Sea surface heating rate accelerates beyond past estimates

Sea surface heating rate accelerates beyond past estimates
by Erica Marchand
Paris, France (SPX) Apr 23, 2025
Satellite-based observations have revealed that global sea surface temperatures (SSTs) have been rising significantly faster in recent years, with warming accelerating to levels far beyond previous trends.

Data spanning from 1985 to 1989 indicated an average increase of 0.06 degrees Celsius per decade. In contrast, between 2019 and 2023, the rate surged to 0.27 degrees per decade, marking a more than fourfold increase in ocean surface warming over the past 40 years.

This trend was identified using global SST data compiled under the European Space Agency's Climate Change Initiative (CCI). The analysis drew from a comprehensive satellite archive, including 20 infrared radiometers aboard platforms such as ESA's ERS-1, ERS-2, Envisat, and Copernicus Sentinel-3, as well as two microwave radiometers. Covering the period from 1980 to 2023, the dataset enables robust, consistent evaluation of ocean surface temperatures worldwide.

Published in the journal Environmental Research Letters, the study attributes the accelerated warming largely to the growing concentration of greenhouse gases in the atmosphere. According to lead researcher Chris Merchant from the University of Reading, this excess of greenhouse gases has caused an imbalance between incoming solar energy and outgoing radiation, resulting in the accumulation of heat in Earth's climate system. "This energy imbalance drives climate change," said Merchant. "Given the accelerations in ocean warming and evolving climate dynamics, we need ongoing monitoring and data improvements to ensure our climate models can accurately reflect future temperature increases."

While natural events like El Nino, volcanic eruptions, and solar fluctuations can influence SSTs on shorter timescales, the research found that these effects do not disrupt the long-term trend. Owen Embury, a co-author and science lead for ESA's CCI SST project, emphasized, "Our study clearly identifies the increasing accumulation of planetary energy as the dominant driver of long-term sea surface warming, while short-term variations from El Nino, volcanic activity and solar changes add variability but do not alter the overall accelerating trend."

This latest analysis supports the objectives of ESA's MOTECUSOMA project, which seeks to better understand Earth's energy imbalance and its broader implications for climate change. Embury added, "Addressing these challenges requires accurate climate projections - increasing ocean heat uptake intensifies extreme weather events, disrupts ecosystems and accelerates sea level rise, making continued observation and model refinement essential."

The long-term SST dataset is publicly accessible via ESA's CCI data portal, with climate-model-ready versions available through the Obs4MIPs framework.