The role of direct air capture and negative emissions technologies in the shared socioeconomic pathways towards +1.5 °C and +2 °C futures

Abstract

The development of the shared socioeconomic pathways (SSPs) and associated integrated assessment modeling exercises did not include direct air capture with carbon storage (DACCS) in their scenarios. Recent progress in DACCS commercialization suggests it could be a viable means of removing CO2 from the atmosphere with far lower land intensity than bioenergy with carbon capture or afforestation but with higher energy demands. Several forms of DACCS are in development, with different costs and energy inputs, as well as potential for future cost and performance improvements. Here, we use the Global Change Analysis Model to understand the role of DACCS across all 5 SSPs for the below 2 °C and below 1.5 °C end-of-century warming goals. We assess DACCS deployment relative to other carbon capture methods, and its side effects for global energy, water, land systems. We find that DACCS could play up to a tens of GtCO2 yr−1 role in many of these scenarios, particularly those with delayed climate policy and/or higher challenges to emissions mitigation. Our ‘sustainable development’ scenarios, consistent with SSP1, have smaller deployments of DACCS and other negative emissions owing to immediate climate policy onset, greater ease of emissions abatement, and tighter constraints on future negative emissions.