Fig. 1: Global growth rates of historical and scenario CO₂ emissions from fossil fuels and industry.

The average scenario growth rates of emissions are calculated for individual marker/illustrative scenarios (filled circles) and low/high model variants (open circles) covering the actual projected period for each series^8,9,19,20,21 compared to growth rates of historical emissions¹⁶ for the equivalent periods (short black lines) and the IPCC period 1990–2019 (dashed gray horizontal line). Individual growth rate lines (short black lines) cover SA90 (34 years), IS92 (29 years), SRES (24 years), RCPs (14 years), SSP-baselines (left) & SSP-mitigation (right) (9 years), and SSP CMIP6 (4 years)^8,22. Scenarios are grouped into four cumulative emissions categories (Total CO₂ emissions 1990–2100)⁵⁵: low (bluish-green), medium-low (Blue), medium-high (orange), and high (vermillion) emissions—the color-coding is optimized for readers with color blindness⁵⁶. For some of the scenarios, the growth rates (1985–2020) do not necessarily reflect the century-long emission trajectory of the scenarios (e.g., several scenarios have a peak-and-decline shaped trajectory, such as SA90-B, IS92c, SRES-A1B/T/B1, RCP4.5, SSP1, and SSP4). The scenario databases commonly report emissions at intervals of 5, 10, or 25 years. The Compound Annual Growth Rates (CAGR) method was used since it calculates the beginning and end value, providing a consistent growth rate comparison between projections and historical developments. Projected scenario estimates for the years 1990, 2020 (SA90), and 1995 (SRES) were calculated using linear interpolation, which is considered robust¹¹. (See Supplementary Fig. 1 and Tables 1 and 2, 4–9).