The fledgling greenhouse gas carbon trading market doubled to about $64 billion from 2006 to 2007, according to an annual emission trading market review (pdf) prepared by the World Bank.

The European Union’s emissions trading scheme (EU ETS) comprised most of the market, as has been the case since the start of the trading market in January 2005. Under that program (see related story, The Yale Forum), companies wanting to exceed their allowable emission limits have to buy spare permits from others not reaching their quotas.