Even if we grant that there is a scientific consensus that human activity is the cause of global warming rather than other natural causes, it just doesn’t follow that we should do anything in particular about it. Let’s say that someone comes up with absolutely conclusive scientific proof that global warming is due to human activity and not variations in solar activity or anything else. What then? We would need to know how much the problem costs and if there are any solutions that cost less than the problem does.
When people like Al Gore say, “See, global warming is caused by human beings, therefore ratify Kyoto and elect me,” they’re leaping over a huge logical ravine.