SOURCE: Vox

DATE: August 8, 2018

SNIP: As we pump more carbon dioxide into the atmosphere and the Earth traps more heat, scientists predict that the severity and frequency of heat waves will continue to increase. Which might lead one to wonder: Is there a way to turn down the planet’s thermostat?

One concept gaining momentum is geoengineering: deliberately manipulating the Earth’s climate. Though currently only being tested in very small experiments, it includes solar radiation management — brightening clouds, making the ground more reflecting — and carbon dioxide removal, whether through direct air capture or planting more trees.

Fortunately, volcanoes are a handy, excellent model for one form of geoengineering. In big eruptions, they can spew huge quantities of sulfate aerosols into the stratosphere — exactly what some advocates have proposed as a way to block some sunlight and manually cool the planet.

In a study published Wednesday in the journal Nature, researchers used two past volcanic eruptions to estimate how geoengineering would affect the yield of major food crops. It’s one of the first studies ever to look at the potential consequences of geoengineering using real-world data. And the consequences look pretty serious.

“If we think of geoengineering as an experimental surgery, our findings suggest that the side effects of the treatment are just as bad as the original disease,” co-author Jonathan Proctor, a researcher at the University of California Berkeley, told reporters. In other words: When it comes to crops, solar geoengineering could trade one problem (heat-related declines) for another (crop losses due to less light).

Specifically, the research team examined what happened to maize, soy, rice, and wheat yields in the wake of the Mount Pinatubo and El Chichón eruptions in the years following their eruptions until the volcanic aerosols dissipated.

They found that the eruptions reduced the amount of direct sunlight hitting the earth but increased the amount of diffuse light. This led to a decline in edible yields from the crops they studied. Global average maize yields declined by 9.3 percent and the harvests of soy, rice, and wheat fell by 4.8 percent after the Mount Pinatubo eruption.