Rain will replace snow as the most common precipitation in the Arctic, research shows as the climate crisis warms the planet’s northern ice cap.
Today, there is more snow in the Arctic than rain. But that will reverse, the study suggests, with all of the region’s land and nearly all of its seas receiving more rain than snow before the turn of the century if the world warms by 3 ° C. Promises made by nations at the recent Cop26 summit could keep the temperature rise at a still disastrous 2.4 ° C, but only if those promises are kept.
Even if the global temperature rise is kept at 1.5 ° C or 2 ° C, the areas of Greenland and the Norwegian Sea will still become dominated by rain. Scientists were shocked in August when rain fell on the top of Greenland’s huge ice sheet for the first time on record.
The research used the latest climate models, which showed the shift from snow to rain will occur decades faster than expected, with fall exhibiting the most dramatic seasonal changes. For example, he found that the central Arctic would become dominated by fall rain by 2060 or 2070 if carbon emissions are not reduced, instead of by 2090 as predicted by previous models. .
The implications of a shift were “profound,” the researchers said, ranging from accelerating global warming and sea level rise to melting permafrost, sinking roads and massive famine of people. reindeer and caribou in the area. Scientists believe that the rapid warming of the Arctic may also increase extreme weather events such as floods and heat waves in Europe, Asia and North America by altering the jet stream.
“What happens in the Arctic doesn’t stay there,” said Michelle McCrystall of the University of Manitoba in Canada, who led the new research. “You might think that the Arctic is far from your daily life, but in fact the temperatures have warmed up so much that [it] will have an impact further south.
“In the central Arctic, where one would imagine there would be snowfall throughout the fall period, we are actually seeing an earlier transition to precipitation. This will have huge implications. The arctic having very heavy snowfall is really important for everything in this region and also for the global climate as it reflects a lot of sunlight. “
Professor James Screen from the University of Exeter in the UK, who was part of the research team, said: ‘The new models could not be clearer than unless global warming is stopped , the future Arctic will be wetter, be open water, rain will replace snow.
Scientists already agree that precipitation will increase dramatically in the Arctic in the future, as more water evaporates from increasingly warm, ice-free seas. But the research, published in the journal Nature Communications, found that this would be largely dominated by rain, which will more than triple in the fall by 2100 if emissions are not reduced.
The scientists concluded: “The transition from a snow-dominated Arctic to rain in summer and autumn is expected to occur decades earlier and at a lower level of global warming, potentially below 1.5 ° C, with profound climatic, ecosystem and socio-economic impacts. ”
Snow is important in the production of sea ice each winter, so less snow means less ice and more heat absorbed by open oceans. Research shows increased rains on the south coast of Greenland. This could further accelerate the sliding of glaciers in the ocean and the consequent rise in sea level that threatens many coastal areas.
Much of the arctic land is tundra, where the ground has been permanently frozen, but more rain would change that. “You put hot water in the ground that could melt the permafrost and that will have global implications, because as we know permafrost is a very big sink of carbon and methane,” McCrystall said.
Impacts in the region include melting vital ice roads, more flooding and famine for herds of animals. When rain falls on snow and then freezes, it prevents animals from feeding. “Reindeer, caribou and muskoxen cannot cross the ice sheet, so they cannot access the grass they need to survive and suffer enormous loss of life,” she said. declared.
Professor Richard Allan, University of Reading in the UK, who was not involved in the research, said: “Using a complex state-of-the-art set of computer simulations, this new study paints a picture worrying about the future arctic climate. faster and more significant change than previously thought. This research sounds alarm bells for the Arctic and beyond.
However, Gavin Schmidt of the Nasa Goddard Institute for Space Studies in the United States said the claim of a faster change was “unsubstantiated” because some of the new climate models predict future temperatures to be warmer than expected.