Oceans Take the Heat, Set Record Temperatures


By Christina P. Hooton

The atmosphere is not the only thing getting warmer because of climate change. Ocean temperatures have reached record-breaking levels in the last three years, with 2021 being the hottest documented. Scientists reported these findings in Advances inAtmospheric Sciences, citing continued greenhouse gas emissions as the cause. Some of the excess heat building up in the atmosphere due to these emissions is absorbed into the oceans. From an increase in storm systems to dwindling marine habitats, rising ocean temperatures have far-reaching implications.

Casting a Wide Net

For the study, scientists collected and analyzed data from floating sensors positioned throughout the world’s oceans, from the Antarctic circle to the tropics and beyond. Two international organizations manage these datasets: the Chinese Academy of Sciences and the National Oceanic and Atmospheric Administration within the United States Department of Commerce.

Tracking a Hot Streak

The data showed that the amount of heat in oceans last year increased by roughly 14 zettajoules, the equivalent of 20 times the entire world’s annual energy consumption. In addition, the previous five years had seen the five hottest ocean levels ever recorded. The 2018 level was a little lower than the 2017 record-breaker, but 2019, 2020, and 2021 each set their own new record-breaking levels. This is despite an ongoing La Niña event, a period of cool waters in the Pacific.

This pattern of warming has happened every decade since 1958, the rate of which has been increasing since the 1980s.

“The ocean heat content is relentlessly increasing, globally, and this is a primary indicator of human-induced climate change,” said study co-author Kevin Trenberth in a statement to Scientific American.

Assessing the Damage

Warmer ocean temperatures can cause stronger, more extreme weather events such as heavy rain, thunderstorms, and tropical cyclones. This can have a deadly and destructive impact, especially on coastal towns.

Marine heatwaves and prolonged periods of warmer temperatures have also become more prevalent. This can displace the habitats of sea creatures by thousands of miles.

Additionally, as water heats up, it expands, which translates into rising sea levels. Melting glaciers exacerbate this problem. Another less desirable characteristic of warmer water is that it absorbs less carbon dioxide. With less carbon dioxide being captured by water, the atmosphere will heat up faster.

The documentation of rising ocean temperatures and their repercussions show just how interconnected climate change is, presenting both a challenge and an opportunity for humankind.

Discussion Questions

  • Describe why the rate of ocean warming continues to increase.
  • Research the different animals and plants affected by warming oceans. How will their disruption alter ocean ecosystems?