Exceeding 1.5°C of global warming would have serious and potentially irreversible consequences for the planet’s frozen regions, according to two United Nations reports released Monday. The findings call for urgent action to limit the duration and extent of any temperature overshoot.
The 2015 Paris Agreement aims to keep warming well below 2°C while pursuing efforts to limit it to 1.5°C. However, one of the reports said passing that threshold would produce widespread impacts across the cryosphere, including glacier and sea-ice loss, permafrost thaw and faster sea-level rise.
Those changes could increase flooding risks and contribute to water shortages. Some effects are already visible: the report cites a 20% reduction in glacial mass in Switzerland. The U.N. also warned that current warming levels are already unsafe for the Arctic, Antarctic, mountain glaciers and polar oceans.
According to the reports, a temperature considered genuinely safe for Earth’s ice may be closer to 1°C or below over the coming centuries. Global warming has reached 1.37°C above preindustrial levels, while the European Copernicus network estimates that the 1.5°C threshold could be exceeded around 2030.
James Kirkham, a glaciologist and lead author of the report “Overshoot and the Cryosphere,” said there would be no positive outcomes from exceeding 1.5°C. He argued that limiting the time spent above the target would reduce the damage caused by ice loss in polar and mountain regions.
Scientists also warned that crossing certain climate tipping points could lead to changes that would recover only very slowly, even if global temperatures later fell below 1.5°C. Lowering warming below 1.5°C, and eventually toward 1°C, could allow some glaciers to partially regenerate and provide benefits for sea ice, but oceanographer and climatologist Matthew England said recovery could take decades to centuries.
The second report, “State of the Cryosphere 2026. The Cost of Overshoot,” examined the consequences of warming above 2.8°C into the next century. It said annual sea-level rise could reach up to five centimetres by 2150, compared with about 0.45 centimetres today. Thawing permafrost could also release an amount of carbon dioxide each year comparable to the current annual emissions of the United States.
The reports describe a scenario in which global warming reaches 2.6°C by 2100 as a worst-case outcome that is nevertheless considered possible even if countries fulfil their existing climate commitments. Kirkham said temporarily exceeding 1.5°C would make the Paris Agreement’s goals more urgent, not irrelevant, and maintained that returning to 1.5°C or below by 2100 remained possible through a faster transition away from fossil fuels and the achievement of net-zero emissions by mid-century.
Nepali glacier researcher Gunjan Silwal said decisions taken over the next few years would determine the scale of future damage. She warned that a mountain and glacier collapse in August, which killed more than 1,400 people and left over 5,000 missing, could be an early indication of what lies ahead.
Sources: Phys.org.