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Coastal sea ice is thinning faster than expected in the Arctic

A recent study led by University College London suggests that sea ice in coastal regions of the Arctic is thinning at up to double the rate that was expected. 

The researchers used a new computer model designed to estimate snow depth as it varies year to year. The results showed that coastal Arctic sea ice is thinning 70 to 100 percent faster than previously thought.

“The thickness of sea ice is a sensitive indicator of the health of the Arctic,” said study lead author Robbie Mallett. “It is important as thicker ice acts as an insulating blanket, stopping the ocean from warming up the atmosphere in winter, and protecting the ocean from the sunshine in summer. Thinner ice is also less likely to survive during the Arctic summer melt.”

“Previous calculations of sea ice thickness are based on a snow map last updated 20 years ago. Because sea ice has begun forming later and later in the year, the snow on top has less time to accumulate. Our calculations account for this declining snow depth for the first time, and suggest the sea ice is thinning faster than we thought.”

According to study co-author Professor Julienne Stroeve, there are a number of uncertainties in measuring sea ice thickness, but the researchers believe their new calculations represent a major step forward in terms of more accurately interpreting satellite data.

“We hope this work can be used to better assess the performance of climate models that forecast the effects of long-term climate change in the Arctic – a region that is warming at three times the global rate, and whose millions of square kilometres of ice are essential for keeping the planet cool.”

The experts used radar from the European Space Agency’s CryoSat-2 satellite to calculate sea ice thickness. They combined the data with a new computer model that calculates snow depth and density using inputs such as air temperature, snowfall, and ice motion. 

Based on this information, the team estimated the overall rate thinning sea ice in the Arctic, as well as the variability of sea ice thickness from year to year.

When compared to earlier calculations, the rate of decline had increased across the three coastal seas of Laptev, Kara and Chukchi seas by 70, 98, and 110 percent respectively. Furthermore, across all seven coastal seas, the variability in sea ice thickness from year to year increased by 58 percent.

The rapid thinning of sea ice in the coastal Arctic seas has implications for human activity in the region, both in terms of shipping along the Northern Sea Route for a larger part of the year, as well as the extraction of resources from the sea floor such as oil, gas and minerals.

“More ships following the route around Siberia would reduce the fuel and carbon emissions necessary to move goods around the world, particularly between China and Europe. However, it also raises the risk of fuel spillages in the Arctic, the consequences of which could be dire,” said Mallett. 

“The thinning of coastal sea ice is also worrying for indigenous communities, as it leaves settlements on the coast increasingly exposed to strong weather and wave action from the emerging ocean.”

The study is published in the journal Cryosphere.

By Chrissy Sexton, Staff Writer

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