Sea salt aerosols contribute to Arctic warming | Polarjournal
Blowing snow is when snow on the ground is lifted and pushed by the wind. A common and natural phenomenon in the Arctic, whether on pack ice or, as here on the ice caps, where the wind lifts the snow off the vast expanses of pack ice. Photo: Wikicommons

The Arctic is warming, and fine particles of sea salt aerosols produced in blizzard conditions or blowing snow are a contributing factor, according to a recently published study.

The snow on the pack ice contains fine particles of sea salt, which find their way into the atmosphere when winds and blizzards blow. A completely natural and normal phenomenon in the polar regions. For a long time, however, the role of these particles was ignored in climate models. A study published earlier this month in Nature Geoscience, has just demonstrated that during episodes of blowing snow, large quantities of sea salt particles affect cloud properties and warm the surface.

The researchers’ findings provide important information for the updating of climate models by including the effects of these particles on the atmosphere and its warming. “Model simulations that don’t include fine sea salt aerosols from blowing snow underestimate aerosol population in the Arctic”, mentions Jian Wang, one of the research authors and professor at Washington University in St. Louis in a press release issued by the university. “Blowing snow happens regardless of human warming, but we need to include it in our models to better reproduce the current aerosol populations in the Arctic and to project future Arctic aerosol and climate conditions.”

The data was collected between September 2019 and October 2020 during the MOSAiC expedition, when the Polarstern, captured by pack ice, drifted for a year in the central Arctic, collecting many scientific data on the atmosphere, ice and ocean. Image: Matthias Jaggi

It has long been known that clouds form around aerosol particles such as dust or soot. On the other hand, it was previously thought that the role of sea salt particles, which represent the largest mass of aerosols, had no particular impact on cloud formation, or on the Arctic climate and its warming.

However, the authors’ conclusions show otherwise. Scientists have estimated that sea salt aerosols produced by blowing snow account for more than 27.6% of the total number of particles. These aerosols increase cloud production, leading to surface warming. Moreover, by inhibiting rain and ice formation, these aerosols lead to greater cloud cover.

This observation could also apply to Antarctica, as the authors suggest in their conclusions: “The [sea salt aerosol] production from blowing snow[aérosols de sel marin] is also expected to play an important role in aerosol–cloud–climate interactions in the Antarctic, given the prevalence of sea ice and strong wind conditions.”

Source: Gong, X., Zhang, J., Croft, B. et al. Arctic warming by abundant fine sea salt aerosols from blowing snow. Nat. Geosci. 16, 768-774 (2023).

Mirjana Binggeli, PolarJournal

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