Because the world has looked at the evidence and made a decision based on science.
You are welcome to debate all you'd like. Feel free, but don't expect me to go back and forth when you both selectively quote from the same National Geo article to make the opposite point to the authors. Actually don't expect me to go back and forth at all. I'm spending a lot of time on health care reform, the green arguement isn't right now.
The pro pollution scientists working for Exon Mobile are also free to debate via the scientific method with submissions to peer review publications in print or online. They must use published numbers and methods allowing for reproduceable results. That's how scientists do it. But they can't, so instead they do media campaigns and conferences of non scientists. Lots of luck being taken seriously that way.
Carbon credits are similar to the trade in polution that the coal fired electric plants were doing in the East and Midwest. It allows more plolution prone plants to keep operating but the less poluting ones to do so cheaper. Companies could buy polution credits from cleaner plants and keep profitable but poluting plants online. As I remember there was even a futures market in credits. Eventually less profitable but more poluting plants are phased out.
I think Canada last week either passed or debated legislation commiting to eliminate coal produced electricity by some time 20 years in the future. That gives people investing in other modes of generation the abliity to plan knowing there will be a revenue stream.
Ultimately you all have to just admit, Americans have made a decision to go with science. We voted on it. Obama was extremely straightforward on his views and objectives re climate change. He publicized it for two years, go look. Now you all can scream and yell all you want, but the other 80% of us don't have to listen.
One has to wonder about supposed consevative hunters being anti conservation pro pollution.