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© 2018. This work is published under https://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

If the Paris Agreement targets are to be met, there may be very few years left for policy makers to start cutting emissions. Here we calculate by what year, at the latest, one has to take action to keep global warming below the 2 K target (relative to pre-industrial levels) at the year 2100 with a 67 % probability; we call this the point of no return (PNR). Using a novel, stochastic model ofCO2 concentration and global mean surface temperature derived from the CMIP5 ensemble simulations, we find that cumulative CO2 emissions from 2015 onwards may not exceed 424 GtC and that the PNR is 2035 for the policy scenario where the share of renewable energy rises by 2 % year-1. Pushing this increase to 5 % year-1 delays the PNR until 2045. For the 1.5 K target, the carbon budget is only 198 GtC and there is no time left before starting to increase the renewable share by 2 % year-1. If the risk tolerance is tightened to 5 %, the PNR is brought forward to 2022 for the 2 K target and has been passed already for the1.5 K target. Including substantial negative emissions towards the end of the century delays the PNR from 2035 to 2042 for the 2 K target and to 2026 for the 1.5 K target. We thus show how the PNR is impacted not only by the temperature target and the speed by which emissions are cut but also by risk tolerance, climate uncertainties and the potential for negative emissions. Sensitivity studies show that the PNR is robust with uncertainties of at most a few years.

Details

Title
The point of no return for climate action: effects of climate uncertainty and risk tolerance
Author
Aengenheyster, Matthias 1 ; Qing Yi Feng 2 ; van der Ploeg, Frederick 3 ; Dijkstra, Henk A 2 

 Atmospheric, Oceanic and Planetary Physics, Department of Physics, Oxford University, Oxford, UK 
 Institute for Marine and Atmospheric Research Utrecht, Department of Physics, Utrecht University, Utrecht, the Netherlands; Centre for Complex Systems Studies, Utrecht University, Utrecht, the Netherlands 
 Centre for the Analysis of Resource Rich Economies, Department of Economics, Oxford University, Oxford, UK 
Pages
1085-1095
Publication year
2018
Publication date
2018
Publisher
Copernicus GmbH
ISSN
21904979
e-ISSN
21904987
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2096470058
Copyright
© 2018. This work is published under https://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.