Cryosphere faces permanent damage when world overshoots 1.5C, scientists warn

Ice sheets covering Greenland and Antarctica are melting about six times faster today than in the 1990s. Photograph: Jason Edwards/ View image in fullscreen Ice sheets covering Greenland and Antarctica are melting about six times faster today than in the 1990s. Photograph: Jason Edwards/ Cryosphere faces permanent damage when world overshoots 1.5C, scientists warn UN-backed report finds even temporary rises above Paris agreement target could cause harm to glaciers and polar ice sheets Earth’s icy regions face such dangerous melting that global heating should be brought back below 1C after an inevitable period of overshooting global temperature targets, a UN report has found. Permanent and widespread losses of snow and ice expose a “persistent myth” that overshooting the 1.5C target of the Paris climate agreement – to 2C or 3C – could be manageable or even preferable to urgent cuts to emissions, the report found. The planet has heated by 1.3C since pre-industrial times and failures to curb greenhouse gas emissions and protect nature have led scientists to conclude that some level of overshoot is inevitable as they fight to keep end-of-century warming to 1.5C. But extreme effects on the cryosphere – Earth’s water in a solid state, including all its ice and snow – mean temperatures must rise above that threshold for as short a period as possible, the scientists urged. Added to this, enough planet-heating carbon should be removed from the atmosphere to bring long-term warming down much further, ideally below 1C by 2150. The threatening thaw: climate professor on heatwave risks to tipping point of permafrost The high overshoot expected under current policies – with peak temperatures of about 3C – would thaw nearly all near-surface permafrost, make “severe and possibly abrupt” disruption to ocean circulation likely, and lead to widespread acidification, the report found. The latest scientific research suggests sea ice recovers more slowly than previously thought. The report, written by 80 scientists brought together (ICCI) and the UN Environment Programme (UNEP), found much of the damage would be permanent even if global temperatures were brought back down to 1.5C, such as glacier melt raising sea levels and threatening water security. Photograph: Athit Perawongmetha/ReutersThe report, which comes as world leaders and diplomats converge on Turkey for the 31st annual Cop climate conference, documented rapid and accelerating melting of the cryosphere and polar oceans, with damages that range from the loss of the Greenland and Antarctic ice sheets, driving sea level rises that threaten hundreds of millions of people, to thawing permafrost, which releases more planet-heating gas.