UN reports warn 1.5C overshoot will damage Earth's ice

Two United Nations reports warned on November 2 that exceeding 1.5C of global warming would bring large-scale and in many cases irreversible damage to Earth's glaciers, sea ice, permafrost and other frozen regions.

The reports said melting ice, thawing permafrost and accelerating sea-level rise would have wide effects, including flooding and water shortages. They said some damage is already visible, including a 20 percent loss of glacial mass in Switzerland.

The UN reports said current warming levels are already unsafe for the Arctic, Antarctic, mountain glaciers and polar oceans. Global warming has reached 1.37C above pre-industrial levels, and the European Copernicus network says the 1.5C threshold could be exceeded around 2030.

One report, "Overshoot and the Cryosphere", was written with 80 scientists. Its lead author, glaciologist James Kirkham, said overshoot above 1.5C should be kept to "the absolute minimum" to limit damage from ice loss.

A second report, "State of the Cryosphere 2026. The Cost of Overshoot", said warming above 2.8C into the next century could lift sea-level rise to as much as five centimetres a year by 2150, compared with about 0.45 centimetres now. It also warned that thawing permafrost could release as much carbon dioxide each year as the United States emits.

The reports said returning to 1.5C or below by 2100 remains possible with sufficient political action, including faster movement away from fossil fuels to reach net zero by mid-century.