The work of Simon Josey, from the National Oceanography Center in Southampton (United Kingdom), and his colleagues, explores a still poorly understood aspect of the impact of sea ice shrinkage: the transfer of heat to the atmosphere. from the ocean surface.
This phenomenon, which increases when the sea ice cover does not fully recover during the winter, is accompanied by an increase in storms according to their results, which combine the analysis of satellite images of the Antarctic sea ice , data on heat fluxes between the ocean and the atmosphere, as well as temperature and wind speed records.
“Repetition of such episodes of sharp decline in sea ice in subsequent winters will reinforce these impacts and are also likely to lead to profound changes in more distant areas, including the tropics and the northern hemisphere,” they warn, recommending in-depth studies of the impact of these phenomena on the global climate system.
In three areas particularly affected by the historic shrinkage of the Antarctic sea ice in 2023, the researchers compared the data collected during the southern winter to the averages observed during the winters of the periods 1990-2015 (marked by a relative stability of its extent) and 2016-2022 (a phase of marked decline).
In these regions, the reduction in sea ice extent reached up to 80% compared to the pre-2016 average and was accompanied by an increase in the redistribution of heat from the ocean. towards the atmosphere up to a doubling.
At the same time, the frequency of storms has increased compared to the period 1990-2015, with sometimes up to seven additional days marked by winds above 36 km/h during the winter of 2023.
“Additional analyzes (…) are necessary” to more precisely determine the cause and effect relationship, emphasize the authors.
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