Framing Climate Goals in Terms of Cumulative CO2‐Forcing‐Equivalent Emissions

Abstract The relationship between cumulative CO2 emissions and CO2‐induced warming is determined by the Transient Climate Response to Emissions (TCRE), but total anthropogenic warming also depends on non‐CO2 forcing, complicating the interpretation of emissions budgets based on CO2 alone. An alterna...

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Main Authors: S. Jenkins, R. J. Millar, N. Leach, M. R. Allen
Format: Article
Language:English
Published: Wiley 2018-03-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1002/2017GL076173
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author S. Jenkins
R. J. Millar
N. Leach
M. R. Allen
author_facet S. Jenkins
R. J. Millar
N. Leach
M. R. Allen
author_sort S. Jenkins
collection DOAJ
description Abstract The relationship between cumulative CO2 emissions and CO2‐induced warming is determined by the Transient Climate Response to Emissions (TCRE), but total anthropogenic warming also depends on non‐CO2 forcing, complicating the interpretation of emissions budgets based on CO2 alone. An alternative is to frame emissions budgets in terms of CO2‐forcing‐equivalent (CO2‐fe) emissions—the CO2 emissions that would yield a given total anthropogenic radiative forcing pathway. Unlike conventional “CO2‐equivalent” emissions, these are directly related to warming by the TCRE and need to fall to zero to stabilize warming: hence, CO2‐fe emissions generalize the concept of a cumulative carbon budget to multigas scenarios. Cumulative CO2‐fe emissions from 1870 to 2015 inclusive are found to be 2,900 ± 600 GtCO2‐fe, increasing at a rate of 67 ± 9.5 GtCO2‐fe/yr. A TCRE range of 0.8–2.5°C per 1,000 GtC implies a total budget for 0.6°C of additional warming above the present decade of 880–2,750 GtCO2‐fe, with 1,290 GtCO2‐fe implied by the Coupled Model Intercomparison Project Phase 5 median response, corresponding to 19 years' CO2‐fe emissions at the current rate.
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spelling doaj-art-ce9588dadebe43b68b4d612a6c21a4c72025-08-20T02:52:16ZengWileyGeophysical Research Letters0094-82761944-80072018-03-014562795280410.1002/2017GL076173Framing Climate Goals in Terms of Cumulative CO2‐Forcing‐Equivalent EmissionsS. Jenkins0R. J. Millar1N. Leach2M. R. Allen3Department of Physics University of Oxford Oxford UKEnvironmental Change Institute University of Oxford Oxford UKDepartment of Physics University of Oxford Oxford UKDepartment of Physics University of Oxford Oxford UKAbstract The relationship between cumulative CO2 emissions and CO2‐induced warming is determined by the Transient Climate Response to Emissions (TCRE), but total anthropogenic warming also depends on non‐CO2 forcing, complicating the interpretation of emissions budgets based on CO2 alone. An alternative is to frame emissions budgets in terms of CO2‐forcing‐equivalent (CO2‐fe) emissions—the CO2 emissions that would yield a given total anthropogenic radiative forcing pathway. Unlike conventional “CO2‐equivalent” emissions, these are directly related to warming by the TCRE and need to fall to zero to stabilize warming: hence, CO2‐fe emissions generalize the concept of a cumulative carbon budget to multigas scenarios. Cumulative CO2‐fe emissions from 1870 to 2015 inclusive are found to be 2,900 ± 600 GtCO2‐fe, increasing at a rate of 67 ± 9.5 GtCO2‐fe/yr. A TCRE range of 0.8–2.5°C per 1,000 GtC implies a total budget for 0.6°C of additional warming above the present decade of 880–2,750 GtCO2‐fe, with 1,290 GtCO2‐fe implied by the Coupled Model Intercomparison Project Phase 5 median response, corresponding to 19 years' CO2‐fe emissions at the current rate.https://doi.org/10.1002/2017GL076173greenhouse gas metriccumulative carbon budgetforcing equivalent indexclimate stabilization
spellingShingle S. Jenkins
R. J. Millar
N. Leach
M. R. Allen
Framing Climate Goals in Terms of Cumulative CO2‐Forcing‐Equivalent Emissions
Geophysical Research Letters
greenhouse gas metric
cumulative carbon budget
forcing equivalent index
climate stabilization
title Framing Climate Goals in Terms of Cumulative CO2‐Forcing‐Equivalent Emissions
title_full Framing Climate Goals in Terms of Cumulative CO2‐Forcing‐Equivalent Emissions
title_fullStr Framing Climate Goals in Terms of Cumulative CO2‐Forcing‐Equivalent Emissions
title_full_unstemmed Framing Climate Goals in Terms of Cumulative CO2‐Forcing‐Equivalent Emissions
title_short Framing Climate Goals in Terms of Cumulative CO2‐Forcing‐Equivalent Emissions
title_sort framing climate goals in terms of cumulative co2 forcing equivalent emissions
topic greenhouse gas metric
cumulative carbon budget
forcing equivalent index
climate stabilization
url https://doi.org/10.1002/2017GL076173
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AT rjmillar framingclimategoalsintermsofcumulativeco2forcingequivalentemissions
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AT mrallen framingclimategoalsintermsofcumulativeco2forcingequivalentemissions