Overview
This lecture discusses the concept of "virtual water," its role in food and goods production, global water scarcity, and strategies for sustainable water use.
Virtual Water and Its Impact
- Virtual water is the hidden water used to produce goods and food, not found literally in the products.
- Example: 683 gallons of water are needed to produce one gallon of milk via alfalfa for dairy cows.
- Food items have varying water footprints: one grape uses 1/3 gallon, a walnut uses 5 gallons, a potato over 6 gallons, and a cup of coffee 37 gallons.
- Meat, especially beef, is highly water-intensive (one hamburger ≈ 600 gallons).
- Manufacturing materials (steel, cement, lumber, plastic) also require large amounts of water (one car ≈ 40,000 gallons).
Global Trade and Policy of Virtual Water
- Water cannot be practically transported across countries, but goods (carrying virtual water) can.
- Dry countries import virtual water via food and goods; wet countries export it.
- Example: Saudi company Al Marai grows alfalfa in Argentina for dairy production in Saudi Arabia.
- Currently, there is no international regulation of virtual water trade.
Types and Sources of Water
- Water is categorized as blue (surface/groundwater), green (rain-fed soil water), or gray (polluted water).
- The water footprint of products includes varying proportions of blue, green, and gray water.
- Blue water can be sourced from lakes/rivers or groundwater (aquifers); excessive groundwater use is unsustainable.
- Example: Libya’s Great Man-Made River system taps ancient groundwater, projected to last only 20 years.
Water Availability and Challenges
- 97% of Earth's water is saltwater; only 3% is freshwater.
- Most freshwater is locked in glaciers/ice caps or underground, with only a tiny fraction as accessible surface water.
- Climate change reduces water supplies (glacier melt, severe droughts) and increases surface water pollution.
- Global demand for water is projected to rise by 55% by 2050.
Consequences and Conflicts
- Growing water scarcity is leading to conflicts worldwide, similar to past oil conflicts.
- Water crisis affects daily life: millions lack easy access, and many girls are deprived of education due to time spent collecting water.
- Every 90 seconds, a child dies from a water-related disease.
Solutions: Reduce, Reuse, Recycle
- Water can't be used up—it's constantly cycled, but needs thoughtful management.
- Reduce: Limit use, especially of water-intensive products and virtual water; eat local and less dairy/meat.
- Reuse: Use water for secondary purposes after initial use.
- Recycle: Develop technologies to rapidly clean and recycle water for continuous reuse.
Key Terms & Definitions
- Virtual Water — Hidden water used in the production of goods and food.
- Blue Water — Water from surface or underground sources used in production.
- Green Water — Rainwater stored in soil and used by plants.
- Gray Water — Water polluted during production.
- Water Footprint — Total water used (blue, green, gray) to produce a product.
Action Items / Next Steps
- Reflect on personal and household virtual water consumption.
- Consider reducing meat and dairy intake; choose local foods.
- Research further innovations in water recycling and reuse.
- Be mindful of water use in daily routines.