Wintertime ice growth in Arctic sea slows long-term decline: NASA

While sea ice in the Arctic continues to be on the decline, a new research from the US Space agency suggests that it is regrowing at faster rates during the winter than it was a few decades ago.

The findings showed 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, explained the researchers, in the paper to be published in the journal Geophysical Research Letters.

However, this does not mean that the ice cover is recovering, though. Just delaying its demise.

“This increase in the amount of sea ice growing in winter doesn’t overcome the large increase in melting we’ve observed in recent decades,” said lead author Alek Petty, a sea ice scientist at NASA’s Goddard Space Flight Center in Maryland.

“Overall, thickness is decreasing. Arctic sea ice is still very much in decline across all seasons and is projected to continue its decline over the coming decades,” she added.

To explore sea ice growth variability across the Arctic, the team used climate models and observations of sea ice thickness from the European Space Agency’s CryoSat-2 satellite.

They found that in the 1980s, when Arctic sea ice was on average 6.6 feet thick in October, about 3.3 extra feet of ice would form over the winter.

This rate of growth may continue to increase, and in the coming decades, we could also have an ice pack that would on average be only around 3.3 feet thick in October, but could experience up to five feet of ice growth over the winter.

However, by the middle of the century, the strong increases in atmospheric and oceanic temperatures will outweigh the mechanism that allows ice to regrow faster, and the Arctic sea ice cover will decline further, Petty said.

The switch will happen once the sea ice is less than 1.6 feet thick at the beginning of winter, or its concentration — the percentage of an area that is covered in sea ice — is less than 50 percent, she noted.