Food and Environment
Alon Shepon
Weizmann Institute of Science, Israel
Prof. Ron Milo lab
environment livestock dietary preferences food security
fish future foods
• <1 billion undernourished and <2 billion overweight.
• Need to increase food production by 70% in coming decades (“food gap”).
• A 1/3 of all food produced is lost.
• Two way interaction between climate and food.
• Dietary changes is imperative to meet future food security and environmental goals.
The food crisis involves issues of food security and sustainability
1. Linear system yet complex.
2. Inefficient segments.
3. Large processing. 4. Pasture is largest
land user. 5. About 1/3 of
cropland to feed. 6. Dairy and beef in
mixed farms; pork and poultry use concentrated feed
Herrero et al (2015) Annu. Rev. Environ. Resour.
Livestock incur major environmental burdens
Ref: Livestock’s long shadow, Steinfeld et al, UN-FAO, 2006
• Dominate anthropogenic land use (habitat fragmentation & biodiversity loss) • Disruption of N, P biogeochemical cycles air pollution, soil acidification,
ecosystem alteration. • Key reason for tropical deforestation, eutrophication, soil erosion, and
antibiotic overuse. • Roughly 20% of global GHG emissions. • Estimated 20% of total global water use (1/3 of agriculture use).
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Steinfeld et al 2006 Livestock’s long shadow
Chicken or beef?
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• USDA use outdated data (often reflecting 1960s feeding practices).
• Aggregate level analyses (meat category) don’t capture individual food items.
• Updated and detailed LCA results vary by geography and agrotechnology difficult to get widely representative costs.
How the calculation was performed?
What is the environmental cost of each feed?
Environmental burden per calorie consumed
How much feed is consumed by each livestock?
15 Eshel et al (2015) J. Agri. Sci.
Ref: Eshel, Shepon, Makov & Milo, PNAS 2014
Beef requires about 10-fold more resources per calorie than other animal categories
Resource needed for a consumed Mcal (1000 kcals)
land water GHG Nr Animal derived
calories in mean US diet
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Diary and eggs are very similar to pork and poultry
Eshel G, Shepon A, Makov T and Milo R (2014) PNAS
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feed to food conversion ratio is a reflection of the environmental burdens
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3 2
concentrates
cultivated feed
beef pork poultry
Avoiding meat and dairy is ‘single biggest way’ to reduce your impact on Earth Gaurdian 31 May, 2018
Poore and Nemecek (2018) Science
“Producers have limits on how far they can reduce impacts. Most strikingly, impacts of the lowest-impact animal products typically exceed those of vegetable substitutes, providing new evidence for the importance of dietary change.”
Cassidy et al (2013) Environ. Res. Lett
o “..shifting the crop calories used for feed and other uses to direct human consumption could potentially feed an additional 4 billion people.”
o Main caveat:
feed cannot be consumed as food directly (not interchangeable!)
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food a
The dietary shift potential is the amount of additional people that can be fed on spared
land resulting from dietary shifts
food b whole diet
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Substitution of beef with poultry entails spared lands that can feed an additional 120-140 million people
beef poultry
Shepon et al (2016) Environ. Res. Lett. Eshel et al (2016) Environ. Sci. Technol
beef plants The dietary shift potential of a dietary transition from beef to a plant based diet is approx. 190 million people
plant-based replacement diets =350 million additional people> supply chain food waste.
Shepon et al (2018) PNAS
• dietary shifts is a necessary strategy to meet targets to limit global warming to 2 degrees. Hedenus et al. Clim. Change 2014
• GHG emissions of mediterranean, pescetarian (vegetarian diet with fish) and vegetarian diets would be 30%, 45%, and 55% lower.
Tilman D and Clark M Nature 2014
• “plant-based diets…could reduce global mortality by 6–10% and food-related GHG emissions by 29–70%”
Springmann et al PNAS 2016
• “We……show that improved diets and decreases in food waste are essential to deliver emissions reductions, and to provide global food security in 2050.”
Bajzelj et al Nature Climate change 2014
• “…dietary shifts towards low-impact foods and increases in agricultural input use efficiency would offer larger environmental benefits than would switches from conventional agricultural systems to alternatives such as organic agriculture or grass-fed beef.”
Clark M and Tilman D Environ. Res. Lett 2017
A system level approach is needed to tackle future challenges
• Animal-based products incur a large disproportionate
environmental toll. • Dietary preferences can potentially reduce environmental costs or
feed millions of additional people with no additional resource usage.
• Supply (agriculture) and demand (diets) side changes are needed simultaneously.
• In developing countries livestock have a different role and foodprint.
• Executing de facto large scale dietary shifts will require further multi disciplinary research (e.g. behavioral economics) and targeted policy.