riding in a CC summer

[tommymck]

As long as we're having a fun and spirited discussion on the topic, I'll toss in my $0.02.

The primary evidence for human contribution to climate change is associated with the rate of change of the temperature rise, not the actual magnitude. The rate of change over the past 75 years is about 10x faster than anything observed in prior epochs. Simultaneous with that was about a 250x increase in the rate of change in CO2 in the atmosphere as compared with any prior epochs.

Most people who study climate think that there is about a 90%+ likelihood that the two are linked. I personally think it's likely. Where it gets more dicey is predictions regarding where it goes from here and the effect that reductions in greenhouse emissions will have. Here, in my opinion, there is a bunch of playing fast and loose with the facts...and it's highly politically motivated. First, climate is a non-linear system and anybody who claims that a reduction of X% will reduce temperature rise by Y% is on shaky ground. The models aren't well defined and tiny changes in the initial conditions of the models produces outputs that are drastically different. Second, most of the goals that have been proposed do little to curb things if we assume that the models are correct. If many of the climate change scientists are correct with their models, the required cuts in emissions would produce as much of a human catastrophe as the effects of climate change. Third, a complex system like the weather often has feedback mechanisms that end up self-regulating at some point.

Still and all, reducing greenhouse emissions is good on a bunch of levels. Getting the population of the planet to go along with a particular policy will likely prove more difficult than the science in any case.