The relationship between science and society changed fairly dramatically in the 1970s, at least in the United States. Prior to that decade, almost all science served a notion of Progress. However, around that time, the consequences of progress could be felt by enough people and observed by enough scientists that the enterprise changed fundamentally. Instead of Making Progress Possible, a growing cadre found themselves in the role of ancient prophets, warning people they had gone too far.
Right now I'm listening to a fascinating discussion about carbon accounting by the CSIS, which has a great series of Energy and Climate Change. A big question asked right off the bat is how actually access how much carbon gets released, much less the impact of those emissions. It's a fascinating to hear a discussion of how to do things like determine the carbon footprint of a screwdriver.
This is a very important question,and any international agreement on managing the transition to a sustainable economy depends on getting this right. However, when science and policy collide like this, uncertainty quickly becomes wiggle room, and wiggle room quickly leads to acrimony by those genuinely worried and "junk science" accusations by those who are not. How is the non-scientist to approach this?
For a partial answer, I recommend reading Michael Pollan's book "In Defense of Food." In it, he quite aggressively attacks the practice of nutrition science, itself not much older than climate science, for pursuing molecules instead of foods, and in so doing allowing themselves to be caught by "regulatory capture" as food manufacturers use their work to selectively add or remove nutrients. We've known that the western diet high in grain-fed meats and highly refined grain products is the best way to encourage heart disease, diabetes and most cancers, but our "science based" policy on food has encouraged trying to find the right balance of molecules instead of encouraging people to eat the whole plant-based foods that kept generations healthier (well, until they died of infections before we figured out penicillin)
Likewise, I recommend a similar approach in discussing climate science and its relationship to public policy. Carbon dioxide absorbs infrared radiation in the wavelength that the Earth radiates out into space, but does not affect the rate at which the Earth receives higher frequency radiation from the sun, resulting in a positive net heat flux, or, put simply, wrapping the planet in a blanket as it spins around its heat-lamp. The precise effect of this is hard to determine, but it's pretty well understood now that the climate is a "meta-stable" system, kind of like a marble on a rough surface. We know that we like were that marble is, and that we probably won't like any of the places it would roll to if we poked it too hard.
The goal of climate policy must be be to limit that poking. The gritty details of exactly how hard a poke we can stand, how to account for the carbon cost of a hammer, and who or what groups gain and lose in the trade off are worthless if we lose sight of that goal. We don't know exactly what will happen if we give the planet over to full-scale human modification, but given how we've treated out bodies, the answer is certainly not going to be good.
