It's getting hot in here: Ocean temperatures reach record highs

(CN)  — 2024 was a year of climate record-breaking — with some of the hottest months on record and the Earth’s warmest day of all time. As if to add to the disheartening list of accomplishments, scientists are now reporting that humans also spent the year recording the hottest ocean surface temperatures ever, a discovery which is already having serious impacts on the largest heat reservoir in the world.

Published in Advances in Atmospheric Sciences Friday, the study reveals that the global mean surface temperatures in 2024 reached nearly 66.50 degrees Fahrenheit, which could have devastating effects on the ocean ecosystem.

Covering nearly 90% of the Earth’s surface, the sea absorbs the majority of the Earth’s excess heat and is a key player in managing climate change, meaning the ocean takes the short end of the stick when things start to get really hot.

According to John Abraham of the University of St. Thomas, who co-authored the study, how the ocean absorbs heat — and how much it absorbs — is the best measurement for monitoring a changing climate.

“To know what is happening to the climate, the answer is in the ocean,” Abraham said in a statement.

The ocean’s significance to understanding climate change is why Abraham joined the study’s team, headed by Lijing Cheng of the Institute of Atmospheric Physics at the Chinese Academy of Sciences. The team, composed of 54 scientists from seven countries, collaborated to track the ocean’s global surface temperatures over the course of the year and uncover what those temperatures could mean for the Earth’s coming years.

“The ocean is our sentinel for planetary warming, acting as the major sink of surplus heat accumulating in Earth climate system as a result of anthropogenic emissions” said Dr. Karina von Schuckmann at Mercator Ocean International, co-author of the study.

In 2023, mean global ocean surface temperatures had already reached a record high, nearing 66 degrees Fahrenheit at its peaks in summer months, a stark difference from the nearly 64 degrees Fahrenheit mean temperature recorded in the 1950s. While that two degree shift may seem miniscule, it’s a big number for climate scientists who say the steady increase in temperature is an anomaly caused by climate change.

“The broken records in the ocean have become a broken record.” Cheng said in a statement.

Now, with the ocean’s surface temperature passing the record levels less than a year later, scientists expect marine life to be some of the first to suffer from the change. Coral bleaching and melting ice sheets are just two side effects that are becoming more and more commonplace as abnormally warm waters become the norm.

The ocean’s heat content packs a heavy punch, too. Over the last year, the upper 2000 meters of the planet’s seas have increased in heat by 16 zettajoules. That number is equivalent to 140 times the world’s total electricity generation in 2023.

Ocean surface temperatures and how they change matter not just because of their impacts on marine ecosystems, but because the world’s seas are one of the strongest natural features propelling worldwide weather patterns. If ocean surface temperatures even just slightly change, evaporation and humidity levels are impacted, meaning more extreme weather in a wider variety of places.

Warmer waters mean increased water vapor, which can act as a greenhouse gas and heat the Earth more rapidly overall. This increased heat then leads to increased drought, which in turn causes natural disasters like wildfires. Heavy water vapor can also fuel storms and cause floods, hurricanes and typhoons, throwing everything out of balance.

In 2024, climate change led to landmark droughts, heat waves, floods and wildfires on nearly every continent. Using the study’s collected data, researchers predicted that climate change will only continue to exacerbate those side effects in 2025. As of the first week of the year, the research rings true as a never-before-seen January wildfire crossed Los Angeles in the most destructive firestorm the city has ever seen, likely caused by historically low rainfall.