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Methane emissions
Image credit: istock/NicoElNino

Guest article: To reduce methane’s impact across agrifood systems, we must measure it properly

June 28, 2024

Editor’s note: Dr. Lee Recht is VP of sustainability at Israeli cultivated meat startup Aleph Farms; Leehee Goldenberg is VP of policy at Oporto Carbon, which is building Israel’s voluntary carbon market; and Dr. Meghan O’Hearn is director of impact at Food Systems for the Future, a nonprofit helping scale agrifoodtech innovations.

The views expressed in this article are the authors’ own and do not necessarily represent those of AgFunderNews.

Methane (CH4) is a potent greenhouse gas second only to carbon dioxide (CO2) in terms of its cumulative effects on the Earth’s climate. Due to methane’s short yet robust atmospheric presence, mitigating its emissions is the most effective way to fight climate change in the here and now.

Methane mitigation is critical for reaching meaningful short-term climate targets and also buying much-needed time for achieving mid- and long-term goals. One notable short-term target is the Global Methane Pledge, which commits signatories (155 countries and counting) to collectively reduce methane emissions by 30% by 2030 – just six years from now.

Of all the sectors covered by the pledge, agrifood offers the strongest potential to meet these targets. Contrary to popular belief, these systems – and not oil & gas – are humanity’s largest methane hotspot, responsible for 54% of global anthropogenic methane emissions.

However, methane action in agrifood systems is lagging. While there are numerous solutions throughout agrifood systems deliberately geared towards decreasing the climate impact of atmospheric methane, and while many of them bring co-benefits for human health, nutrition, economic prosperity, and equity, much of these solutions’ potential remains untapped.

One way that we can advance better climate outcomes in agrifood is by measuring the impact of methane emissions more accurately.

anthropogenic sources of methane
Source: Climate Advisors

In emissions tracking, metrics have serious consequences

A GHG’s warming impact is calculated in terms of how much of the most prominent greenhouse gas, carbon dioxide, would have the same impact on a defined timescale – also known as carbon dioxide equivalence (CO2eq).

The default timescale is a century and is expressed by GWP100 (Global Warming Potential over a hundred years), a useful metric for carbon dioxide, given the fact that it remains in the atmosphere for hundreds of years. But as a standalone metric, GWP100 is problematic when it comes to measuring the effects of short-lived climate pollutants (SLCPs), which remain in the atmosphere for far less than a century.

While methane, the most prominent SCLP, stays in the atmosphere for approximately 12 years, far less time than carbon dioxide (anywhere between 300 and 1,000 years), its global warming impact within that time is far greater. This impact is represented significantly better by shorter timescales, such as GWP20 – Global Warming Potential over twenty years. Like GWP100, GWP20 is recognized by the Intergovernmental Panel on Climate Change (IPCC), but it is used far less frequently.

The choice of timescale has serious ramifications. For a greenhouse gas that is present in the atmosphere for fewer than twenty years, measuring that gas’s impact across an entire century dilutes perception of that impact. After being emitted into the atmosphere, methane’s GWP over the next twenty years is 80 times that of carbon dioxide in the same span, but its GWP over the next one hundred years is only 27 times that of carbon dioxide.

To meet both short- and long-term climate deadlines, decision-makers need to be able to understand climate impact over the short term as well as over the long term, which in turn requires relevant, practical timescales. Relying solely on GWP100, which is focused on the long term, obscures a considerable portion of methane’s effects by spreading it out over a hundred years.

Cows are a big source of methane emissions
A potent greenhouse gas, methane is generated by manure as it decomposes, but is also burped out by ruminants, who produce it in a stomach compartment called the rumen. Here, microbes break down complex carbs and produce gases that are converted into methane by another set of microbes (methanogens). Image credit: istock/Clara Bastian

Concealing some of agrifood innovation’s influence on methane

When we fail to understand the true climate impact of various behaviors, we also end up distorting mechanisms meant to catalyze methane mitigation.

For instance, many agrifood solutions that help avoid, reduce or remove atmospheric methane may be eligible for environmental attribute certificates such as carbon credits. These can open the door for financing from corporations and other entities seeking to offset (or inset) some of their own emissions. However, inaccurate measurement prevents these solutions from receiving adequate financing.

Even though GWP20 offers a timescale that is more appropriate than GWP100 for methane, these solutions – from water management in rice cultivation to food waste circularity to additives for livestock feed – are currently subject to methodologies that measure impact exclusively according to GWP100. By ignoring GWP20, these methodologies hide part of the solutions’ respective impacts. As a result, implementation of and investment in these methane mitigation solutions are less incentivized than carbon dioxide-focused analogs.

In similar fashion, life cycle assessments (LCAs), which measure various products’ and services’ environmental impacts and are relied upon for significant public and private policy choices, continue to rely overwhelmingly on GWP100. As a result, they end up inadvertently hiding much of the impact of current methane hotspots and their potential solutions.

The measurement distortion is particularly obvious in the case of beef production. Conventional beef production has a heavy GHG footprint, especially in terms of methane. Other methods of production, such as using cellular agriculture to grow cultivated beef directly from individual cow cells, have the potential to avoid a substantial proportion of the methane emissions associated with raising cattle. In the case of cultivated beef, the main GHG emitted is carbon dioxide (from energy use), which can be significantly reduced by transitioning fully to renewable energy, leaving few if any greenhouse gas emissions at all.

Independent research and consultancy organization CE Delft compared its previously published LCA findings, determined via GWP100, with updated findings based on GWP20. It found that conventional beef’s climate impact is made more clear by GWP20 than by GWP100 due to the substantial methane emissions created in production. It also found that when it comes to cultivated beef’s capacity to avoid GHG emissions, GWP20 showed a larger avoidance potential than GWP100.

When GWP100 hides part of methane emissions’ impact, decision-makers cannot understand the extent to which methane affects climate. This impedes efforts to evaluate and differentiate between solutions that aim to reduce this impact.

Methane emissions predictions

Accurate measurement can enable better decision-making

Mitigating methane’s climate impact offers tremendous opportunity, but doing so requires that we measure methane and its effects properly – in ways that accord with climate goals’ urgent timelines.

Policymakers need to mandate disclosures of greenhouse gas emissions that are based on multi-value reporting standards like GWP20/100. Such standards can help private corporations, carbon standard bodies, LCA consultancies and governments themselves disclose – and therefore deal with – methane’s climate impact while it is present in the atmosphere.

For agrifood systems, a multi-value measurement approach can show a given solution’s entire impact through all stages of production and consumption, rather than only portions of this impact. Better measurement can enable more informed allocation of financial incentives and facilitate more accurate modeling of the broader agrifood system transformations required to maximize positive effects.

In measuring GHGs, GWP100 can’t stand alone. Multi-value timescales are widely available. To foster optimal climate policy, it is vital that we implement them as soon as possible.

Further reading:

CRISPR: A gamechanger for livestock methane reduction? ‘It’s high-risk, high-reward,’ says UC Davis professor

Bluemethane unveils novel tech to capture methane from water

Red seaweed was billed as a gamechanger for livestock methane reduction… so when will it deliver?

Danone VP on methane reduction in dairy: ‘You can’t force this on farmers, you have to meet them where they are’

🎥CH4 Global CEO: ‘Cow burps are the single largest source of methane globally’


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