This paper presents an estimate of the costs of reducing CO2 emissions asagreed in Kyoto by Annex 1 countries. Unlike most of the existing literature, this paper uses an Almost Ideal Demand System model for energyproducts to estimate the role of each country within the Annex 1 market. A major result is the provision of marginal (and total) abatement costs foreach. The recent position of the US is also discussed, showing the cost ofsome alternative outcomes.