Unlike most previous research, which has focused on estimating carbon shadow prices at regional or sectoral levels, this paper attempts to estimate carbon shadow prices at a worldwide level. A non-parametric robust framework estimates carbon shadow prices for 119 countries from all continents in 12 large groups. Our empirical results reveal that the global carbon shadow price is increasing by around 2:24% per annum and reached 2845 US dollars per ton in 2011. Regional carbon shadow prices present significant disparities over the analyzed period. We find a substantial sigma convergence process of carbon shadow prices among countries during 1990-2007 while divergence appears after the global financial crisis. We then analyze the relationship between carbon shadow prices and the implementation of the Kyoto Protocol.