'The amount of heat we have put in the world's oceans in the past 25 years equals 3.6 billion Hiroshima atom bomb explosions'
The world's oceans were the hottest in recorded history in 2019, scientists said on Tuesday, as manmade emissions warmed seas at an ever-increasing rate with potentially disastrous impacts on Earth's climate.
Oceans absorb more than 90% of excess heat created by greenhouse gas emissions and quantifying how much they have warmed up in recent years gives scientists an accurate read on the rate of global warming.
A team of experts from around the world looked at data compiled by China's Institute of Atmospheric Physics (IAP) to gain a clear picture of ocean warmth to a depth of 2,000 metres over several decades.
They found that oceans last year were by far the hottest ever recorded and said that the effects of ocean warming were already being felt in the form of more extreme weather, rising sea levels and damage to marine life.
The study, published in the journal Advances in Atmospheric Sciences, said that last year the ocean was 0.075°C hotter than the historical average between 1981-2010.
That means the world's oceans have absorbed 228 Zetta Joules of energy in recent decades.
"That's a lot of zeros," said Cheng Lijing, lead paper author and associate professor at the International Centre for Climate and Environmental Sciences at the IAP.
"The amount of heat we have put in the world's oceans in the past 25 years equals 3.6 billion Hiroshima atom bomb explosions."
The past five years are the five hottest years for the ocean, the study found.
As well as the mid-term warming trend, the data showed that the ocean had absorbed 25 Zetta Joules of additional energy in 2019 compared with 2018's figure.
"That's roughly equivalent to everyone on the planet running a hundred hairdryers or a hundred microwaves continuously for the entire year," Michael Mann, director of Penn State's Earth System Sciences Center, told AFP.