Researchers find unexpected pattern in ocean warming

The fact that the oceans are warming is nothing new. However, this is not happening evenly: scientists have found a pattern.

According to this pattern, the oceans are warming faster in two bands that run around the entire globe. The stripes are located in the northern and southern hemispheres, each in the area around 40 degrees latitude. This is the conclusion reached by a team led by climate researcher Kevin Trenberth, who conducts research at the University of Auckland in New Zealand and at the National Center of Atmospheric Research (NCAR) in Boulder, Colorado.

"This is very striking," said Trenberth. "It's unusual to discover such a distinct pattern jumping out of the climate data."

The strip that is warming the fastest is located in the southern hemisphere between 40 and 45 degrees latitude. The effects are particularly pronounced in the area around New Zealand and Tasmania in the South Pacific and in the South Atlantic east of Argentina, the researchers said. The second strip lies at around 40 degrees north latitude – which is roughly at the level of Sardinia. Here, the temperature rise is strongest in the North Atlantic east of the USA and in the North Pacific east of Japan.

The jet streams are moving towards the poles

These two bands have developed over the past 20 years, parallel to the shift of the jet streams towards the poles and the associated shifts in ocean currents. The jet streams are strong winds that blow from west to east at a height of around 10 kilometers.

According to the researchers, they have evaluated an immense amount of data from the atmosphere and the seas in order to record the oceans in strips from one degree of latitude to a depth of 2000 meters over a period from 2000 to 2023. They have published their results in the Journal of Climate.

In addition to the zones mentioned, the scientists found a significant rise in temperature in the area between 10 degrees north and 20 degrees south latitude. However, the effect is less pronounced in the area that covers a large part of the tropics, which is due to the fluctuations caused by the El Niño phenomenon.

In the subtropics, in the 20s latitudes, on the other hand, no warming was observed, said Trenberth. This is "unusual". The climate is changing due to the increase in greenhouse gases. "Most of the additional heat ends up in the ocean," said the researcher. "However, the results are by no means uniform, as this study shows. Natural fluctuations are probably also involved."

(wpl)