Washington, DC— Major volcanic eruptions spew ash particles into the atmosphere, which reflect some of the Sun’s radiation back into space and cool the planet. But could this effect be intentionally recreated to fight climate change? A new paper in Geophysical Research Letters investigates.
Solar geoengineering is a theoretical approach to curbing the effects of
climate change by seeding the atmosphere with a regularly replenished layer of
intentionally released aerosol particles. Proponents sometimes describe it as
being like a “human-made” volcano.
“Nobody likes the idea of intentionally tinkering with our climate
system at global scale,” said Carnegie’s Ken Caldeira. “Even if we hope these
approaches won’t ever have to be used, it is really important that we understand
them because someday they might be needed to help alleviate suffering.”
He, along with Carnegie’s Lei Duan (a former student from Zhejiang
University), Long Cao of Zhejiang University, and Govindasamy Bala of the
Indian Institute of Science, set out to compare the effects on the climate of a
volcanic eruption and of solar geoengineering. They used sophisticated models
to investigate the impact of a single volcano-like event, which releases
particulates that linger in the atmosphere for just a few years, and of a
long-term geoengineering deployment, which requires maintaining an aerosol
layer in the atmosphere.
They found that regardless of how it got there, when the particulate
material is injected into the atmosphere, there is a rapid decrease in surface
temperature, with the land cooling faster than the ocean.
However, the volcanic eruption created a greater temperature difference
between the land and sea than did the geoengineering simulation. This resulted
in different precipitation patterns between the two scenarios. In both
situations, precipitation decreases over land—meaning less available water for
many people living there—but the decrease was more significant in the aftermath
of a volcanic eruption than it was in the geoengineering case.
“When a volcano goes off, the land cools substantially quicker than the
ocean. This disrupts rainfall patterns in ways that you wouldn’t expect to
happen with a sustained deployment of a geoengineering system,” said lead
Overall, the authors say that their results demonstrate that volcanic
eruptions are imperfect analogs for geoengineering and that scientists should
be cautious about extrapolating too much from them.
“While it’s important to evaluate geoengineering proposals from an
informed position, the best way to reduce climate risk is to reduce emissions,”
This work was supported by the National Key Basic Research Program of China, the National Natural Science Foundation of China, and the Carnegie Department of Global Ecology.
The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.