In December, dozens and dozens of world leaders will descend on Copenhagen, for the 2009 Copenhagen Climate Summit. It's variously been billed as a major crossroads for battling climate change--and one unlikely to yield much in the way of action, due to disagreements over how the costs of these efforts should be split.

So in that light, it's useful too look at who's actually been emitting all of the carbon. And that's what The Washington Post's Global Emissions chart does. The graph focuses only on the world's heaviest polluters: The so-called G-20 countries, which represent the world's twenty largest economies. Together, they account for 75% of world GDP and 75% of its carbon emissions. But their performance, relative to each other, varies quite a lot.

The graph allows you to see both total and per capita emissions in the last 60 years. A slider above the map allows you to adjust the time, and to the left, there's an ordinal ranking. They've shuffled tremendously over time, as countries such as China, India, Brazil, and Russia have developed. Empty bubbles represent the carbon emissions in a region; colored bubbles show the emissions of individual countries--thus, you can see who exactly the biggest polluters are in a given region.

But what might be most surprising is that, per capita, the U.S. has always been very high--but other countries have rapidly caught up to us, even as we've remained somewhat steady. The world has quickly taken up bad habits that we pioneered.

The point being: The U.S. has been slow-rolling its participation in any global climate effort. But if any change is going to happen, it only makes sense that it should start with us.

[Via Treehugger]