UN reports warn of lasting damage to glaciers and ice beyond 1.5C

Two U.N. reports released on Monday warn that exceeding 1.5C of global warming will have irreversible consequences for glaciers, sea ice and the Earth's frozen regions. The reports call for urgent action.

The 2015 Paris Agreement commits the world to limiting warming to well below 2C and pursuing efforts to hold it at 1.5C. According to the European Copernicus network, warming has already reached 1.37C above preindustrial levels, and the 1.5C threshold could be exceeded around 2030.

One report, 'Overshoot and the Cryosphere', was written with 80 scientists. It says overshooting 1.5C will bring large-scale and in many cases irreversible impacts for the cryosphere. Melting glaciers and sea ice, thawing permafrost and accelerating sea level rise will have widespread repercussions, including flooding and water shortages. Glacial mass in Switzerland has already fallen by 20%.

The U.N. warns that current warming levels are already unsafe for the Arctic, Antarctic, mountain glaciers and polar oceans. It says a safe temperature for Earth's ice is now thought to be closer to 1C or below over the coming centuries.

James Kirkham, a glaciologist and lead author of the report, said: "There are no good outcomes in exceeding 1.5C." He also said: "To contain the global fallout and damage from ice loss in the world's polar and mountain regions, overshoot needs to be kept to the absolute minimum."

The scientists warn about the risk of crossing certain tipping points, and say recovery would be very slow even if temperatures return below 1.5C. Matthew England of the University of New South Wales said recovery could take decades to centuries. Reducing warming to under 1.5C or 1C could let some glaciers partially regenerate and benefit sea ice.

The second report, 'State of the Cryosphere 2026. The Cost of Overshoot', says exceeding 2.8C into the next century would have significant consequences. Sea levels could rise by up to 5 centimeters a year by 2150, compared with 0.45 centimeters a year now. Thawing permafrost could release as much carbon dioxide each year as the United States.

The report describes a worst-case but not-so-improbable scenario in which the world heads toward 2.6C of warming by 2100 even if countries meet their climate commitments. It says returning to 1.5C or below by 2100 remains possible with political ambition, including speeding the move away from fossil fuels to reach net zero by midcentury.

Gunjan Silwal, a Nepali glacier researcher, said August's mountain and glacier collapse killed more than 1,400 people and left over 5,000 missing. She called it only a foretaste of future damage, and said overshoot "will lock in the scale of the damage".