Editors’ Note: November 14, 2018

An earlier version of this article included a conclusion from a study about ocean warming that is now in doubt. The researchers are working to revise their study because of errors detected in their calculations and it appears unlikely that they will be able to support their original conclusion that the oceans have warmed an average of 60 percent more per year than the current official estimates by the Intergovernmental Panel on Climate Change. The sections of the article dealing with that conclusion have been removed and the headline has been updated.

Update: Sept. 26, 2019: Nature, the journal which initially published the study last year, announced on Wednesday that it was retracting the paper.

How do you take the ocean’s temperature?

The question might sound like the prelude to a children’s joke. But for climate scientists, the answer has serious consequences.

Climate change is rapidly warming the world’s oceans, killing off aquatic organisms — like coral reefs and kelp forests — that anchor entire ecosystems. The warmer waters also cause sea levels to rise and make extreme weather events like hurricanes more destructive.