Differences between carbon budget estimates unravelled
Several methods exist to estimate the cumulative carbon emissions that would keep global warming to below a given temperature limit. Here we review estimates reported by the IPCC and the recent literature, and discuss the reasons underlying their differences. The most scientifically robust number — the carbon budget for CO2-induced warming only — is also the least relevant for real-world policy. Including all greenhouse gases and using methods based on scenarios that avoid instead of exceed a given temperature limit results in lower carbon budgets.
To limit warming below the internationally agreed temperature limit of 2 °C relative to pre-industrial levels with >66% chance, the most appropriate carbon budget estimate is 590–1,240 GtCO2 from 2015 onwards.
Variations within this range depend on the probability of staying below 2 °C and on end-of-century non-CO2 warming. Current CO2 emissions are about 40 GtCO2 yr–1, and global CO2 emissions thus have to be reduced urgently to keep within a 2 °C-compatible budget.
Authors
Specifications
- Publication title
- Differences between carbon budget estimates unravelled
- Publication date
- 24 February 2016
- Publication type
- Publication
- Magazine
- Nature Climate Change
- Product number
- 2384
