Arctic may lose 1 million km² more winter sea ice than expected

Researchers from Cambridge and CIMAT revised winter Arctic sea ice projections downward by about 1 million km² using evidence from a warmer Arctic 6,000 years ago. The Bayesian weighting of 27 climate models cut projection uncertainty by up to 85%.

• Winter sea ice projections lowered by roughly 1 million km²
• Model uncertainty narrowed by as much as 85%
• Study used IP25 biomarker and 27 climate models
• March 2025 set a record low for maximum sea ice extent