But researchers cautioned that the glacier is still adding to global sea level rise because it is still losing more ice to the ocean than it gains from snow accumulation, although at a slower rate.
They theorized that the slowdown in ice melt was caused by an ocean current that brought much colder water to the glacier's ocean face in 2016. Water temperatures near the glacier are now colder than they've been since 2016, according to NASA.
The researchers were shocked by the discovery that the glacier was thickening again.
“At first, we didn’t believe it,” Ala Khazendar, with the Jet Propulsion Lab, said. “We had pretty much assumed Jakobshavn would just keep going on as it had over the last 20 years.”
Khazendar pointed to the cold water near the glacier for three straight years as one of the reasons it’s growing again.
Researchers said they don't expect that trend to continue. When the climate pattern flips again, the glacier will most likely start accelerating and thinning again, researchers said.