CU Boulder — EVEN 2909 — Food Systems & Agriculture
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Food Systems & Agriculture

EVEN 2909: Introduction to Sustainability Engineering — Week 9

University of Colorado Boulder

The Global Food System

8B
People fed today
10B
Projected by 2050
~30%
of global GHG from food
828M
People undernourished

The global food system is one of the largest drivers of environmental change. From farm to fork to landfill, food production accounts for roughly one-third of all greenhouse gas emissions, uses 50% of habitable land, and is the leading cause of biodiversity loss.

At the same time, the system fails to nourish everyone: 828 million people are chronically undernourished while 2 billion are overweight or obese. By 2050, we must feed 10 billion people on a warming planet with degrading soils and shrinking freshwater supplies.

The core challenge: Produce more food with less environmental impact — while making it equitable, nutritious, and resilient.

Sources: IPCC AR6 WGIII Ch. 7; FAO State of Food Security 2023; Poore & Nemecek, Science 2018

Industrial Agriculture & the Green Revolution

The Green Revolution (1950s–1970s)

  • High-yield crop varieties (wheat, rice, maize) bred by Norman Borlaug and others
  • Synthetic fertilizers: Haber-Bosch process enabled mass nitrogen fixation
  • Pesticides & herbicides: chemical crop protection scaled rapidly
  • Mechanization: tractors replaced draft animals; combine harvesters
  • Global cereal production tripled between 1950–2000, averting predicted famines

Unintended Consequences

  • Monoculture dependency: vast fields of single crops reduce biodiversity and increase pest vulnerability
  • Fertilizer runoff: nitrogen & phosphorus cause dead zones (e.g., Gulf of Mexico hypoxia)
  • Water depletion: Ogallala Aquifer declining 1–3 ft/year in parts of the High Plains
  • Soil degradation: loss of organic matter and microbial diversity
  • Social displacement: smallholders squeezed out by capital-intensive farming

Sources: Pingali, Agricultural Economics 2012; Tilman et al., Nature 2002

The Food–Water–Energy Nexus

70%
Freshwater used for irrigation
30%
of energy used in food systems
~4B
People face water scarcity

Water for Food

  • Agriculture withdraws 70% of global freshwater
  • It takes ~1,800 liters of water to produce 1 kg of wheat; ~15,000 liters for 1 kg of beef
  • Groundwater depletion accelerating in India, China, US High Plains
  • Climate change intensifies drought cycles and flood risk

Energy for Food

  • Fertilizer production: Haber-Bosch process consumes ~1–2% of global energy
  • Farm machinery: diesel-powered tillage, planting, harvesting
  • Processing & cold chain: refrigeration, packaging, transportation
  • Cooking: 2.4 billion people still rely on solid fuels for cooking

Key insight: You cannot solve food sustainability without simultaneously addressing water and energy. Interventions in one domain create ripple effects across the others.

Sources: FAO AQUASTAT; IEA World Energy Outlook 2023

Soil Health: The Foundation of Agriculture

33%
of global soils degraded
2,500 Gt
Carbon stored in soil
24 Bt
Topsoil lost per year
60
Harvests left (at current rates)

Why Soil Matters

  • Soil stores more carbon than the atmosphere and all plants combined (~2,500 Gt C)
  • Healthy soils filter water, cycle nutrients, and support biodiversity
  • One tablespoon of healthy soil contains more microorganisms than people on Earth
  • Soil formation is extremely slow: ~1 cm per 200–1,000 years

The Degradation Crisis

  • Erosion: 24 billion tonnes of topsoil lost annually from wind and water erosion
  • Compaction: heavy machinery reduces porosity and root penetration
  • Salinization: affects 20% of irrigated lands worldwide
  • Carbon loss: tilled soils have lost 50–70% of original carbon stocks
  • Chemical degradation: pesticide accumulation disrupts soil food webs

Sources: FAO Status of World’s Soil Resources 2015; Lal, Science 2004

Regenerative Agriculture

Regenerative agriculture goes beyond “sustainable” — it aims to actively restore ecosystem health, rebuild soil organic matter, and increase biodiversity while maintaining productive farming.

No-Till / Minimum Till
Eliminates plowing to preserve soil structure, retain moisture, and keep carbon in the ground. Reduces erosion by up to 90%. Requires adjusted weed management strategies.
Cover Crops
Planting between cash crop seasons to protect soil, fix nitrogen (legumes), suppress weeds, and build organic matter. Examples: crimson clover, winter rye, radishes.
Rotational Grazing
Moving livestock frequently across pastures mimics natural herd behavior. Stimulates grass regrowth, distributes manure, and builds soil carbon. Can sequester 1–3 t CO₂/ha/yr.
Agroforestry
Integrating trees with crops and/or livestock. Provides shade, windbreaks, habitat corridors, and additional income (fruit, timber, nuts). Sequesters significant carbon above- and below-ground.
Composting & Biological Inputs
Replacing synthetic fertilizers with compost, biochar, and microbial inoculants. Feeds the soil food web rather than just the plant, building long-term fertility.

Sources: Rodale Institute; Project Drawdown; LaCanne & Lundgren, PeerJ 2018

Precision Agriculture

Precision agriculture uses technology to optimize inputs — applying the right amount of water, fertilizer, and pesticides at the right place and time. The goal: maximize yields while minimizing waste and environmental impact.

Remote Sensing & Drones
Multispectral cameras on drones and satellites detect crop stress, nutrient deficiencies, and pest damage weeks before visible to the eye. NDVI mapping guides targeted interventions.
Soil & Weather Sensors
IoT sensors measure soil moisture, temperature, and nutrient levels in real time. Weather stations provide hyper-local forecasts for irrigation scheduling and frost protection.
Variable Rate Application
GPS-guided equipment adjusts seed, fertilizer, and water delivery zone by zone. Can reduce fertilizer use by 15–25% while maintaining or increasing yields.

The equity challenge: Precision ag technologies require capital investment, data literacy, and internet connectivity. Most of the world’s 500 million smallholder farmers lack access. How do we democratize these tools?

Sources: Gebbers & Adamchuk, Science 2010; McKinsey Global Institute

Food Waste

1/3
of all food produced is wasted
1.3 Bt
Tonnes wasted per year
8–10%
of global GHG from food waste
$1T
Economic loss per year

Where Waste Happens

  • Low-income countries: losses mainly at harvest and post-harvest (lack of storage, cold chain, roads)
  • High-income countries: waste concentrated at retail and consumer stages (cosmetic standards, over-purchasing, confusion over date labels)
  • Supply chain: overproduction buffers, damaged packaging, transportation losses

Climate Impact

  • Food in landfills decomposes anaerobically, producing methane (CH₄) — 80x more potent than CO₂ over 20 years
  • If food waste were a country, it would be the 3rd largest emitter after the US and China
  • All the water, energy, and land used to grow wasted food — also wasted

Solutions

  • Improved cold chains and storage in developing countries
  • Standardized date labeling (“best by” vs. “use by”)
  • Composting and anaerobic digestion for unavoidable waste

Sources: UNEP Food Waste Index 2021; Project Drawdown; FAO 2013

Meat, Dairy & Alternative Proteins

14.5%
of global GHG from livestock
77%
of ag land for livestock
18%
of calories from animal products

The Footprint of Animal Agriculture

  • Land use: 77% of agricultural land supports livestock (grazing + feed crops), yet provides only 18% of calories
  • Water: 1 kg of beef requires ~15,000 L of water vs. ~1,800 L for wheat
  • Emissions: enteric fermentation (methane from ruminants), manure management, feed production, land-use change
  • Deforestation: cattle ranching is the #1 driver of tropical deforestation, especially in the Amazon

Emerging Alternatives

  • Plant-based proteins: Beyond Meat, Impossible Foods — using 90% less land, water, and emissions
  • Cultivated (lab-grown) meat: real animal cells grown in bioreactors; still expensive but costs dropping rapidly
  • Precision fermentation: engineered microbes produce dairy proteins (whey, casein) without cows
  • Insect protein: crickets, black soldier fly larvae — high protein, low footprint
  • Dietary shift: even modest reductions in meat consumption have outsized climate benefits

Sources: Poore & Nemecek, Science 2018; FAO GLEAM; Springmann et al., Nature 2018

Local Food Systems

The concept of “food miles” — the distance food travels from farm to plate — has popularized the idea that local food is always better. The reality is more nuanced.

Food Miles: Complicated Math
Transportation accounts for only ~6% of food’s total emissions. What you eat matters far more than where it comes from. A locally grown tomato in a heated greenhouse can have a higher footprint than one shipped from a sunny climate. But local food systems offer other benefits beyond carbon.

Benefits of Local & Regional Food Systems

  • Food security & resilience: shorter supply chains are less vulnerable to disruption (as COVID-19 demonstrated)
  • Economic multiplier: money spent at local farms circulates 2–3x more in the local economy
  • Freshness & nutrition: less time in transit means less nutrient degradation
  • Community connection: farmers markets, CSAs, and farm-to-table build social capital

Urban Agriculture

  • Community gardens: improve food access in underserved neighborhoods, build social cohesion
  • Vertical farms: controlled-environment agriculture in urban settings; high yields per sq ft but energy-intensive
  • Rooftop gardens & greenhouses: utilize unused urban space, reduce building heat load

Sources: Weber & Matthews, ES&T 2008; USDA Economic Research Service

Climate Impacts on Agriculture

Agriculture is both a major driver of climate change and one of its most vulnerable sectors. The feedback loop is vicious: farming degrades the climate, which degrades farming.

Changing Growing Seasons
Warmer temperatures shift planting zones poleward. Some high-latitude regions gain growing days while tropical regions face heat stress that reduces yields. Frost dates and monsoon timing are increasingly unpredictable.
Extreme Weather
More frequent droughts, floods, heat waves, and storms destroy crops and livestock. A single extreme event can wipe out an entire season’s harvest. Insurance costs are rising fast.
Crop Migration & Adaptation
Coffee, cocoa, and wine grape regions are shifting. Farmers must adopt heat-tolerant varieties, adjust planting dates, and invest in irrigation — but adaptation has limits at higher warming levels.

Projected yield impacts by 2050 (IPCC): Maize yields decline 5–20% in tropics. Wheat yields decline in most regions above 2°C warming. Rice yields threatened by heat stress during flowering. Fisheries disrupted by ocean warming and acidification.

Sources: IPCC AR6 WGII Ch. 5; Zhao et al., PNAS 2017

Colorado Agriculture

$8.7B
Annual ag output
31.6M
Acres of farmland
#1
In U.S. for proso millet

Water Rights & the Colorado Doctrine

  • Colorado uses prior appropriation (“first in time, first in right”) — not riparian rights
  • Agriculture uses ~85% of Colorado’s water but generates ~1% of GDP
  • The Colorado River Compact (1922) allocates more water than the river actually carries
  • Arkansas River basin: intense competition between agricultural, municipal, and environmental uses

Front Range Development Pressure

  • Colorado’s population grew ~15% in the 2010s, concentrated along the Front Range
  • Farmland conversion: urban sprawl consuming productive agricultural land
  • “Buy and dry”: cities purchasing agricultural water rights, leaving fields fallowed
  • Alternative Transfer Methods (ATMs): sharing water between ag and cities to avoid permanent drying

Climate Challenges

  • Earlier snowmelt reduces late-season irrigation water
  • Increasing wildfire risk degrades watersheds
  • Dust-on-snow accelerates melt, reducing water storage in snowpack

Sources: Colorado Water Plan 2023; USDA NASS; Colorado Dept. of Agriculture

Feeding 10 Billion: The Path Forward

No single solution will feed 10 billion people sustainably. The EAT-Lancet Commission (2019) outlined a “planetary health diet” and identified five strategies that must work in concert:

Reduce Waste
Halve food loss & waste
+
Shift Diets
More plants, less meat
+
Sustainable Intensification
More yield, less impact
+
Protect Ecosystems
No new agricultural land
+
Reduce Pollution
N, P within boundaries
“Food is the single strongest lever to optimize human health and environmental sustainability on Earth.” — EAT-Lancet Commission, 2019

This is fundamentally an engineering challenge: designing food systems that operate within planetary boundaries while meeting human nutritional needs equitably.

Source: Willett et al., The Lancet 2019

Discussion

Think About Your Plate

Consider what you ate in the last 24 hours. Trace one meal back through the food system:

Where?
Where were the ingredients grown? How far did they travel? What inputs (water, fertilizer, energy) were required?
What was wasted?
What packaging, scraps, or leftovers were discarded? Where did that waste go?
What would you change?
If you could redesign one part of that meal’s supply chain for sustainability, what would you target and why?

Key Takeaways

1. Food is a systems problem
The food-water-energy nexus means you cannot optimize one without affecting the others. Systems thinking is essential.
2. Soil is our most undervalued resource
Healthy soil is the foundation of food security and a massive carbon sink. Regenerative practices can rebuild it.
3. Waste is the lowest-hanging fruit
Reducing food waste is the single most impactful climate action in the food system — it requires no new technology.
4. What you eat matters more than where it comes from
Dietary choices — especially reducing meat — have a far larger footprint impact than food miles.
5. Technology alone is not enough
Precision ag and alternative proteins help, but equity, access, and policy are equally critical to feeding 10 billion sustainably.

Further Reading

  • Poore & Nemecek (2018). “Reducing food’s environmental impacts through producers and consumers.” Science, 360(6392).
  • Willett et al. (2019). “Food in the Anthropocene: The EAT-Lancet Commission on healthy diets from sustainable food systems.” The Lancet, 393(10170).
  • Lal, R. (2004). “Soil carbon sequestration impacts on global climate change and food security.” Science, 304(5677).
  • Project Drawdown: Food, Agriculture & Land Use Solutions
  • IPCC AR6 WGIII, Chapter 7: Agriculture, Forestry and Other Land Use
  • Our World in Data: Environmental Impacts of Food Production

Next week: Circular Economy & Materials — How do we design waste out of the system?