Oceans warming four times faster than in 1980s, finds study

Researchers explained that the accelerated warming of oceans is driven by a growing imbalance in the Earth's energy -- whereby energy from the Sun being absorbed by Earth is more than that escaping back to space.

New Delhi: A new study has found that the rate at which oceans are warming has become four times faster as compared to the last four decades.

Published in the journal Environmental Research Letters, the study showed that ocean temperatures are rising at 0.27 degrees Celsius per decade during 2019-23, compared to 0.06 degrees Celsius every decade in the late 1980s.

"If the oceans were a bathtub of water, then in the 1980s, the hot tap was running slowly, warming up the water by just a fraction of a degree each decade," lead author Chris Merchant from the University of Reading, UK, said.

"But now the hot tap is running much faster, and the warming has picked up speed. The way to slow down that warming is to start closing off the hot tap, by cutting global carbon emissions and moving towards net-zero," Merchant explained.

"The underlying rate of change of GMSST (global mean sea surface temperature) rises in proportion with Earth's energy accumulation from 0.06 (Celsius per decade) during 1985-89 to 0.27 (Celsius per decade) for 2019-23," the authors wrote.

They explained that the accelerated warming of oceans is driven by a growing imbalance in the Earth's energy -- whereby energy from the Sun being absorbed by Earth is more than that escaping back to space.

The energy imbalance has roughly doubled since 2010, partly due to increasing levels of greenhouse gas, and because the Earth is now reflecting less sunlight to space than before, they said.

In their analysis, the team found that nearly half (44 per cent) of the record-breaking heat experienced in 2023 and early 2024 could be traced back to oceans warming at an accelerating rate.

Global ocean temperatures are known to have hit record highs for 450 days straight in 2023 and early 2024.

Other factors contributing to the record heat included El Nino, a natural warming event in the Pacific, the researchers said.

Comparing the recent El Nino to that of 2015-16 -- considered one of the strongest on record -- the team found that the remainder of the record heat experienced during 2023-24 was explained by sea surface warming at a rate that was faster over the past 10 years than the earlier decades.

The authors said that the ocean temperature increase seen over the past 40 years could be exceeded in just the next 20 years.

This accelerating warming of oceans underscored the urgency of reducing fossil fuel burning to prevent even more rapid temperature increases in the future and to begin to stabilise the climate, they said. PTI KRS NB NB NB