That global warming is an important issue.*

*This is not a claim that climate change isn't changing, or that it isn't man made, or that the changes will not have a net negative impact. Rather, even a superficial cost/benefit analysis will quickly show that the benefit or acting towards many other values will have a much higher payoff than any attempt to influence climate change. For example, adding iodine to salt is very cheap, but can save many millions of lives with a high degree of certainty and in a short time frame.

Bjorn Lomborg did some research on this: http://www.ted.com/talks/bjorn_lomborg_sets_global_priorities.html