Our planet’s oceans are warmer than they’ve ever been in recorded human history. And ocean temperatures are not only increasing, they are heating up at an accelerating rate, according to a new analysis.
In 2019, the ocean temperature was about 0.135 degrees Fahrenheit (0.075 degrees Celsius) higher than the average between 1981 and 2010, an international group of researchers reported on Jan. 13 in the journal Advances in Atmospheric Sciences.
That means that the ocean — which absorbs almost all of the greenhouse gases humans spew into the atmosphere — has taken in 228 sextillian (228,000,000,000,000,000,000,000) joules of heat above its average, according to a statement. By comparison, the energy released by the Hiroshima atom-bomb explosion was about 63,000,000,000,000 Joules.
«The amount of heat we have put in the world’s oceans in the past 25 years equals to 3.6 billion Hiroshima atom-bomb explosions,» lead author Lijing Cheng, associate professor with the International Center for Climate and Environmental Sciences at the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences (CAS), said in the statement. «There are no reasonable alternatives aside from the human emissions of heat-trapping gases to explain this heating.»
To analyze temperature changes in the oceans, Cheng and the team used all of the available data — measured from a number of different devices, including 3,800 drifting so-called Argo floats scattered across the oceans — published by the World Ocean Database and the National Oceanic and Atmospheric Administration. All of the measurements were taken between the surface of the water and a depth of 6,562 feet (2,000 meters).
They compared data taken between 1987 and 2019 with that taken from 1955 to 1986 and found that the oceans warmed 450% more in the more recent time stint than in the earlier bracket, according to the statement. The ocean has been the warmest in the past 10 years than it’s been since measurements were first taken in the 1950s.
The oceans can be a good measure of the effect of climate change since they absorb the majority of excess heat from the atmosphere, the researchers wrote. The effects of the warming are already appearing as more extreme weather, rising sea levels and harm to ocean animals, according to the statement.
Though humans can work to reverse the effects of climate change, the oceans — which absorbed more than 90% of the excess heat — will take longer to bounce back than the land and atmosphere, which only absorbed 4%, according to the statement.
«Even with that small fraction affecting the atmosphere and land, the global heating has led to an increase in catastrophic fires in the Amazon, California and Australia in 2019, and we’re seeing that continue into 2020,» Cheng said. «The global ocean warming has caused marine heat waves in Tasman Sea and other regions.»
One famous marine heat wave was the «blob,» which led to major loss of marine life in the North Pacific between 2013 and 2015. Another hotspot found in 2017 in the Gulf of Mexico helped to fuel Hurricane Harvey; and in 2018, another hotspot in the Atlantic Ocean was blamed for fueling Hurricane Florence.
«Global warming is real, and it’s getting worse,» co-author John Abraham, professor of thermal sciences at the University of St. Thomas in Minnesota, said in the statement. «And this is just the tip of the iceberg for what is to come.»