An Australian report argues that the standard metric used to measure livestock methane, GWP100, exaggerates the warming effect of stable cattle and sheep populations. Methane researcher Alan Lauder points out that methane is a flow gas that breaks down in about 12 years, unlike CO2 which accumulates. With Australian herd sizes stable since the 1970s, new methane largely replaces old methane, maintaining warming rather than adding to it. The report suggests GWP* as an alternative that better reflects whether emissions are rising, stable, or falling. The report does not say livestock methane should be ignored. Reducing methane from a stable herd would still produce a cooling effect. But using GWP100 for stable herds may overstate warming impact, which could affect farming regulations, bank lending, and land values. Australia could publish supplementary data using GWP* but currently does not. This matters for carbon accounting and agricultural policy globally.
