Persistent growth of CO2 emissions and implications for reaching climate targets
Van Vuuren, DP
Le Quéré, C
Nature Publishing Group
Efforts to limit climate change below a given temperature level require that global emissions of CO2 cumulated over time remain below a limited quota. This quota varies depending on the temperature level, the desired probability of staying below this level and the contributions of other gases. In spite of this restriction, global emissions of CO2 from fossil fuel combustion and cement production have continued to grow by 2.5% per year on average over the past decade. Two thirds of the CO2 emission quota consistent with a 2°C temperature limit has already been used, and the total quota will likely be exhausted in a further 30 years at the 2014 emissions rates. We show that CO2 emissions track the high end of the latest generation of emissions scenarios, due to lower than anticipated carbon intensity improvements of emerging economies and higher global gross domestic product growth. In the absence of more stringent mitigation, these trends are set to continue and further reduce the remaining quota until the onset of a potential new climate agreement in 2020. Breaking current emission trends in the short term is key to retaining credible climate targets within a rapidly diminishing emission quota.
P.F. was supported by the European Commission's 7th Framework Programme (EU/FP7) under Grant Agreements 282672 (EMBRACE) and 603864 (HELIX). G.P.P. and R.M.A. were supported by the Norwegian Research Council (236296). J.G.C. acknowledges the support from the Australian Climate Change Science Program. C.L.Q. was supported by the UK Natural Environment Research Council (NERC)'s International Opportunities Fund (project NE/103002X/1) and EU/FP7 project 283080 (GEOCarbon). This work is a collaborative effort of the Global Carbon Project (http://www.globalcarbonproject.org).
This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.
Nature Geoscience, 2014, Vol. 7, pp. 709 - 715