Overview
- From October 2024 to September 2025, Arctic surface air temperatures averaged 1.60°C above the 1991–2020 mean, marking the warmest year in records dating to 1900 and including the warmest autumn, second-warmest winter, and third-warmest summer.
- The March 2025 sea-ice maximum was the smallest in the 47-year satellite era, and roughly 95% of the Arctic’s oldest, thickest ice has vanished, shrinking reflective cover and reinforcing regional warming.
- Satellite analyses identified more than 200 “rusting rivers” where permafrost thaw is releasing iron and other elements, turning waters orange and degrading water quality through higher acidity and metal concentrations.
- Greenland continued to add meltwater to the ocean, contributing to sea-level rise, as the Arctic grew warmer and wetter with record-high spring precipitation and increasing tundra greenness.
- Scientists report advancing “Atlantification,” with warmer, saltier Atlantic waters moving north and reshaping ecosystems and heat transfer, and they cite cascading impacts including an October 2025 storm that struck Alaska with hurricane-force winds.