Blocking the Sun to Save Crops From Rising Temperatures Will Actually Harm Them, Study Warns

Scientists released a new study investigating the effects on crops of a popular solar geoengineering solution. It turns out the costs outweigh the benefits.
Loukia Papadopoulos

There is no shortage of studies today revealing ever new consequences of the looming effects of climate change. From research warning about a 'hothouse' planet to catastrophic rising sea levels, the message is clear; our earth is in danger.

Scientists have been responding to the panic proposing inventive geoengineering solutions to our impending environmental woes. However, these suggestions are often followed with additional research dismissing their effects or worse revealing their inherent flaws.

One such study was once again released by University of California, Berkeley this week. The new work squashed hopes that injecting particles into the atmosphere to cool the planet could help prevent much-feared crop damage from rising global temperatures.

A rather logical conclusion

The authors came to their conclusion by analyzing past effects of Earth-cooling volcanic eruptions combined with crop responses to sunlight changes. However, in hearing lead author Jonathan Procter explain the results, it becomes quite obvious the outcomes could have simply been predicted by logic.

"Shading the planet keeps things cooler, which helps crops grow better. But plants also need sunlight to grow, so blocking sunlight can affect growth,” said Procter, a UC Berkeley doctoral candidate in the Department of Agricultural and Resource Economics.

Solar engineering, also called solar radiation management, has often been proposed as a solution to save the planet's crops from rising temperatures. One of the most popular options would see sulfate aerosols purposely injected into the upper atmosphere to reflect some sunlight back into space, cooling the Earth by a few degrees.

Side-effects as bad as the illness

“For agriculture, the unintended impacts of solar geoengineering are equal in magnitude to the benefits. It’s a bit like performing an experimental surgery; the side-effects of treatment appear to be as bad as the illness," warned Proctor.


Proctor and his team studied the effects on crops measured after the 1991 volcanic explosion of Mt. Pinatubo in the Philippines. It is estimated that Pinatubo injected about 20 million tons of sulfur dioxide into the atmosphere which lead to a 2.5% reduction in sunlight and an average global temperature reduced by about half a degree Celsius (about 1 degree Fahrenheit).

The researchers compared maize, soy, rice and wheat production from 105 countries from 1979-2009 to global satellite observations of Pinatubo's aerosols. “We are the first to use actual experimental and observational evidence to get at the total impacts that sulfate-based geoengineering might have on yields,” Proctor said.

Blocking the Sun to Save Crops From Rising Temperatures Will Actually Harm Them, Study Warns
Source: UCBerkeley/ Solomon Hsiang, Jonathan Proctor graphic

The results, however, were unexpected even for Proctor. “Before I started the study, I thought the net impact of changes in sunlight would be positive, so I was quite surprised by the finding that scattering light decreases yields," he added.

Despite his findings, Proctor does not believe the technology should be discounted altogether. "There are other sectors of the economy that could potentially benefit substantially," he added.

The researcher simply hopes his research will encourage others to explore all sides of geoengineering, both good and bad. 

The study was published in the journal Nature.