New research from scientists at the University of California, Berkeley has set out to think more critically about an idea that perhaps you haven’t even heard of: injecting particles into the atmosphere to cool the planet in an attempt to mitigate the warming effects of climate change.
This idea of solar geoengineering the planet to become in essence shadier has gained momentum in some fields because it is thought that crops might be able to grow better in cooler temperatures. Yet, after analyzing the past effects of several Earth-cooling volcanic eruptions as case studies for their hypothesis, the UC Berkeley team concluded that any improvements in crop yields from cooler temperatures would be overshadowed (pun intended) by lower productivity due to reduced sunlight. After all, plants need sunlight to photosynthesize
"Shading the planet keeps things cooler, which helps crops grow better. But plants also need sunlight to grow, so blocking sunlight can affect growth. For agriculture, the unintended impacts of solar geoengineering are equal in magnitude to the benefits," said lead author Jonathan Proctor. "It's a bit like performing an experimental surgery; the side-effects of treatment appear to be as bad as the illness."
One of the volcanos that the team analyzed in order to come up with this conclusion was the eruption of Mt. Pinatubo in the Philippines in 1991. After this eruption, 20 million tons of sulfur dioxide were emitted into the atmosphere. That led affected the whole world by reducing sunlight by 2.5 percent and lowering the average global temperature by almost 1 degree Fahrenheit. Sounds pretty good in this epic wave of heat that we’re experiencing right now, doesn’t it? So why not just geoengineer something similar, using sulfuric acid aerosols?
"Unknown unknowns make everybody nervous when it comes to global policies, as they should," said Solomon Hsiang, co-lead author. "The problem in figuring out the consequences of solar geoengineering is that we can't do a planetary-scale experiment without actually deploying the technology. The breakthrough here was realizing that we could learn something by studying the effects of giant volcanic eruptions that geoengineering tries to copy."
This study only focused on the agricultural impacts of this solar geoengineering idea. While the scientists found that such a scenario would negatively affect both C4 (maize) and C3 (soy, rice and wheat) crops, they suggest that more research is needed in order to understand the consequences that solar radiation management would have on other global systems like human health or ecosystem function.