Is it true that some countries that are less industrialised and therefore produce lower levels of industrial pollution, that these smaller countries may "trade" their "carbon credits" (ie. the margin between how much they pollute and how much they are "allowed" to pollute) with countries who pollute in excess of their allowance?

ie. can a country like mexico, china, india, brazil or any of the other sweatshops, can they "buy carbon credits" from countries like Malawi which are predominantly agrarian in economy?