Air samples from the Arctic region show how fast the Earth is warming

While climate change is taking effect everywhere on Earth, the Arctic Circle is feeling its effects primarily, in the form of melting glaciers, melting ice sheets, and decreasing sea ice.

Key players in climate change include clouds covering the Earth’s surface and microscopic aerosols in the air called ice core particles that seed the formation of ice in these clouds. This dance of ice cores, cloud cover and heat all play a major role in climate. But the all-important ice-forming aerosols, which can be mineral dust, microbes, or ocean spray, are rarely studied in the Arctic – where they need to be studied most – because little is known about their effects there, and not many scientists venture further north. .

However, Colorado State University scientists did. In 2019, an intrepid team including atmospheric research scientist Jessie Creamean boarded a ship, sailed north, collected thousands of samples of air, seawater, sea ice, snow, and meltwater, and brought home the physical evidence needed to determine exactly how nucleation occurs. ice and clouds covered it. The Arctic Ocean ebbs and flows from time to time.

Creamean and the team descend into the frozen Arctic aboard a German icebreaker called Polarstern as part of the MOSAiC expedition. The CSU researchers’ goal is to report never-before-seen observations of particle ice nucleation in the central Arctic, away from land-based locations affected by terrestrial aerosol sources. MOSAiC is a major international expedition that organizes Arctic-focused scientific research projects from around the world.

In an open access paper published in Nature Communications, Creamean and colleagues report their direct observations of ice nucleating particles fragmenting in the central Arctic, spanning the entire cycle of sea ice growth and decline. Their results show a strong seasonality of these particles, with lower concentrations in winter and spring, and increased concentrations during summer melt from local biology. Never before had anyone directly observed this cycle before in this region.

“It’s important to know the natural background of these ice core particles before we can really assess how climate change is affecting these aerosol populations,” explains Creamean, a veteran Arctic Ocean explorer whose research has taken him several times to the planet’s northernmost reaches. The team that worked on the analysis of samples collected during the MOSAiC expedition and authored the paper included CSU atmospheric scientists Kevin Barry, Tom Hill and Paul DeMott.

Understanding such ice nucleating particles is critical to understanding the effects of climate change on the planet due to its impact on clouds. Adding ice to a cloud changes the way it interacts with light and heat from the sun, and the heat that bounces back off the Earth’s surface. And ice is important for initiating precipitation.

“This is an important process that we don’t have a good understanding of, especially in the Arctic,” Creamean said. “The model is not accurate in predicting these ice core particles or the cloud effect. So this is a big observation – to see where these things form, and how they change over the course of a year.”

Read the paper: nature.com/articles/s41467-022-31182-x

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