreme snowfall events, the fit between the model and observations was stronger than if they only considered rainfall and other events. In other words, the ongoing earthquake swarm that Noto residents have been experiencing can be explained in part by seasonal precipitation, and particularly, heavy snowfall events.

“We can see that the timing of these earthquakes lines up extremely well with multiple times where we see intense snowfall,” Frank says. “It’s well-correlated with earthquake activity. And we think there’s a physical link between the two.”

The researchers suspect that heavy snowfall and similar extreme precipitation could play a role in earthquakes elsewhere, though they emphasize that the primary trigger will always originate underground.

“When we first want to understand how earthquakes work, we look to plate tectonics, because that is and will always be the number one reason why an earthquake happens,” Frank says. “But, what are the other things that could affect when and how an earthquake happens? That’s when you start to go to second-order controlling factors, and the climate is obviously one of those.”

This research was supported, in part, by the National Science Foundation.

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BBC Science Focus reporter Alex Hughes spotlights a new study by MIT scientists that suggests more heavy snowfall and rain linked to climate change could increasingly contribute to earthquakes worldwide. “The researchers made these conclusions based on how weather patterns in northern Japan have seemingly contributed to a new 'swarm' of earthquakes,” writes Hughes, “a pattern of multiple, ongoing quakes – that is thought to have begun in 2020.”

A new study conducted by MIT researchers suggests “heavy snowfall could be a factor in triggering swarms of earthquakes,” reports Evan Bush for NBC News . "Those big snowfall events seem to correlate well with the start of these big earthquake swarms," says Prof. William Frank. "We shouldn’t forget the climate itself can also play a role in changing the stress state at depth where earthquakes are happening." 

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