A new study has found that the cooling power of sea ice is decreasing faster than its area

As sea ice disappears and becomes less reflective, the Arctic has lost about a quarter of its cooling capacity since 1980, and the world has lost up to 15%, according to new research led by University of Michigan scientists.

Using satellite measurements of cloud cover and solar radiation reflected by sea ice between 1980 and 2023, the researchers found that the percentage decrease in the cooling power of sea ice is about twice the percentage decrease in the average annual Arctic sea ice area. and Antarctica. Another warming impact from this change in sea ice cooling is toward the upper end of climate model estimates.

“When we use climate simulations to quantify how melting sea ice affects the climate, we typically simulate for a century before we have an answer,” said Mark Flanner, professor of climate and space sciences and engineering and corresponding author of the study published in Geophysical Research Letters. “We are now getting to the point where we have a long enough satellite data record to estimate the sea ice climate feedback using measurements.”

The Arctic has seen the largest and most steady decline in the cooling energy of sea ice since 1980, but until recently the South Pole appeared to be more resilient to a changing climate. Its sea ice cover remained relatively stable from 2007 to 2010, and the cooling power of Antarctic sea ice actually increased during that time.

That view suddenly changed in 2016, when an area larger than Texas melted on one of the continent’s largest ice shelves. Antarctica also lost sea ice then, and its cooling power has not recovered, according to the new study. As a result, 2016 and the following seven years had the weakest global sea ice cooling effect since the early 1980s.

Behind the disappearing ice sheet, the remaining ice is also less reflective, as warming and increased precipitation create thinner, wetter ice and more melting ponds that reflect less sunlight. This effect was most pronounced in the Arctic, where sea ice was less reflective during the sunniest parts of the year, and the new study raises the possibility that it could be an important factor in Antarctica as well — in addition to the lost sea. ice sheet.

“Changes in Antarctic sea ice since 2016 increase the warming feedback due to sea ice loss by 40%. If we did not account for this change in the radiative effect of Antarctic sea ice, we could lose a significant part of the total global energy absorption.” ” said Alisher Duspayev, a PhD student in physics and first author of the study.

The research team hopes to provide their updated estimates of sea ice cooling capacity and climate feedback from less reflective ice to the climate science community through a website that will be updated whenever new satellite data becomes available.

“Climate change adaptation plans should include these new numbers as part of an overall calculation of how quickly and how widely the effects of cryospheric radiative cooling will affect the global climate system,” said Aku Riihelä, a research professor at the Finnish Meteorological Institute. and co-author of the study.