941. Oceans Break Heat Records for Fifth Consecutive Year

Nature reports that the oceans broke heat records for the fifth year in a row in 2023.
 
Driven by a robust El Niño event, sea surface temperatures rose to unprecedented levels in 2023, with an annual average about 0.23°C higher than in 2022. The editorial points to the findings of an international collaborative research paper, which shows that ocean warming has accelerated at an unprecedented rate since 2019, with continued increases in anthropogenic greenhouse gas emissions providing the backdrop for this alarming trend.
 
The paper‘s lead author, Cheng Lijing, an oceanographer at the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences, emphasized that more than 90% of the Earth system's excess heat is absorbed by the ocean. He warned that if atmospheric greenhouse gas concentrations continue to rise, the ocean will continue to absorb energy from the Earth system, further increasing its heat storage capacity. Ocean heat storage, he noted, serves as a reliable indicator of climate change because it is less sensitive to natural variations in the Earth system than changes in air and sea surface temperatures.
 
The research involved a comprehensive analysis of several ocean heat storage datasets from the IAP and the National Center for Environmental Information (NCEI)at the National Oceanic and Atmospheric Administration in the USA. Both datasets consistently showed a warming trend and an increase in heat storage (NCEI: 9 zettajoules). This substantial heat accumulation in the oceans, when compared to total global energy consumption of 0.6 zettajoules in 2022, underscores the magnitude of heat stored in the oceans and highlights the potential global impact that even small changes in ocean heat uptake can have.
 
It is well known that about 50% of sea level rise is due to the expansion of ocean volume as a result of rising water temperatures. In addition, rapid ocean warming influences global weather patterns, affecting precipitation, droughts, and floods. The worrying implication is that accelerated ocean warming may contribute to the intensification of extreme weather events, potentially bringing humanity closer to a tipping point in climate change. Alarmingly, the data raise serious concerns about the trajectory of our planet's climate.

Reference
Nature 625, 434-435 (2024) doi: https://doi.org/10.1038/d41586-024-00081-0

Contributor: Solongo TUMUR and IYAMA Miyuki (Information Program)