Considering that the US share of greenhouse gases is fairly small (15% of world total), has decreased quite a lot over time, and becomes harder on the margin, I'd say it's mostly just slinging words for political power at this point.
My own take is that you can avoid ecological devastation only through population reduction and in the short term by not up-leveling the Third World via mass immigration and industrialization.
My own take is that you can avoid ecological devastation only through population reduction and in the short term by not up-leveling the Third World via mass immigration and industrialization.