At this late stage I just got around to reading the controversial article by Robert Laughlin, Nobel-prize-winning physicist, "What the Earth Knows." Large parts seem totally uncontroversial to me:
Carbon dioxide from the human burning of fossil fuel is building up in the atmosphere at a frightening pace, enough to double the present concentration in a century. This buildup has the potential to raise average temperatures on the earth several degrees centigrade, enough to modify the weather and accelerate melting of the polar ice sheets.
The IPCC couldn't say it better. And he understands the distinction, which I discussed here, between what is a big deal for humans and a big deal in terms of the time scale of the earth.
It's not at all controversial to say AGW will be a tiny ripple in geologic history: global thermonuclear war would be a tiny ripple in geologic history. That's a function of the vastness of geologic time; on a human timescale these things are quite a bit more important.
There are a couple of silly ideas, one, which has been discussed at length in the blogosphere, being the idea that there is "no solid scientific support" for our ideas about the causes of past climate change. That mistake could be a function of ignorance of the subject, or it could be a function of a physicist's unrealistic idea of what constitutes "solid scientific support" outside his own field.
Then, after seeming to comprehend so well the difference between human and geologic time, he goes off the rails and equates them:
The geologic record suggests that climate ought not to concern us too much when we’re gazing into the energy future, not because it’s unimportant, but because it’s beyond our power to control.
No. This is like saying that because the earth is sometime struck by giant meteors, it's pointless to try and avoid nuclear war. Human-caused is different in a very practical sense from natural changes, because natural changes happen over geologic time: that is, from a human perspective, they occur hugely infrequently and usually very slowly. They occur so infrequently, in the earth's 4.5 billion-year history, that the chances of the next thousand years seeing even one of these natural shifts is tiny.
Whereas human-triggered changes occur with blinding swiftness by the earth's standards and, by logical necessity, humans are always around to suffer the consequences.