International Emission Trading (IET) has been a key element of the cost-containing flexible mechanisms of the Kyoto Protocol and could prove to be a useful tool in the future. However, trading of AAUs from countries whose emissions have declined since their baseline year under the Kyoto Protocol has led critics to be skeptical of carbon markets due to the lack of actual emission reductions that occur as a result of these trades.
Aldrich, Elizabeth. (2010). "The Importance of a Clearly Defined Policy Goal for AAU Trading". Joint Implementation Quarterly, 16(3), .