Ocean warming has more than quadrupled over the past 40 years, scientists have revealed.
Back in the late 1980s, ocean temperatures were rising at a rate of about 0.06°C per decade, according to experts from the University of Reading.
Now, that rate has surged to a whopping 0.27°C per decade.
‘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,’ explained Professor Chris Merchant, lead author of the study.
‘But now the hot tap is running much faster, and the warming has picked up speed.’
Looking ahead, it is ‘plausible’ that the ocean temperature increase seen over the past 40 years will be exceeded in just the next 20 years.
According to the researchers, there’s only one surefire way to slow the ocean warming.
‘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,’ Professor Merchant added.
Ocean warming has more than quadrupled over the past 40 years, scientists have revealed. Pictured: a polar bear on melting ice in the Arctic
The acceleration in ocean warming is being diven by Earth’s growing energy imbalance, according to the team.
This means that more energy from the sun is being absorbed by our oceans than is escaping back to space.
Since 2010, this imblance has roughly doubled.
This is partly due to increasing greenhouse gas concentrations, and because the Earth is now reflecting less sunlight to space than before.
In particular, 2023 and early 2024 saw ‘unprecedented’ ocean temperatures – with 450 days straight of record-breaking highs.
The researchers say that some of this warmth came from El Nino – a natural warming event in the Pacific.
But when the team compared it to a similar El Nino in 2015-16, they found that the rest of the record warmth could be explained by the sea surface warming up faster in the past 10 years than in earlier decades.
In fact, 44 per cent of the record warmth was attributable to the oceans absorbing heat at an accelerating rate.
Warming of ocean water might sound pleasant for holidaymakers, but previous research has warned that it could have devastating effects, including coral bleaching (pictured)
Warming of ocean water might sound pleasant for holidaymakers, but previous research has revealed that it could have devastating effects.
‘Warming of ocean water is raising global sea level because water expands when it warms,’ the NOAA previously explained.
‘Combined with water from melting glaciers on land, the rising sea threatens natural ecosystems and human structures near coastlines around the world.
‘Warming ocean waters are also implicated in the thinning of ice shelves and sea ice, both of which have further consequences for Earth’s climate system.
‘Finally, warming ocean waters threaten marine ecosystems and human livelihoods.
‘For example, warm waters jeopardize the health of corals, and in turn, the communities of marine life that depend upon them for shelter and food.
‘Ultimately, people who depend upon marine fisheries for food and jobs may face negative impacts from the warming ocean.’
Worryingly, the University of Reading team predicts that the worst is yet to come.
‘It is plausible that the ocean temperature increase seen over the past 40 years will be exceeded in just the next 20 years,’ they said in a statement.
Based on the findings, the researchers are calling for urgent action to curb carbon emissions.
‘This accelerating warming underscores 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 concluded.
Coral expel tiny marine algae when sea temperatures rise which causes them to turn white
Corals have a symbiotic relationship with a tiny marine algae called ‘zooxanthellae’ that live inside and nourish them.
When sea surface temperatures rise, corals expel the colourful algae. The loss of the algae causes them to bleach and turn white.
This bleached states can last for up to six weeks, and while corals can recover if the temperature drops and the algae return, severely bleached corals die, and become covered by algae.
In either case, this makes it hard to distinguish between healthy corals and dead corals from satellite images.
This bleaching recently killed up to 80 per cent of corals in some areas of the Great Barrier Reef.
Bleaching events of this nature are happening worldwide four times more frequently than they used to.
An aerial view of Australia’s Great Barrier Reef. The corals of the Great Barrier Reef have undergone two successive bleaching events, in 2016 and earlier this year, raising experts’ concerns about the capacity for reefs to survive under global-warming
