Fig. 2: Comparison of recent remaining carbon budget estimates for limiting global warming to 1.5 °C (blue) and to 2 °C (red) relative to preindustrial levels, and overview of factors affecting their variation. | Nature

Fig. 2: Comparison of recent remaining carbon budget estimates for limiting global warming to 1.5 °C (blue) and to 2 °C (red) relative to preindustrial levels, and overview of factors affecting their variation.

From: Estimating and tracking the remaining carbon budget for stringent climate targets

Fig. 2

Estimates are shown for a 50% probability of limiting warming to the indicated temperature levels (additional estimates for a 66% probability are provided in Supplementary Table 2). Several studies do not report formal probabilities, but report the frequency distribution across model simulations instead. The latter estimates are marked N in the ‘Formal TCRE uncertainty distribution’ column. Estimates shown with dashed lines indicate carbon budget estimates with an imprecise level of implied global warming, for example, because they were reported for a radiative forcing target instead. TEB means threshold exceedance budget37; TAB means threshold avoidance budget37 (see Box 1). Data are taken from the IPCC Special Report on Global Warming of 1.5 °C (ref. 48), ref. 39 (with values for 1.5 °C based on our own calculations using the same method), the IPCC Fifth Assessment Report (ref. 28) and refs 12,30,31,32,36,41,43. The latest IPCC assessment of the remaining carbon budget48 assumes 0.97 °C of historical warming until 2006–2015, whereas other estimates assume either higher or lower warming for that period (Supplementary Table 1). The background and values for all studies are provided in Supplementary Tables 1 and 2. The assumptions made for each study are coloured (right-hand side of figure) for ease of visual grouping: N, no; Y, yes; SAT, global near-surface air temperatures; BT, blended temperatures (surface air temperature over land and sea-ice regions combined with sea surface temperature over open ocean); RCP, Representative Concentration Pathway; CMIP5, Phase 5 of the Coupled Model Intercomparison Project.

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