Mount Pinatubo's 1991 eruption in the Phillippines injected sulfates into the atmosphere and cooled the earth. One geoengineering scheme would potentially replicate the cooling effects of volcanic eruptions. Photo: D. Harlow, USGS.
Would massive crop failures from heat waves and drought in the grain-growing regions of the American midwest be a sufficient reason to intentionally manipulate the atmosphere and cool the earth?
That was the opening question posed by Ken Caldeira of the Carnegie Institution and Stanford during a recent panel discussion on geoengineering at the Aspen Environment Forum. (Disclosure: I helped organize the session and event.)
This question of "geoengineering" -- whether, when, and how to intentionally change earth's atmosphere -- is poised for more attention as the carbon pollution we unintentionally produce by burning coal and oil keeps rising. As atmospheric carbon dioxide levels rise, they trap more of the sun's reflected radiant energy near the earth and drive up land and ocean temperatures.
And as temperatures go up, droughts already seen in Australia's Murray-Darling basin, or heatwaves that hit Europe in 2003 likely will become the norm, according to scientists such as David Battisti and Rosamond Naylor. Their study published in SCIENCE this year examines the likelihood and potential impact of future heatwaves on food supply as carbon emissions and temperatures rise.
Jamais Cascio, a founder of worldchanging.org and now writing at Open the Future published in early 2009 a very readable and insightful short book on this subject, "Hacking the Earth: Understanding the Consequences of Geoengineering." Cascio lays out the choices and ethical implications of "geoengineering" the atmosphere to control planetary heating.
In theory, several options exist: shoot sulfate particles or millions of light-reflecting disks high into the atmosphere to block the sun; fertilize the oceans with iron to encourage carbon-absorbing phytoplankton blooms; plant millions of trees to absorb carbon; spray seawater into the sky to create heat-reflecting white clouds; and somehow capture and bury carbon already in the sky.
So what to do as our rising carbon emissions heat the planet? Is there any realistic large-scale way to cool earth, or stem the heating? Volcanic eruptions have, and a recent example is the Phillippines' Mount Pinatubo. In 1991 the volcano cooled the earth when its eruptions injected massive amounts of sulfates into the atmosphere, partially blocking the sun.
So if we shoot sulfate particles into the sky much like volcanoes do to reduce the amount of sun hitting the earth, won't the oceans continue to acidify? (Yes.) If we add sulfates to the sky to reduce the amount of sun hitting the earth wouldn't this reduce the effectiveness of solar power installations? (Likely yes.)
At the Aspen session Caldeira and fellow panelists David Keith of the University of Calgary and David Victor of Stanford worried for humanity's future unless we drastically cut fossil fuel emissions, and they see geoengineering as a last ditch emergency strategy if all else fails.
Keith said it was time for geoengineering discussions to "move out of the shadows," for no other reason than to help the world understand why we should not pursue it as a solution to global warming.
Geoengineering comes with a host of complications and ethical challenges: Who decides? If we start, what do we do and for how long? It's like driving a car: who will steer, accelerate, and who will brake? Once we begin injecting sulfate into the atmosphere we must keep doing it or cooling effects will disappear when we stop, and heating from rising atmospheric carbon will become severe.
Reliance on geoengineering can also create what is called "moral hazard," in that polluters are absolved and there is less reason to cut back on carbon emissions because we have found a "solution" to global warming. Alan Robock of Rutgers wrote a valuable article on these issues for the Bulletin of Atomic Scientists last year: 20 Reasons Why Geoengineering May Be a Bad Idea.
One of Keith's key concerns is that politicians of the world already have great difficulty agreeing on anything, and the idea that all nations could work in a synchronized fashion to manipulate the "knobs and dials" of the atmosphere boggles the mind.
The panelists (and several audience members) spend their life studying the issue. Keith has written on the history and prospect of geoengineering, and on carbon removal from the atmosphere. Caldeira has studied acidification of the ocean as atmospheric carbon levels keep rising. Victor writes extensively on climate policy and regulation challenges, and co-authored an a new article in Foreign Affairs on geoengineering's various political drivers, dilemmas, and implications: "The Geoengineering Option: A Last Resort Against Global Warming?"
Joining the discussion as audience members were Marty Hoffert of NYU, who has studied the need for radical change in the way we produce energy, and Robert Socolow of Princeton, co-author of the significant "Stabilization Wedge" carbon mitigation paper in SCIENCE in 2004.
Why all this scientific brain power in one room contemplating orchestration of global scale atmospheric change in a way that that sounds like a plot for a science-fiction film? Because we are making no progress in limiting carbon pollution, in fact we are going the wrong direction.
Newsweek Int'l.: How to Fix a Climate Emergency
Signs From Earth: Geoengineering Page
Open the Future: New Geoengineering Study: Can We Fix the Planet? by Jamais Cascio
NGM Blog Central: Engineering the Climate Could Buy Time
Jamais Cascio: Hacking the Earth: Understanding the Consequences of Geoengineering (Buy)
Zeebe, Zachos, Caldeira, and Tyrell, SCIENCE: Carbon Emissions and Acidification
New York Times Op-Ed: Ken Caldeira, How to Cool the Globe
NATURE, Ken Caldeira: Oceanography: Anthropogenic carbon and ocean pH
Battisti and Naylor, SCIENCE: Historical Warnings of Future Food Insecurity with Unprecedented Seasonal Heat
David Victor, Foreign Policy: The Geoengineering Option: A Last Resort Against Global Warming?
David Victor, Foreign Policy: What to Read on Climate Change
Alan Robock, Bulletin of the Atomic Scientists: 20 Reasons Why Geoengineering May Be A Bad Idea
TED: Geo-engineering to slow global warming. David Keith on TED.com
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