Human Impact on Human Impact on the Biospherethe Biosphere

Ecosystems as affected by Ecosystems as affected by Human activityHuman activity

Human ImpactsHuman Impacts

Humans are using energy and altering Humans are using energy and altering

the environment at astonishing ratesthe environment at astonishing rates

We are altering natural processes before We are altering natural processes before

we even understand themwe even understand them

PollutantsPollutants

Substances with which an ecosystem Substances with which an ecosystem

has had no prior evolutionary experiencehas had no prior evolutionary experience

No adaptive mechanisms are in place to No adaptive mechanisms are in place to

deal with themdeal with them

Air PollutantsAir Pollutants

Carbon oxidesCarbon oxides

Sulfur oxidesSulfur oxides

Nitrogen oxidesNitrogen oxides

Volatile organic compoundsVolatile organic compounds

Photochemical oxidantsPhotochemical oxidants

Suspended particlesSuspended particles

Industrial SmogIndustrial Smog

Gray-air smogGray-air smog

Forms over cities that burn large amounts Forms over cities that burn large amounts

of coal and heavy fuel oils; mainly in of coal and heavy fuel oils; mainly in

developing countriesdeveloping countries

Main components are sulfur oxides and Main components are sulfur oxides and

suspended particlessuspended particles

Photochemical smogPhotochemical smog

Brown-air smog Brown-air smog

Forms when sunlight interacts with Forms when sunlight interacts with

components from automobile exhaust components from automobile exhaust

Nitrogen oxides are the main culpritsNitrogen oxides are the main culprits

Hot days contribute to formationHot days contribute to formation

Thermal InversionThermal Inversion

Weather pattern in which a layer of cool, Weather pattern in which a layer of cool, dense air is trapped beneath a layer of dense air is trapped beneath a layer of warm airwarm air

cool air

warm inversion air

cool air

Acid DepositionAcid Deposition

Caused by the Caused by the

release of sulfur and release of sulfur and

nitrogen oxidesnitrogen oxides

Coal-burning power Coal-burning power

plants and motor plants and motor

vehicles are major vehicles are major

sourcessources

Ozone ThinningOzone Thinning

In early spring and In early spring and

summer ozone layer summer ozone layer

over Antarctica thinsover Antarctica thins

Seasonal loss of Seasonal loss of

ozone is at highest ozone is at highest

level ever recordedlevel ever recorded

SouthAmerica

Antarctica

Effect of Ozone ThinningEffect of Ozone Thinning

Increased amount of Increased amount of UV radiationUV radiation

reaches Earth’s surfacereaches Earth’s surface

UV damages DNA and negatively UV damages DNA and negatively

affects human healthaffects human health

UV also affects plants, lowers UV also affects plants, lowers

primary productivityprimary productivity

Protecting the Ozone LayerProtecting the Ozone Layer

CFC productionCFC production has been halted in has been halted in

developed countries, will be phased out in developed countries, will be phased out in

developing countries developing countries

Even with bans it will take more than 50 Even with bans it will take more than 50

years for ozone levels to recoveryears for ozone levels to recover

Generating GarbageGenerating Garbage

Developed countries generate huge Developed countries generate huge

amounts of wasteamounts of waste

Paper products account for half the total Paper products account for half the total

volumevolume

Recycling can reduce pollutants, save Recycling can reduce pollutants, save

energy, ease pressure on landfillsenergy, ease pressure on landfills

DeforestationDeforestation

Removal of all trees from large tracts of Removal of all trees from large tracts of

landland

38 million acres logged each year38 million acres logged each year

Wood is used for fuel, lumberWood is used for fuel, lumber

Land is cleared for grazing or cropsLand is cleared for grazing or crops

Effects of DeforestationEffects of Deforestation

Increased leaching and soil erosionIncreased leaching and soil erosion

Increased flooding and Increased flooding and

sedimentation of downstream riverssedimentation of downstream rivers

Regional precipitation declinesRegional precipitation declines

Possible amplification of the Possible amplification of the

greenhouse effectgreenhouse effect

Regions of DeforestationRegions of Deforestation

Rates of forest loss are greatest in Brazil, Rates of forest loss are greatest in Brazil,

Indonesia, Mexico, and ColumbiaIndonesia, Mexico, and Columbia

Highly mechanized logging is proceeding Highly mechanized logging is proceeding

in temperate forests of the United States in temperate forests of the United States

and Canadaand Canada

Destroying BiodiversityDestroying Biodiversity

Tropical rainforests have the greatest Tropical rainforests have the greatest

variety of insects, most bird speciesvariety of insects, most bird species

Some tropical forest species may prove Some tropical forest species may prove

valuable to humansvaluable to humans

Our primate ancestors evolved in forests Our primate ancestors evolved in forests

like the ones we are destroying like the ones we are destroying

DesertificationDesertification

Conversion of large tracts of grassland to Conversion of large tracts of grassland to

desertlike conditions desertlike conditions

Conversions of cropland that result in Conversions of cropland that result in

more than 10 percent decline in more than 10 percent decline in

productivityproductivity

Ongoing DesertificationOngoing Desertification

Sahel region of Africa is undergoing rapid Sahel region of Africa is undergoing rapid

desertificationdesertification

Causes are overgrazing, overfarming, and Causes are overgrazing, overfarming, and

prolonged droughtprolonged drought

One solution may be to substitute native One solution may be to substitute native

herbivores for imported cattleherbivores for imported cattle

Water Use and ScarcityWater Use and Scarcity

Most of Earth’s water is too salty for Most of Earth’s water is too salty for

human consumptionhuman consumption

Desalinization is expensive and Desalinization is expensive and

requires large energy inputsrequires large energy inputs

Irrigation of crops is the main use of Irrigation of crops is the main use of

freshwaterfreshwater

Negative Effects of IrrigationNegative Effects of Irrigation

Salinization, mineral buildup in soilSalinization, mineral buildup in soil

Elevation of the water table and Elevation of the water table and

waterloggingwaterlogging

Depletion of aquifersDepletion of aquifers

Aquifer ProblemsAquifer Problems

Water PollutantsWater Pollutants

SewageSewage Animal wastesAnimal wastes FertilizersFertilizers PesticidesPesticides Industrial chemicalsIndustrial chemicals Radioactive materialRadioactive material Excess heat (thermal pollution) Excess heat (thermal pollution)

Wastewater TreatmentWastewater Treatment

Primary treatment Primary treatment Use of screens and settling tanksUse of screens and settling tanks Addition of chlorine to kill pathogensAddition of chlorine to kill pathogens

Secondary treatment Secondary treatment Microbes break down organic matterMicrobes break down organic matter

Tertiary treatment removes additional toxic Tertiary treatment removes additional toxic substances; rarely usedsubstances; rarely used

Energy UseEnergy Use

Only 10 percent of energy used in Only 10 percent of energy used in

developed countries is from developed countries is from

renewable sourcesrenewable sources

Less developed countries rely more Less developed countries rely more

heavily on renewable sources heavily on renewable sources

(primary biomass)(primary biomass)

Fossil FuelsFossil Fuels

Coal, oil, natural gasCoal, oil, natural gas

Main energy source of developed Main energy source of developed

countriescountries

Burning of fossil fuels contributes to Burning of fossil fuels contributes to

global warmingglobal warming

OilOil

Reserves are decliningReserves are declining

Many reserves are in ecologically fragile Many reserves are in ecologically fragile

wilderness areaswilderness areas

Environmental costs of extracting and Environmental costs of extracting and

transporting reserves from such areas are transporting reserves from such areas are

highhigh

CoalCoal

Extensive reserves existExtensive reserves exist

Mining is very destructiveMining is very destructive

Burning coal releases sulfur dioxides Burning coal releases sulfur dioxides

that cause acid depositionthat cause acid deposition

Nuclear EnergyNuclear Energy

Used extensively in some energy-Used extensively in some energy-poor developed countries…clean poor developed countries…clean production of energy.production of energy.

Controversial in the United StatesControversial in the United States Emits very few air pollutants but Emits very few air pollutants but

creates radioactive waste (must be creates radioactive waste (must be securely stored)securely stored)

Potential for meltdown ?? Potential for meltdown ??

Chernobyl Accident - 1986Chernobyl Accident - 1986

Core meltdown at a nuclear power plant in Core meltdown at a nuclear power plant in the Ukrainethe Ukraine

31 immediate deaths, radiation sickness 31 immediate deaths, radiation sickness and death for othersand death for others

Cloud of radiation spread by winds across Cloud of radiation spread by winds across EuropeEurope

Long-term health impacts downwindLong-term health impacts downwind

Solar-Hydrogen EnergySolar-Hydrogen Energy

Photovoltaic cells use sunlight energy Photovoltaic cells use sunlight energy

to split water to split water

Hydrogen gas produced in this way Hydrogen gas produced in this way

can be used as fuel or to generate can be used as fuel or to generate

electricityelectricity

Clean, renewable technologyClean, renewable technology

Wind EnergyWind Energy

An indirect use of solar energyAn indirect use of solar energy

Wind farms are arrays of turbinesWind farms are arrays of turbines

Can supplement needs of some Can supplement needs of some

regions but is not dependable regions but is not dependable

enough on it ownenough on it own

Fusion Fusion

Energy is released when atomic nuclei Energy is released when atomic nuclei fuse fuse

This process produces solar energyThis process produces solar energy Attempts to mimic this process on Earth Attempts to mimic this process on Earth

require use of lasers, magnetic fieldsrequire use of lasers, magnetic fields Not yet a commercially viable energy Not yet a commercially viable energy

sourcesource