Global Climate Change Mitigation: Burden Sharing

Dr Gabrial Anandarajah, UCL Energy Institute

Christophe McGlade, UCL Institute for Sustainable Resources

Olivier Dessens, UCL Energy Institute

Although world leaders did not come to any agreement in Copenhagen in setting greenhouse gas (GHG) reduction targets for individual countries or for major emitters, they did agree that inaction on emissions reductions would lead to irreversible consequences and that substantial cuts were required. Since no mechanism was agreed upon for enacting such cuts, numerous ways remain open for determining individual regions’ allowable GHG emissions under any global climate agreement. An important issue with this issue of ‘burden sharing’ is who should bear the cost. It is widely discussed in the literature that developed countries should take a lead, given their historical contribution to the problem and their ability to pay.

This paper develops global least-cost mitigation pathways and discusses burden sharing by comparing the additional investments necessary to meet various climate change mitigation targets with a ‘no climate policy’ scenario. We carry out this analysis at a regional level by grouping countries into three categories: high income, middle income and low-income countries. The global GHG emissions mitigation pathways have been developed using a multi-region TIAM-UCL global energy system model.

Three scenarios are thus developed. The first is simply a reference scenario that has no emissions reduction requirements. The two other scenarios are constrained to achieve around a 60% chance of a 2°C (2DS) rise and 3°C rise (3DS) in the average surface temperature in 2100. The results are analysed by grouping the countries into three categories, broadly following the classifications set out by the World Bank: high income countries (‘developed’ countries), middle income countries (China, the Former Soviet Union and the Middle East) and low income countries (the rest of the world).

Results show that high-income regions per capita emissions fall steadily and by the largest degree: to less than a quarter of their 2010 level by 2050. The drop in low and middle-income countries is not as severe but is still over 50%. As expected, total annual energy systems costs are greater on a global level in the mitigation scenario. However, the percentage changes in total energy system costs are not the same among the different income groups. In 2020, overall costs are higher in high-income regions (compared to the other groups) since these are required to meet the emissions reductions they pledged as part of the Copenhagen Accord. The percentage change in total annual energy systems costs is higher for middle-income countries than for low-income countries throughout the period until 2050. The middle-income regions are assumed to develop rapidly over the model period, and in a no-policies case the consequent increases in energy-service demand is predominantly met through an increase in coal consumption. Given that coal consumption needs to be severely restricted in any mitigation scenario, these regions require a greater level of investment to meet the emissions reductions required. In contrast, in low-income regions it is assumed that the investment costs of many of the low-carbon technologies (such as carbon capture and storage) are higher than in the high-income regions. These are consequently more expensive to deploy and overall costs are higher. Therefore, despite the fact that high-income regions are responsible for majority of the cumulative emissions emitted since industrialisation, model results suggest that mitigation costs will be noticeably higher for middle and low-income regions. This analysis therefore poses difficult questions for the agreeing of a global agreement on emissions mitigation, but should help inform whether, or the extent to which, financial support should be provided by high-income regions.