A study released on Tuesday revealed that New York was responsible for a full 1% of the United States' greenhouse gases. Coming much later in the article is the key point - that at 8.7 million people the Big Apple accounts for almost 3% of the total US population, meaning that the footprint of your average New Yorker is about 1/3 that of your average American.
The lesson? If every American lived like a New Yorker the US wouldn't have to agree to the Kyoto Protocol - because they already would have reached its targets.
Mayor Michael Bloomberg had commissioned the study to evaluate the city's progress in reducing their greenhouse gas emissions 30% by 2030. Cheers to real leadership.