Abstract: The Brazilian proposal for differentiated greenhouse gas emissions reduction targets for Annex I parties of the UNFCCC should be based on attribution of contribution to global climate change due to historical emissions of greenhouse gases. Numerical models are used to calculate the climate change due to past emissions of greenhouse gases, and to partition the climate change among nations or regions. We use historical emissions and population databases, and a simple climate model (SCM) to calculate national and their per capita historical contributions to climate change. There is great difference between the results using national accumulative emissions and accumulative per capita emissions data, respectively. The developing countries are in lower accumulative per capita emission than the developed countries. Our calculations give the per capita contributions to climate change in the evaluation year over the period between the choosing start and end years. Comparing the contribution of per capita historical emissions calculated by SCM with the accumulative per capita emissions, we find that the results are similar. For equity between humans, there is a need to define new indicators to consider the differentiation of per capita historical emission responsibilities such as contributions of per capita historical emissions to global warming (sea level rise, etc.).

Key words: contributions of accumulative per capita historical emissions, climate change