Geoengineering the Climate May Reduce Vital Monsoonal Rains

Geoengineering the climate holds the potential to potentially reduce the amount of carbon dioxide in the atmosphere. Now, though, scientists have found that this method may not be the "quick fix" that some once believed it to be. It turns out that geoengineering could severely impact rainfall and snowfall, reducing vital rains to certain areas.

"Geoengineering the planet doesn't cure the problem," said Simone Tilmes, one of the researchers, in a news release. "Even if one of these techniques could keep global temperatures approximately balanced, precipitation would not return to preindustrial conditions."

Geoengineering can take various forms. Some methods involve the capture of carbon dioxide before it even enters the atmosphere. Other techniques involved shading the atmosphere by injecting sulfate particles into the stratosphere or launching mirrors to orbit with the goal of reducing global surface temperatures. In the case of this study, the researchers focused on how shading the planet might actually impact our climate.

In order to learn a bit more about the impact on the climate, the researchers turned to 12 of the world's leading climate models. They simulated global precipitation patterns if the atmospheric levels of carbon dioxide reached four times the level of the preindustrial era. Then, they simulated the effect of reduced incoming solar radiation on the global precipitation patterns.

So what did they find? It turns out that an increase in carbon dioxide levels would significantly increase global average precipitation, though it would be likely that there would be significant regional differentiations. They also found that if a geoengineering approach partially reflected incoming solar radiation, rains would decrease significantly. These effects would be greater over land than over ocean and particularly pronounced during months of heavy, monsoonal rains.

"It's very much a pick-your-poison type of problem," said John Fasullo, one of the researchers, in a news release. "If you don't like warming, you can reduce the amount of sunlight reaching the surface and cool the climate. But if you do that, large reductions in rainfall are unavoidable. There's no win-win option here."

The findings reveal how important it is to understand the impacts of geoengineering before actually implementing any of these methods. The fact that some techniques may actually make things worse shows that the best possible way to halt the tide of warming may be to reduce greenhouse emissions.

The findings are published in the Journal of Geophysical Research: Atmospheres.