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The Arctic Ocean ice sheet will disappear in summer as soon as the 2000s and a decade sooner than previously thought, no matter how aggressively humanity pulls in the carbon pollution that drives global warming, scientists said Tuesday. scientists.
Even limiting global warming to 1.5 degrees Celsius in line with the Paris climate treaty won’t stop the North Pole’s vast expanse of drift ice from melting in September, they reported in Nature communications.
“It is too late to protect Arctic summer sea ice as a landscape and as a habitat any longer,” co-author Dirk Notz, a professor at the University of Hamburg’s Institute of Oceanography, told AFP.
“This will be the first major component of our climate system that we lose as a result of our greenhouse gas emissions.”
Declining ice cover has serious impacts over time on climate, people and ecosystems, not just within the region, but globally.
“It can accelerate global warming by melting greenhouse gas-laden permafrost and sea level rise by melting the Greenland ice sheet,” lead author Seung-Ki Min, a researcher at Pohang University of Science, told AFP. and Technology in South Korea.
Greenland’s kilometre-thick ice sheet contains enough frozen water to lift the oceans by six metres.
In contrast, melting sea ice has no visible impact on sea level because the ice is already in the ocean water, like ice cubes in a glass.
But it fuels a vicious cycle of warming.
Three times faster
About 90 percent of the sun’s energy hitting white sea ice is reflected back into space.
But when sunlight hits dark, unfrozen ocean water instead, nearly the same amount of that energy is absorbed by the ocean and scattered around the world.
Both the North Pole and South Pole regions have warmed by three degrees Celsius since late 19th-century levels, nearly three times the global average.
An ice-free September in 2030 “is a decade faster than recent projections by the Intergovernmental Panel on Climate Change (IPCC),” the United Nations’ scientific advisory body, said the min.
In its landmark 2021 report, the IPCC predicted with “high confidence” that the Arctic Ocean would become virtually ice-free at least once by mid-century, and even then only under more extreme greenhouse gas emission scenarios.
The new study, which draws on observational data covering the period 1979-2019 to adjust IPCC models, finds that the threshold will most likely be exceeded in the 2040s.
Min and his colleagues also calculated that human activity was responsible for up to 90 percent of the shrinkage of the ice sheet, with only minor impacts due to natural factors such as solar and volcanic activity.
The record low Arctic sea ice extent of 3.4 million square kilometers (1.3 million square miles) occurred in 2012, with the second and third lowest ice covered areas in 2020 and 2019 , respectively.
Scientists describe the Arctic Ocean as “free of ice” if the area covered by ice is less than one million square kilometers, about seven percent of the total ocean area.
Sea ice in Antarctica, meanwhile, fell to 1.92 million square kilometers in February, the lowest level on record and almost a million square kilometers below the 1991-2020 average.
Yeon-Hee Kim et al, Observationally limited projections of an ice-free Arctic even under a low-emissions scenario, Nature communications (2023). DOI: 10.1038/s41467-023-38511-8
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