"The broken records in the ocean have become a broken record," said Prof. Lijing Cheng with the Institute of Atmospheric Physics at the Chinese Academy of Sciences. He led a team of 54 scientists from seven countries and discussed how a hotter ocean affects our lives on land and what this means for our future.

Why is the ocean so important?

The ocean is a critical part of the Earth's climate—most of the excess heat from global warming is stored in the ocean (90%) and the ocean covers 70% of the Earth's surface. Because of this, the ocean dictates our weather patterns by transferring heat and moisture into the atmosphere. The ocean also controls how fast climate change happens.

"To know what is happening to the climate, the answer is in the ocean," said Prof. John Abraham at the University of St. Thomas, co-author of the study.

Results from three international teams who collaborated on this project were consistent—the ocean is warming, and 2024 was a record.

From 2023 to 2024, the global upper 2000 m ocean heat content increase is 16 zettajoules (10²¹ Joules), ~140 times the world's total electricity generation in 2023.

"OHC has increased steadily by 15–20 ZJ over the past five years despite the La Niña and El Niño cycles," said Prof. Michael Mann from the University of Pennsylvania.