Emission budgets and pathways to 1.5 degrees in the context of the global stocktake
An informal seminar and Q&A with one of the leading authors of the concept of the global “carbon budget”, discussing recent updates and their implications for the long-term temperature goal, plus how the notion of a finite carbon budget could be incorporated into the global stocktake mechanism.
Myles Allen, Environmental Change Institute and Oxford Martin School, University of Oxford.
The 2015 Paris Agreement committed the world to “pursue efforts to limit the [global average] temperature increase to 1.5 degrees C above pre-industrial levels,” but is this an achievable goal? Even if greenhouse gas emission reductions begin immediately and reach net zero in the second half of this century, what is the probability that combined past and future emissions commit us to more than 1.5 degrees C of warming already? Professor Allen first drew attention to the importance of cumulative carbon dioxide emissions determining global temperatures a decade ago, and co-authored a recent paper “Emission budgets and pathways consistent with limiting warming to 1.5 degrees C” (Millar et al, Nature Geoscience, DOI: 10.1038/NGEO3031, 2017) that argued that, for some reasonable definitions of both pre-industrial and global average temperature, keeping warming likely below 1.5 degrees C is still possible, but only if emissions are reduced directly to zero over about 40 years, which implies substantially more ambitious and sustained reductions than indicated by current NDCs. Professor Allen will explain how (contrary to some media misreporting) this result is entirely consistent with core conclusions of the IPCC 5th Assessment Report and other more recent assessments of 1.5 degree C pathways such as the 2017 UNEP Emissions Gap Report. This is an opportunity to join an informal and interactive discussion of the science behind carbon budgets and different kinds of warming commitments.