Extended Data Fig. 8: MACCs.

a, The functional form of MACs,\(\,{\rm{MAC}}(a)=b[\tfrac{1}{\nu }((\tfrac{L-A}{a-A}{)}^{\nu }-1){]}^{c}\), is derived from the inverse generalized logistic function. It is relatively flexible with respect to replicating a wide range of MACCs derived from the SSP database. Here A = 1 and L = 0 are upper and lower asymptotes along the y axis. Notably, MAC(a = A) = ∞; therefore, A is a maximum abatement rate built into the MAC curve. b defines the y position of the pivot point. The x position of the pivot point is determined by ν and for ν = 1 it is exactly the middle of the interval (L, A), (L + A)/2. c defines the level of rotation with respect to the pivot point. b, Six stylized MACCs for DACS covering the literature range for costs from US$20 to US$1,000 per t CO₂ (orange area). Low-cost MACCs (dotted lines) start at approximately US$50 per t CO₂ and reach US$1,000 per t CO₂ at abatement rates a_DACS = 0.07 (low capacity, blue line) and a_DACS = 0.27 (high capacity, red line) equivalent to approximately 3 and 12 Gt CO₂ yr⁻¹ at current emission levels, respectively. Medium-cost MACCs (dashed lines) start at US$250 per t CO₂ and reach US$1,000 t CO₂ at a_DACS = 0.05 (low capacity, blue line) and a_DACS = 0.22 (high capacity, red line), that is, roughly 2 and 10 Gt CO₂ yr⁻¹ at current emission levels, respectively. High-cost MACCs (solid lines) start at approximately US$500 per t CO₂ and reach US$1,000 per t CO₂ at a_DACS = 0.03 (low capacity, blue line) and a_DACS = 0.12 (high capacity, red line), amounting to roughly 1 and 5 Gt CO₂ yr⁻¹ at current emission levels, respectively.