By the end of the century, over half of the world’s population will be battling to breathe, as climate change increases the frequency of stagnant air days — dramatically decreasing air quality.
That’s the takeaway message of a new study published this week in Nature Climate Change. While many studies have shown how our continued dependence on the burning of fossil fuels will fill our air with harmful pollutants, this study examined how the changing climate itself will lead to weather patterns that will make bad air even worse for billions of people around the world.
The research team, led by Daniel Horton, a climate modeler at Stanford, used 15 global climate models to track changes in the number and duration of atmospheric stagnation events in the past. They then used these models to forecast air stagnation frequency over the coming decades under the assumption that greenhouse gases continue to accumulate in the atmosphere at the current rate. The models predicted that by 2099, 55 percent of the world’s population will experience more air stagnation days each year. Much of India, Mexico, the Amazon, and the western U.S. are expected to see 40 more stagnant air days every year by the end of the century. For India, that’s a 40 percent increase in stagnation events.
Air stagnation occurs when winds are light, the lower atmosphere is stable and little or no precipitation occurs. While it is not dangerous by itself, under these weather conditions, soot, dust, and ozone build up in the lower atmosphere and can become trapped over cities for days. The disturbing smog in Paris this spring, which blotted out the Eiffel tower and drove city officials to set up check points limiting access to the city by car, was the result of just such an air stagnation event.
“Much of the air-quality community focuses on pollutants,” writes Horton in the study. “This study takes a step back and looks at the weather or climate component that can lead to the formation of hazardous air quality.”
According to the World Health Organization, outdoor air pollution caused 3.7 million premature deaths globally in 2012. Fine particulate matter air pollution can lead to heart disease, stroke, lung cancer, respiratory infections, and chronic obstructive pulmonary disease. Ground-level ozone can make asthma and other respiratory conditions much worse and over time can permanently scar the lungs. As climate change makes heat waves more frequent and intense, ground-level ozone is expected to increase as it forms when certain pollutants bake in the sun.
President Obama highlighted some of the health benefits of curbing greenhouse gases as one of the driving reasons behind the EPA’s new proposed rule that will cut power plant carbon emissions 30 percent by the year 2030. The proposed rule is expected to result in up to 100,000 fewer asthma attacks and 2,100 fewer heart attacks in its first year alone.