How carbon dioxide removal lost its way: tracing the origin and transformation of the 10-Gt durable CDR target

Durably removing ~10 Gt CO₂ yr⁻¹ by 2050 is widely treated as necessary for meeting Paris temperature goals. I found three problems with the 10-Gt benchmark when I tracked carbon-dioxide-removal (CDR) estimates across 51 sources and analyzed the underlying scenarios from the Intergovernmental Panel on Climate Change (IPCC). First, the citation pathway traces almost exclusively to IPCC reports, but the 10-Gt magnitude did not come from a direct reading of IPCC outputs. The number first appeared in a 2017 news piece as an informal estimate, was declared the 'needed' amount in a 2019 National Academy report, and propagated from there; low-CDR scenarios in both IPCC and independent sources were largely ignored. Second, 10 Gt CO₂ yr⁻¹ is larger than the IPCC ensemble medians, which are themselves CDR-reliant, treating emissions reductions and future removals as interchangeable. In the 6th Assessment Report (AR6) I found CDR magnitude correlated with near-term mitigation pace, and as target temperatures rose, the additional carbon-budget space was, on median, filled by continued emissions rather than by reduced CDR. Third, as CDR estimates moved into NGO and industry sectors, the discourse shifted: language describing CDR changed from conditional (e.g., 'scenarios show') to prescriptive (e.g., 'CDR is necessary'), risk discussion diminished, and CDR type narrowed to durable approaches only, excluding the nature-based methods the IPCC scenarios included. The 10-Gt benchmark is therefore larger than warranted by the underlying scenarios, disconnected from the mitigation choices that produced it, and stripped of the context decision-makers need. With the next IPCC assessment report (AR7) underway, there is an opportunity to build a better CDR discourse. One that connects CDR magnitude to mitigation choices, includes lower-CDR pathways, matches CDR durability to its varied roles, and characterizes feasibility, costs, and risks.