Full length articleOptimal allocation of tomato supply to minimize greenhouse gas emissions in major U.S. metropolitan markets
Introduction
Our food system places high demands on natural resource use and emissions, being responsible, for example, for the emissions of approximately 2.6 metric tons of CO2e (tonCO2e) per person per year, or 8.4 kg CO2e per person per day (Weber and Matthews, 2008) in the United States, or roughly 10% of overall greenhouse gas (GHG) emissions (Weber and Matthews, 2008, US EPA. Inventory of U.S 2016). It demands 140 MJ of energy per person per day—four times the global average—and 1,200 liters (330 gallons) of water per person per day (Canning, 2010, UNESCO 2014), accounting for approximately 14% of national energy consumption and half of water withdrawals.
As the global population continues to grow and the middle class expands, demand for food, and different kinds of food—in particular, high-value products such as vegetables, fruits, and meat—will increase. The United Nations estimates that global food production must increase by 70% by 2050 in order to satisfy demand (United Nations 2011). If this expansion in production is to occur in a sustainable manner, care must be taken to minimize the environmental impact of the agricultural systems at regional, national, and global levels. (Bell and Horvath, 2020, Dorr et al., 2021)
In this study, we build a linear optimization model to estimate the cradle-to-market GHG emissions associated with fresh tomatoes supplied to 10 of the 12 most populous metropolitan areas in the United States (Table 1) based on 6 unique geographic production regions and four tomato growing practices (United States Census Bureau 2016). (The U.S. Department of Agriculture's Agricultural Marketing Service has not compiled data for Houston and Phoenix.) The 10 metropolitan statistical areas account for roughly one quarter of the U.S. population and 26% of tomato consumption.
Tomatoes were chosen as the focus of this study for a few reasons. First, tomatoes are one of the most popular “specialty commodities” in the United States. Roughly 9 kilograms (21 pounds) of fresh tomatoes and 30 kilograms (66 pounds) of processed tomatoes are consumed annually per person (USDA 2020). Second, tomatoes are grown using a variety of production methods, including indoors. In 2012, greenhouse tomatoes were a $400 million industry with over 1,000 acres of greenhouse tomatoes under production (USDA 2020). Tomatoes account for more than half of all greenhouse production of fruits and vegetables by area and nearly two-thirds of all greenhouse production by economic value (USDA 2020). Although indoor tomato production often requires more energy relative to conventional production, transportation distances to the consumer are typically shorter. Third, tomato production in the United States is diffuse; in 2019, 10 states reported over 1000 acres harvested (USDA 2020) .
Section snippets
Background
Environmental assessments of tomatoes are numerous in the literature, but not for the United States. Table 2 presents 48 cradle-to-farm-gate GHG intensity values collected from 30 peer-reviewed journal articles. The values represent a variety of growing practices and geographic regions, but only four were calculated for a United States region. The data in Table 2 reflect only the farm stage; processing, transportation, storage, and other stages beyond the farm gate are not included. (In some
Methods
We calculate the GHG emissions associated with fresh tomatoes supplied to each of the metropolitan areas during each week of a year. Next, we implement a linear optimization algorithm to compute the optimal tomato distribution scheme for the 10 metropolitan areas that minimizes total GHG emissions. Last, we comment on whether the presence of an omnipresent national-level agricultural “social planner” could potentially mitigate food-related GHG emissions, or whether the current scheme—whereby
Results
Under the current (i.e., baseline) scenario, supplying the 10 metropolitan areas with fresh tomatoes releases roughly 277,000 tonCO2e per year. Fig. 1 was created by summing the environmental impact of fresh tomatoes across all 10 destination cities. Optimization can save roughly 35,000 tonCO2e per year—a 13% improvement. Our model assumes fixed supply and demand, thus the only opportunity for improvement is in reducing transportation-related emissions by varying the supply portfolios of the 10
Discussion
Out of 10 major metropolitan statistical areas in the United States, Dallas has the lowest-impact tomatoes—0.61 kgCO2e per kg on average—due to its relatively close proximity to Mexican agriculture. Boston has the highest impact at 0.87 kgCO2e per kg on average, an increase of roughly 40%. More significant is the tomato production origin: open-field tomatoes supplied to Philadelphia from Virginia were found to have emissions of 0.38 kgCO2e per kg, whereas controlled-environment tomatoes
Supplementary material
See the attached separate file.
CRediT authorship contribution statement
Eric Bell: Methodology, Data curation, Formal analysis, Software, Writing – original draft. Yuwei Qin: Investigation, Validation, Visualization, Writing – review & editing. Arpad Horvath: Conceptualization, Funding acquisition, Project administration, Resources, Supervision.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgment
This material is based upon work supported by the National Science Foundation under Grant No. 1739676. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
References (64)
- et al.
Life cycle environmental impacts of cucumber and tomato production in open-field and greenhouse
J. Saudi Soc. Agric. Sci.
(2019) Carbon footprint and energetic analysis of tomato production in the organic vs the conventional cropping systems in Southern Italy
J. Clean. Prod.
(2019)- et al.
Testing the environmental performance of urban agriculture as a food supply in northern climates
J. Clean. Prod.
(2016) Integrated systematic approach increase greenhouse tomato yield and reduce environmental losses
J. Environ. Manage.
(2020)- et al.
Screening life cycle assessment (LCA) of tomato ketchup: a case study
J. Clean. Prod.
(1998) - et al.
Assessment of tomato Mediterranean production in open-field and standard multi-tunnel greenhouse, with compost or mineral fertilizers, from an agricultural and environmental standpoint
J. Clean. Prod.
(2011) - et al.
Effect of eating seasonal on the carbon footprint of Swedish vegetable consumption
J. Clean. Prod.
(2013) - et al.
Quantification of greenhouse gas emissions from open field-grown Florida tomato production
Agric. Syst.
(2012) Life cycle inventory analysis of fresh tomato distribution systems in Japan considering the quality aspect
J. Food Eng.
(2008)- et al.
LCA of local and imported tomato: an energy and water trade-off
J. Clean. Prod.
(2015)
The environmental impacts of organic greenhouse tomato production based on the nitrogen-fixing plant (Azolla)
J. Clean. Prod.
Protein efficiency per unit energy and per unit greenhouse gas emissions: potential contribution of diet choices to climate change mitigation
Food Policy
Carbon and water footprint tradeoffs in fresh tomato production
J. Clean. Prod.
Life cycle analysis of organic tomato production and supply in Sweden
J. Clean. Prod.
An evaluation of environmental sustainability in the food industry through Life Cycle Assessment: the case study of tomato products supply chain
J. Clean. Prod.
Aeration of different irrigation levels affects net global warming potential and carbon footprint for greenhouse tomato systems
Sci. Hortic.
Environmental assessment of an integrated rooftop greenhouse for food production in cities
J. Clean. Prod.
From the LCA of food products to the environmental assessment of protected crops districts: a case-study in the south of Italy
J. Environ. Manage.
Uncertainty of input parameters and sensitivity analysis in life cycle assessment: An Italian processed tomato product
J. Clean. Prod.
Climate change and dietary choices—how can emissions of greenhouse gases from food consumption be reduced?
Food Policy
The relative greenhouse gas impacts of realistic dietary choices
Energy Policy
Reducing greenhouse gas emissions with urban agriculture: a life cycle assessment perspective
Landsc. Urban Plan.
What contributes more to life-cycle greenhouse gas emissions of farm produce: production, transportation, packaging, or food loss?
Res. Conserv. Recycl.
Boundaries matter: greenhouse gas emission reductions from alternative waste treatment strategies for California's municipal solid waste
Res. Conserv. Recycl.
Food-miles and the relative climate impacts of food choices in the United States
Environ. Sci. Techn.
Energy use in the US Food System
The United Nations world water development report 2014
Water and Energy
Cited by (2)
Calculation and utility analysis of lychee life-cycle carbon emissions considering food loss and waste
2024, Journal of Cleaner ProductionMeasurement and spatio-temporal transfer of greenhouse gas emissions from agricultural sources in China: A food trade perspective
2023, Resources, Conservation and Recycling