Sustainability Climate Change

Oceans have hit highest temperatures ever recorded

Ocean temperatures are higher than ever recorded

Story at a glance

  • The oceans absorb 90 percent of the excess heat trapped by the greenhouse gases humans have been pumping into the atmosphere since the industrial revolution.
  • This means ocean temperatures offer a crystal clear window into the progression of global heating caused by climate change.
  • A new analysis finds the oceans are now hotter than ever recorded, revealing the acceleration of climate change.

Ocean temperatures in 2019 were higher than ever, capping the end of a decade that contained all 10 of the hottest years ever recorded, according to new research

The oceans absorb 90 percent of the excess heat trapped in the atmosphere by human greenhouse gas emissions. As a result, the ocean is ruthlessly accurate in tracking the “irrefutable and accelerating” progression of climate change. The last five years also included the five hottest ever seen in the oceans, the Guardian reports.  

The heat energy absorbed by the oceans raised its temperature to about 0.135 degrees Fahrenheit above the 1981-2010 average in 2019. The heat energy that human activity has bombarded the oceans with over the last 25 years is equivalent to the detonation of 3.6 billion Hiroshima atomic bombs, lead author Lijing Cheng said in a press release.

“The oceans are really what tells you how fast the Earth is warming,” John Abraham, one of the authors of the new paper, told the Guardian. “Using the oceans, we see a continued, uninterrupted and accelerating warming rate of planet Earth. This is dire news.”

Another of the researchers who worked on the analysis, Michael Mann, underscored its results: “We found that 2019 was not only the warmest year on record, it displayed the largest single-year increase of the entire decade, a sobering reminder that human-caused heating of our planet continues unabated.” 

Apart from reflecting the increasing global temperatures caused by human-induced climate change, warming seas have negative consequences for humans and the natural world. Hotter oceans fuel stronger storms and cause sea level to rise. Increasingly common marine heatwaves have decimated the coral reefs as well as kelp forests around the world — destroying key habitats for countless fish, crustaceans and other species.

The research leveraged ocean temperature data from all available sources, but the most comprehensive measurements come from a fleet of 3,800 floating instruments called Argo floats scattered throughout the world’s oceans. 

The researchers found ocean temperatures are increasing at an accelerating rate, in lockstep with the accumulation of greenhouse gases in the atmosphere caused by human activities. The rate of warming from 1987 to 2019 is four and a half times faster than it was between 1955 and 1986. 

The data is the best available and the statistical analysis is state of the art, according to climate researcher Dan Smale, who was not part of the analysis team. 

The National Oceanographic and Atmospheric Administration conducted an independent analysis using the same data and came to the same worrying conclusions.

“The data we have is irrefutable, but we still have hope because humans can still take action,” Abraham told the Guardian. “We just haven’t taken meaningful action yet.”