Clouds above the Arctic Ocean. US Geological Survey/Flickr
Clouds, often called the wild card of climate change, are particularly enigmatic in the North. Many questions remain about how our cloud cover will change over time.
When clouds cloaked Yellowknife’s skies for weeks earlier this year, Richard McIntosh, owner of tour operator Sundog Adventures, was left wondering about the future.
Under relentless cloudy nights, tourists visiting the city missed out on seeing the northern lights. McIntosh told Cabin Radio the disappointment on their faces was obvious.
If cloudier skies were to become a trend, he wondered what that would mean for tourism.
“Word of mouth, as we know, is one of the best ways of promoting an area. If they go back and say they didn’t see the northern lights, it’s definitely not good for the industry,” he said.
In the coming years, precipitation is projected to increase in the Northwest Territories. But what does climate change mean for the future of clouds in the North?
“You’re asking the million-dollar question,” said Zen Mariani, a research scientist with Environment and Climate Change Canada and principal investigator at a weather station “supersite” that collects meteorological data in Iqaluit.
Not only would a cloudier future bode ill for aurora-viewing and potentially hinder the effectiveness of solar panels, but a change in clouds also has important implications for future warming – both in the Arctic and globally.
Clouds can act like a blanket, trapping heat in the atmosphere, but they can also reflect the sun’s heat back out into space, cooling the surface below. How these competing effects balance out, to either amplify or counteract warming, is a major area of research. For more than a decade, clouds have been one of climate change’s largest sources of uncertainty.
“It gets really complicated and muddy, and you can go down a rabbit hole very quickly,” Mariani said.
Even so, scientists are gradually learning about the processes that affect Arctic clouds, and there are reasons to think there will be more grey skies ahead.
“There’s a lot of different things changing at once,” said Casey Wall, a postdoctoral researcher who studies clouds and climate change at the University of Oslo. “But I think it’s more likely than not that the net effect of all these different changes and feedback loops will increase cloud cover in the Arctic.”
Here’s what we know about clouds in the North, and why we lack firm answers.
How have northern clouds changed so far?
Some research suggests that the Arctic has become cloudier in recent decades, although trends for different seasons have been inconsistent.
A 2004 study, for example, found that cloud fraction – a measure of the proportion of sky occupied by clouds – increased in the spring but decreased in the winter between the 1980s and early 2000s. A 2010 study, in contrast, showed increases in cloudiness in all seasons, particularly in the spring and autumn.
The differing results likely stem from the data sources used. Whereas the 2004 study largely drew from satellite records, the 2010 study used cloud observations reported by ships and weather stations on land and sea ice.
“I hesitate to say ours was right,” said Ryan Eastman, a research scientist at the University of Washington who was involved in the 2010 study. But the satellite data “looked pretty wrong,” he said.
Comparing trends in cloud records from satellites and surface observations, Eastman and a colleague found that the largest decrease in cloud cover coincided with the replacement of a satellite. Satellite measurements also varied most in winter and autumn, when light was limited.
“When you have these situations where a satellite is trying to sense cloud cover at odd angles, and the sun is low, and there’s also a bunch of frozen mountains right below the clouds, it’s just almost impossible using those early technologies to get a good signal,” Eastman said.
Surface observations have their issues too, according to Eastman. They are geographically sparse, and methods for tracking clouds from the surface have changed over time, making it hard to get reliable, continuous records.
The conflicting findings point to a major hurdle in research on Arctic clouds. To find out how clouds are changing in response to warming, scientists need long-term records, said Tim Carlsen, a postdoctoral researcher at the University of Oslo, who studies clouds. So far, he said, we don’t have observations for long enough.
How are clouds expected to change in the future?
Looking to the future, several climate models project increasing cloud cover and cloud thickness in the Arctic.
When scientists analyzed cloud simulations from 20 global climate models, for instance, they found that cloud amount is generally expected to increase north of the 70th parallel. The increases were particularly pronounced during autumn and over sea ice, they reported.
These predictions come with a caveat, though, according to Mariani, from Environment and Climate Change Canada. Models are considerably more reliable at predicting variables such as temperature than clouds, he said.
“A lot of issues revolve around trying to model clouds.”
According to Wall, from the University of Oslo, part of the challenge is that many interconnected physical processes affect clouds, from the tiny particles on which clouds form to the global climate’s effect on heat and moisture.
“Everything down from the microscopic scale to the hemispheric scale is all linked,” he said. Not only is it difficult to understand this complicated web, he said, but researchers currently don’t have the computing power to resolve all of these processes at once.
Nonetheless, there are reasons to think that the North may get cloudier.
Firstly, in a warmer climate, there’s more energy at the surface, which means more evaporation, said Howard Barker, a research scientist with Environment and Climate Change Canada. A warmer atmosphere can also hold more moisture than a colder one. In general, he said, the result is more moisture to arguably produce clouds.
The jet stream, an air current that circulates at mid-latitudes, is also expected to move poleward as global temperatures rise, according to Wall, which would bring more winter storms to the North. (There are signs this shift is already under way, the Washington Post reported in 2016.)
In addition, a warming climate might influence the balance of liquid and ice particles within clouds, which could alter precipitation patterns and extend clouds’ lifespan, according to Wall.
The loss of sea ice is thought to affect cloud cover, too. A 2018 modelling study revealed that cloud cover increased over newly open water in all seasons except summer.
“As the sea ice goes away, that means there’s more open ocean exposed to the atmosphere, which leads to more evaporation and more heat transferred into the atmosphere,” Wall explained. “And that’s favourable for clouds.”
Finally, a warming climate might bring more aerosols to the North, a subset of which could act as cloud condensation nuclei – tiny particles in the air on which water vapour condenses to form cloud droplets. When these droplets accumulate, they create a cloud.
A variety of particles can seed the growth of clouds, such as dust, blowing snow and aerosols.
In the Arctic, aerosol concentrations may be increasing through several pathways. For example, iodine released from melting sea ice and the ocean’s surface can efficiently create cloud-forming particles, as Quanta Magazine reported.
Warm, moist air from lower latitudes is also increasingly being transported into the Arctic, sometimes carrying a heavy load of pollutants. Scientists observed one of these so-called air-mass intrusions in the spring of 2020 during a year-long expedition in the central Arctic.
Within 48 hours, the temperature rose from roughly -30C to just below 0C, said Lubna Dada, a scientist at the Paul Scherrer Institute, who studied the event during her postdoc in the Extreme Environments Research Laboratory at École Polytechnique Fédérale de Lausanne (EPFL).
Not only was the air warm, it was also dirty. Pollution concentrations suddenly reached levels comparable to a European city, she said.
This injection of aerosols was accompanied by a change in clouds: they formed closer to the surface and became more opaque, trapping heat in the atmosphere, the researchers reported.
Increased aerosol levels are thought to lead to the formation of clouds that contain smaller, more numerous droplets. The heightened concentration of particles inhibits precipitation, creating longer-lasting, opaque clouds that act like a blanket, Dada said. In the Arctic, this may lead to additional warming, which reinforces the formation of clouds.
“It’s kind-of a loop,” she said. “We’re bringing in more aerosols, more clouds are forming, their lifetime is longer, and then more ice is melting,” resulting in larger areas of open ocean. Then, she said, the loop repeats.
Can Yellowknifers expect more cloudy days ahead?
Most of the experts Cabin Radio interviewed said they suspect that the North will get cloudier in the future, but it’s still too early to make any detailed forecasts.
“I’d say we have a general idea, but to say definitively, ‘Oh, in 12 years, it’s going to be twice as cloudy,’ we’re not quite there yet,” Mariani said.
Research also tends to focus on Arctic latitudes rather than specifically the subarctic region that Yellowknife occupies, though some of the science may be applicable.
Much of what we know is still dogged by uncertainty. In a 2021 report, the United Nations Intergovernmental Panel on Climate Change assessed Arctic cloud feedback to be positive, meaning that clouds amplify warming. But “a negative feedback is almost as probable as a positive feedback,” the report stated.
Continuing investigation may bring more clarity.
In the mid-2000s, space agencies launched satellites that overcome some issues faced by earlier instruments. According to Eastman, these records are now reaching timescales that may prove useful for studying cloud trends.
Experts are also now preparing to launch a new batch of satellites that sense clouds and aerosols.
Barker, for example, is one of the lead scientists in a mission called EarthCARE, led by European and Japanese space agencies, that aims to help discern the relationships between clouds, aerosols and warming.
Closer to the surface, Carlsen is organizing a field campaign that involves measuring clouds with ground instruments and by flying aircraft through them. Dada, meanwhile, is involved in work led by colleagues at EPFL’s Extreme Environments Research Laboratory that aims to take a broader look at air-mass intrusions throughout the Arctic, including where they originate and what they may carry.
A lot of money is still being spent on figuring out what’s going on with clouds, Barker said.
According to Carlsen, the North may be well-suited for uncovering answers.
“The Arctic is kind-of like a natural laboratory,” he said, adding that the isolated environment may help scientists study cloud processes in an undisturbed way. With the North warming faster than the rest of the globe, he said it’s also possible the region will be the first where changes in clouds appear.
“That could be one hypothesis,” Carlsen said. But as with anything related to clouds, he added: “It’s not so easy to say.”