An integrated approach to quantifying uncertainties in the remaining carbon budget

• Published in: Communications earth & environment Vol. 2; no. 1
• Main Authors: Damon Matthews, H., Tokarska, Katarzyna B., Rogelj, Joeri, Smith, Christopher J., MacDougall, Andrew H., Haustein, Karsten, Mengis, Nadine, Sippel, Sebastian, Forster, Piers M., Knutti, Reto
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.01.2021; Nature Publishing Group
• Subjects: 704/106/694/2786; 704/106/694/682; Carbon; Carbon dioxide; Carbon dioxide emissions; Climate change; Earth and Environmental Science; Earth Sciences; Emissions; Environment; Geophysics; Global warming; Meteorological satellites; Socioeconomics; Uncertainty
• ISSN: 2662-4435; 2662-4435
• DOI: 10.1038/s43247-020-00064-9

The remaining carbon budget quantifies the future CO 2 emissions to limit global warming below a desired level. Carbon budgets are subject to uncertainty in the Transient Climate Response to Cumulative CO 2 Emissions (TCRE), as well as to non-CO 2 climate influences. Here we estimate the TCRE using observational constraints, and integrate the geophysical and socioeconomic uncertainties affecting the distribution of the remaining carbon budget. We estimate a median TCRE of 0.44 °C and 5–95% range of 0.32–0.62 °C per 1000 GtCO 2 emitted. Considering only geophysical uncertainties, our median estimate of the 1.5 °C remaining carbon budget is 440 GtCO 2 from 2020 onwards, with a range of 230–670 GtCO 2 , (for a 67–33% chance of not exceeding the target). Additional socioeconomic uncertainty related to human decisions regarding future non-CO 2 emissions scenarios can further shift the median 1.5 °C remaining carbon budget by ±170 GtCO 2 . Integrating uncertainties using insights from both observations and models narrows the range on the remaining carbon budget for 1.5 °C, as well as the transient climate response to cumulative CO 2 emissions.