Ocean heating is critical marker of climate change because an estimated 93 per cent of the excess solar energy trapped by greenhouse gases accumulates in the world’s oceans.
Unlike surface temperatures, ocean temperatures are not affected by year-to-year variations caused by climate events like El Nino or volcanic eruptions.
Heat trapped by greenhouse gases is raising ocean temperatures faster than previously thought, according to a new research which shows that earlier claims of a slowdown or “hiatus” in global warming over the past 15 years were unfounded.
“If you want to see where global warming is happening, look in our oceans,” said Zeke Hausfather, a graduate student at the University of California (UC) Berkeley, in the US.
“Ocean heating is a very important indicator of climate change, and we have robust evidence that it is warming more rapidly than we thought,” said Hausfather.
The new analysis, published in the journal Science, shows that trends in ocean heat content match those predicted by leading climate change models, and that overall ocean warming is accelerating.
Assuming a “business-as-usual” scenario in which no effort has been made to reduce greenhouse gas emissions, the Coupled Model Intercomparison Project 5 (CMIP5) models predict that the temperature of the top 2,000 metres of the world’s oceans will rise 0.78 degrees Celsius by the end of the century.
“The Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report, published in 2013, showed that leading climate change models seemed to predict a much faster increase in ocean heat content over the last 30 years than was seen in observations,” Hausfather said.
A fleet of nearly 4,000 floating robots drift throughout the world’s oceans, every few days diving to a depth of 2,000 metres and measuring the ocean’s temperature, pH, salinity and other bits of information as they rise back up.