Negative emissions—Part 2: Costs, potentials and side effects

Summary/Abstract

This paper, part 2 of a 3 part series on negative emissions, presents estimates of costs, potentials, and side-effects for these technologies, and qualify them with the authors’ assessment. Based on a systematic review of the literature, the best estimates for sustainable global NET potentials in 2050 are 0.5–3.6 GtCO₂ yr⁻¹ for afforestation and reforestation, 0.5–5 GtCO₂ yr⁻¹ for BECCS, 0.5–2 GtCO₂ yr⁻¹ for biochar, 2–4 GtCO₂ yr⁻¹ for enhanced weathering, 0.5–5 GtCO₂ yr⁻¹ for DACCS, and up to 5 GtCO₂ yr⁻¹ for soil carbon sequestration. Costs vary widely across the technologies, as do their permanency and cumulative potentials beyond 2050. The paper identifies that it is unlikely a single NET will be able to sustainably meet the rates of carbon uptake described in integrated assessment pathways consistent with 1.5 °C of global warming.