PNNL

Abstract

This paper provides a novel and comprehensive model-based assessment of possible outcomes of the Durban Platform negotiations with a focus on emissions reduction requirements, the consistency with the 2°C target and global economic impacts. The Durban Action scenarios investigated in the LIMITS study—all assuming the implementation of comprehensive global emission reductions after 2020, but assuming different 2020 emission reduction levels and different long-term stabilization targets—show that the probability of exceeding the 2°C limit increases with stabilization target from below one third for 450-470 ppm to 40-60% for 490-510 ppm in 2100. Global time-averaged economic costs of the Durban Action scenarios are limited across models, and are largely unaffected by the stringency of 2020 pledges. By contrast, the economic impact of delaying action beyond 2030 is much stronger on transitional costs. The main significance of short term action in the period 2010-2030 lies in preparing the ground for steep emissions reductions thereafter by inducing global emissions to peak and decline. The institutional challenges of all scenarios with fragmented near-term climate policy can be expected to be high as reflected in a steep rise of carbon prices and decarbonization rates until 2040. We conclude that an agreement on comprehensive emissions reductions to be implemented from 2020 onwards has particular significance for meeting long term climate policy objectives.