Strong waves crash against rocks in southwestern France during high tide on the Atlantic Ocean in February 2014. A recent study suggests that the global warming slowdown of the past 15 years may be due to heat 'hiding' deep in the Atlantic.

(GAIZKA IROZ/AFP/Getty Images)

Global warming accelerated rapidly from the 1970s through the 1990s but abruptly slowed down after that, and exactly why has been a puzzle climate scientists have been trying to solve ever since.

This pause or hiatus in warming, as it's come to be known, has been blamed on a range of causes, from a lack of adequate surface temperature measurements around the world to a buildup of heat in the Pacific Ocean, which many scientists believe will be released with the next El Niño.

But a new investigation published this week in the journal Science says the cause lies not in either of those, but in the Atlantic Ocean. “We found the missing heat,” said study co-author Xianyao Chen, an oceanographer with the Ocean University of China in Qingdao, in an interview with Science.

He and his co-author Ka-Kit Tung of the University of Washington say their research -- millions of measurements of ocean temperatures taken around the world by sensors on buoys and ships since 1970 -- suggests that an Atlantic "conveyor belt" current has been taking heat that otherwise would have come to surface down instead to the depths of the sea.

The sensors included floats that could dive to depths of nearly a mile below the ocean surface, National Geographic points out, and that's how the scientists discovered that temperatures in the Atlantic are warming up more and at much deeper depths than in the Pacific or Indian Oceans.

"This heat storage deep in the Atlantic, below about a thousand feet (300 meters), is what has allowed the current pause in rising average surface temperatures globally," National Geographic says of Tung and Chen's research.

It's worth pointing out that since the so-called "pause" in global warming began, however, the world has experienced 13 of its 14 hottest years on record and the United States saw its hottest year in history in 2012.

Also, this study is one in a long line of studies in recent years that seek to explain the cause of the "pause" -- and that it likely will continue to be a source of intensive scientific study at least until this hiatus ends, a phenomenon that could occur at any time.

"The frightening part," Tung told National Geographic, is that "it's going to warm just as fast as the last three decades of the 20th century, which was the fastest warming we've seen."

See the full story in National Geographic, or read the study in Science.

MORE FROM WEATHER.COM: Powerful Photos of Climate Change Impacts

An emaciated polar bear is seen on a small sheet of ice in this image taken in August in Svalbard, north of mainland Norway. (Kerstin Langenberger)