Ocean Temperatures Are Off the Charts, and El Niño is Only Partly to Blame

In a world of worsening climate extremes, a single red line has caught many people’s attention.

The line, which charts sea surface temperatures in the North Atlantic Ocean, went viral over the weekend for its startling display of unprecedented warming — nearly 2 degrees (1.09 Celsius) above the mean dating back to 1982, the earliest year with comparable data.