A panel convened by the National Research Council of the U.S. National Academy of Sciences recently released a report that called for further study of "climate engineering" -- efforts to re-engineer the planet’s climate to battle global warming. We asked Assistant Professor Simon Nicholson, an expert on geoengineering and a founder of the Forum for Climate Engineering Assessment, for some insights:
Q: Climate engineering was once considered a fringe idea. Why is it gaining currency now?
A: It’s quite true that climate engineering was an idea that used to be confined to the darkest fringes of the conversation about responses to climate change. That has changed in the last handful of years for three main reasons:
• First, a small but vocal cohort of climate scientists has become disillusioned enough with the lack of political and social progress on climate change that they are pushing hard for serious consideration of ideas that in the past would have been seen as outlandish.
• Second, modeling studies have confirmed that the leading climate engineering proposal -- reflecting some amount of incoming sunlight by deploying sulfate particles high in the earth’s atmosphere -- would likely indeed have a cooling effect, though the positive and negative side effects attached to such an action are still being puzzled through.
• And third, studies and other activities like the recent reports from the National Academy of Sciences (NAS) make it clear that there are people within major governments giving thought to climate engineering.
There are no guarantees that climate engineering proposals will ever advance from the drawing board stage. These are still speculative, unproven technological suggestions, and none are any kind of substitute for the hard yet critical work of reducing greenhouse gas emissions and adapting to the impacts of a changing climate. At the same time, it can now be said that consideration of climate engineering is not going away, and will only grow louder and more insistent as the climatic condition worsens.
Q: What concepts did the expert panel propose to study and test?
A: The NAS panel decided to release two separate reports on climate engineering, and in doing so they reinforced categories that most people use when looking at climate engineering options. The first report is titled, “Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration.” It examines the state of scientific knowledge around so-called carbon dioxide removal (CDR) proposals -- basically, imagined technologies that would draw large amounts of CO2 down from the atmosphere and hold it in long-term storage.
The second (and much thicker) report is titled, “Climate Intervention: Reflecting Sunlight to Cool Earth.” It looks at the state of scientific knowledge, this time around solar radiation management (SRM) proposals. These are technologies that might, someday, be developed and deployed to reflect some amount of incoming sunlight back into space before it can warm the earth’s atmosphere, as a way to lower regional or global average atmospheric temperatures.
In common with prior reports conducted by other bodies, the NAS documents suggest that CDR proposals are probably the less risky of the two approaches, but given current understandings and technologies would be incredibly costly and difficult to deploy at any useful scale, and work over such long timeframes that they don’t offer any kind of near-term help in combatting climate change. Some SRM proposals, on the other hand, most notably the injection of sulfates into the stratosphere, would likely be relatively cheap and could set to work tackling one major aspect of climate change, atmospheric temperature increase, almost immediately. SRM, though, is a much riskier undertaking.
The reports ended up calling for modest research agendas to advance the physical science of both CDR and SRM. Interestingly, the reports made clear that the knowledge gap on the physical science side is dwarfed by our lack of collective understanding of the social and political implication of climate engineering. There is, in other words, a huge amount of work that needs to be done on governance, public engagement, and civil society outreach. These are the major areas in which my SIS-based group, the Forum for Climate Engineering Assessment, are engaged.
Q: What could be the side effects and dangers of climate engineering?
A: We still have a great deal to learn about the potential upsides and downsides of climate engineering. At the rollout event for the NAS reports, a couple of the speakers characterized CDR technological options as largely free from risk. This is not true. Drawing down CO2 from the atmosphere is a good thing on its face, but the prevailing proposals would have enormous implications for landuse patterns, would require the development of huge new industrial infrastructures to transport and store CO2, and would require extraordinary new arrangements to enable international cooperation.
Leading SRM proposals like the injection of sulfates into the stratosphere pose their own sets of conundrums. I break the risks down into three categories: material (what if, as some models suggest, cooling the atmosphere shuts off the monsoon rains in India?); political (who gets to decide how SRM technologies are used, and how would conflicts be adjudicated?); and existential (what does all of this mean for our collective capacities to respond to climate change and for the sorts of future technological and social pathways we privilege?).
The Forum for Climate Engineering Assessment works to build a more robust, inclusive, and informed climate engineering assessment. Its next event, co-sponsored with Resources for the Future, will be held on February 24: “What’s Next for Climate Engineering?” Follow the Forum on Twitter at @CEAssessment.
Follow Simon Nicholson on Twitter @simonnicholson4. For media requests, please call J. Paul Johnson at 202-885-5943.