According to NASA, the increased rate of thickening of sea ice in the Arctic is due to Global Warming.
Wintertime Arctic Sea Ice Growth Slows Long-term Decline: NASA
Dec. 7, 2018
New NASA research has found that increases in the rate at which Arctic sea ice grows in the winter may have partially slowed down the decline of the Arctic sea ice cover.
As temperatures in the Arctic have warmed at double the pace of the rest of the planet, the expanse of frozen seawater that blankets the Arctic Ocean and neighboring seas has shrunk and thinned over the past three decades. The end-of-summer Arctic sea ice extent has almost halved since the early 1980s. A recent NASA study found that since 1958, the Arctic sea ice cover has lost on average around two-thirds of its thickness and now 70 percent of the sea ice cap is made of seasonal ice, or ice that forms and melts within a single year.
But at the same time that sea ice is vanishing quicker than it has ever been observed in the satellite record, it is also thickening at a faster rate during winter. This increase in growth rate might last for decades, a new study accepted for publication in Geophysical Research Letters found.