The Arctic could be deprived of sea ice in summer as early as the 2030s, much earlier than previously estimated, even under a scenario of low greenhouse gas emissions, say researchers in a paper published on Tuesday 6 June.
The scientists, based in Korea, Canada and Germany, used observational data from the period 1979-2019 to run new simulations. "The results indicate that the first month of September without sea ice will occur as early as the 2030s-2050s, regardless of emissions scenarios," they conclude in the journal Nature Communications.
When experts refer to the absence of sea ice, this corresponds to an area of less than 1 million square kilometers; there may still be residual ice along the coasts. By way of comparison, the surface of the sea ice fluctuated between 10 and 14 million square kilometers in 2022, according to the National Snow and Ice Data Center (NSIDC), an American university institute specializing in the study of regions covered by ice.
"This is about a decade earlier than recent IPCC projections," the UN-mandated Intergovernmental Panel on Climate Change, says paper co-author Seung-Ki Min, of universities South Koreans from Pohang and Yonsei.
Scientists also believe that the decline of this ice can be attributed mainly to greenhouse gas emissions, the other factors (aerosols, solar and volcanic activity in particular) being much less important.
"Accelerating Global Warming"
Pack ice – or sea ice – is made up of salt water on the surface of an ocean, which has frozen over due to the cold. Its melting does not directly cause a rise in the level of the oceans (unlike that of the ice cap and glaciers), since its volume is already part of the liquid ocean but still has harmful consequences.
Indeed, this ice plays a very important role in summer, by reflecting the Sun's rays back into space, which cools the Arctic. This mirror effect, called albedo, is now increasingly weak, and the Arctic is therefore warming much faster than other regions.
The disappearance of the ice will "accelerate arctic warming, which can increase extreme weather events at mid-latitudes, such as heat waves and wildfires," says co-author Seung-Ki Min, from South Korea's Pohang and Yonsei Universities. of the item. "It may also accelerate global warming, by melting permafrost (grounds that remain frozen year-round), as well as sea level rise by melting the Greenland Ice Sheet," the researcher adds.
"This will be the first major component of our climate system that we lose through our greenhouse gas emissions," adds Dirk Notz of the University of Hamburg, another co-author of the study. "Scientists have been warning about this disappearance for decades, and it's sad to see that these warnings have largely gone unheeded," he said.
Notz now hopes policymakers will pay heed to the researchers' findings "so that we can at least protect the other components of our climate system, limiting future warming as much as possible."
