Methane (CH4) is a potent greenhouse gas, second only to carbon dioxide (CO2) in terms of its cumulative effects on the Earth’s climate. Its short yet robust atmospheric presence makes mitigating methane emissions one of the most effective ways to combat climate change in the immediate term. This urgency is underscored by the Global Methane Pledge, which commits 155 countries to collectively reduce methane emissions by 30% by 2030. With only six years left to meet this target, the agrifood sector stands out as the area with the greatest potential for impactful methane reduction.
Contrary to popular belief, agrifood systems – not the oil and gas industry – are humanity’s largest methane hotspot, accounting for 54% of global anthropogenic methane emissions. Despite this, methane action within agrifood systems is lagging. Numerous solutions exist to decrease the climate impact of atmospheric methane, many of which also bring additional benefits for human health, nutrition, economic prosperity, and equity. However, much of this potential remains untapped.
One significant barrier to effective methane mitigation is the way we measure the impact of methane emissions. Greenhouse gases (GHGs) are typically measured in terms of their carbon dioxide equivalence (CO2eq) over a century, known as GWP100 (Global Warming Potential over a hundred years). While this metric is useful for carbon dioxide, which remains in the atmosphere for hundreds of years, it is problematic for short-lived climate pollutants (SLCPs) like methane, which have a much shorter atmospheric lifespan but a far greater immediate impact.
Methane stays in the atmosphere for approximately 12 years, during which its global warming impact is 80 times that of carbon dioxide over the same period. However, when measured over a century, methane’s GWP is only 27 times that of carbon dioxide. This discrepancy highlights the need for shorter timescales, such as GWP20, to more accurately represent methane’s impact. The Intergovernmental Panel on Climate Change (IPCC) recognizes GWP20, but it is rarely used, leading to a diluted perception of methane’s true impact.
This mismeasurement has serious ramifications. For instance, many agrifood solutions that help reduce or remove atmospheric methane could be eligible for environmental attribute certificates such as carbon credits. These credits could attract financing from corporations and other entities seeking to offset their emissions. However, the exclusive use of GWP100 prevents these solutions from receiving adequate financing, as it hides part of their impact. This issue is particularly evident in life cycle assessments (LCAs), which measure the environmental impacts of products and services and are crucial for policy decisions. LCAs that rely on GWP100 obscure much of the impact of methane emissions and the potential of solutions to mitigate them.
The case of beef production illustrates this distortion. Conventional beef production has a heavy GHG footprint, especially in terms of methane. Alternative methods, such as cultivated beef produced through cellular agriculture, have the potential to avoid substantial methane emissions. Independent research by CE Delft found that conventional beef’s climate impact is more accurately represented by GWP20 than by GWP100 due to its significant methane emissions. Conversely, cultivated beef’s capacity to avoid GHG emissions is more apparent when using GWP20.
To meet both short- and long-term climate goals, decision-makers need to understand climate impact over relevant timescales. Policymakers should mandate disclosures of GHG emissions based on multi-value reporting standards like GWP20/100. Such standards can help private corporations, carbon standard bodies, LCA consultancies, and governments better disclose and address methane’s climate impact while it is present in the atmosphere.
For the agrifood sector, a multi-value measurement approach can reveal a solution’s entire impact throughout all stages of production and consumption. This can enable more informed allocation of financial incentives and facilitate more accurate modeling of the broader agrifood system transformations needed to maximize positive effects. In measuring GHGs, GWP100 alone is insufficient. Implementing multi-value timescales is essential for fostering optimal climate policy and achieving meaningful methane mitigation.