I believe the earth's atmosphere/ocean system is a complex collection of feedback mechanisms that is capable of small scale transients but fairly resistant to catastrophic, runaway excursions. I don't believe we're capable of destroying the biosphere with our industrial activities, it's not even clear if we could do it with a full scale nuclear war. The geological record supports this position, the planet has been subject to a variety of cosmic and geological catastrophes, both of long and short term duration, and it has been able to survive for billions of years.

On the other hand, even a slight change in climate would upset delicate balances which could affect agricultural conditions and settlement patterns over wide areas. It is questionable whether the global economic system could adapt to, say, the desertification of the USA's agricultural midlands, or the melting of the permafrost. We also know that purely natural processes (like the proposal that the sun is actually a variable star) may be playing a role in climate variability. I concede it is possible that climate change may not be occuring, I concede that if it is it may not be our fault, I concede that even if it is our fault our proposed fixes to the problem may be inadequate or just plain wrong. What I cannot accept is that we should do nothing or that we should ignore and undermine all warnings because it might have unfortunate economic consequences.

This is a technical problem (if it exists at all) and it will have a technical solution (if any solution is possible). I simply do not trust that interests who have every incentive to do nothing should be allowed to take precedence over, and take control of, the political discussion and the scientific debate.