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5.1 Tragedy of the Commons 🌎

Definition of Tragedy of the Commons

Individuals will use shared/public resources in their own self-interest, degrading them.

• Must be a public resource (not privately owned)

• Must be degraded, overused, depleted, used-up in some way

Examples

• Overfishing

• Air pollution

• Overuse of groundwater

Why it Happens

• When no one owns the resource (land, water, air), no one directly suffers the negative consequences of depleting, degrading, or overusing it.

• People assume others will overuse the resource if they don't.

• There is no penalty for overusing, degrading, or polluting many public resources.

The Problem: Externalities

• Externalities: negative costs associated with a human action that aren't accounted for in the price.

  • Overfishing can lead to fishery collapse (population crash), loss of income, and starvation.

  • Air pollution from coal power plants can lead to bronchitis, asthma, and increased healthcare costs (unintended side effects).

  • Pesticide runoff from farms contaminates drinking water.

Solutions

5.2 Clearcutting 🪓

Direct Effects of Clearcutting

• Soil Erosion: Caused by loss of stabilizing root structure

  • Removes soil organic matter & nutrients from forest

  • Deposits sediments in local streams

  • Warms water & makes it more turbid

• Increased Soil & Stream Temperatures

  • Loss of tree shade increases soil temperature

  • Soil has lower albedo than leaves of trees

  • Loss of tree shade along rivers & streams warms them

  • Erosion of sediments into rivers also warms them

• Flooding & Landslides

  • Logging machinery compacts soil

  • Increased sunlight dries out soil

  • Loss of root structure = erosion of topsoil & O horizon

  • All of these factors decrease H2O holding capacity of soil causing flooding

Tree Plantations

Areas where the same tree species are repeatedly planted, grown, and harvested.

• Lowers Biodiversity: Biodiverse, mature forests are replaced with single-species forests.

  • Less species diversity = lower resilience

  • Less habitat diversity for other organisms

• All the Same Age: All trees planted at the same time = all the same age

  • Lowers biodiversity further (no dead trees for woodpeckers, insects, decomposers)

Forest Benefits

• Filtering of Air Pollutants

  • Stomata (leaf pores) remove VOCs, NOX, PM2.5 from air & store in tree

• Removal & Storage of CO2 from Atmosphere

  • Trees take in CO2, store carbon as sugar, wood, other tissue & release O2

• Habitat for Organisms

  • Many organisms live in forests (biodiversity, ecotourism)

Deforestation Consequences

• Reduces air filtering and carbon storing services

• Cutting trees down releases CO2 from decomposition of leftover organic material

• Slash & burn method of clearing land for agriculture by cutting trees & burning them releases CO2, N2O and water vapor into the atmosphere (all GHGs)

5.3 The Green Revolution 🚜

Definition of the Green Revolution

Shift in agriculture away from small, family-operated farms to large, industrial-scale agribusiness

• Increased use of mechanization, GMOs, irrigation, fertilizers, and pesticides

• Greatly increases efficiency of lands, short-term profitability, and food supply

• Decreased world hunger and increased Earth's carrying capacity for humans

• Bring negative consequences (soil erosion, biodiversity loss, ground & surface water contamination)

Mechanization

• Increased use of tractors for plowing and tilling fields, and combines for harvesting = increased yield + profits

• Increases reliance on fossil fuels (gasoline/diesel fuel)

  • Emits GHGs to atmosphere climate change

• Heavy machinery also compacts soil, decreasing H2O holding capacity

  • Makes topsoil more prone to erosion

High-Yield Variety (HYV) Crops

Hybrid, or genetically modified crops that produce a higher yield (amount of crop produced per unit of area)

• Hybrid = cross-pollinating different species

  • Increased plant size and food stability in regions previously prone to famine (India, Pakistan, Mexico)

• GMOs = crops with new genes spliced into their genome

  • Genetically modified crops have genes for drought tolerance, pest resistance, faster growth, and larger fruit/grain

  • Increases profitability with fewer plants lost to drought, disease, or pests + larger plant size + yield/acre

  • GMO crops are all genetically identical so genetic diversity is decreased and susceptibility to diseases or pest is increased

    • Ex: Bt corn has been modified with a gene from soil bacteria (Bacillus thuringiensis) to produce a protein that kills many different insects

Synthetic Fertilizer

• Shift from organic fertilizers (like manure and compost) to synthetic fertilizers (man made ammonium, nitrate, phosphate)

  • Increases yield and profits with more key nutrients needed for plant growth (N, P, K) added to the soil

  • Excess nitrate, phosphate are washed off fields and into nearby waters where they cause eutrophication (algae blooms)

  • Require FFs for production, releasing CO2 (climate change)

Irrigation

• Drawing water from the ground or nearby surface waters and distributing it on fields to increase plant growth

  • Make agriculture possible in many parts of the world that are naturally too dry (don't receive enough rain)

  • Can deplete groundwater sources, especially aquifers

  • Overwatering can drown roots (no O2 access) and cause soil salinization (increase salt level in soil)

Pesticides

• Increase in use of synthetic pesticides - chemicals sprayed on crops that kill weeds, insects, rodents, and other pests that eat or damage crops

  • Increases yield and profits with fewer plants lost to pests

  • Can wash off crops in runoff and kill or harm non-target species in local soil or waters

    • Ex: DDT thinned shells of bird eggs, especially eagles

    • Atrazine turns amphibians and fish intersex

5.4 Impact of Agricultural Practices 🧑‍🌾

Monocropping

Growing one single species (corn, wheat, soy) of crop

• Highly efficient for harvest, pesticide and fertilizer application

  • Greatly decreases biodiversity (more prone to pests, fewer natural predators)

  • Increases soil erosion (crops harvested all at once & soil left bare)

  • Decreases habitat diversity for species living in the area

Tilling

Mixing and breaking up soil to make planting easier

• Also loosens soil for roots

  • Increases erosion by loosening topsoil, breaking up leftover root structure from harvest

  • Loss of organic matter & topsoil nutrients over time

  • Increased PM in air (respiratory irritant) and sediments in nearby water (turbidity)

Slash & Burn

Cutting down vegetation and burning it to clear land for ag. & return nutrients in plants to soil

• Deforestation

• Loss of: habitat, biodiversity, CO2 sequestration (storage), loss of air pollutant filtration

• Releases CO, CO2, CH4, N2O - all GHGs that lead to global warming

• Increases PM in air (asthma)

• Lowers albedo, making area warmer

Synthetic (inorganic) Fertilizer

• Don't return organic matter to soil; no increased H2O holding cap. & no soil decomposers

• Leaching: water carries excess nutrients (nitrates & phosphates) into groundwater or into surface waters (as runoff)

  • Contaminates groundwater for drinking

  • Causes eutrophication of surface waters

5.5 Irrigation 💧

Irrigation Methods

Waterlogging

• Overwatering can saturate the soil, filling all soil pore space with water

• Doesn't allow air into pores, so roots can't take in O2 they need

• Can stunt growth or kill crops

  • Solution: drip irrigation, or soil aeration - poking holes or cores in soil to allow air in & water to drain through soil

Soil Salinization

Salinization is the process of salt building up in a soil over time

• Groundwater used for irrigation naturally has small amounts of salt

• Water evaporates, and salt is left behind in soil. Over time, it can reach toxic levels, dehydrating plant roots & preventing growth

  • Solution: drip irrigation, soil aeration, flushing with fresh water, switch to fresh water source

Global Human Water Use

• Industrial: power plants, metal/plastic manufacturing

• Municipal: households (toilet, shower, drinking water)

• Agriculture: water for livestock, irrigation water for crops

Aquifers

H2O stored in pore space of permeable rock & sediment layers

• Aquifers useable groundwater deposits for humans

• Replenished by groundwater recharge (rain water percolating down through soil into aquifer)

• Unconfined aquifers recharge quickly

• Confined aquifers recharge are longer-term water deposits that recharge more slowly

Depletion of Aquifers

• Saltwater Intrusion: excessive pumping near coast lowers water table pressure, allowing saltwater to seep into groundwater

• Cone of depression: forms when water table is lowered by excessive pumping, depleting water & drying nearby wells

5.6 Pest Control Methods 🐛

Pesticides

Chemicals that are toxic to pests

• Rodenticides kill rodents

• Fungicides kill fungi

• Insecticides kill insects

• Herbicides kill plants

• Can cause pests to become resistant to pesticide with overuse

  • Genetic biodiversity gives some pests resistant traits to pesticide

  • Pesticide artificially selects for pests with resistance by killing all the non-resistant individuals, leaving only resistant ones

GMOs (Genetic Modification)

• Gene for pest resistant trait is added to the plant through genetic modification

  • Bt corn with bacteria gene that produces Bt crystals toxic to pests

  • Roundup Ready crops are GM to be resistant to broad herbicide (Roundup) meaning roundup will kill weeds, but not crops

GMOs & Pesticide Use

• Roundup Ready crops have increased herbicide (glyphosate) use since crops can't be harmed by it

• Bt corn has decreased insecticide use, since corn makes its own insecticide (Bt crystals)

GMOs & Genetic Diversity

• GM crops are all genetically identical (clones) so there is no genetic diversity in the pop.

  • If there is disease or pest that does affect the GM crops, they're all vulnerable and there's no chance of a genetic mutation providing an adaptive trait

5.7 Meat Production Methods 🥩

CAFOs

Also called feedlots - densely crowded method where animals are fed grain (corn) to raise them to as quickly as possible

• Maximizes land use and profit (most meat production per/unit of area)

• Minimizes cost of meat for consumers

• Given antibiotics & growth hormones to prevent disease outbreak & speed meat production

• Animals produce large volume of waste which can contaminate nearby surface or groundwater

• Produces large amounts of CO2, CH4 (methane), and N2O (greenhouse gasses climate change)

Manure Lagoons

Large, open storage pits for animal waste (manure)

• Waste contains: ammonia (N), hormones, antibiotics, fecal coliform bacteria (e. coli)

• Heavy rain can flood lagoons & contaminate nearby surface and ground water with runoff

• E. Coli toxic to humans

• Ammonia (N) eutrophication

• Denitrification of ammonia in manure produces N2O (extremely powerful GFG)

• Antibiotics & growth hormones alter endocrine (hormonal system) of humans

• Can be emptied and buried in landfills, or turned into fertilizer pellets

Free Range Grazing

• Animals (usually cows) graze on grass & grow at a natural rate without growth hormones

  • No need for antibiotics with dispersed pop.

  • Doesn't require production of corn to feed animals

  • Waste is dispersed over land naturally, acting as fertilizer instead of building up in lagoons

  • Requires more total land use/pound of meat produced

  • More expensive to consumer

  • Animals can graze on land too dry for most crop growth

Overgrazing

• Too many animals grazing an area of land can remove all the vegetation (grass) which leads to topsoil erosion

• Animals also compact soil, decreasing H2O holding capacity more erosion

• Desertification can occur if plants are killed by overgrazing & soil is compacted so much that it can't hold enough water anymore

  • Rotational grazing (moving animals periodically) can prevent overgrazing

  • Can even increase growth of grass by distributing manure (natural fertilizer) & clipping grass back to size where growth is most rapid

Inefficiency of Meat Production

• Producing meat for humans to eat is far less efficient than producing plants in terms of energy, land, and water use

  • Energy: all of the energy needed to plant, grow, harvest plants to feed to animals PLUS: energy needed to bring water to animals energy needed to house animals energy needed to slaughter & package

  • Land: all of the energy needed to grow plants to feed animals PLUS room the animals take up

  • Water: all of the water for crops that animals eat PLUS the water the animals drink

5.8 Impacts of Overfishing 🐟

Fisheries

Populations of fish used for commercial fishing

Fishery Collapse

When overfishing causes 90% population decline in a fishery

• Pop. may never recover from fishery collapse due to: decreased biodiversity, inability to find mates, inbreeding depression

  • Decreases genetic biodiversity of fish populations & species biodiversity of ocean ecosystems if species are lost from ecosystem

  • Economic consequences: lost income for fishermen, lost tourism dollars for communities

Bottom Trawling

• Especially harmful fishing method that involves dragging a large net along ocean floor

  • Bycatch: unintended species like dolphins, whales, turtles caught in nets

  • Stirs up ocean sediment (turbidity) & destroys coral reef structure

  • Decreases biodiversity by killing non-target species & removing coral reef habitat

Fishing Down the Food Web & Trophic Cascade

• As we deplete large, predatory fisheries, we move down to smaller fish species

• Depletion of smaller fish pop. limits fishery recovery and decreases food supply of marine mammals & seabirds

5.9 Mining ⛏

Mining Basics

Surface Mining

• Removal of overburden to access ore near surface

• Different types: open pit, strip, mountaintop removal, placer mining

  • Mountaintop removal = esp. damaging to landscape & habitats, streams nearby

    • Removal of vegetation & soil

    • Topsoil erosion

    • Habitat loss

    • Increased stream turbidity

    • Increase PM in air

Subsurface Mining

• As ore near surface becomes more scarce, mining moves deeper underground to subsurface mining (more dangerous & expensive)

• More expensive due to higher insurance & health care costs for workers

  • Risks: poor ventilation leading to toxic gas exposure, mine shaft collapse, injury from falling rock, lung cancer, asbestos, fires, explosions

• Vertical shaft drilled down into ground

• Elevator to carry down workers & transport out resource

• Often used for coal

• Increasingly used as surface coal deposits are depleted

Environmental Impacts of Mining

• Acid mine drainage: rainwater leaks into abandoned mine tunnels & mixes with pyrite, forming sulfuric acid

  • Rainwater carrier sulfuric acid into nearby streams, or infiltrates ground w Loa wte er rs pH of water, making toxic metals like mercury & aluminum more soluble in water sources (killing aquatic org.)

• Methane Release: coal mining releases methane gas (CH4) from rock

  • Vented out of mine to prevent explosion & continues seeping out after mine closes

  • GHG climate change

• PM Release: coal mining especially, releases lots of soot and other particulates that can irritate human & animal lungs

Mine Reclamation

Process of restoring land to original state after mining has finished

1. Filling of empty mineshafts/hole

2. Restoring original contours of land

3. Returning topsoil, with acids, metals, and tailings removed

4. Replanting of native plants to restore community to as close to original state as possible

5.10 Urbanization 🏙

Definition of Urbanization

Removing of vegetation to convert natural landscape to city

• Replaces soil, vegetation, wetlands, with impervious surfaces (concrete, asphalt, cement) which don't allow water to infiltrate into the ground

  • Prevents groundwater recharge

  • Causes precipitation to runoff into local bodies of water

• CO2 emissions:

  • Cement production

  • Construction machinery

  • Deforestation (loss of future carbon sequestration + decomposition of cut trees)

Urbanization in Coastal Cities

• Population growth in coastal cities can lead to saltwater intrusion due to:

  • Sea level rise due to warming of ocean (thermal expansion) and melting of ice caps (increasing ocean volume) can contaminate fresh groundwater with salt

  • Excessive groundwater withdrawal near coast lowering water table pressure, allowing saltwater to seep into groundwater

Trends in Population

• People move from rural urban areas for jobs, entertainment, cultural attractions

• Urban areas are more densely populated, minimizing driving & land use per person (decreases env. Impact per person)

• Overall trend in US & many other nations is away from less dense rural (country) areas and toward more urban (city) areas

• Highest growth currently is suburban

  • Suburbs less dense areas surrounding urban areas

    • Ex: Grand Rapids Kentwood, Wyoming, Forest Hills, ect.

Urban Sprawl

Population movement out of dense, urban centers to less dense suburban areas surrounding the city

• Causes:

  • Cheaper property in suburbs than in cities (larger home for same price)

  • Cars make it easy to still get from the suburbs into the city for work, entertainment, (cultural attractions, less so if you leave)

• Effects:

  • Fewer residents in cities leads to decline in tax revenue for city (decrease in city services)

  • Residents leave, so businesses follow

  • Abandoned homes + businesses create blight (unsightly, rundown infrastructure) so more people leave

Causes of Urban Sprawl

• Expanded highway system makes travel easier and increases driving

• Increase in driving increases fuel tax revenue, which is used to build more highways

• Highway expansion makes it easier and easier to commute from suburbs into urban areas

Solutions

• Urban growth boundaries: zoning laws set by cities preventing development beyond a certain point

• Public transit & walkable city design that attract residents to stay

• Mixed land use: residential, business, and entertainment buildings all located in the same area of a city

  • Enables walkability & sense of place

5.11 Ecological Footprint 👣

Definition of Ecological Footprint

Measure of how much a person/group consumes, expressed in area of land

• Factors (Land required for):

  • Food production

  • Raw materials (wood, metal, plastic)

  • Housing

  • Electricity production Coal, Natural gas, solar, wind, etc.

  • Disposing waste produced (landfill space)

Ecological Footprint vs. Carbon Footprint

Factors That Affect Footprint

If The Whole World Lived Like Us

• Ecological footprint can also be expressed in number of earths required if the entire world consumed same level of resources as a given individual or group

  • Current average US footprint is 5.1 earths

    • 5.1 earths worth of resources needed if the entire world consumed resources of avg. American

  • Current global footprint is 1.85 earths

    • Meaning each year humanity consumes 1.85 x what the Earth can produce in a year

5.12 Sustainability ♻

Definition of Sustainability

Consuming a resource or using a space in a way that does not deplete or degrade it for future generations

• Ex: using compost (renewable) over synthetic fertilizer (fossil fuel dependent)

Maximum Sustainable Yield

The maximum amount of a renewable resource that can be harvested without reducing or depleting the resource for future use

• Roughly carrying capacity. Maximizes yield (resource harvest) and regeneration rate of population

Environmental Indicators of Sustainability

Factors that help us determine the health of the environment and guide us towards sustainable use of earth's resources

5.13 Reducing Urban Runoff 🌧

Definition of Mitigate

Reduce

Environmental Consequences of Urban Runoff

• Decreased infiltration (groundwater recharge)

• Rain washes pollutants into storm drains & into local surface waters:

  • Salt (plant & insect death)

  • Sediment (turbidity)

  • Fertilizer (eutrophication)

  • Pesticides (kill non target species)

  • Oil & gasoline (suffocate fish/kill aq. insects)

Permeable Pavement

• Specially designed to allow stormwater to infiltrate & recharge ground water

  • Decreases runoff, decreasing pollutants carried into storm drains & into local surface water

  • Decreases likelihood of flooding during heavy rainfall

  • More costly than traditional pavement

Rain Garden

• Gardens planted in urban areas, especially surrounding a storm drain

  • Decreases runoff by allowing it to soak into garden soil surrounding storm drain

  • Decreases likelihood of flooding during heavy rainfall

  • Creates hab. for pollinators, sense of place stores CO2

Public Transit

• More cars on the road = more pollutants on streets to runoff into storm drains & local waters

  • Motor Oil

  • Gasoline

  • Tire pieces

  • Antifreeze

• More cars = more lanes & parking lots (impervious surfaces) & more stormwater runoff

• Public transit decreases urban runoff, pollutants on road, CO2 emissions & even traffic!

Building Up, not Out

• Building vertically decreases impervious surfaces (decreasing urban runoff)

• Can be combined with green roof or rooftop gardens to further decrease runoff

• Green roof also sequesters CO2 and filters air pollutants out

  • Plants absorb NOX, PM, & other pollutants into stomata & store in tissue

5.14 Integrated Pest Management (IPM) 🌿

Definition of Integrated Pest Management (IPM)

Using a variety of pest control methods that minimize env. disruption and pesticide use & monitoring pests and targeting methods to specific pest life cycles

• Biocontrol (Bringing in a natural predator or parasite to control the pest)

• Crop rotation

• Intercropping

Biocontrol

• Introducing a natural predator, parasite, or competitor to control the pest population

  • Can include actually purchasing & spreading the control organisms in fields, or building homes for them/planting habitat they need to attract them naturally

    • Ladybugs for aphids

    • Spiders for many pest insects

    • Parasitic wasps for caterpillars

Crop Rotation

• Many pests prefer one specific crop or crop family. They lay eggs in the soil, so when larvae hatch, they have preferred food source

• Rotating crops (planting a different crop each season) can prevent pests from becoming established since it disrupts their preferred food choice

• Also disrupts weed growth since diff. crops can be planted at different times, preventing bare soil from being taken over by weeds

Intercropping

• Push-pull system can be used

  • Push plants emit volatile chemicals that naturally repel pests away from crop

  • Pull plants emit chemicals that attract moths to lay eggs in them, instead of crop

• Can provide habitat, or pull plants that emit chemicals that attract natural pest predators

Benefits & Drawbacks of IPM

5.15 Sustainable Agriculture 🌱

Soil Conservation

Agricultural techniques that minimize erosion (US is losing topsoil to erosion 10x faster than it forms)

• Prevents loss of:

  • Nutrients in topsoil

  • Soil moisture

  • Decomposers in topsoil

  • Organic matter that traps soil moisture

Soil Conservation Methods

Soil Fertility

Methods of restoring nutrient levels in the soil (N, P, Ca, Mg)

Crop Rotation

• Replanting same crops continuously depletes soil of these same nutrients

• Crop rotation can allow soil to recover from nitrogen-demanding crops like corn

• Peas/beans (legumes) have nitrogen fixing bacteria in their root nodules that can return nitrogen to the soil

Green Manure

• Green manure is leftover plant matter from a cover crop - a crop planted in the offseason, between harvest & replanting of main crop

• Cover crop roots stabilize soil limiting topsoil erosion

• Remains of cover crops (green manure) left on field breakdown to release nutrients into the soil

Limestone

• Limestone releases calcium carbonate (base) which neutralizes acidic soil

• Acidic soil has high H+ ion concentration, which displaces + charge nutrients from soil (leeching them out)

• Acidic soil also makes toxic metals (aluminum) more soluble in soil

• Calcium is a needed plant nutrient as well

Rotational Grazing

• Regular rotation of livestock to different pastures to prevent overgrazing

• Overgrazing can kill plants, compact soil, and lead to erosion of topsoil

• Rotational grazing can actually promote pasture growth at faster than normal rate

  • Clips grass back to length where growth is fastest & encourages deeper root growth

5.16 Aquaculture 🐠

Definition of Aquaculture

Raising fish, or other aquatic species in cages/enclosures underwater

Aquaculture Benefits

• Requires only small amount of water, space, and fuel

• Reduces risk of Fishery collapse (90% population decline in a fishery)

• Doesn't take up any land space (compared to beef, pork, chicken)

Aquaculture Drawbacks

• High density produces high concentration of waste (e.coli & eutrophication risks)

• High density increases disease risk, which can be transmitted to wild populations as well

• May introduce non-native species or GMOs to local ecosystem if captive fish escape

• Fish are fed antibiotics which can contaminate water via their waste

5.17 Sustainable Forestry 🌲

Definition of Ecologically Sustainable Forestry

Forestry (using trees for lumber) that minimizes damage to ecosystem (habitats destruction, soil erosion, etc.)

Sustainable Forestry Practices

• Selective cutting or strip cutting Only cutting some of the trees in an area (biggest & oldest) to preserve habitat (biodiv.) and topsoil

• Using human & pack animal labor to minimize soil compaction from machinery

• Replanting same species being logged

• Maximizes long-term productivity of land & preserves forest for future generations

• Using recycled wood, or simply reusing without recycling (furniture, decoration)

• Wood can be chipped and used as mulch for gardens or agricultural fields

• Reforestation: replanting of trees in areas that have been deforested

• Selectively removing diseased trees to prevent spread of infection through entire forest

  • Removes host for disease

  • Decreases density, making spread less likely

Fire Stopping