Climate Impacts of Cultured Meat and Beef Cattle

Lynch J, Pierrehumbert R. Climate Impacts of Cultured Meat and Beef Cattle. Frontiers in Sustainable Food Systems. 2019 2019-February-19;3(5). 

Relevant to: 

In addition to the results comparing the climate impacts of the two systems of meat production, this is of particular interest to Dietitians-Nutritionists who desire a deeper understanding of the differences that varying climate change metrics make on measuring the impacts of food production. 

Question: 

The authors compare cultured meat and beef system emissions on climate change. Rather than using the typical warming impact measurement of carbon dioxide equivalent comparisons, they use an atmospheric modeling approach. Three different consumption scenarios are predicted up to 1000 years in the future.    

Bottom line for nutrition practice: 

Cultured meat does not necessarily have less impact on global warming than cattle. The impact varies dependent on the production system of different ways cultured meat is produced and on different systems of producing beef. It also varies dependent on how far into the future impacts are measured; cultured meat systems have lower initial warming potential than cattle systems, but in the long term 

this advantage decreases, and in some scenarios cattle systems causes less warming. 

Abstract:

Improved greenhouse gas (GHG) emission efficiency of production has been proposed as one of the biggest potential advantages of cultured meat over conventional livestock production systems. Comparisons with beef are typically highlighted, as it is a highly emissions intensive food product. In this study, we present a more rigorous comparison of the potential climate impacts of cultured meat and cattle production than has previously been made. Warming impacts are evaluated using a simple climate model that simulates the different behaviors of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), rather than relying on carbon dioxide equivalent (CO2e) metrics. We compare the temperature impact of beef cattle and cultured meat production at all times to 1,000 years in the future, using four synthetic meat GHG footprints currently available in the literature and three different beef production systems studied in an earlier climate modeling paper. Cattle systems are associated with the production of all three GHGs above, including significant emissions of CH4, while cultured meat emissions are almost entirely CO2 from energy generation. Under continuous high global consumption, cultured meat results in less warming than cattle initially, but this gap narrows in the long term and in some cases cattle production causes far less warming, as CH4 emissions do not accumulate, unlike CO2. We then model a decline in meat consumption to more sustainable levels following high consumption, and show that although cattle systems generally result in greater peak warming than cultured meat, the warming effect declines and stabilizes under the new emission rates of cattle systems, while the CO2 based warming from cultured meat persists and accumulates even under reduced consumption, again overtaking cattle production in some scenarios. We conclude that cultured meat is not prima facie climatically superior to cattle; its relative impact instead depends on the availability of decarbonized energy generation and the specific production systems that are realized. 

Details of results: 

The authors pose that this study of potential warming impacts of cattle production and cultured meat is more rigorous than those previously completed. Instead of using carbon dioxide equivalent (CO2e) metrics, impacts are measured using carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). This is important, as these gases differ in their initial radiative force, and how long they last in the atmosphere. Methane has a significantly higher radiative force than CO2, but only lasts in the atmosphere about 12 years, whereas CO2 lasts over millennia. Nitrous oxide has a greater initial force than CO2 or methane, and lasts approximately 100 years in the atmosphere. The authors argue that the frequently used “carbon dioxide equivalence metric, the 100-years Global Warming Potential (GWP100) equates each gas by integrating the amount of radiative forcing that a one-off emissions pulse would exert over a 100-years period” (p.2); it both fails to capture the longer term impacts of CO2 beyond 100 years, and also overestimates the impact of methane (the latter being substantial in cattle production, whereas cultured meat emits primarily CO2). Impacts on warming from land use was not included in this study. 

Four cultured meat systems (detailed in studies derived from the literature) were compared with three different cattle production systems: i) organic Swedish ranch (low input system with low methane emissions due to rapid weight gain of animals); ii) Brazilian pasture system (low input but higher methane emissions due to slower weight gain of animals), and iii) Midwest USA pasture system (high input with faster weight gain). These systems are mapped against three consumption scenarios:  
i) constant high levels of meat consumption (approximating current USA consumption); ii) same (USA) high levels of meat consumption followed by an exponential decline after 100 years; iii) more sustainable, approximating current global consumption then exponentially decreasing after 100 years.  

Overall, the two lowest emitting cultured meat systems have a lesser warming impact than the cattle systems. This advantage decreases over time, causing the authors to remark that the advantages of cultured meat are not as dramatic as would be shown in GWP100 measurements. The worst emitting cultured meat system has lower CO2 emissions at first, but performs far worse than all cattle production systems over the long term (within 200 years, the Swedish cattle system is superior, and the worst cattle system – (USA) – outperforms it at 450 years). This results from the fact that unlike CO2, CH4 emissions do not accumulate.  

The authors suggest that the timing of climate objectives need to be taken into account. At 100 years, the Swedish cattle system is the only system to outperform the highest emitting cultured meat system.  

Finally, the authors note that detailed lifecycle analysis data must be made available from cultured meat production systems. There are also uncertainties in these systems (e.g., growth media). They also stress the need for decarbonized energy generation before cultured meat systems “replace” cattle system (and that cattle systems may also benefit from decarbonization of energy generation).  

Of additional interest: 

This blog challenges the idea of high investment into cultured meat, suggesting that we need to hold meat processors more accountable: 
https://civileats.com/2021/05/05/opinion-we-dont-need-a-moonshot-for-faux-burgers-we-need-to-hold-big-meat-accountable/ 

Editor’s comments:  

The authors bring much clarity to their explanation of temporal dynamics of the different emissions impacting global warming (i.e., identifying how long different emissions last in the atmosphere).   

The information presented needs to be considered against the urgency of the climate problem (as authors discuss re: climate objectives), and the broader concept of sustainability. There is urgent need to lower our GHGe rapidly to stabilize Earth’s climate. However, as health professionals, we want to advocate for investing in sustainable systems – those that make sense in the long term. One also needs to consider other potential environmental benefits of traditional grazing in terms of increased biodiversity and carbon sequestration. This article asks us to question the logic of significant investment in/recommendations for cultured meat, unless decoupled from fossil carbon. It also asks us to consider simultaneous investment/recommendation for low-input, rapid growth cattle models (e.g., the Swedish Ranch system). 

Open access link to article: 

https://www.frontiersin.org/articles/10.3389/fsufs.2019.00005/full 

 Conflict of interest/ Funding:  

This research was funded by the Wellcome Trust, Our Planet Our Health.  
No conflict of interests declared.  

External relevant links:  

N/A

Corresponding author: 

john.lynch@physics.ox.ac.uk  

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