I'm on ecomodder because efficiency is interesting to me. Making the best use of resources makes sense, and can be a fun pursuit of its own.
That said, global warming doesn't even make the top 20 list of most threatening things to humanity.
In no particular order, the following far outweigh the consequences of global warming:
War (especially nuclear, biological, genetic, etc)
We'll figure out how to mitigate or adapt to changing climate, but I fear we will not figure out how to improve compassion and rationality before we figure out how to destroy ourselves.