Is your carbon footprint stepping on the global poor?
A couple of the reasons given by the U.S. for not ratifying the Kyoto treaty to reduce green house emissions is that it would do very little to stop big global polluters, such as China, and would have a big negative impact on the American economy. This interesting graphic represents the carbon footprint of each state as equivalent to some nation in the world. Seems clear that the U.S. has a significant ability to affect the global environment.
This map also suggests that state regulation on environmental issues can possibly be quite effective. The battleground is never too small to make a difference. You can check out the figures used for calculating the map here.
As to the negative impact on the economy: here's a graphic that represents each state as comparable to the GDP of some nation in the world. Figures are explained here. Given the low levels of foreign aid that the U.S. gives to the world, then, perhaps, a little give is called for in the name of global justice?