Addressing the Diet-Climate Connection
What we eat plays a significant role in climate change. In alignment with the United Nations’ annual climate change Conference of Parties (COP23) and the American Public Health Association’s annual meeting, which in 2017 is focused on “Creating the Healthiest Nation: Climate Changes Health,” the Johns Hopkins Center for a Livable Future (CLF) has highlighted resources regarding ways that everyone can address climate change – at the table.
How does the food system exacerbate climate change?
By 2050, food production alone is expected to nearly exhaust the 2° C emissions budget
World leaders have agreed on the goal of keeping average global temperature rise within 2° C above pre-industrial levels in order to avoid the most catastrophic climate change scenarios. Even if this goal is met, climate change is projected to have significant global impacts, many of which will likely continue for centuries.
In order to have at least a 66% chance of keeping global warming below 2° C, estimates indicate that global greenhouse gas (GHG) emissions from human activities must be kept at or below 21 ± 3 gigatons (Gt) of carbon dioxide equivalents (CO2e) per year. Under the business‐as‐usual scenario modeled by Bajželj et al., in which global population increases to 9.6 billion and global meat and dairy consumption increases with rising GDP, emissions from food production alone (20.2 Gt CO2e) would nearly exhaust the emissions budget in 2050. This projection includes emissions associated with land-use change, such as deforestation. Combined with non‐agricultural sectors, global emissions would greatly exceed 21 Gt, with severe consequences for people, public health, economies, and ecosystems. Additional studies have demonstrated the need for dietary shifts to mitigate climate change.,,,,
Food system activities, including producing, transporting and disposing of food, generate up to 30% of total global GHG emissions., Of these sources, livestock production is the largest, accounting for an estimated 14.5% of global GHG emissions from human activities, according to the United Nations. Meat and dairy from ruminant animals, such as cattle and goats, are particularly emissions-intensive.
Globally about 30% of the food supply is never eaten. If all the world’s food losses and waste were represented as a country, that “country” would be the third highest GHG emitter, after China and the U.S. Discarding food is akin to discarding all the embodied GHG emissions involved in its production, processing, transportation, cold storage, and preparation.14 Additionally, when food decomposes in landfills, it generates significant quantities of methane, a GHG which is up to 84 times more potent than carbon dioxide.
How can we mitigate climate change?
Dramatic reductions in meat and dairy consumption and wasted food, alongside reductions in GHG emissions from energy use, transportation, and other sources, are crucial for avoiding the most catastrophic climate change scenarios.
1) Cut wasted food
The United Nations Sustainable Development Goal 12.3 calls for cutting wasted food in half by 2030. The United States Environmental Protection Agency and U.S. Department of Agriculture have set the same goal. According to estimates by climate scientists, meeting this goal alone can reduce projected food production-related carbon dioxide equivalents (CO2e) by 22% (4.5 Gt) in 2050.3 Interventions to reduce wasted food in higher‐income countries should focus on the consumer, including expiration date labeling and quality standards, improving shopping/eating practices, and controlling market supply. In lower- and middle-income countries, the greatest need for change is at the production end, including improvements to infrastructure, storage capacity, mechanization, packaging, and roads.
2) Eat healthy diets – with less meat and dairy
Diets that are high in plant-based foods and low in animal-based foods offer significant health benefits, along with climate and other environment benefits, including more efficient use of land, water, nitrogen, and other resources.,, For example, researchers modelled potential GHG emissions reductions from a diet limiting intake of red meat (maximum of two 85g / 3 oz. portions per week), poultry (maximum of one 85g / 3 oz. portion per day), dairy (maximum of two 200g portions – about 2 cups – per day), eggs (5 per week), sugars, and oils to levels recommended by Harvard Medical School, WHO, FAO, and the American Heart Association, and sets a minimum for fruit and vegetable intake.3 That shift would entail, in part, a 31% reduction in global animal product intake relative to projected 2050 levels, with greater reductions in regions with higher intake. For example, Western Europe and North America would need to reduce red meat intake by 76% and 81%, respectively. Behavioral campaigns, such as Meatless Monday, can raise awareness of the impacts of dietary shifts, and introduce consumers to plant-based eating patterns.
What about grass-fed? Some advocates claim that by sequestering carbon from the atmosphere, grazing livestock can solve climate change. While grass-fed or pasture-raised animal products may offer many health, ecological, and animal welfare benefits compared to conventional animal products, they do not offer significant climate benefits. Under specific soil, climate, and animal density conditions, well-managed livestock grazing may sequester carbon, but this potential is small, time-limited, reversible, and substantially outweighed by the GHG emissions generated by grazing systems.
What about local/regional? Eating local or regional foods may be a worthwhile practice for social and economic values, but should not be pursued as a major climate mitigation strategy. While choosing local sources for some types of foods can reduce GHG footprints (e.g., fresh berries or fish that would otherwise be shipped on planes), in other cases, local foods that require significant energy inputs to grow during the winter (e.g., tomatoes or lettuce grown in heated greenhouses) can have significant GHG footprints. When eating local, individuals and institutions should choose in-season foods, which are typically produced and transported with a lower climate impact.
Ultimately, changing the types of foods people eat and how those foods are produced is better for the climate than reducing the distances foods travel. One study from the United Kingdom estimated that avoiding air-freighted and hothouse-grown foods could reduce dietary GHG emissions by 5%—compared with a 35% reduction from eliminating meat from diets. Another study from the U.S. found that avoiding red meat and dairy one day a week reduces GHG emissions more than eating locally every day.22
3) Work for broader food system change
Shifting diets and reducing wasted food on an international scale will require more than just educating consumers. National and subnational policies that address dietary recommendations, agricultural subsidies, and procurement practices will also need to support such transitions.
What is the Johns Hopkins Center for a Livable Future doing?
- Generating evidence on how to cut wasted food in half by 2030:
- Developed a report on Government plans to address wasted food (2017)
- Studied US consumer attitudes and behaviors related to wasted food (2015)
- Modeling country-specific environmental impacts of wasted food interventions (in progress)
- Advancing the science and awareness about the diet-climate connection:
- Modeling the climate and water footprints of 11 diets specific to 140 countries (in progress)
- Organized and convened “Less Meat, Less Heat: A Workshop on Civil Society Engagement at COP23 and Beyond” workshop in April 2017
- Co-leading the Food and Climate Coalition, a group of NGOs and academics who research and advocate for a more sustainable global food system
- Providing ongoing technical assistance to the Meatless Monday Campaign
- Guiding and evaluating efforts to implement meat reduction initiatives in institutional food service settings, with resources such as this report and accompanying toolkit on Meatless Monday best practices in food service operations
- Supported the inclusion of sustainability considerations in the Dietary Guidelines for Americans 2015-2020, as recommended by the Dietary Guidelines Advisory Committee
- Translating food systems science into free, online resources for public audiences:
- Food System Primer on food and climate change
- Lesson plan for high school teachers on food and climate change
- Sustainable Diets for Healthy People and a Healthy Planet. United Nations Standing Committee on Nutrition. 2017.
- Redefining Protein: Adjusting Diets to Protect Public Health and Conserve Resources. Health Care Without Harm. 2017.
- Shifting Diets for a Sustainable Food Future. World Resources Institute. 2016.
- The Importance of Reducing Animal Product Consumption and Wasted Food in Mitigating Catastrophic Climate Change. Johns Hopkins Center for a Livable Future. 2015.
- Policies and Actions to Shift Eating Patterns: What Works? Food Climate Research Network and Chatham House. 2015.
- Changing Climate, Changing Diets: Pathways to Lower Meat Consumption. Chatham House. 2015.
- Tackling Climate Change through Livestock: A global assessment of emissions and mitigation opportunities. Food and Agriculture Organization of the United Nations. 2013.