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

Abstract

Typically, the metric GWP₁₀₀ 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 GWP₁₀₀, due to substantial reduction of short-lived methane (CH₄) 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 GWP₁₀₀ due to the substantial CH₄ 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 GWP₁₀₀ describes the climate impact of the short-lived CH₄, however, its application is connected with consequences regarding fairness and control feedback.