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Increasingly extreme Arctic weather could threaten the survival of wildlife, biologists are warning. In 2018, it snowed so heavily that many areas remained covered in snow well into the summer, preventing almost all plants and animals from breeding.

“If this is a one-time event, it’s not an issue,” says Niels Martin Schmidt at Aarhus University in Denmark. Arctic wildlife can cope with occasional bad years, he says.

But he fears that this kind of extreme weather could become much more common, potentially leading to the extinction of some species. “This could be a glimpse into the future,” says Schmidt.

He is part of a team that has been monitoring ecosystems around Zackenberg in north-east Greenland for more than 20 years. The growing season there is very short – just July and August – so if the ground remains covered by snow it has a major impact. “The window for plant growth is very narrow,” he says.

During the past 23 years, on average only 4 per cent of land has still been covered by snow by the third week of July – the height of summer. In 2018, it was 45 per cent. For the first time since monitoring began, almost all plants and animals – including Arctic foxes and musk ox – failed to breed. Some migratory birds starved to death as they waited for the snow to melt.

There was heavy snow across much of the Arctic in 2018, not just north-east Greenland, says team member Tomas Roslin at the Swedish University of Agricultural Sciences in Uppsala. “It was fairly widespread,” he says.

While many people assume that a warming world means less snow, this isn’t the case in colder regions. Cold air can’t hold much moisture, limiting snowfall. As the Arctic warms and the sea ice shrinks more each summer, the atmosphere there gets moister, meaning more snow can fall when conditions are right.

This year, the weather has flipped from one extreme to another, with so little snow falling that a lack of water was limiting plant growth during the summer. “People don’t realise water availability is one of the limiting resources in large parts of the Arctic,” says Roslin.

The changing weather isn’t just a problem for wildlife. There’s growing evidence that the warming in the Arctic is causing more extreme weather across much of the northern hemisphere by affecting the polar jet stream, which could hit crop yields and lead to “food shocks”.