When we include all greenhouse gas emissions emitted in 1850-2010, the relative contribution to global cumulative emissions of developing countries is now 48%. The group of developed countries is responsible for 52%. Calculations of PBL – the Netherlands Environmental Assessment Agency, , Ecofys and the European Commission’s Joint Research Centre (JRC), show that the share of developing countries will probably amount to 51% in 2020. Hence somewhere in the current decade the share of the cumulative historical emissions of developing countries will surpass those of developed countries.
Discussions at the UN climate negotiations tend to focus on which countries have contributed most to climate change. In a recent article, researchers of PBL, Ecofys and JRC argue that there are several ways to calculate countries’ contributions to climate change, with widely varying outcomes.
In the article, which was published in the international journal Climatic Change and is now available in print, the authors compare several ways of calculating historical emissions and assess the effect of these different approaches on countries’ relative contributions to cumulative global emissions.
Discounting historical emissions for technological progress, for example, reduces the relative contributions of some developed countries and increases those of some developing countries, in total to 52%. This variant takes into account that emerging economies benefit from technologies that have been developed earlier elsewhere. Another variant, one that is often used by experts from developing countries, excludes recent emissions (2000-2010), non-CO2 greenhouse gases, and land-use change and forestry CO2. This increases the relative contribution of developed countries as a group to as high as 80%. From a scientific perspective, however, it is preferable to include all greenhouse gases, as well as the most recent emission trends, as was done in the reference calculations in this paper.
The results presented in this paper show the importance of the choices made when calculating historical contributions of countries. Such choices have to be made by the policy makers when negotiating a future international climate agreement. Providing the transparency in this paper on the implications of such choices can help governments to do so.