Copenhagen Accord pledges imply higher costs for staying below 2 C warming: a letter

摘要: This study compares emission pathways aimed at limiting temperature increase to 2°C under varying constraints. In a first set of pathways, the timing of emission reductions is such that over the 2010–2100 period, assuming full participation from 2013 onwards, mitigation costs are minimized. In a second set of pathways, we set emissions in 2020 at a level based on the pledges of the Copenhagen Accord. In the ‘Copenhagen Potential’ scenario, climate talks result in satisfying conditions linked by countries to their ‘most ambitious’ proposals. Contrasting, in the ‘Copenhagen Current’ scenario, climate talks fall short of satisfying the conditions to move beyond current unilateral pledges. We include scenarios with and without the availability of bio-energy in combination with carbon capture and storage. We find that for a ‘Copenhagen Potential’ scenario, emissions by 2020 are higher (47 GtCO2eq/yr) than for a …