A US Congressional committee held hearings on engineered approaches to cooling the planet.

In addition to multiple articles and books in the popular media, the United Kingdom's Royal Society, the authoritative national academy of science there, issued an in-depth review of geoengineering and President Obama's science advisor, John Holdren, has repeatedly stated that geoengineering must be on the table as a possible approach to addressing climate change.

Makes sense to debate and study the option decades before it might become necessary to use it.

Yesterday, the House of Representatives' Committee on Science and Technology held a hearing that its chairman, Bart Gordan (D-TN), said was, "the first time that a congressional committee has undertaken a serious review of proposals for climate engineering."

Gordan was quick to say that this doesn't mean he supported geoengineering, and that the consensus at the hearing seemed to be that no one should deploy geoengineering until we've done a lot more research.

I've been writing about climate engineering for years. My own take: Cooling the planet with aerosols or a huge array of reflective satellites might some day deliver a net benefit. But climate engineering is problematic for a few reasons:

• Cooling the planet doesn't reverse the effects of ocean acidification caused by more carbon dioxide dissolving into the ocean.
• The cooling method would likely change rain patterns as compared to the same level of coolness as a result of reduced CO2 in the atmosphere. So some large populations could come out net losers.
• The effects of any cooling method would not all be foreseeable in advance or even accurately attributable once they happened. Did the torrential rains or drought in some country happen due to the cooling or would they have been even worse without the cooling?
• Some of the perceived costs and benefits would be highly subjective to different people in the same area. Even farmers of different kinds of crops would see the same changes in climate as delivering different costs and benefits.

So one needs to be looking at a pretty dire and certain future (e.g. big sea level rises flooding out southern Florida, New York City, Bangladesh, and London) before launching into such a drastic undertaking.

On the other hand, it is possible to wade into climate engineering with some measures that would be widely seen as quite innocuous. For example, building roofs, which are human constructions in the first place could all be painted white to delay global warming. US Energy Secretary Steven Chu sees white roofs as fairly benign. One could argue that white roofs and white roads would counteract changes in albedo that we caused in the first place by constructing dark roofs and black asphalt roads. So the argument will be made that roof painting represents a restoration of previous natural albedo.

My guess is we'll see policies put into place to do mild forms of climate engineering and once started down that path if the world really starts to heat up bigger and bigger interventions will get implemented.