Calculating balance of cumulative non-fossil methane emissions over consecutive or non-consecutive periods of livestock production

Methane (CH 4 ) emissions from livestock production are conventionally reported as annual methane emissions (AME) or converted to carbon dioxide equivalents. However, these assessments cannot determine the methane burden or removal in the atmosphere, as they do not account for continuous methane removal and short-term accumulation. Consequently, they may obscure the identification of livestock (sub)sectors or (sub)populations with methane burden or removal, thereby limiting optimal mitigation efforts. Here, a novel method is developed and demonstrated to calculate the balance of cumulative non-fossil methane emissions (BME) over consecutive or non-consecutive livestock production periods, considering the atmospheric methane decay. Two BME approaches are defined: BME with a chain base (BME C ), which allows comparison of two cumulative methane emissions (CME) in consecutive years i and i + 1; and BME with a fixed base (BME F ), which allows comparison of CME in year j (where j can range from -∞ to ∞) with a fixed CME in year i. The average BME F for Slovenian dairy cows and non-dairy cattle between 2018 and 2022, compared to the fixed year 2001, was −46.45 kt CH 4 and 19.76 kt CH 4 , indicating a long-term methane removal and burden, respectively, from these sectors. For practical use, BME C and BME F can be applied across livestock farming systems to assess and monitor short-term and long-term efficiency, respectively, in any (sub)sector or (sub)population. In addition, BME provides a template for developing novel tools for farmers and enables the incorporation of reduced AME through methane mitigation measures.