It's well-known that the United States and China are the two biggest greenhouse-gas polluters in the world. But relatively few people can name number three on that list. It's Indonesia, thanks to heavy deforestation:

It is that frenzied rate of deforestation that has propelled Indonesia, home to 237 million people, into its top-three spot in the global league table of climate change villains. According to a government report released last month, the destruction of forests and carbon-rich peatlands accounts for 80 per cent of the 2.3 billion tons of carbon dioxide emitted in the country annually.

And, for similar reasons, Brazil now ranks as the fourth-largest CO2 emitter in the world. So, while getting the United States and China to agree to binding emission targets is on top of the to-do list at Copenhagen this December, hammering out some sort of agreement on deforestation isn't far behind. The most promising contender, at the moment, is a program to pay developing countries not to chop down their trees or burn their peatlands. Incidentally, this is one of the cheapest ways to reduce CO2 emissions, but, as Michael McCarthy points out, some of the current options being considered make environmentalists queasy. Like this one:

"Halting forest cover loss" means you can cut down the forests but replace them with other trees, so that "forest cover", the general area covered in trees, remains the same.

These other trees are likely to be commercial monocultures such as eucalyptus or oil palms, not remotely as valuable ecologically, or as a store of carbon, as virgin forest, and although it might be better to have those trees growing than bare ground, many environmentalists would stress that not cutting the virgin forest down in the first place is the best option of all.

There are also worries about whether the price of offsets in carbon-trading programs will actually be high enough to make conservation worthwhile for Indonesians and Brazilians, who can currently make a lot of money from cutting down trees and setting up palm-oil plantations or cattle ranches. (Even if, in the long run, deforestation isn't actually a very lucrative development strategy for those countries.)