SCIENCE: Oceans are heating faster in 2 bands stretching around globe - U.S. Affected

Greenhouse gases continue to play a part in warming our oceans, affecting sea life, changing weather patterns and more. New research from the University of Auckland, New Zealand shows that ocean waters along the 40th parallel south and north have warmed. Here's the story from the press release.  

(Photo: U.S. Navy photo by Petty Officer 3rd Class Joshua Scott.) 

Oceans are heating faster in two bands stretching around globe

Countries affected include the US, Japan, Argentina, New Zealand 

University of Auckland,April 30, 2025

The world’s oceans are heating faster in two bands stretching around the globe, one in the southern hemisphere and one in the north, according to new research led by climate scientist Dr Kevin Trenberth.

In both hemispheres, the areas are near 40 degrees latitude.

The first band at 40 to 45 degrees south is heating at the world’s fastest pace, with the effect especially pronounced around New Zealand, Tasmania, and Atlantic waters east of Argentina.

The second band is around 40 degrees north, with the biggest effects in waters east of the United States in the North Atlantic and east of Japan in the North Pacific.

EDITOR'S NOTE: WHERE THE OCEAN IS WARMING MOST NEAR U.S. - The official name for the line is the “40th parallel north.“ It runs through coastal California on the Pacific side and New Jersey on the Atlantic side.

“This is very striking,” says Trenberth, of the University of Auckland and the National Center of Atmospheric Research in Boulder, Colorado. “It’s unusual to discover such a distinctive pattern jumping out from climate data,” he says.

WHY IT MATTERS: Ocean heating upsets marine ecosystems, increases atmospheric levels of water vapour, which is a powerful greenhouse gas, and fuels rain-storms and extreme weather.

The heat bands have developed since 2005 in tandem with poleward shifts in the jet stream, the powerful winds above the Earth’s surface that blow from west to east, and corresponding shifts in ocean currents, according to Trenberth and his co-authors in the Journal of Climate.

The scientists processed an “unprecedented” volume of atmospheric and ocean data to assess 1 degree latitude strips of ocean to a depth of 2000m for the period from 2000 to 2023, Trenberth says. Changes in heat content, measured in zettajoules, were compared with a 2000-04 baseline.

Besides the two key zones, sizeable increases in heat took place in the area from 10 degrees north to 20 degrees south, which includes much of the tropics. However, the effect was less distinct because of variations caused by the El Niño-Southern Oscillation climate pattern, Trenberth says.

“What is unusual is the absence of warming in the subtropics, near 20 degrees latitude, in both hemispheres,” he says.

Co-authors of the paper were Lijing Cheng and Yuying Pan, of the Chinese Academy of Sciences, John Fasullo of NCAR, and Michael Mayer of the University of Vienna and the European Centre for Medium-Range Weather Forecasts.

“Despite what Donald Trump thinks, the climate is changing because of the build-up of greenhouse gases, and most of the extra heat ends up in the ocean,” says Trenberth. “However, the results are by no means uniform, as this research shows. Natural variability is likely also at play."

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JOURNAL REFERENCE: Oceans are heating faster in two bands stretching around globe University of Auckland Journal of Climate DOI 10.1175/JCLI-D-24-0609.1 

 Media Contact Paul Panckhurst University of Auckland paul.panckhurst@auckland.ac.nz Cell: 0220328475