EGU2020-2452
https://doi.org/10.5194/egusphere-egu2020-2452
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Quantifying non-CO2 contributions to remaining carbon budgets

Stuart Jenkins1, Michelle Cain1, Pierre Friedlingstein2,3, Nathan Gillett4, and Myles Allen1,5
Stuart Jenkins et al.
  • 1University of Oxford, Department of Physics, Oxford, United Kingdom of Great Britain and Northern Ireland (stuart.jenkins@wadham.ox.ac.uk)
  • 2College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK
  • 3Laboratoire de Meteorologie Dynamique, Institut Pierre-Simon Laplace, CNRS-ENS-UPMC-X, Departement de Geosciences, Ecole Normale Superieure, 24 rue Lhomond, 75005 Paris, France
  • 4Canadian Centre for Climate Modelling and Analysis, Environment Canada, Victoria, British Columbia, Canada
  • 5University of Oxford, School of Geography, Oxford, United Kingdom of Great Britain and Northern Ireland

The IPCC Special Report on 1.5°C concluded that the maximum level of anthropogenic global warming is “determined by cumulative net global anthropogenic CO2 emissions up to the time of net zero CO2 emissions and the level of non-CO2 radiative forcing” in the decades prior to the time of peak warming. Here we quantify this statement, using CO2-forcing-equivalent (CO2-fe) emissions to calculate remaining carbon budgets without treating available mitigation scenarios as a representative sample of possible futures.

CO2-fe emissions are used to calculate an observationally-constrained estimate of the Transient Climate Response to cumulative Emissions (TCRE) using a large ensemble of historical radaitve forcing timeseries. This observationally-constrained TCRE is used to calculate remaining total CO2-fe budgets from 2018 to 1.5°C, which we compare with results discussed in Chapter 2, SR15. We consider contributions to this total remaining budget from CO2 and non-CO2 sources using both historical observations and the available mitigation scenarios in the IAMC scenario database.

We calculate remaining CO2 budgets for a 33, 50 or 66% chance of limiting peak warming to 1.5°C and use these to assess the extent to which scenarios in the IAMC scenario database are consistent with ambitious mitigation as outlined in the Paris Agreement. We argue that, assuming no change in the definition of observed global warming and no increase in TCRE due to non-linear feedbacks, scenarios currently classified as “lower 2°C-compatible” are consistent with a best-estimate peak warming of 1.5°C.

How to cite: Jenkins, S., Cain, M., Friedlingstein, P., Gillett, N., and Allen, M.: Quantifying non-CO2 contributions to remaining carbon budgets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2452, https://doi.org/10.5194/egusphere-egu2020-2452, 2020

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