The Arctic’s cooling power has decreased by about a quarter since 1980, and the world has lost up to 15% of its cooling ability, according to new research led by University of Michigan scientists.
Satellite measurements of cloud cover and the solar radiation reflected by sea ice between 1980 and 2023 have revealed that the decline in sea ice’s cooling power is approximately double the decrease in annual average sea ice area in both the Arctic and Antarctic. This change in sea ice cooling power is contributing to a greater warming impact, aligning with the higher end of climate model estimates.
“When we use climate simulations to quantify how melting sea ice affects climate, we typically simulate a full century before we have an answer,” said Mark Flanner, professor of climate and space sciences and engineering and the corresponding author of the study published in Geophysical Research Letters. “We’re now reaching the point where we have a long enough record of satellite data to estimate the sea ice climate feedback with measurements.”
The Arctic has experienced significant and consistent declines in sea ice cooling since 1980. In contrast, the Antarctic had seemed more resilient to climate change until recently, with stable sea ice cover from 2007 to the 2010s. However, in 2016, an area larger than Texas melted on one of the continent’s largest ice shelves, leading to a decline in Antarctic sea ice.
Unfortunately, its cooling power has not recovered since. This study suggests that 2016 and the subsequent seven years have had the weakest global sea ice cooling effect since the early 1980s.
The changing climate is causing the remaining ice to become less reflective, as warming temperatures and increased rainfall lead to thinner, wetter ice and more melt ponds. This is particularly evident in the Arctic, where sea ice has become less reflective during the sunniest parts of the year. A new study suggests that this trend could also be a significant factor in the Antarctic, alongside the loss of sea ice cover.
“The changes to Antarctic sea ice since 2016 boost the warming feedback from sea ice loss by 40%. By not accounting for this change in the radiative effect of sea ice in Antarctica, we could be missing a considerable part of the total global energy absorption,” said Alisher Duspayev, doctoral student in physics and the study’s first author.
The research team is dedicated to providing the climate science community with their latest estimates on sea ice’s cooling impact and the climate feedback from less reflective ice. This valuable information will be accessible through a regularly updated website that incorporates new satellite data as it becomes available.
“Climate change adaptation plans should bring aboard these new numbers as part of the overall calculus on how rapidly and how widely the impacts of cryospheric radiative cooling loss will manifest on the global climate system,” said Aku Riihelä, research professor at the Finnish Meteorological Institute and co-author of the study.
The research has been made possible through generous funding from the University of Michigan Rackham Graduate School and the Research Council of Finland.
Journal reference:
A. Duspayev, M. G. Flanner, A. Riihelä. Earth’s Sea Ice Radiative Effect From 1980 to 2023. Geophysical Research Letters, 2024; DOI: 10.1029/2024GL109608
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