Climate, that’s why sea ice responds quickly to changes

Cnr researchers, Ca ‘Foscari University and Padua: “The reaction time is almost instantaneous”

The marine glacier responds immediately to the effects of climate changes. A study conducted by two research institutes of the National Research Council – Institute of Atmospheric and Climate Sciences (Isac) and Institute of Polar Sciences (Isp) – in collaboration with the Ca ‘Foscari University of Venice, the University of Padua and with various international institutes (Awi, Cic, Csic, Psi), has reconstructed, with high temporal resolution, the evolution of the coverage of sea ​​ice in the sub-polar region between Baffin Bay and the Labrador Sea, examining a series of sudden swings of the climate occurred between 36 and 44 thousand years ago. The research is published in Proceedings of the National Academy of Science (PNAS).

“The work combines two sea ice records: the first obtained through the analysis of sea salts (bromine and sodium) present in a glacial core extracted in north-western Greenland; the second based on the association of bio-markers present in a marine sediment core taken from the Labrador Sea “explains Federico Scotus of Cnr-Isac, who led the study. “The results show how, between the sub-polar regions of Baffin Bay and the Labrador Sea, the reaction time of sea ice, following a sharp increase in temperatures in Greenlandeither nearly synchronous, instantaneous or occurring over a decade, shifting from persistent thick multi-year coverage to offshore conditions and seasonal ice, “adds Scotus.

This evidence provides further evidence for the close relationship between global warming and Arctic sea ice reduction. “The climatic cycles known as Dansgaard-Oeschger (DO) events are characterized by an increase of up to +15 ° C in atmospheric temperatures in Greenland in a few decades, followed by a progressive cooling that can last up to 1-2 thousand years “continues Carlo Barbante, director of Cnr-Isp, professor at Ca ‘Foscari University and co-author of the study. Barbante adds that “although some hypotheses link these fluctuations to the change in coverage of the sea ​​ice in the Arctic, the dynamics and temporal link of the two processes were not entirely clear. This study sheds light on these aspects and confirms the importance of studying the climatic variations of the past to better understand the present ones and develop models for the future “.

The researchers recall that sea ice, or sea ice, forms in winter in the polar regions and is one of the fundamental climatic variables. The thickness of the Arctic sea ice can vary from a few tens of centimeters up to 5 meters, depending on the age of the ice: the newly formed first-year sea ice rarely exceeds one meter, is more fragile and subject to summer melting. compared to the multi-year one (multiyear sea ice), often up to several meters and longer lasting.

“In recent decades, due to anthropogenic warming, there has been a reduction in the extent of sea ice in the Arctic by 13% every ten years, compared to the period 1981-2010, and a volume loss of more than 60% compared to 1982, largely due to the progressive disappearance of multi-year ice. At this rate, based on future climate scenarios, the Arctic Ocean will be ice-free in summer as early as 2050 “warns Barbante.

“The new data confirms what was argued in a previous study that aimed to reconstruct the evolution of sea ice in the Canadian Arctic during the entire last Ice Age, but without the time resolution necessary to solve in detail the cyclical transitions from cold staging periods. , at warm inter-stadium periods “concludes Andrea Spolaor, researcher at Cnr-Isp, finally underlining that” thanks to the high resolution we have discovered that the multi-year sea ice has recovered in the period of return of the cold climate, suggesting a feedback cycle in which persistent sea ice accumulation could help the climate system transition to cold conditions. ”