An anonymous reader quotes a report from The Guardian: Greenland’s ice sheet is melting much faster than previously thought, threatening hundreds of millions of people with inundation and bringing some of the irreversible impacts of the climate emergency much closer. Ice is being lost from Greenland seven times faster than it was in the 1990s, and the scale and speed of ice loss is much higher than was predicted in the comprehensive studies of global climate science by the Intergovernmental Panel on Climate Change, according to data. That means sea level rises are likely to reach 67cm by 2100, about 7cm more than the IPCC’s main prediction. Such a rate of rise will put 400 million people at risk of flooding every year, instead of the 360 million predicted by the IPCC, by the end of the century.
Greenland has lost 3.8 trillion tons of ice since 1992, and the rate of ice loss has risen from 33 billion tons a year in the 1990s to 254 billion tons a year in the past decade. Greenland’s ice contributes directly to sea level rises as it melts because it rests on a large land mass, unlike the floating sea ice that makes up much of the rest of the Arctic ice cap. About half of the ice loss from Greenland was from melting driven by air surface temperatures, which have risen much faster in the Arctic than the global average, and the rest was from the speeding up of the flow of ice into the sea from glaciers, driven by the warming ocean. The scale and speed of the ice loss surprised the team of 96 polar scientists behind the findings, published on Tuesday in the journal Nature. The Ice Sheet Mass Balance Inter-comparison Exercise comprised 26 separate surveys of Greenland from 1992 to 2018, with data from 11 different satellites and comparisons of volume, flow and gravity compiled by experts from the UK, Nasa in the US, and the European Space Agency.