Editing IPCC:AR6/SR15/Chapter-1 (section)

==== Implications of different approaches to calculating aggregate greenhouse gas emissions on a pathway to net zero. ====

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(a) Aggregate emissions of well-mixed greenhouse gases (WMGHGs) under the RCP2.6 mitigation scenario expressed as CO2-equivalent using GWP100 (blue); GTP100 (green) and GWP* (yellow). Aggregate WMGHG emissions appear to fall more rapidly if calculated using GWP* than using either GWP or GTP, primarily because GWP* equates a falling methane emission rate with negative CO <sub>2</sub> emissions, as only active CO <sub>2</sub> removal would have the same impact on radiative forcing and GMST as a reduction in methane emission rate. (b) Cumulative emissions of WMGHGs combined as in panel (a) (blue, green and yellow lines &amp; left hand axis) and warming response to combined emissions (black dotted line and right hand axis, Millar et al. (2017a) <sup>[[#fn:r204|204]]</sup> . The temperature response under ambitious mitigation is closely correlated with cumulative WMGHG emissions aggregated using GWP*, but with neither emission rate nor cumulative emissions if aggregated using GWP or GTP.

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