Recalculating the global warming impact of italian livestock methane emissions with new metrics

The warming impact of methane (CH4) emissions calculated using the metrics proposed by the Intergovernmental Panel on Climate Change (IPCC), which measure its global warming potential in 100 years (GWP100) expressed as carbon dioxide equivalents (CO2 e), accounts for the greatest impact in animal production chains. This work uses the new metrics, proposed to consider the difference between short living climate pollutants (SLCP), such as CH4, and long living climate pollutants (LLCP), such as carbon dioxide (CO2), which measure the warming equivalent (we) effect relative to that of CO2 in a given time frame (GWP*) and expressed as CO2 we. The GWP* was applied to CH4 emissions from all Italian livestock supply chains and compared with GWP100 for annual and cumulative assessment from 2010 to 2020 of the impact of this gas on climate change. Using official data published by Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA) from 1990 to 2020, almost all species, except for buffalo (+272.6% of emissions calculated with the new metrics), revealed lower CH4 emissions with the greatest re-dimensioning for non-dairy cattle (-53786 kt of CO2 we of calculated with GWP* compared to +66437 kt of CO2 e estimated with the GWP100 method). The total cumulative contribution of Italian livestock production to global warming over the past 10 years, including the nitrous oxide (N2O) emissions, has been greatly negative (-48759 kt of CO2 we) compared to the data calculated using the GWP100 method (+206091 kt of CO2 e). In conclusion, the application of GWP* metric to CH4 emissions of all Italian livestock supply chains allowed to better identify the role of Italian livestock on climate change. Over the 2010–2020 time frame, the Italian animal supply chains reduced the warming impact related to its CH4 emission, with the ruminants (expect buffaloes) being the major contributor to this positive effect.HIGHLIGHTS The application of GWP* metric reduced the warming impact of CH4 emissions of Italian dairy cattle, non-dairy cattle, sheep, goats, poultry and rabbits. The reduction of CH4 emission from the major ruminant species is the major contributor to the positive effect on climate change detected over 2010–2020 time frame. The application of GWP* metric to CH4 emissions of all Italian livestock supply chains allowed to better identify the role of Italian livestock on climate change.