New! Coastal Arctic Sea Ice Is Thinning More Rapidly Than Expected

Sea ice in the Arctic’s coastal regions may be decreasing far quicker than experts previously thought.
According to research released yesterday, ice in locations like the Kara, Laptev, and Chukchi seas, which border sections of Siberia and Alaska, looks to be vanishing roughly twice as quickly as projections have shown.
That’s likely because a prior study didn’t adequately account for a major aspect in the Arctic: the effects of climate change on snow.

Measuring sea ice thickness is a hard job. The thickness of sea ice, unlike its extent (the area of water covered by ice at any particular time), cannot be estimated using satellite pictures.
Instead, scientists use special satellite equipment to send out radar pulses that hit the ice and reflect, telling them the height of the ice jutting up from the water’s surface. This data aids them in determining the thickness of the ice.
“It’s a little like yelling at a faraway wall and waiting for the echo to come back,” said Robbie Mallett, a Ph.D. student at University College London and the main author of the new study.
However, there is a catch.

As snow accumulates, it can weigh the ice down, forcing it to sink deeper into the lake. To precisely determine the thickness of the ice, scientists must account for the quantity of snow on top.
Until recently, several research organizations relied on a snow map created from data gathered by floating stations strewn across the ocean. The map shows how thick the snow is in different locations of the Arctic at different times of the year.
The problem is that the information is many decades old.

The graphic doesn’t take into account changes in sea ice over time, especially those driven by Arctic warming.
“The Arctic was primarily covered with multi-year ice when it was built,” said Nathan Kurtz, a NASA sea ice expert who spoke to E&E News about the new findings.
Multi-year ice is thicker than first-year ice because it has survived more than one season. However, research suggests that the melting Arctic has seen most of its multi-year ice vanish in recent decades. The remaining younger ice hasn’t had as much time to gather snow as the older ice.

As a result, the earlier snow map may not accurately depict the new, warmer Arctic.
The new study estimates ice thickness in the coastal Arctic waters using a more dynamic snow model. It discovers that ice thickness varies considerably more substantially from year to year than prior research has predicted.
It also discovers that ice is thinning over time and that these weakening patterns are significantly more pronounced than a prior study suggested.

Sea ice thickness is a trend that receives less attention than sea ice extent. Thinner, more unstable ice, on the other hand, might have major consequences for the Arctic climate system as well as human operations in the Arctic Ocean.
In the summer, thinner ice breaks easier melts faster and enables more sunshine to reach the lake below. It has the potential to hasten Arctic warming and cause ice extent to disappear even more rapidly. It may make shipping and oil drilling simpler, but it will make ice fishing and hunting more difficult, especially for Indigenous peoples.

Climate models use sea ice thickness to create predictions about how the Arctic will evolve in the future. As a result, the data must be correct.
The necessity of adopting up-to-date snow readings is demonstrated in this recent study. It also shows how different snow maps yield varied results in various Arctic locations.
However, it is not the first to raise the concern.
Scientists began revising the older snow map around a decade ago to adapt it for a warmer Arctic with younger ice, according to Kurtz.

“It looked to operate quite well,” he remarked, “but it was still quite constrained.” “It’s preferable to start working towards it when we have better tools and better model data.”
Research institutes have begun to switch to newer, more dynamic snow models in recent years.
For example, NASA has built its model, which it is putting to use in studies by ICESat-2, a satellite mission that is studying polar climate change, including the height and thickness of the world’s ice. According to Kurtz, the NASA scientist, it’s comparable to the snow model used in Mallett’s current study.

At the same time, a 2019 special report from the Intergovernmental Panel on Climate Change noted that data on the level of snow on sea ice is still scarce. According to the paper, this is a major constraint in estimating sea ice thickness.
However, there are a few tendencies that stand out. Arctic sea ice has been thinner on average over the last few decades as older ice has vanished and new ice has replaced it.

While scientists seek to improve their predictions of how quickly and where the ice is diminishing, Mallett believes that improved snow data is a step in the right direction.
“Probably, it’s about to be a lot more fascinating for sea ice aficionados who watch sea ice thickness,” he added.