The trading of greenhouse gas (GHG) emissions has recently emerged as one of the most dynamic and promising areas of global environmental governance. According to the latest assessment by the International Panel on Climate Change (IPCC, 2007), global GHG emissions must peak, if not decline, by 2015 in order to limit global mean temperature increases to 2°C above pre-industrial levels. The Panel predicted that without a reduction of GHG emissions, the globe would experience an overall temperature rise of 6.4°C by the end of this century, which is a catastrophic scenario.