But the heat the ocean had stored had to go somewhere: “It’s come out and been distributed around the world,” which helps explain record warm temperatures and wildfires in the Southern Hemisphere, Mr. Trenberth said.

To get an idea of how much of the record heat is caused by El Niño and how much by global warming, Dr. Blunden said that scientists at NOAA compared this El Niño to the last strong one, in 1997-98, which was also record-setting for its warmth. This one has pushed past those records by raising global temperatures an additional 0.8 degree or so, Dr. Blunden said.

The high temperatures in March probably signaled the last gasp of El Niño, and surface temperatures across the globe are likely to begin to fall this year. Often, El Niños are followed by La Niña storm systems, which can usher in cooler periods, Dr. Blunden said.

But after more than two record-setting hot years — 2014 and 2015 and an extremely warm few months in 2016 — many of the devastating effects of the one-two punch of global warming and El Niño may be inescapable, setting the world on a course for an extended period of rapid global warming, after a period of relatively slow warming that began in 1998 and lasted for about a decade.