It's fascinating to watch the evolution of the mainstream media coverage of the geoengineering concept. I'm actually pretty pleasantly surprised: most of the articles I've seen have had an overall tone of caution about the proposals, even while recognizing that if we end up using geoengineering technologies, it's because things have gotten so bad that we're down to our last-ditch methods of avoiding disaster. The basics of the stories have been pretty consistent: we're in an even bigger climate mess than we thought, so real scientists have begun to consider options for climate modification that they might have dismissed in the past, simply to head off catastrophe; nonetheless, more research needs to be done. I haven't seen any news stories (as opposed to opinion pieces, or blog articles) that even imply that geoengineering would be considered a replacement for decarbonization, and I'm seeing fewer news articles that start from the perspective that such climate modification is inherently wrong, period.

Greg Lamb's new article in the Christian Science Monitor, "Can we engineer a cooler earth?" is an example of the current model for mainstream coverage of the concept. It's not just that he quotes me in the piece, but that he does so without too badly distorting what I tried to say. It does make me sound like more of an enthusiast than I really am, but it gets the essential point across: we need to get our carbon emissions down, but the climate is changing faster and harder than even the most pessimistic models had predicted a few years ago.

Blocking sunlight, adds futurist Cascio, “is at best a delay of the worst temperature-related consequences of global warming in order to give us more time for de-carbonization.”

Any long-term approach to solving global warming, Thernstrom says, almost certainly will have three aspects: emissions reductions, geoengineering, and steps to adapt to an altered climate. “The question is, ‘What is the ratio among those three pieces?’ ”

Schemes to slightly dim sunlight also wouldn’t solve the problem of ocean acidification, caused by airborne CO2 entering seawater. More-acidic oceans would harm coral reefs and upset ocean ecology, with possible far-reaching effects. Ocean acidification is “at least as big” a problem as that of CO2 in the air, Cascio says.

That last point is critical. Even if we manage to avoid a heat-related crisis with geoengineering, we'll still need to eliminate our industrial carbon emissions as quickly as possible to avoid ocean ecosystem collapse. I suspect that we'll come to see ocean acidification as a bigger problem than atmospheric warming, in fact.