12-3 What Environmental Problems Arise from Food Production?

• Concept 12-3 Food production in the future may be limited by its serious environmental impacts, including soil erosion and degradation, desertification, water and air pollution, greenhouse gas emissions, and degradation and destruction of biodiversity.

Producing Food Has Major Environmental Impacts

• Higher yield crops have __________________ the amount of land used to grow food

• Good News! – This has helped to protect biodiversity by reducing the destruction of ________________ and _______________________

• Despite this encouraging news, many analysts point out that industrialized agriculture has ____________ environmental effects than any other human activity

reduced

forestsgrasslands

greater

Fig. 12-10, p. 289

Natural Capital Degradation

Food Production

Biodiversity Loss Soil Water Air Pollution Human Health

Loss and degradation of grasslands, forests, and wetlands in cultivated areas

Erosion Water waste Emissions of greenhouse gas CO2 from fossil fuel use

Nitrates in drinking water (blue baby)

Loss of fertility Aquifer depletion

Pesticide residues in drinking water, food, and air

Salinization Increased runoff, sediment pollution, and flooding from cleared land

Emissions of greenhouse gas N2O from use of inorganic fertilizers

Fish kills from pesticide runoff

Waterlogging

Contamination of drinking and swimming water from livestock wastes

Killing wild predators to protect livestock

Desertification Pollution from pesticides and fertilizers Emissions of

greenhouse gas methane (CH4) by cattle (mostly belching)

Increased acidity

Loss of genetic diversity of wild crop strains replaced by monoculture strains

Algal blooms and fish kills in lakes and rivers caused by runoff of fertilizers and agricultural wastes

Bacterial contamination of meat

Other air pollutants from fossil fuel use and pesticide sprays

Topsoil Erosion Is a Serious Problem in Parts of the World

• Soil erosion is the movement of soil components, especially surface litter and topsoil, by ___________ and __________________

• Some erosion of topsoil is ________________, but much is caused by human activities

• In undisturbed, vegetated ecosystems, the roots of plants help to ________________ the topsoil.

• Undisturbed topsoil can also _____________ the water and nutrients needed for plants

waterwind

natural

anchor

store

Topsoil Erosion on a Farm in Tennessee

Fig. 12-11, p. 289

Flowing water is the ___________ cause of erosion largest

Natural Capital Degradation: Gully Erosion in Bolivia

Fig. 12-12, p. 290

Severe erosion by water can lead to _______________ gullies

Wind Removes Topsoil in Dry Areas

Fig. 12-13, p. 290

Wind loosens and blows topsoil away, especially in areas witha __________ climate and relatively ___________, exposed land dry flat

Topsoil Erosion Is a Serious Problem in Parts of the World

• Two major harmful effects of soil erosion are…• Loss of soil ___________________ through the

depletion of plant nutrients

• Water __________________ in nearby surface water where eroded topsoil ends up as _________________

fertility

pollutionsediment

Natural Capital Degradation: Global Soil Erosion

Fig. 12-14, p. 291

Drought and Human Activities Are Degrading Drylands

• In arid and _________________ parts of the world, food production is being threatened by desertification…

• This occurs when the productive potential of topsoil falls by ___________ or more due to…• Prolonged _______________________• Human activities such _____________________ and

___________________________

• Results in the ________________________ of existing desert areas or the ___________________ of new ones

semi-arid

10%drought

deforestationovergrazing

expansioncreation

Severe Desertification

Fig. 12-15, p. 291

Sand dunes threatening to take over an oasis in the Sahel regionof West Africa

Fig. 12-16, p. 292

Moderate Severe Very severe

Moderate (10-25% drop) Severe (25 – 50% drop) Very severe (more than 50% drop)

Excessive Irrigation Has Serious Consequences

• Irrigation accounts for ______ of the water that humans use and helps to produce ______ of our food

• Irrigation water is a dilute solution of various ______ that are picked up as the water flows over soil and rocks

• Salinization is the gradual ___________________ of salts in the soil from irrigation water• Lowers crop yields and can even kill plants• Affects 10% of world croplands

70%45%

salts

accumulation

Depletion of ground and surface water supplies!

Natural Capital Degradation: Severe Salinization on Heavily Irrigated Land

Fig. 12-17, p. 292

• Another problem with irrigation is ________________________• Occurs when water accumulates underground and

gradually ______________ the water table.• This can deprive plants from getting the _________

they need…(they need oxygen as well)

If you don’t respire, you expire

waterlogging

raisesgases

Agriculture Contributes to Air Pollution and Projected Climate Change

• Industrialized agriculture contributes to climate change any time forests or grasslands are ___________ or _______________• Less ________ absorption• Burning results in the __________________ of many

greenhouse gases into the atmosphere

• A related problem is the increasing loss of ______________________ - the genetic variety of animal and plant species used to provide food• Scientists estimate that we have lost ________ of the

genetic diversity of agricultural crops

cleared burned

CO2

release

agrobiodiversity

3/4

Fig. 12-18, p. 294

Trade-Offs

Genetically Modified Crops and Foods

Advantages Disadvantages

Need less fertilizer Unpredictable genetic and ecological effectsNeed less water

Harmful toxins and new allergens in foodMore resistant to

insects, disease, frost, and drought No increase in yields

Grow faster More pesticide-resistant insects and herbicide-resistant weedsMay need less

pesticides or tolerate higher levels of herbicides

Could disrupt seed market

May reduce energy needs

Lower genetic diversity

There Are Limits to Expanding the Green Revolutions

• Green revolutions (increased yield) are _________________...• Usually require large ________________ of fertilizer,

pesticides, and water• Often too __________________ for many farmers

• Can we expand the green revolution by• Irrigating more cropland?• Improving the efficiency of irrigation?• Cultivating more land? Marginal land?• Using GMOs?• Multicropping?

limitedinputs

expensive

Fig. 12-19, p. 295

Trade-Offs

Animal Feedlots

Advantages Disadvantages

Large inputs of grain, fish meal, water, and fossil fuels

Increased meat production

Greenhouse gas (CO2 and CH4) emissions

Higher profits

Less land use

Reduced overgrazing

Concentration of animal wastes that can pollute water

Reduced soil erosion Use of antibiotics can

increase genetic resistance to microbes in humans

Protection of biodiversity

ConnectionsMeat Production and Ocean Dead Zones

• Our Midwest, for example, uses much manufactured, inorganic ___________________ just to grow crops for use as animal ______________

• Much of this fertilizer runs off cropland and ends up in the _____________________ river which eventually flows to the ______________

• Each year, this creates an oxygen ________________ dead zone slightly larger than the state of Massachusetts

fertilizersfeed

Mississippiocean

depleted

ConnectionsMeat Production and Ocean Dead Zones

Fig. 12-20, p. 296

Trade-Offs

Aquaculture

Advantages Disadvantages

Large inputs of land, feed, and water

High efficiency

High yield Large waste output

Reduced over- harvesting of fisheries

Loss of mangrove forests and estuaries

Some species fed with grain, fish meal, or fish oilLow fuel use

Dense populations vulnerable to diseaseHigh profits

Review Questions

• What are two main detrimental effects of soil erosion?

• Distinguish between…• Desertification• Salinization• Waterlogging

Decrease in soil fertilityWater pollution

Soil potential decreases by 10%Accumulation of salts in soil

Accumulation of water in soil…Raises the water table

Review Questions

• What are some detrimental environmental effects of industrialized meat production?

• What are some detrimental environmental effects of aquaculture?

High inputs of food, water, energy

Concentrated animal waste & gas production

Antibiotic use..passes through food chain

Use of land/water space (estuaries)High inputs of food

Dense populations…vulnerable to disease