The deep oceans have recently been soaking up much of the excess heat trapped under the ever-thickening blanket of greenhouse gases that humans pump into the atmosphere, according to a recent study.

The finding may help explain why the pace of global warming at the surface has slowed in recent years compared to the 1990s, a phenomenon that has left members of the climate science community scratching their heads.

“The warming at the surface hasn’t stopped, but it has been less than most of the climate models have been predicting,” David Pierce, a climate researcher with the Scripps Institution of Oceanography, explained to NBC News. “So the question is: Where is that extra heat going?”