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Sound decisions in international climate policy depend on comprehensive and reliable emission data as well as accurate analysis and comparisons of policy proposals. In this context, the emission module of the Potsdam Real-time Integrated Model for the probabilistic Assessment of emission Paths (PRIMAP) has been developed. This article describes its design and functionality. The emission module allows for the flexible combination of data sources contained in its custom-built database into composite datasets, and the calculation of national, regional and global emission pathways following various emission allocation schemes. The resulting emission pathways can further be used to determine atmospheric CO"2 concentrations and temperature probability distributions using the PRIMAP climate module, which currently incorporates the reduced complexity climate and carbon-cycle model MAGICC. In addition to the calculation of emission pathways, the PRIMAP emission module supports analysis of policy options, like the quantification of different land use, land-use change and forestry (LULUCF) accounting provisions for Annex I countries. We discuss three applications of the PRIMAP emission module. In a bottom-up approach, we implement the pledges from the Copenhagen Accord, the announced developed country emission targets, in which provisions from LULUCF are taken into account. For the derivation of developing country emission pathways two different approaches are applied: capped per capita emissions and equal cumulative per capita emissions at average developed country levels. As a third example we implement a top-down approach, which equalises cumulative per capita emissions in a global emission pathway to achieve the 2 ^oC target with a likely (greater than 66%) probability.

National targets give virtually no chance of constraining warming to 2 °C and no chance of protecting coral reefs.

This analysis of the Copenhagen Accord evaluates emission reduction pledges by individual countries against the Accord's climate-related objectives. Probabilistic estimates of the climatic consequences for a set of resulting multi-gas scenarios over the 21st century are calculated with a reduced complexity climate model, yielding global temperature increase and atmospheric CO2 and CO2-equivalent concentrations. Provisions for banked surplus emission allowances and credits from land use, land-use change and forestry are assessed and are shown to have the potential to lead to significant deterioration of the ambition levels implied by the pledges in 2020. This analysis demonstrates that the Copenhagen Accord and the pledges made under it represent a set of dissonant ambitions. The ambition level of the current pledges for 2020 and the lack of commonly agreed goals for 2050 place in peril the Accord's own ambition: to limit global warming to below 2 degrees C, and even more so for 1.5 degrees C, which is referenced in the Accord in association with potentially strengthening the long-term temperature goal in 2015. Due to the limited level of ambition by 2020, the ability to limit emissions afterwards to pathways consistent with either the 2 or 1.5 degrees C goal is likely to become less feasible.

Nations will probably meet only the lower ends of their emissions pledges in the absence of a binding international agreement Nations can bank an estimated 12 gigatonnes of Co2 equivalents surplus allowances for use after 2012 Land-use rules are likely to result in further allowance increases of 0.5 GtCO2-eq per year Global emissions in 2020 could thus be up to 20% higher than today Current pledges mean a greater than 50% chance that warming will exceed 3°C by 2100 If nations agree to halve emissions by 2050, there is still a 50% chance that warming will exceed 2°C and will almost certainly exceed 1.5°C