The influence of speed and scale of carbon dioxide removal on overshoot peak temperature and duration

Nina Rynne, Michael Bode, Melanie E Roberts, Ryan F Heneghan

CO2 emissions are pushing global temperatures higher, with the Paris Agreement temperature target of limiting warming to no more than 1.5°C above the preindustrial average likely to be exceeded within the next two decades. Overshooting this target before reducing global temperature by the end of the century is increasingly viewed as a potential pathway to still meet the Paris Agreement target, however this approach would require significant carbon dioxide removal. Yet, how the speed and scale of carbon dioxide removal deployment affects overshoot peak temperature and duration is not well understood. Here we use a climate-economic model to investigate peak temperature and overshoot duration across a range of deployment rates for the five baseline Shared Socioeconomic Pathways. We find that the speed of deployment, is the primary determinant of overshoot magnitude, with peak temperatures reaching 2.46°C under slow deployment and overshoot duration varying from 19 to 59 years. Fast deployment speeds limit peak temperature to 1.58°C, while high maximum capacity leads to temperature peaking at 1.88°C. Together, these results provide a clear direction for carbon dioxide removal efforts.