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Earth's Oceans Absorbing Heat at Record Rates

Why Does the Ocean Absorb Heat?

Excess heat is created by the warming of surface water, which is a result of global warming. Upon reaching the surface of Earth, the oceans absorb a significant amount of heat due to water's high heat capacity compared to air. The air the ocean stores comes in handy to release moisture into the atmosphere when rain cannot. Surface waters are not being warmed homogeneously; instead, they warm in a "pattern effect" due to multiple factors, including ocean circulation.

How Does the Ocean Absorb Heat?

Anthropogenic (relating to or caused by humans) global surface warming is directly related to carbon emission, partially due to ocean absorption of heat and carbon. Another factor is the ocean carbon buffer capacity, or the ocean's ability to resist changes in pH. Southern Hemisphere oceans uptake more heat than Northern Hemisphere in the climate system. "Atmospheric forcing and ocean circulation determine heat uptake and redistribution in Southern Hemisphere oceans." Approximately ⅔ of net surface heat gain gets redistributed to the north, which explains the greater heating at the middle latitudes.

Image is courtesy of National Centers for Environmental Information.

What Was Significant About 2020?

Oceans absorb over 90% of excess heat. 2020 marked the highest upper ocean temperatures on record. They were given by OHC (ocean heat content), measurement of ocean warming. Both IAP (Institute of Atmospheric Physics) and NOAA (National Oceanic and Atmospheric Administration) use datasets that take mapping data and create a “comprehensive picture of the ocean.”

Effects of Ocean Warming

The warming of the Earth's oceans is not a topic to be taken lightly. There are many consequences of said warming on the natural world. Storms, water cycles, and marine life are all put at risk as ocean temperatures rise.

Image is courtesy of IUCN.

“The upper layers of the ocean are vital for marine biodiversity, as they support some of the most productive and rich ecosystems on Earth, and warming of this magnitude will dramatically impact on marine life” (Dan Smale at Marine Biological Association in the UK)

Ocean warming indicates how the climate system is currently at risk. The influence of human-created carbon emissions impacts natural energy flows that affect ocean heat uptake.

Higher temperatures have many adverse effects, including:

  • More intense storms

  • Disruption of the water cycle

  • More frequent wildfires, floods, droughts

  • Rising sea levels

  • Harm to marine wildlife

Another negative impact of ocean warming is deoxygenation, which is a severe consequence of global warming. Deoxygenation harms algae-blooms and nutrient cycles in marine ecosystems, which has devastating effects on marine life.

Image is courtesy of IUCN.

Ocean warming also affects the pH levels (acidification) of the oceans. When the pH levels of our oceans decrease, acid levels increase. Since the beginning of the industrial revolution in the 1700s, our oceans' pH levels have plummeted. Fossil fuels are the reason for ocean acidification, as humans have been abusing them for coal mining and other means of nonrenewable energy production. When the oceans' pH levels decrease, the levels of carbonic acid produced from carbon dioxide molecules when they react with water molecules also reduce.

Image is courtesy of epa.gov.


Bronselaer, B., & Zanna, L. (2020, August 12). Heat and carbon coupling reveals ocean warming due to circulation changes. Retrieved from https://www.nature.com/articles/s41586-020-2573-5

J. Abraham, J. R., J. Abraham, L. J., L. Caesar, S. R., L J. Cheng, K. E., L J. Cheng, J. A., L J. Cheng, K. E., . . . F. Xiao, D. X. (1970, January 01). Upper Ocean Temperatures Hit Record High in 2020. Retrieved from https://link.springer.com/article/10.1007/s00376-021-0447-x

Jiang, L., Carter, B. R., Feely, R. A., Lauvset, S. K., & Olsen, A. (2019, December 09). Surface ocean pH and buffer capacity: Past, present and future. Retrieved from https://www.nature.com/articles/s41598-019-55039-4

Lyu, K., Zhang, X., Church, J. A., & Wu, Q. (2020, April 01). Processes Responsible for the Southern Hemisphere Ocean Heat Uptake and Redistribution under Anthropogenic Warming. Retrieved from https://journals.ametsoc.org/view/journals/clim/33/9/jcli-d-19-0478.1.xml

Newsom, E., Zanna, L., Khatiwala, S., & Gregory, J. M. (2020, September 15). The Influence of Warming Patterns on Passive Ocean Heat Uptake. Retrieved from https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL088429

Featured photo is courtesy of Wix

Article Authors: Maria Giroux, Mina Chong

Article Editor: Stephanie Sahaedo