Rain fell at Greenland’s summit this year for the first time. It’s going to happen more often, study says

By Rachel Ramirez, CNN

Rain fell on the summit of Greenland instead of snow for the first time on record in August, as the Northern Hemisphere experienced warmer-than-usual summer temperatures. A new study suggests that’s likely to be the norm in just four or five decades.

The Arctic is expected to experience more rain than snow some time between 2060 and 2070, marking a major transition in its precipitation patterns as the climate crisis jacks up temperatures in the region, according to the study published on Tuesday in the journal Nature Communications.

New climate modeling shows the transition could happen earlier than scientists had previously projected. Michelle McCrystall, the lead author of the study and climate researcher at the University of Manitoba in Winnipeg, told CNN that earlier modeling suggested it wouldn’t occur until between 2090 and 2100.

“But with the new set of models, this actually has been pushed forward to about between 2060 and 2070, so there’s quite a jump there by 20 years with this early transition,” she said.

The study notes that the increase in rainfall is due in large part to the loss of sea ice. More open water and warmer air temperatures mean more evaporation, which primes the atmosphere for a wetter Arctic. The researchers say a rainfall-dominated Arctic has the potential to destabilize Greenland’s ice sheet mass balance, triggering a global rise in sea levels.

“Things that happen in the Arctic don’t specifically stay in the Arctic,” McCrystall said. “The fact that there could be an increase in emissions from permafrost thaw or an increase in global sea level rise, it is a global problem, and it needs a global answer.”

In August, the UN’s Intergovernmental Panel for Climate Change (IPCC) published its authoritative report which concluded the planet is quickly approaching 1.5 degrees Celsius above pre-industrial temperatures — a threshold scientist say the world should stay under to avoid the worst consequences of the climate crisis. But the authors of Tuesday’s study said the transition from snow to rain will likely occur in some parts of the Arctic, particularly Greenland, even if warming is contained to 1.5 degrees.

An analysis by Climate Action Tracker of the world’s current policies showed that the Earth is currently on track for 2.7 degrees Celsius of warming. That’s assuming countries will follow through with their plans to reduce greenhouse gas emissions. At around 3 degrees of warming, researchers found that most areas in the Arctic will transition to a rainfall-dominated regime.

“If we did stay within this 1.5-degree world, the Arctic could remain snow-dominant by the end of the century, but some parts probably still will transition,” and some of them are already transitioning, McCrystall said. “But we are still on the trajectory of a 3-degree world.”

Though scientists not involved with the study overwhelmingly agreed that the Arctic is undergoing rapid change amid the climate crisis, some expressed caution about the study’s results and specifically pointed to the critical need for more observations and more research.

Tim Palmer, a climate physicist at the University of Oxford, said future Arctic precipitation trends need “more careful quantification.”

“All this points to the need for high-quality observations of precipitation for regions such as the Arctic and the development of a new class of high-resolution climate model, with smaller biases and more realistic estimates of natural variability on the regional scale,” Palmer said in a statement. “Together these will give us more confidence in the impact of carbon emissions on precipitation in places like the Arctic. We need these urgently if they are to impact on mitigation policy.”

Bob Spicer, a professor emeritus at the Open University who spent years studying past climates of the Arctic, said “this research is entirely in line with what the fossil record tells us the Arctic was like during previous episodes of global warmth.”

7 billion tons of water

Scientists have concluded that the burning of fossil fuels led to Greenland melting over the past two decades. A recent study published in the journal Cryosphere found Earth has lost a staggering 28 trillion tonnes of ice since the mid-1990s, a large portion of which was from the Arctic, including the Greenland ice sheet.

The region already saw a preview of its rainy future last August, when temperatures at the Greenland summit rose above freezing for the third time in less than a decade. The warm air fueled an extreme rain event that dumped 7 billion tons of water on the ice sheet, enough to fill the Reflecting Pool at the National Mall in Washington, DC, nearly 250,000 times.

It was the heaviest rainfall on the ice sheet since record-keeping began in 1950, according to the National Snow and Ice Data Center, and the amount of ice mass lost on that one summer day was seven times higher than the daily average for that time of year.

“While it’s inevitable that Arctic rainfall will increase as the climate warms, rains are also likely to become more intense,” Mark Serreze, co-author of the study and director of NSIDC, told CNN. “It’s a nasty one-two punch to an ecosystem already reeling in the face if rapid environmental change.”

While the projections aren’t definitive, McCrystall said more rain events in Greenland — and the Arctic region as a whole — are expected to occur the more humans continue to pump more greenhouse gases into the atmosphere.

“With the oceans getting warmer and [the Greenland] rainfall event that has happened, there are some indications that maybe things are even more extreme or changing much more rapidly than even our models are projecting, potentially,” she said.

But “the fact that everything is shifting to show that there’s greater extremes in precipitation, that in itself is an indication of human-induced climate change for sure,” McCrystall said.

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