Influence of national governments for or against the entry into force of the Kyoto Protocol: a Banzhaf index analysis

The recent announcement by the USA to withdraw their support for the Kyoto Protocol has drawn attention to the conditions under which the Protocol will enter into force: at least 55 member states to the United Nations Framework Convention on Climate Change (UNFCCC) have to ratify the Protocol, and those industrialized countries (Annex-I parties) that ratify it have to make up for at least 55% of the carbon dioxide emissions of this group in 1990. In this article, we analyze the a priori decision making power of individual parties, or groups of these, for the entry into force of the Kyoto Protocol, utilizing a mathematical approach known as the Banzhaf index. The results of our analysis suggest that the conditions for the entry into force of the Kyoto Protocol give more influence to the USA than might have been anticipated: while the USA has more voting power than the relative share of emissions suggests, all other Annex-I parties have less. Based on a mathematical model, this analysis shows that the Banzhaf index is a more realistic indicator of voting power than the bare numbers fixed in the Kyoto Protocol. This method could be used more extensively in the future for the analysis of voting procedures, in particular within the UNFCCC.