Carbon was taken up by tons of plant material that got buried and trapped below the earth's surface.
Gradual global warming wouldn't be bad, b/c we'd have time to adjust.
The real problem with global warming is that it will cause sea levels to rise, and if it happens fast enough, it will end up displacing about a billion people or so.
It may result in more arable land in the alpine and boreal country, but the short-term affect of the rising sea levels is a threat to be taken seriously. Even if you take warming out of it (good or bad), the acidification to the oceans as a result of it absorbing more and more CO2 has the potential to cause huge seafood collapses.
Also, I'm not opposed to a technological solution to global warming, but I don't think we should bank on them.
As I've said before on this board, even if you don't disaster is likely, that doesn't mean you shouldn't provide some insurance against it. I'm unlikely to die in the next 5 years, but I still have life insurance for my family if I do.
The argument we should be having is what level of sacrifice (like my life insurance premiums) is appropriate given the risk level.
As long as there are people that think the whole thing is a hoax, we'll never have the debate we should. Because of the polarization and politicization of the topic, both sides have gone to extremes. For example, just because I believe global warming is real doesn't mean I'm opposed to the Keystone Pipeline. I'd gladly trade the Keystone Pipeline for cap-and-trade legislation (originally a Republican idea) any day.