Study suggests effects of climate change will slow air circulation around the world.
Climate change is poised to worsen air quality in many parts of the globe, according to a study published today in Nature Climate Change1. By the end of the century, more than half of the world’s population will be exposed to increasingly stagnant atmospheric conditions, with the tropics and subtropics bearing the brunt of the poor air quality.
A team led by Daniel Horton, a climate modeller at Stanford University in California, used 15 global climate models to track changes in the number and duration of atmospheric stagnation events, in which stationary air masses develop and allow soot, dust and ozone to build up in the lower atmosphere. “Much of the air-quality community focuses on pollutants,” says Horton. “This study takes a step back and looks at the weather or climate component that can lead to the formation of hazardous air quality.”
Air stagnation arises from three meteorological ingredients: light winds, a stable lower atmosphere and a day with little or no precipitation to wash away pollution.
In a high greenhouse gas emissions scenario, Horton and his colleagues calculate that 55% of the global population will experience more air stagnation by 2099. Large swathes of India, Mexico and the Amazon could see up to 40 more stagnant air days per year compared to the average annual tally from 1986 to 2005, representing increases of 40%, 19% and 28% respectively.