The phenomenon, known as Arctic amplification, sees the region warming two to four times faster than the global average. Traditionally, this is attributed to the so-called ice-albedo feedback: as snow and ice melt, darker surfaces emerge, absorbing more sunlight and increasing surface temperatures. But researchers led by Professor Chuanfeng Zhao have identified a counteracting mechanism involving cloud dynamics that may buffer some of this warming.
Using two decades of satellite data from NASA's CERES mission (2000-2020) alongside CMIP6 climate model simulations, the team observed that the loss of snow and ice coverage - declining by 0.016 per decade - has intensified the cloud short-wave radiative cooling effect. Even when cloud characteristics remain static, this effect alone generates measurable cooling.
"This, in turn, partially slows down further melting of snow and ice, offering a new perspective on the self-regulating mechanisms of the climate system," said Annan Chen, a PhD candidate and lead author of the study.
Their analysis indicates that the cooling effect leads to a radiative reduction of -1.25 +/- 0.49 W/m at the top of the atmosphere and -0.21 +/- 0.20 W/m at the surface each decade. This has translated into an average decrease of 3.45 cm in sea ice melt per year, with peak local reductions reaching up to 10 cm. The influence is most pronounced during the summer months of continuous daylight, particularly June and July.
Under the high-emissions SSP585 scenario, model projections suggest that Arctic sea ice will shrink by 83% by 2100. However, the associated increase in cloud-induced radiative cooling is expected to intensify, illustrating a complex co-evolution among clouds, surface albedo, and cryospheric change.
While the cooling influence of clouds cannot reverse overall melting trends driven by greenhouse gases, it adds an important regulatory layer to climate models. The research underscores that despite this moderating effect, Arctic ice loss remains a largely irreversible process in the context of continued global warming.
Professor Zhao is the corresponding author, with contributions from Professors Jing Li and Qinghong Zhang, Assistant Professor Yan Yu, postdoctoral researchers Haotian Zhang and Yikun Yang, and doctoral researcher Jiefeng Li.
Research Report:Weakened snow and ice melting by enhanced cloud short-wave cooling effect in the Arctic
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