In recent years, international forums for accelerating action on climate change have turned into finger pointing exercises about which countries should do the heavy-lifting when it comes to tackling global warming. The US and China are usually deemed the worst culprits because they produce the most carbon dioxide in absolute terms, accounting for a combined 42 percent of global pollution. But population and economy size are two major determinants of a country's carbon footprint. When CO2 emissions are considered on a per-capita basis, for instance, China doesn't even make the top ten. Here's a comparative look at the countries that pollute the most.