Arctic ice is disappearing at some of the fastest rates in centuries as global temperatures rise. Now, scientists suggest that melting glaciers may, in turn, be influencing the Arctic climate.
As glaciers melt and retreat, exposing more and more ice-free earth as they go, they can kick up clouds of dust into the atmosphere. New research suggests that these dust particles may strongly affect the formation of Arctic clouds, which have a major influence over the region’s temperatures and precipitation.
Small particles in the atmosphere—whether from dust, pollution, fires or other sources—are necessary for clouds to form. Particles in the air provide a kind of nucleus that water can cling to, helping to form the liquid droplets or ice crystals that condense into clouds. Studies from regions around the world have suggested that increased pollution, emissions from wildfires or other events that pour aerosols into the atmosphere can have a major influence on the formation and behavior of clouds.
Cloud research is especially important today in the rapidly warming Arctic. Clouds have the potential to influence the Arctic climate in a variety of complex ways, which scientists are still working to understand.
Researchers have suggested that increased cloud cover in the summer could reflect sunlight away from Earth and help lessen the impact of rising temperatures. On the other hand, research has also suggested that cloud cover during other times of the year can trap heat near the surface of Earth and could speed up melting of Arctic sea ice.
As a result, Arctic cloud research is a growing priority among climate scientists, including the influence of aerosol particles on cloud formation.
A study published this week in Nature Geoscience zeroes in on the Svalbard islands off the coast of Norway, a region with abundant clouds. Some recent studies have begun investigating the effects of pollution or wildfire smoke drifting into the Arctic from other regions. But the new study notes that there’s been less focus on dust that originates from inside the Arctic itself.
To help bridge the gap, the researchers took samples of sediments from the exposed plains that had formed in front of melting Svalbard glaciers. They tested the particles in special lab experiments designed to simulate their ability to become “ice-nucleating particles,” and thus to form clouds at low temperatures.
They found that the Svalbard dust samples were unusually effective at generating the ice crystals that lead to the formation of clouds. That’s because they contain traces of organic matter, which tends to be particularly good at forming ice nuclei, the researchers note.
Additional atmospheric measurements, along with model simulations, suggest that these cloud-forming particles are likely to be most concentrated at Svalbard during the summer—the time when glaciers are melting the fastest and when the most ice-free land is exposed.
For now, the researchers can’t say for sure if dust particles behave the same way in other parts of the Arctic, but it may be an important possibility to keep in mind. Dust storms have been known to occur throughout the Arctic, including in Alaska and Greenland, and some scientists suggest they could become more common as glacier melt speeds up.
In general, an increase in ice-nucleating particles across the Arctic could have a significant effect on the formation of clouds, said NASA researcher Patrick Taylor, who was not involved with the study but has experience researching Arctic clouds.
For one thing, many low-lying clouds in the Arctic are currently classified as “mixed-phase” clouds—they consist of both liquid water and ice crystals. But some scientists suggest that the reason these clouds contain so much water is because there just aren’t that many ice crystals in the atmosphere to go around.
“The leading thought right now in the research is saying if there were more ice-nucleating particles around, a lot of these mixed-phase clouds would actually turn to ice or there would be a lot more ice,” he told E&E News.
Clouds containing more ice tend to have shorter life spans in the atmosphere, he added. So in a surprising way, more cloud-forming dust particles could actually lead to less cloud cover, if they’re the kinds of particles that favor ice.
The consequences could differ depending on the time of year. If the effect turns out to be strongest in the summertime, as the Svalbard research implies, then fewer clouds might allow more sunlight to get through, leading to even greater warming.
But that’s mostly speculation for now. Clouds are notoriously complicated, and there are a variety of other factors that can influence both their behavior and their effect on the local climate. Future warming might lead to an increase in dust from melting glaciers, but it’s also likely to cause changes in local air temperatures, humidity and wind currents, all of which affect the formation of clouds.
Parsing out all of these different factors, and improving the way they’re represented in model simulations, is a growing priority among climate scientists.
“We really do need to focus on these Arctic clouds because we don’t know a lot about them,” Taylor said. “And everything we do know about them is pointing to them having this central role in how the Arctic climate system is going to evolve going forward.”
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.