Thèse de doctorat en Analyse et politique économiques
Sous la direction de Thomas Piketty.
Soutenue le 18-06-2018
à Paris Sciences et Lettres (ComUE) , dans le cadre de École doctorale d'Économie (Paris) , en partenariat avec École des hautes études en sciences sociales (Paris) (établissement de préparation de la thèse) et de Paris-Jourdan Sciences Économiques (laboratoire) .
Le président du jury était Yann Algan.
Insoutenables inégalités? Essais sur les inégalités mondiales de revenu et de pollution
Cette thèse porte sur la dynamique des inégalités de revenu et de pollution entre individus, à l’intérieur des pays et au niveau mondial. Plus précisément, l'objectif de ces travaux est de mieux mesurer et mieux comprendre les déterminants de la dynamique sur moyen ou long terme des inégalités de revenu à l'échelle d’un pays (chapitre I) ou au niveau mondial (chapitre II). Il s'agit également de mieux comprendre et mesurer les liens articulant les inégalités de revenu aux inégalités environnementales au niveau national (chapitre III) et mondial (chapitre IV). Enfin, la thèse discute de l’impact des indicateurs de mesure des inégalités sur l'action politique (chapitres V et VI).
Chapter I, entitled “Indian income inequality dynamics, 1922-2015: From British Raj to Billionaire Raj?” , discusses the methodological issues at stake when reconstructing historical income inequality series in a country as populated as India, but with very scarce data. The chapter shows that despite many important data limitations, one can combine tax data, surveys and national accounts in a systematic manner to reconstruct income inequality estimates robust to a wide range of alternative strategies. In the case of India, the results are striking as they reveal that income inequality is currently at its highest level since the creation of the Indian Income tax in 1922. The top 1% capture more than 22% of national income today, up from 6% in the mid-1980s, when the top 1% captured about 6% of total income. Chapter II, entitled “Building a global income distribution brick by brick” , builds on chapter I (and many other similar endeavors carried out by my colleagues at the WIL) to construct a global distribution of income based on a systematic combination of tax, survey data and national accounts. Our results are notable as some go against preconceived ideas on globalization and its impacts on economic inequality. In particular, we show that the global top 1% captured twice as much global income growth as the bottom 50% since 1980. We demonstrate that inequality increased, rather than decreased between world individuals since 1980, despite strong growth in the emerging world. In other words, rising inequality within countries was stronger than the effect of reduced inequality between countries since 1980. Looking into the future, the chapter also reveals that under “Business as Usual”, global inequality is likely to further rise (despite strong growth in emerging regions) contrary to what has been argued in academic and public debates on the matter. The Appendices to the chapter present the details of the method and reveal that our results are robust alternative strategies to account for missing data at the country level.How to move from global income inequality to global environmental inequality? A first step is to understand the role of income and non-income drivers of individual pollution levels within countries. This is the work that is discussed in Chapter III, entitled “Are younger generations higher carbon emitters than their elders?” , which focuses on the determinants of individual level CO2 emissions and focus on the role of income, technology and other factors, such as date of birth. We show that the French baby-boom generation emitted relatively more CO2 than their parents and their children, throughout their lifetime (about 20% more direct CO2 emissions). This is due to a combination of income, technological lock-in and cultural effects. Chapter IV, entitled “Carbon and inequality: From Kyoto to Paris” , builds on the results obtained in the previous chapters to construct a global distribution of carbon emissions. At the time of writing this chapter, global income inequality estimates presented in Chapter II were not available, so we had to rely on work done by other researchers to obtain global income series (Lakner and Milanovic, 2015). These were corrected with tax data and then used to reconstruct a global carbon emissions database. We show that the top 10% emitters account for about 45% of global emissions today and that twenty years ago, global inequality of carbon emissions was essentially a between-country inequality phenomena. Today, the situation is being reversed as within-country emissions inequality accounts for as much of global emissions inequality as the between-country dimension. On the basis of our results, we propose schemes to better share contributions to climate adaptation funds. The history of climate negotiations shows the extreme difficulty to implement any kinds of allocation rules to share a climate burden.