This study re-analysed emissions data produced for the IPCC Fifth Assessment Report. It presents the spread in emissions from this dataset at 2020, 2030 and 2050 compatible with warming limits of 1.5 °C up to 4 °C. Confidence is provided in the modelling system by comparison of elements of this analysis with similar reported results from IPCC and UNEP.
The analysis is then extended by sampling different climate outcomes at pre-specified levels of emissions in 2030, giving an alternative way of viewing the IPCC database.
The final part of this assessment is to go beyond the IPCC Working Group 3 assessment by demonstrating how a key climate uncertainty (the equilibrium climate response) leads to a very large spread in the emissions compatible with different warming levels.