Arctic sea ice thinning faster than expected: Researchers

Scientists adjust for this using a map of snow depth in the Arctic that is decades out of date and does not account for climate change.

New Delhi: 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 flow 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Scientists adjust for this using a map of snow depth in the Arctic that is decades out of date and does not account for climate change. 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 per cent faster than previously thought.

Robbie Mallett (UCL Earth Sciences), the PhD 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. Our calculations account for this declining snow depth for the first time, and suggest the sea ice is thinning faster than we thought.”

The researchers 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.