The pack ice located on the coasts of the Arctic is melting up to twice as fast as estimated so far, according to a study published on Friday, June 4, 2021. – Gavriil Grigorov / TASS / Sipa USA / SIPA
Twice as worrying as expected. According to a study, published in the journal The Cryosphere, the sea ice on the coasts of the Arctic is melting up to twice as fast as previously estimated. According to surveys from University College London (UCL), the ice in the main Arctic coastal regions is thinning at a rate 70 to 100% faster than the consensus.
If there is such a difference with the previous results, it is because the researchers used more recent maps of the thickness of the snow above the ice, which this time take into account the impact. decades of climate change. The thickness of the pack ice is in fact estimated by measuring the height of the ice above the water, a measurement distorted by the amount of snow hanging over the pack ice.
Previous calculations based on 20 year old maps
“Previous calculations of pack ice thickness were based on a snow map last updated 20 years ago,” said doctoral student Robbie Mallett, who led the study. “As the pack ice begins to form later and later in the year, the snow that covers it has less time to accumulate,” he continues. “Our calculations take this decrease into account for the first time and suggest that the sea ice is melting faster than we thought.”
The researchers used a European Space Agency satellite to calculate the height of the ice above the water and derive its actual total thickness, supplementing this estimate with a new model to calculate the thickness of the snow, developed with Colorado State University (USA). Combined, these results allowed them to measure the overall rate of ice decline, as well as its variability from year to year.
Towards an acceleration of global warming?
This is “a major step forward” to make “more precise the interpretation of the data we receive from satellites”, said Professor Julienne Stroeve, co-author of the report, recalling that the Arctic is warming three times faster than the world average. The thickness of the sea ice is also a “sensitive indicator of the health of the Arctic,” added Robbie Mallett.
“It’s important because thicker ice acts as an insulating blanket, preventing the ocean from warming the atmosphere in winter, and shielding the ocean from the sun in summer,” he explained, adding that ” thinner ice was also less likely to survive during the summer melt ”.