Solar geoengineering: Is it worth the risk?

Do the potential pitfalls of solar geoengineering outweigh the dangers of a warming planet?

On the Catalyst with Shayle Kann podcast this week:

In some climate circles, solar geoengineering” is akin to a swearword. Also known as solar radiation modification, it refers to the process of deliberately modifying the earth’s atmosphere to reflect solar radiation. The idea provokes forceful pushback because it’s unclear how it would affect the earth’s agriculture, ozone layer and ecosystems.

But it’s been attracting interest because it’s clear it would probably do one thing well: cool the planet.

If we’re not moving fast enough on emissions reductions and carbon removal to avoid 1.5 degrees Celsius of warming, could solar geoengineering, despite its risks, be less dangerous than a hotter world?

In this episode, Shayle talks to Dan Visioni, a climate modeler who conducts research on solar geoengineering at Cornell University’s Sibley School of Mechanical and Aerospace Engineering.

They discuss what solar geoengineering might look like in the real world. 

Stratospheric sulfate injections could be used to mimic the effects of volcanic eruptions like Mount Pinatubo in 1991, which cooled the planet by 0.5 degrees Celsius in the following year. 

Marine cloud brightening would use salt aerosols to brighten a type of cloud that reflects solar radiation, a phenomenon already created by oceangoing ships.

Shayle and Dan also cover cirrus cloud thinning and — straight out of a sci-fi movie — space mirrors.

They explore key questions, including:

  • What do we know about the potential effects on ozone, precipitation and ecosystems? What do we need to research, and what could we learn by testing?

  • Which could scale faster: carbon dioxide removal or solar geoengineering? 

  • Solar geoengineering could cost a tiny fraction of the amount required to scale up carbon dioxide removal. Does that mean it could buy us time to draw down emissions in a less expensive manner? Or would its relative affordability enable a rogue actor to deploy it without international collaboration?

  • And who gets to make the final decision on whether the world should deploy solar geoengineering? Whose hand is on the thermostat, so to speak?

Recommended reading:

  • Nobel Prize winner Paul Crutzen’s influential 2006 paper on stratospheric sulfur injection

  • A provocative New York Times opinion piece promoting geoengineering from David Keith, professor of applied physics and public policy at Harvard who studies geoengineering


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