Aerosol formation by blizzards contribute to Arctic warming, study finds

Fine sea salt aerosols produced under blizzardy conditions has been found to contribute to Arctic warming, according to new research published in the journal Nature Geoscience.

The sea salt aerosols thus produced account for 30 per cent of all the aerosols in the Arctic, the study found.

Fine sea salt aerosols, which refer to the suspended sea salt particles in the air, are good for forming clouds, which trap the heat emitted by Earth and contribute to warming, the research team from Washington University, US, said in their study.

"Considering the absence of sunlight in the winter and spring Arctic, these clouds have the capacity to trap surface long-wave radiation, thereby significantly warming the Arctic surface," said Jian Wang, professor of energy, environmental & chemical engineering, who led the team.

In the central Arctic, the coldest winter nights are the clearest, when heat from Earth can escape into space unimpeded.

While the presence of sea salt in the Arctic atmosphere is common because of breaking ocean waves, these particles are large and not abundant, according to Wang.

However, under blizzardy conditions, when snow is blown about by strong winds, the sea salt particles were much finer and abundant, Wang and team found.

Wang's study has further revealed that the sea salt aerosols thus produced "contributes a more substantial fraction to the total aerosol population in the central Arctic", even as 'Arctic haze', resulting from pollutants being transported over long distances, has previously been identified as the primary source of aerosols in the Arctic during winter and spring.

Wang's team analysed data collected by the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC), an international collaboration and a year-long expedition into the Central Arctic from September, 2019 to October, 2020.

The observational confirmation of the ever-present fine sea salt aerosol production phenomenon allows for it to be included in climate models, the study said.

"Model simulations that don't include fine sea salt aerosols from blowing snow underestimate aerosol population in the Arctic," said Wang.

"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," said Wang.