1. Introduction
Energy consumption and CO2 emissions per capita differ largely across
countries and regions around the world. Consequently, people between
countries and regions contribute at different degrees to the intensity of the
greenhouse effect. Several studies have analyzed such differences using
distributive analysis tools and have drawn energy and climatic policy
implications (see among others, Heil and Wodon, 1997, 2000; Millimet and
Slottje, 2002; Hedenus and Azar, 2005; Padilla and Serrano, 2006; Duro and
Padilla, 2006, 2008; Cantore and Padilla, 2010a, 2010b; Groot, 2010).
One of the most commonly used tools to analyze the driving forces of emissions
and their evolution is the so-called Kaya identity (Kaya, 1989; Yamaji et al.,
1991; Alcantara and Padilla, 2005). According to the Kaya identity, the factors
explaining the evolution of per capita emissions are the carbon intensity of
energy, the energy intensity of GDP, and the affluence, which is usually
measured in terms of GDP per capita. In a previous article in this journal, Duro
and Padilla (2006) used a Theil index decomposition that allows decomposing
inequality into different Kaya factors and two interaction terms to analyze the
determinants of cross-country inequality in CO2 emissions per capita between
1971 and 1999. The authors highlighted the greater importance (although
decreasing over time) of income inequality in explaining differences in
emissions per capita. Nevertheless, they also highlighted the importance of
carbonization index inequalities and energy intensities in globally reducing
inequality in per capita emissions. As regards energy intensities, the authors
point to the existence of considerable divergence worldwide. However, due to
the reduction of energy intensity in some developing countries such divergence
has been reduced. Another finding from these authors is the relevance of
convergence in energy intensities in reducing CO2 inequality in the Temperate
zone group of countries, which is basically composed of rich countries. Sun
(2002) and Alcantara and Duro (2004) also show a downtrend in energy
intensity inequality among the OECD countries. Sun (2002) uses mean
deviation as a dispersion measure to analyze this inequality. Alcantara and