This paper focuses on the equity aspects of international burden sharing for global CO2 emission stabilization. It first summarizes and classifies five equity principles that may play a role in allocating emission entitlements to countries. These principles are then used to examine ten burden-sharing rules --  proposed in the published literature of the field -- by analyzing the degree to which each rule incorporates the five equity principles. 

The burden-sharing rules surveyed are not readily comparable because they do not use a common global emission (reduction) goal. For that reason, our paper carries out a detailed examination of three sets of quantitative emission entitlements, which are based on three typical burden-sharing rules -- the equal emissions per capita approach, the carbon intensity approach, and the Triptych approach -- with the idea of comparing their implications for carbon emission entitlements for 67 countries and 9 world regions. To make the three rules comparable, we used a global carbon emission target that leads asymptotically to an atmospheric CO2 concentration of 550 ppmv. 

Reducing carbon emissions to meet this concentration target requires significant global efforts. No burden-sharing scheme aiming at this target can therefore be expected to lead to a negligible burden on all countries. Depending on the equity principle chosen, a scheme can allocate more of the global burden to developing countries or to industrialized countries. Developing countries receive relatively higher entitlements under the equal emissions per capita approach whereas industrialized countries are relatively better off under the carbon intensity approach. The Triptych approach leads to in-between allocations for most countries. Only countries with high carbon intensity in 1990 (for example China, Russia, and Poland) receive the highest entitlements under this burden-sharing rule. 

In some countries and regions, emission entitlements as calculated by any of the three burden-sharing rules are so tight that it appears unrealistic to assume that domestic measures alone can be successful in limiting their actual emissions to the emission entitlements assigned to them. It would therefore seem natural to assume that the calculated entitlements determine the initial allocation of tradable emission allowances of countries or regions. Although we make this assumption, we considered any numerical determination of carbon trade flows to be outside the scope of our paper.