Removing atmospheric CO₂ through mass scaleup of crops with enhanced root systems

Abstract The Intergovernmental Panel on Climate Change estimates that societies may need to remove 5–16 GtCO 2 from the atmosphere annually to reach global net-zero CO 2 emissions within this century. Yet there has been little analysis of how quickly carbon dioxide removal (CDR) strategies could scale to meet this expected need. We develop a new integrated modeling approach for assessing scalability that combines insights from the history of analogous technological revolutions with information about the efficacy and specific constraints of CDR strategies. We illustrate our approach with genetically enhanced crops that grow larger roots and, in turn, increase soil carbon. Unlike many CDR technologies whose deployment will be slowed by the need for novel and costly infrastructures, history suggests that crop innovations can scale rapidly in countries that admit them. Within 13 years of first deployment, diffusion of enhanced crops could peak and remove 0.9–1.2 GtCO 2 yr –1 —about 7 times larger than all CO 2 offsets supplied today to the global voluntary offsets market. Upscaling depends on policy and politics, as they affect the total land area on which carbon-absorbing crops are allowed. Early scaling could allow crop engineering to play an outsized role in a portfolio of CDR strategies that, overall, scales to IPCC-like levels of carbon removal, even though carbon storage in soils is less permanent than geological storage.