I think the debate over AGW has grown confused for many reasons, but one of the important ones is that there actually two related but separate propositions being argued. For political reasons, proponents of the AGW theory have deliberately fused the two propositions, but for clarity of perception I think it important that we separate them and see them in their actual relatioship.
The first proposition is that due to the activities of mankind – eating, breathing, farming, building cities and factories, driving – the planet is getting somewhat warmer – not drastically, but measurably.
The second proposition is that these changes, combined with our species’ other environmental depredations, is going to lead to some type of Climate Armageddon, with the species’ future in doubt and our poverty all but assured. (I regularly see AGW-friendly commentators expounding this doom and gloom as a simple stated fact, something assumed as obvious, as a consequence of AGW.)
Science has largely decided that the first element – it’s getting warmer, mostly – is true. Wrangles over the CRU’s exact level of culpability aside, they don’t need to fudge the data to show some warming; the exact instances of malfeasance at CRU look at this early date to be in areas like trying to eradicate inconvenient truths like historical climate optima when things were a bit warmer than they are now. That effort, to dampen debate by trying to create a pretend consensus that something inconvenient to a simple, easily-sold narrative simply never happened – an “unevent” – is reprehensible and vile, but not central to the core of AGW proposition number one. Other data sources also show a warming trend, and while I am very willing to believe that there are corrupt scientists in the world, I do not believe that they are everywhere. Someone is always willing to be the hero by proving the truth in the face of such conspiracies of lies, and climate science is hardly Mafia-like enough to enforce complete silence.
It’s the second element where the real debate should be occurring, and mostly, it isn’t.
Could AGW lead to catastrophic scenarios? Sure. I’d wager it won’t, for complex reasons having to do with human adaptability and the survival instinct, but I’ll readily admit I could be wrong in my guess. But the burden of proof for such catastrophic possibilities is on the people proposing them; the rest of us don’t have to justify our use of energy to selfishly heat our homes and feed our families by first disproving that this is going to cause Gotterdammerung.
Society must tread warily. Advocates of the strong AGW position are fond of arguing the precautionary principle, but seem much less heedful of its guidance when it comes to social engineering. Our EPA has just declared that every human being (and other breathing life form) on the planet to be polluters, by virtue of our respiratory metabolism and its production of carbon dioxide. Global elites are meeting now in Copenhagen to throw bones to the developing world and monkey wrenches into their own economies.
I do not believe that the science justifies such strong measures. A social precautionary principle, that we should not throw away centuries of economic progress and betterment of human welfare on a whim, must guide us as we determine how best to match the needs of our species with the constraints of our planet.