Assessing alternative methane emission metrics conducive to quantifying global warming and setting near-term climate goals

Abstract Climate metrics, like Global Warming Potential (GWP), are frequently relied on to relate emissions of greenhouse gasses (GHGs) to globally averaged temperature change. However, most metrics struggle to accurately represent temperature change across different time scales, especially in response to short-lived GHGs such as methane (CH 4 ). GWP* has been developed as a more accurate climate metric, but it has implementation challenges, such as its misuse to create the false impression of climate neutrality. We propose a new metric, Sum44, the 44 year lagged cumulative sum of methane, that can accurately predict temperature change without the implementation challenges identified for GWP*. Here, we compare the performance of Sum44 and GWP* in projecting temperature change under various emissions scenarios. We perform these comparisons using strictly CH 4 emissions scenarios, although other GHGs could be included in the future. We show that for the wide range of scenarios considered here, Sum44 is comparable to GWP* as a temperature indicator, and frequently outperforms it. Given this, we suggest that there are substantial implementation advantages to using Sum44 when considering policy controls to meet near-term climate change targets.