Sustainable Diets Food for Healthy People and a Healthy Planet: Workshop Summary (2014) / Chapter Skim
Currently Skimming:
3 Quantifying Synergies and Trade-Offs: Moving Forward from Conceptual Links to Empirical Data
3 Quantifying Synergies and Trade-Offs: Moving Forward from Conceptual Links to Empirical Data
Pages 35-60
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 35... ...
dietary guidelines. Emily Cassidy from the University of Minnesota quantified the environmental impacts of different diet preferences using three metrics: land use, water use, and greenhouse gas (GHG)
|
From page 36... ...
• Regardless of methodology used, results generated thus far gener ally indicate that a reduction in the animal protein content in the U.S. diet would reduce greenhouse gas emissions, land use, and other environmental impacts.
|
From page 37... ...
is not very surprising given higher per capita meat consumption in the United States compared to 1 This section summarizes information presented by Emily Cassidy, B.S., Institute on the Environment, University of Minnesota.
|
From page 38... ...
Diet Cassidy used land, water, and GHG emission metrics to explore the likely environmental impacts if the typical U.S. diet were to shift toward less protein.
|
From page 39... ...
She assessed land requirements for 100 grams each of various food products, categorizing her findings using the same groups Food and Agricultural Organization uses (beef, pig, chicken, egg, dairy, oil crops, vegetable, fruit, cereals, sugars, tree nuts, starchy roots, pulses)
|
From page 40... ...
(2012) , who estimated that agriculture accounts for roughly 19 to 29 percent of global anthropogenic GHG emissions, with about 80 to 86 percent of agricultural emissions occurring during the production stage and associated with fertilization (nitrous oxide emissions)
|
From page 41... ...
. An estimated 85 percent of beef GHG emissions are enteric methane emissions, and the remaining 15 percent are from feed production for the beef cattle.
|
From page 42... ...
food diet, Cassidy estimated the environmental impact of the observed shift in purchases by weight. Preliminary results show an 8-13 percent decrease in land requirements, a 7-12 percent decrease in the water footprint, and an 8-10 percent decrease in greenhouse gas emissions.
|
From page 43... ...
diet from 123 to 30 kilograms of meat per person per year would impact land, water, and greenhouse gas footprints. new figure 3-5.eps SOURCE: Unpublished results from Cassidy.
|
From page 44... ...
The dietary guidelines recommend more lean meat, which would eventually require breeding leaner animals. But, in the short term, a shift to a leaner-meat diet would require more animals because the fattier cuts of meat would be discarded, with land 3 This section summarizes information presented by Christian J
|
From page 45... ...
The change in land required per year from where the United States is today with its average diet, that is, mid-way along the x-axis, and a vegetarian diet is more than a twofold difference. Thus, Peters opined, "the assumptions made about what constitutes healthy eating with respect to meat are incredibly important in terms of trying to understand what the impacts will be on land use." 4 One meat equivalent ounce = 1 ounce of fish; 0.25 cup cooked dry beans, 1 egg, or 0.5 ounce of nuts or seeds.
|
From page 46... ...
bitmap with masks and some vector type Other Ways to Project Land Use Impacts Peters identified three other methods to estimate change in land use, all of which are in use today and all of which are evolving to address not just land use but environmental impacts generally. One is economic modeling, with the goal of modeling demand and the potential supply given that demand (Rosegrant and IMPACT Development Team, 2012)
|
From page 47... ...
In Peters's opinion, there are many good data sources for tracking land use. Temporal trends can be tracked using annual crop production survey data collected by the USDA National Agricultural Statistics Service or 5-year USDA Census of Agriculture data.
|
From page 48... ...
Balancing Health and Environment Assuming that enough data exist to understand the context of the environmental impact of land use change, how can environmental benefits versus health benefits be weighed? Peters identified two types of situations: ethical synergy versus ethical dilemma.
|
From page 49... ...
First, "The jury is still out on the land use impact of diet." Data from ERS suggest that diet changes have a modest impact overall, unless meat consumption changes. Second, researchers have the tools needed to begin both projecting the impacts of dietary change and tracking changes in land use.
|
From page 50... ...
The ultimate aim of LCA is to connect all of the inputs and outputs and quantify their environmental significance using impact assessment models. Typical LCAs consider impacts on energy use, global warming potential, eutrophication, acidification, tropospheric ozone, and human toxicity.
|
From page 51... ...
milk production serves as a good example of the type of results LCA provides. As shown in Figure 3-7, although it may be possible to squeeze out some efficiency gains during processing, transport/distribution, or at the retail end of the life-cycle, the bulk of GHG emissions from farm milk kg CO2 e / kg milk consumed Other Methane, fossil Nitrous oxide Methane, biogenic Carbon dioxide, fossil transport/distribution milk production processing retail consumer packaging feed production FIGURE 3-7 An example of life-cycle assessment results: Greenhouse gas emissions associated with U.S.
|
From page 52... ...
Because those losses -- and their impacts -- are induced by the consumer and at the retail stage, efforts to reduce impacts associated with loss should target the consumer and retail stages. Food losses are often overlooked as a potential opportunity for reducing environmental kg CO2e / kg milk consumed contributions due to losses feed production milk production farm milk transport to processor processing packaging transport/distribution from...processor retail consumer FIGURE 3-8 An example of life-cycle assessment results: Greenhouse gas emission contributions of food losses during the retail and consumer stages of the milk life-cycle.
|
From page 53... ...
If LCA is going to be used to compare the environmental impacts of different foods, it is pertinent to begin to think about foods in terms of TABLE 3-1 A Comparison of Life-Cycle Assessment Results for Greenhouse Gas Emissions Associated with Different Foods Per gram Per kcal Per as- of protein food energy sold weight (kg CO2e/gram (kg CO2e/kcal (kg CO2e/kg) of protein)
|
From page 54... ...
But if they are compared on the basis of grams of protein delivered, the impact of milk is nearly nine times that of dry beans. Ideally, LCA researchers would like to come up with a functional unit that serves as a measure of comprehensive nutritional quality.
|
From page 55... ...
The USDA census provides good agricultural production data, with the USDA LCA Digital Commons10 beginning to roll those data into a format that is more useful for LCA, but researchers need more region-specific data. With respect to environmental impact data, environmental impact categories need to be expanded beyond GHG emissions.
|
From page 56... ...
Diets, Including Plant-Only Diets, Processed Foods, and Functional Foods An audience member commented on the fact that most speakers identified plant production as the most sustainable type of food production. She asked the panelists to comment on how they might expand their analyses to include the full range of diets, including plant-only diets.
|
From page 57... ...
Environmental Impacts of Different Animal Production Systems Several speakers addressed the environmental impacts of different quantities of meat in the diet or different types of meat in the diet. An audience member questioned whether there have been any analyses of different animal production systems, for example, grass-based animal production versus intensified production systems.
|
From page 58... ...
He added that uncertainty in LCAs stems not just from data measurement but also from impact assessment methods, especially the more complex impact assessment methods (e.g., those associated with human health and eco-toxicity)
|
From page 59... ...
2012. Sustainable diets for the future: Can we contribute to reducing greenhouse gas emissions by eating a healthy diet?
|
From page 60... ...
2013. Greenhouse gas emissions from milk production and consumption in the United States: A cradle-to-grave life cycle assessment circa 2008.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.