Southern Antarctic waters found to absorb as much heat as Atlantic, Pacific and Indian Ocean combined

There is an urgent need for international action from big-emitting nations to meet their net-zero carbon targets as soon as possible and limit the damage from uncontrolled ocean warming.

New Delhi, Nov 2 (PTI) The southern waters surrounding Antarctica, or the Southern Ocean, absorbed the highest amount of human activity-caused heat over the past two decades, almost equal to that taken up by the Atlantic, Pacific and Indian Ocean combined, researchers have found in a new study.

Ocean warming has accelerated dramatically since the 1990s, nearly doubling during 2010-2020 relative to 1990-2000, the researchers led by the University of New South Wales (UNSW), Australia, said.

However, the region-wise distribution of ocean warming was far from uniform and thus, the newfound knowledge had implications for our understanding of sea-level rise and climate impacts, they said in their study published in the journal Nature Communications.

Increase in atmospheric levels of greenhouse gases, caused by human activity, traps heat within the Earth's climate system, warming air, land and oceans, and melting polar ice.

The oceans take up most of this heat, absorbing more than 90 per cent of the excess human-generated heat, thereby moderating atmospheric temperature rises.

While ocean warming helps slow the pace of climate change, it is not without cost, said Matthew England, co-author of the study from the UNSW Centre for Marine Science and Innovation.

'What we wanted to do in this study was to figure out exactly where this ocean heat uptake has been occurring,' said lead researcher Zhi Li.

For the study, the researchers compared all available observations of ocean warming activity spanning modern Argo float data - an international ocean research program collecting information using robotic instruments - to those taken in the 1950s when only sparse measurements were made from ship-borne devices.

They then analysed the heat uptake across water masses and quantified each water mass's role in ocean heat content change.

'Melting ice caps, extreme weather, and marine ecosystems, including coral reefs, are all highly sensitive to ocean temperature changes,' said Sjoerd Groeskamp, co-author of the study from the Royal Netherlands Institute for Sea Research.

'It is critical we understand exactly how and where the ocean warms – both now and into the future,' said Groeskamp.

The scientists said their findings highlighted an urgent need to increase monitoring of the global oceans, especially in remote polar locations, as well as key regions of the subtropical and coastal seas to better understand and predict sea-level rise and impacts on marine ecosystems.

The team also called for more international action from big-emitting nations to meet their net-zero carbon targets as soon as possible and limit the damage from uncontrolled ocean warming.

'The world ocean, in 2023, is now the hottest ever recorded, and sea levels are rising because heat causes water to expand and ice to melt. Ecosystems are also experiencing unprecedented heat stress, and the frequency and intensity of extreme weather events are changing rapidly, and the costs are enormous,' said England.