MAY 24, 2017 12:56 PM PDT

Reduced air pollution could mean more rain

We know that air pollution is bad, and that pollution from sulfur dioxide causes acid rain and cardiovascular and respiratory diseases. Yet due to regulations on aerosols, in the last decades, sulfur dioxide emissions are declining and scientists are still uncertain in what effects this decreasing air pollution will have. Following a new study in the Journal of Geophysical Research: Atmospheres, it is plausible that falling sulfur dioxide emissions in the United States will impact more than just the immediate region. The study reports that fewer emissions will actually increase rainfall in Africa's semi-arid Sahel, while bringing slightly more rain to the U.S., as well.

Sulfur dioxide is dangerous because it both cools and dries the planet by reflecting sunlight back to space and suppressing heat-driven evaporation near the ground, reports Science Daily. Sahel, which is encompasses a long West to East strip of Africa between the Sahara Desert to the north and the Sudanian Savanna to the south, has had severe droughts since the 1970s and 80s. The scientists are now wondering if those droughts are linked to conditions in other areas of the world.

"We were surprised to find that removing sulfur emissions in just one country would significantly influence rainfall on another continent, thousands of miles away," said study coauthor Arlene Fiore, an atmospheric scientist at Lamont-Doherty.

The cycle of acid rain. Photo: Shutterstock

Looking at three models, the team of researchers quantified the global and regional precipitation responses to U.S. sulfur dioxide emission reductions. There is hope that U.S. sulfur dioxide emissions could reach zero by 2100, so the researchers set their projections with this zero-emissions scenario. If this is the case, the projections show that rainfall over the Sahel could increase up to 10 percent from 2000 levels. All three models also showed a slight increase in average global rainfall, with higher levels in the United States and other northern-hemisphere regions.

The consequential rainfall would come because the tropical rain belt would shift to its normal, northernmost position above the equator during northern hemisphere summer, moving the rain belt roughly 35 kilometers north where more of it reaches Sahel. That could have significant implications for such a drought-worn region. Agriculture could become more reliable and profitable for those living there.

"Reducing emissions in one region can influence rainfall far away because our global atmosphere is interconnected," said the study's lead author, Dan Westervelt, an atmospheric scientist at Columbia University's Lamont-Doherty Earth Observatory. "We show that the health and environmental benefits of U.S. clean air policies extend to global climate as well."

Drought threatens the Sahel. Photo: Al Jazeera

Sources: Science Daily, Journal of Geophysical Research: Atmospheres

About the Author
  • Kathryn is a curious world-traveller interested in the intersection between nature, culture, history, and people. She has worked for environmental education non-profits and is a Spanish/English interpreter.
You May Also Like
NOV 24, 2018
Earth & The Environment
NOV 24, 2018
Five places on Earth where gravity doesn't work
There are five places on our planet where gravity doesn't seem to work. It might sound crazy, so maybe you should just check them out for yourself!&nbs...
NOV 29, 2018
Earth & The Environment
NOV 29, 2018
How serious are we about solar geoengineering?
Just how close are we exactly to launching a large-scale solar geoengineering project? That’s the question a new study published recently in Environm...
DEC 18, 2018
Plants & Animals
DEC 18, 2018
Learn Why the State of Utah Drops Fish From Airplanes
Utah’s Division of Wildlife Resources drops thousands of fish into mountain lakes from airplanes every single year, and while it might seem like a po...
DEC 26, 2018
Plants & Animals
DEC 26, 2018
Salmon Face Impaired Olfactory Function Amid Ocean Acidification
Olfaction, or more colloquially known as the sense of smell, is essential for coho salmon. The fish depend on their noses to sniff their way through a vari...
FEB 04, 2019
Videos
FEB 04, 2019
Biodegradable Packaging, Inspired by Fungus
The planet is awash in plastic, and disposing of it is challenging. But we can start to reduce its use....
FEB 04, 2019
Genetics & Genomics
FEB 04, 2019
A Rapid New Method to Help Modern Crops Resist Disease
Scientists can now find genes in wild plants that can make modern crops more resistant to disease, without impacting yield or using pesticides....
Loading Comments...