Towards climate neutrality: Comparison of mitigation strategies for agricultural emissions using GWP100 and GWP* metrics

• Using GWP*, agricultural climate impact is reduced to one fourth compared to GWP 100 . • The lower climate impact results from considering the reduction of short-lived CH 4 emissions. • Without measures, future GHG emissions from German agriculture will increase. • The feed additive 3-NOP reduces CH 4 , helping achieve a climate-neutral agriculture by 2030. • GWP* accurately assesses agricultural climate impacts but raises questions of fairness. Typically, the metric GWP 100 is used to assess the climate impact of a pulse emission of greenhouse gases ( GHG ) over 100 years. The alternative metric GWP* additionally takes the dynamics of current and historical GHG emissions into account. For a comparison of both approaches, we use the case of past and future German agricultural GHG emissions that were assessed with both metrics for the time series 1990 to 2021 and for scenarios until 2030 to represent the metric's impact for European and other countries. GHG emissions over the time series reduce to one quarter when assessed with GWP* instead of GWP 100 , due to substantial reduction of short-lived methane (CH 4 ) emissions from livestock, mainly ruminants. While future GHG emissions increase in both metrics in a ‘no-measures scenario’, they decrease in the ‘with-measures scenario’ and a ‘reduced-meat-consumption scenario’. The feed additive 3-nitrooxypropanol ( 3-NOP ) shows high GHG mitigation potential, whose effect is more pronounced for GWP* than under GWP 100 due to the substantial CH 4 mitigation. With 3-NOP usage and if other measures were taken, GHG neutrality could be reached in German agriculture by 2030. In conclusion, GWP* better than GWP 100 describes the climate impact of the short-lived CH 4 , however, its application is connected with consequences regarding fairness and control feedback.