Hexbyte Glen Cove Arctic sea ice thinning faster than expected thumbnail

Hexbyte Glen Cove Arctic sea ice thinning faster than expected

Hexbyte Glen Cove

The research vessel Polarstern drifting in Arctic sea ice. Source: MOSAiC website image library https://multimedia.awi.de/mosaic/ . Credit: Alfred-Wegener-Institut

Sea ice in the coastal regions of the Arctic may be thinning up to twice as fast as previously thought, according to a new modelling study led by UCL researchers.

Sea ice thickness is inferred by measuring the height of the ice above the water, and this measurement is distorted by snow weighing the ice floe down. Scientists adjust for this using a map of snow depth in the Arctic that is decades out of date and does not account for .

In the new study, published in the journal The Cryosphere, researchers swapped this map for the results of a new computer model designed to estimate snow depth as it varies year to year, and concluded that sea ice in key coastal regions was thinning at a rate that was 70% to 100% faster than previously thought.

Robbie Mallett (UCL Earth Sciences), the Ph.D. student who led the study, said: “The thickness of sea ice is a sensitive indicator of the health of the Arctic. 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.”

3D picture of the floe based on highly resolved aerial imagery from the helicopter nadir camera. Source: MOSAiC image gallery https://multimedia.awi.de/mosaic/#1622663686901_1 . Credit: Alfred-Wegener-Institut / Niels Fuchs

Co-author Professor Julienne Stroeve (UCL Earth Sciences) said: “There are a number of uncertainties in measuring sea ice thickness but we believe our new calculations are a major step forward in terms of more accurately interpreting the data we have from satellites.

“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.”

To calculate sea ice thickness researchers used radar from the European Space Agency’s CryoSat-2 satellite. By timing how long it takes for radar waves to bounce back from the ice, they can calculate the height of the ice above the water, from which they can infer the ice’s total thickness.

In the new study, researchers used a novel snow model previously developed by researchers at UCL and Colorado State University, SnowModel-LG, which calculates snow depth and density using inputs such as air temperature, snowfall and ice motion data to track how much snow accumulates on sea ice as it moves around the Arctic Ocean. By combining the results of the snow model with satellite radar observations, they then estimated the overall rate of decline of sea ice thickness in the Arctic, as well as the variability of sea ice thickness from year to year.

Polar bears close to the research vessel Polarstern. Source: MOSAiC image gallery https://multimedia.awi.de/mosaic/#1622663686901_1 . Credit: Alfred-Wegener-Institut

They found that the rate of decline in the three coastal seas of Laptev, Kara and Chukchi seas increased by 70%, 98% and 110% respectively, when compared to earlier calculations. They also found that, across all seven coastal seas, the variability in from year to year increased by 58%.

Sea ice in the coastal seas typically varies from half a metre to two metres thick. Increasingly, the ice in this region is not surviving the summer melt. The faster 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.

Mallett said: “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. 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.”

Mallett, Professor Stroeve and co-author Dr. Michel Tsamados (UCL Earth Sciences) spent several weeks investigating and ice in the Arctic onboard the German research vessel Polarstern, which explored the central Arctic Ocean in 2019 and 2020.

More information:
“Faster decline and higher variability in the sea ice thickness of the marginal Arctic seas when accounting for dynamic snow cover”, The Cryosphere (2021). tc.copernicus.org/articles/15/2429/2021/

Arctic sea ice thinning faster than expected (2021, June 3)
retrieved 4 June 2021
from https://phys.org/news/2021-06-arctic-sea-ice-thinning-faster.html

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part may be reproduced without the written permission. The content is provided for information purposes only.

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Hexbyte Glen Cove Arctic ground squirrels recycle nutrients to endure deep hibernation thumbnail

Hexbyte Glen Cove Arctic ground squirrels recycle nutrients to endure deep hibernation

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A researcher at the University of Alaska Fairbanks holds a hibernating Arctic ground squirrel. Credit: Carla Frare

By studying the body chemistry of hibernating Arctic ground squirrels, researchers have found that the animals are able to recycle their body’s own nutrients to survive during a long, inactive winter.

A University of Alaska Fairbanks-led study monitored in a laboratory environment for two years, measuring the almost undetectable flow of nutrients through their hibernating bodies. As the ground squirrels’ muscles slowly broke down in temperatures just above freezing, researchers found that the animals were able to convert the free nitrogen they were creating into amino acids.

Using those , the ground squirrels may be able to synthesize protein in tissues such as lungs and kidneys, and .

The discovery could unlock more of the mysteries of hibernation, leading to new insights in human medicine. The study was published Dec. 7 in the journal Nature Metabolism.

Researchers have been fascinated by the body chemistry of Arctic ground squirrels because of the rodents’ long, deep hibernation periods. Their bodies almost entirely shut down for as long as 8 months a year, going without food and water while breathing just once per minute. Despite that, hibernating ground squirrels are uniquely resilient to muscle loss and long-term cellular damage.

“They’re just this extreme hibernator, and during the time they hibernate they don’t eat, they don’t drink, and they don’t have any underlying injuries to their bodies,” said Sarah Rice, a Ph.D. student at UAF’s Institute of Arctic Biology and lead author of the paper.

The findings complement previous research that suggested that hibernators recycle urea, a waste product that is excreted in urine. Researchers had theorized that those animals also recycle nitrogen to retain their body tissue during extreme fasting, but the new study offers the first time that process has been confirmed in on a metabolic scale.

Learning more about the biochemistry of hibernation could contribute to a variety of potential medical treatments for humans, including the prevention of muscle loss in cancer patients and the elderly. Understanding biological adaptations that are made during hibernation could also help treat traumatic injuries and aid astronauts during .

By analyzing how hibernators keep themselves healthy, the approach offers a than therapies that often focus on overcoming and treating injuries, Rice said.

“It’s fun to kind of turn that idea on its head,” Rice said. “Instead of studying what goes wrong in the world, it’s important to study what goes right.”

More information:
Nitrogen recycling buffers against ammonia toxicity from skeletal muscle breakdown in hibernating arctic ground squirrels, Nature Metabolism (2020). DOI: 10.1038/s42255-020-00312-4, www.nature.com/articles/s42255-020-00312-4

Arctic ground squirrels recycle nutrients to endure deep hibernation (2020, December 7)
retrieved 7 December 2020
from https://phys.org/news/2020-12-arctic-ground-squirrels-recycle-nutrients.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.