Seth Borenstein of the AP caused a volcanic eruption yesterday with his interview of science adviser John Holdren, “Obama looking at cooling air to fight warming.”  Too bad the story isn’t quite accurate, as Holdren confirmed in an e-mail to me today and a separate email to others (that the NYT’s Revkin published here).

Geoengineering is “the intentional large scale manipulation of the global environment” to counteract the effects of global warming or “emergency interventions to cool the atmosphere should less drastic measures fail.”  It is a last resort at best (see “Geo-engineering remains a bad idea”” and “Geo-Engineering is NOT the Answer“).

Rather than  focusing on what Holdren doesn’t believe, let’s focus on what he does.  I asked him a simple question.  Does he stand by what he published 3 years ago, which I often quote:

“The ‘geo-engineering’ approaches considered so far appear to be afflicted with some combination of high costs, low leverage, and a high likelihood of serious side effects.“

He wrote back, “I said exactly that to Seth Borenstein.” In his earlier email, Holdren wrote bluntly:

I said that the approaches that have been surfaced so far seem problematic in terms of both efficacy and side effects, but we have to look at the possibilities and understand them because if we get desperate enough it will be considered. I also made clear that this was my personal view, not Administration policy. Asked whether I had mentioned geo-engineering in any White House discussions, though, I said that I had. This is NOT the same thing as saying the White House is giving serious consideration to geo-engineering – which it isn’t — and I am disappointed that the headline and the text of the article suggest otherwise.

Another thing I know Holdren understands — though it gets left out of many articles on the subject — is that geo-engineering approaches considered so far do not replace mitigation as the primary strategy for avoiding catastrophic impacts.  Indeed, the scientists I have seen discuss this in the literature tend to see geo-engineering as perhaps a relatively modest, temporary strategy after you have tried as hard as possible to keep concentrations at or below 450 ppm.  It might buy you a little time to get back to 350 (or lower) if that proves necessary.

But if we stay anywhere near our current emissions path for the next few decades, we make it extremely unlikely that geo-engineering can plausibly make enough of a contribution to matter.

One final point:  Conservatives like geoengineering as a talking point because they think it obviates the need for serious mitigation, which it doesn’t.  The AP notes, “The conservative think tank American Enterprise Institute has its own geoengineering project, saying it could be ‘feasible and cost-effective.’ “  But this is just a talking point.  In reality, actual deployment of serious geo-engineering requires two things that conservatives completely reject today — climate scientists and climate models.

If you don’t believe climate models, then you would never contemplate geo-engineering in a million years.  Only models can tell you what geo-engineering might do –  there is no way to run a global experiment at scale and there are no paleoclimate analogs of the kind of geo-engineering that is being contemplated.  But this is the Catch-22.  Long before you had enough faith in climate scientists and climate models to justify geo-engineering, you would have a near certain understanding of the catastrophic global warming impacts we face on our current emissions path and a near certain understanding of how mitigation is the wisest and safest response.

I will blog more on this later.


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