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David Moss's avatar

Great piece Janette. I have also been advocating for GWP*, but recently have been exposed to a broader perspective on this topic.

There is a great article titled "GWP∗ is a model, not a metric" by Malte Meinshausen and Zebedee Nicholls. Where they argue (quite effectively) that GWP* is not well suited as an emission metric. I quote "Notably, for a stakeholder with high historical CH4 emissions, and somewhat lower current CH4 emissions, the waning temperature effect of the past will dominate the additional warming from current emissions. As a result, they are considered net negative in the GWP∗-framework. Yet current emissions still warm the planet compared to what would have happened without those emissions. Metrics should reflect this marginal/additional warming. Instead, GWP∗ folds the waning effect of past emissions into metric-style assessment of the impact of future emissions. While GWP∗ is well-suited to assessing the temperature effect of time-series of emissions (hence is an excellent model), it is ill-suited as an emission metric to approximate the marginal climate effect of GHG emissions from a particular year or, say, a 5 year long commitment period."

On the surface, GWP* seems like a "no-brainer", but when one starts to dig a bit deeper, there are some serious holes in the calculation. Some have attempted to address these issues Smith et al (2021) or Allen et al (2018) methods - but the problems with the model mostly still exist.

I should state, I work in the beef industry and certainly see and advocate for the scientific community (and consumer perception for that matter) to shift from the reductionist, unicentric focus on carbon, to a more holistic, systems-based, multi-metric view of beef production globally. We very much have a first-world view of the problem, and worse, 'solution' to GHG emissions in livestock production.

Another great article that expands on this is titled "Carbon myopia: The urgent need for integrated social, economic and environmental action in the livestock sector" (I won't list all 11 researchers responsible for this publication). I quote " Globally, livestock production systems exist for several reasons, many of which are critical to livelihoods. In many areas, livestock are needed to satisfy a variety of human needs. In addition to production of meat, milk, eggs, wool, hides and skin, livestock provide draught power and nutrient cycling, supporting the environmental sustainability of production Steinfeld et al., 2003). Ruminant livestock utilize non-arable land, converting fibrous and cellulosic materials into edible human protein. In many low and middle income countries (LMIC), livestock constitute the main (if not only) household capital reserve, serving as a strategic financial reserve that reduces risk and adds financial stability to the farming system (Steinfeld et al., 2003)."

It is human nature to look for a simple solution to a smoking gun. However, I feel we need to broaden our perspective on the social, economic and environmental impact of livestock production - globally (not just from our western societal view), and be open to how best to calculate its environmental impact. Rushing to GWP* on the surface appears to be a simple solution, but we need to accept it also has its issues. On the other side, viewing livestock production from only an environmental lens is dismissing the economic, and perhaps most importantly, societal impact to people and their families - especially those in LMIC.

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Jennifer Barney's avatar

This was GREAT

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