Earth’s atmosphere more chemically reactive in cold climates

Becky Alexander in the cold room of the UW’s IsoLab with sections of an ice core. Her group is now analyzing ice cores from Antarctica to see if they show the same trend as in Greenland.

Unseen in the air around us are tiny molecules that drive the chemical cocktail of our atmosphere. As plants, animals, volcanoes, wildfires and human activities spew particles into the atmosphere, some of these molecules act as cleanup crews that remove that pollution.

The main molecules responsible for breaking down all these emissions are called oxidants. The oxygen-containing molecules, mainly ozone and hydrogen-based detergents, react with pollutants and reactive greenhouse gases, such as methane.

A University of Washington study published May 18 in the journal Nature finds that during large climate swings, oxidants shift in a different direction than researchers had expected, which means they need to rethink what controls these chemicals in our air. Lei Geng, former UW postdoctoral researcher now at Grenoble Alpes University, is the study’s first author.

“Oxidants are very reactive, and they react with pollutants and greenhouse gases and clean up the atmosphere,” said corresponding author Becky Alexander, a UW associate professor of atmospheric sciences. “We wanted to see how the ability of the atmosphere to clean itself might change with climate.”