New Study Concludes Anthropogenic Activities Affect Atlantic Ocean Surface Temperatures More than in the Pacific, Where Natural Processes Have the Biggest Effect on Temperatures

       Florida State University researchers recently published a paper in Geophysical Research Letters that concludes that multidecadal sea surface temperatures (SSTs) are mainly anthropogenically forced in the Atlantic Ocean and mainly generated internally in the Pacific Ocean. The researchers utilized “a novel Rotated Low-Frequency Component Analysis to large-ensemble climate model simulations and observational SST data sets to disentangle the forced and unforced components” of multidecadal SSTs in the Atlantic and Pacific.

     Many natural and human-caused, or anthropogenic, factors affect ocean temperatures. Greenhouse gases in the atmosphere heat the atmosphere and the oceans significantly. Natural phenomena like the oceanic thermohaline circulation conveyor belt, El Niño, and La Niña events affect ocean temperatures. Aerosols from combustion pollution and also from sandstorms emanating from the Sahara Desert region cool the Atlantic region. One of the paper’s authors noted that since Atlantic Ocean temperatures are more influenced by anthropogenic emissions, they could more easily be reduced, but that is a long shot at present.  

     As noted in an article about the study in the Miami Herald, sea surface temperatures are mainly on the surface, and the water is colder at depth.

“Sea surface temperatures are basically skin deep,” said Nick Shay, a professor of oceanography University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science. Shay studies ocean heat content, how hot the water gets when you plunge hundreds of meters down below the surface. “The idea here is the deeper the warm water goes, the more likely a storm is to form or intensify.”

“Deeper pockets of warm water serve as much more intense fuel reserves for storms. It’s why we sometimes see storms in the Gulf suddenly intensify when they cross over one.”

“And while it’s clear that the ocean is absorbing more heat as human-caused climate change rages on, parsing what can be blamed on humans or natural variability in ocean heat content is a little more difficult,” he said.

     Temperatures have definitely been rising in the Atlantic and the Gulf.

     The paper notes that uncertainties remain about its conclusions, with the possibility that anthropogenic forcing in the Atlantic region is overestimated.

“These results have important implications for understanding historical and future climate variability, and challenge the more traditional view of AMV as an internal mode. Thus, we suggest that much of the observed evolution in multidecadal Atlantic SSTs reflects anthropogenic forcing rather than internal ocean dynamics. However, some uncertainty remains in this decomposition, as the forced response may be overestimated due to potential aliasing of internally generated variability as external forcing. This could occur if observed internal patterns align with the model's forced reference modes during rotation, thereby misattributing internal variability to external forcing. Under such circumstances, the contrast between the forced and unforced components of AMV would be reduced, implying a larger role for internal oscillatory variability. In contrast, separating PDO components would reveal an exaggerated difference, leaving little room for external forcing to contribute to PDO variability. Future work could refine this method using single-forcing or all-but-one-forcing simulations to more directly identify the contributions of greenhouse gases and aerosols.”

  

 

 

References:

 

What's warming (and cooling) the Atlantic? Study points to humans. Alex Harris. Miami Herald. June 24, 2026. What's warming (and cooling) the Atlantic? Study points to humans

Multidecadal SST Variability Assessed as Primarily Forced in the Atlantic and Internal in the Pacific Using Rotated Low-Frequency Component Analysis. Anthony S. Freveletti, Michael S. Diamond, Robert C. J. Wills. Geophysical Research Letters. Volume 53, Issue 7. 16 April 2026. Multidecadal SST Variability Assessed as Primarily Forced in the Atlantic and Internal in the Pacific Using Rotated Low‐Frequency Component Analysis - Freveletti - 2026 - Geophysical Research Letters - Wiley Online Library