Differences between carbon budget estimates unravelled

作者：Rogelj Joeri^*; Schaeffer Michiel; Friedlingstein Pierre; Gillett Nathan P; van Vuuren Detlef P; Riahi Keywan; Allen Myles; Knutti Reto

来源：Nature Climate Change, 2016, 6(3): 245-252.

DOI：10.1038/NCLIMATE2868

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. For a >66% chance of limiting warming below the internationally agreed temperature limit of 2 degrees C relative to pre-industrial levels, the most appropriate carbon budget estimate is 590-1,240 GtCO(2) from 2015 onwards. Variations within this range depend on the probability of staying below 2 degrees C and on end-of-century non-CO2 warming. Current CO2 emissions are about 40 GtCO(2) yr(-1), and global CO2 emissions thus have to be reduced urgently to keep within a 2 degrees C-compatible budget.

• 出版日期2016-3
• 单位国际应用系统分析学会(IIASA)