Ges 120 Exam 2

Highest density

temperature, subtropical, tropical biomes and close to water

cities are local high density areas

Lowest density

away from water, extreme environments

altering nature to meet our needs

Reducing biodiversity

Increasing use of net primary productivity

Increasing genetic resistance in pest species and disease-causing bacteria

Eliminating many natural predators

Introducing harmful species into natural communities

Using some renewable resources faster than they can be replenished

Disrupting natural chemical cycling and energy flow

Relying mostly on polluting and climate-changing fossil fuels

age structure diagrams

describes the relative numbers in each age class within a population

- wide base denotes many young (high reproduction, rapid population growth)

- even age distribution remains stable as births keep pace with deaths

- narrow base denotes fewer young than old (pop. will decline over time)

Demographic momentum

rapid population growth where there is a large percent of people younger than 15 (specifically girls entering reproduction age)

Birth rate

number persons born per 1,000 individuals (in population in given year)

Death rate

number persons who die per 1,000 individuals (in population in given year)

Rate of natural increase

birth rate - death rate

Growth rate

(birth rate + immigration rate) - (death rate + emigration rate)

Total fertility rate

average number of children born to each female (key factor in determining the size of a human population)

replacement fertility

the tfr that keeps the size of a population stable (about 2.1)

natural rate of population change

change due to birth and death rates alone (no migration)

Global population now

- 9 billion by 2045

- more than half in cities

bad news- largest generation of adolescents in history will enter childbearing years within 20 years

Demographic transition

a model of economic and cultural change and explains the declining death and birth rates in industrializing nations

many nations are experiences it in countries with good sanitation, health care, and food, people live longer

Demographic transition stages

stage 1 (preindustrial): population grows very slowly because of a high birth rate (to compensate for high infant mortality) and high death rate

stage 2 (transitional): population grows rapidly because birth rates are high and death rates drop because of improved food production and health

stage 3 (industrial): population growth slows as both birth and death rates drop because of improved food production, health, and education

stage 4 (post industrial)- population growth levels off and then declines as birth rates equal and then fall below death rates

Economic/social consequences that might result from below replacement fertility rates

- threaten economic growth

- less gov revenue with fewer workers

- less entrepreneurship and new business formation

- less likelihood for tech dev

- increasing public deficits to fund higher pension and health care costs

- pensions may be cut and retirement age incrreased

how to slow population growth

- reduce poverty through economic dev

- elevate the status of women

- encourage family planning and reproductive health care

China's One Child Policy

In 1960's- China's large population growing causes serious threat of mass starvation and social upheavel

1978- "temporary measure" institute a system of rewards and punishments to enforce a one child limit

consequences

- TFR dropped from 5.7 to 1.5

Gov claims beneficial effects:

- lower pressure on society, economy, and environment

- better delivery of healthcare and services

- lower cost for families

4-2-1 problem: each child will likely have to bear the burden of care for 2 parents and 4 grandparents

Dependency ratio

measure of proportion of population that is too old or too young to work

Thomas Malthus

Eighteenth-century English intellectual who warned that population growth threatened future generations because, in his view, population growth would always outstrip increases in agricultural production.

Paul Ehrlich

The Population Bomb (1968 warned that overpopulation would drain resources and kill millions by the 1980s)

Cornucopians believe

we can disregard Malthus and Ehrlich

pop growth poses no problem if new resources can be found or creates to replace depleted ones

Urban Sprawl

Land and Biodiversity

- loss of cropland

- loss and fragmentation of forests, grasslands, wetlands, and wildlife habitat

Water

- increased use and pollution of surface water and groundwater

- increased runoff and flooding

Energy, Air, and Climate

- increased energy use and waste

- increased emissions of carbon dioxide and other air pollutants

Economic Effects

- decline of downtown business districts

- more unemployment in central cities

Why Food Security is Difficult to Abtain

- in less dev countries, people suffer from health problems associated with not getting enough to eat

- in more dev countries, others suffer health problems from having too much to eat

- factors influencing food supply: poverty, war, bad weather, climate change, and effects of industrialized food prod

- many people suffer from chronic hunger and malnutrition and don't get enough vitamins and minerals

chronic undernutrition

(hunger) not enough food to meet basic energy needs

chronic malnutrition

not enough protein and other key nutrients

- low income, less dev countries- diets center on high carbohydrate grains and very little protein (low on the food chain)

- food deserts (no access to fresh food) in dev countries: diets high in fat, sugar, salt and little protein

overnutrition

when food energy intake exceeds energy use and causes excess body fat

- lowers life expectancy

- increases susceptibility to disease and illness

- lowers productivity and life quality

What does agriculture use to produce the world's food supply?

High input industrialized and lower input traditional methods

3 systems supply most of the world's food

- croplands (rice, wheat, corn)

- rangelands, pastures, and feedlots (meat and meat products)

- fisheries and aquaculture (fish and shellfish)

3 major tech advances

- irrigation (artificial methods that supply water to crops)

- synthetic fertilizers

- synthetic pesticides

industrialized/high input agriculture

heavy equipment, fossil fuel, commercial fertilizer/pesticides and money (monoculture: growing one to two crops)

- food supply vulnerable to disease

traditional/low income agriculture

solar energy and human labor to grow a crop that will feed a family with no surplus (polyculture: growing several crops)

industrial agriculture

- uses synthetic inorganic fertilizers and sewage sludge to supply plant nutrients

- makes use of synthetic chemical pesticides

- uses conventional and genetically modified seeds

- depends on non renewable fossil fuels (mostly oil and natural gas)

- produces significant air and water pollution and greenhouse gases

- is globally export oriented

- uses antibiotics and growth hormones to produce meat and meat products

organic agriculture

- emphasizes prevention of soil erosion and the use of organic fertilizers such as animal manure and compost, but no sewage sludge, to supply plant nutrients

- employs crop rotation and biological pest control

- uses no genetically modified seeds

- reduces fossil fuel use and increases use of renewable energy such as solar and wind power for generating electricity

- produces less air and water pollution and greenhouse gases

- is regionally and locally oriented

- uses no antibiotics or growth hormones to produce meat and meat products

organic agriculture

crops grown without the use of synthetic pesticides and inorganic fertilizers, or genetic engineering

green revolution

higher yields from existing cropland

- plant monocultures of selectively bred crops

- large amounts of water; synthetic fertilizers and pesticides

- multiple cropping

hidden costs

- pollution

- environmental degradation

- health costs (GMO's)

- farm subsidies

sustainable agriculture

agriculture we can practice in the same way and same place far into the future

soil

a complex plant supporting system

- consists of disintegrated rock, organic matter, water, gases, nutrients, and microorganisms

- a renewable resource that can be depleted

topsoil

the fertile top layer of many soils

is a significant natural component because it stores water and nutrients needed by plants

- topsoil renewal is one of earth's most important ecosystem services

- topsoil nutrients recycle endlessly as long as they are removed faster than natural processes replace them

soil comes from rock in 3 ways

- physical weathering (wind, rain, thermal expansion and contraction, water freezing)

- chemical weathering (water and gases)

- biological weathering (tree roots and lichens)

soil erosion

the movement of soil from one place to another by nature and by human activity

flowing water

largest cause of soil erosion

carries away soil loosened by rainfall

wind loosens and blows away topsoil particles

from flat land in dry climates

farming, deforestation, and overgrazing

expose land and hasten soil erosion

desertification

the process in which the productive potential of topsoil falls by 10% or more

- caused primarily by wind and water erosion but also by:

- deforestation, soil compaction, and overgrazing

- drought, salinization, water depletion

- climate change

The Dust Bowl in the US

Massive dust storms from erosions of millions of tons of topsoil in the 1930's

- drought worsened the human impacts

- dust storms traveled up to 1250 mi

- thousands of farmers left their land

- longest lasting natural disaster in history

Desertification reduces the productivity of arid lands

- Desertification affects 1/3 of planet's land area

- It costs tens of billions of dollars each year

- Desertification is intensified by positive feedback (degradation forces farmers onto poorer land and farmers reduce fallow periods, so land loses nutrients)

the soil conservation service

pioneered measures to address soil degradation

- started in 1935, the service works with farmers to dev conservation plans from individual farms

conservation districts

districts that promote soil conservation practices at the county level

- operate with federal direction, authorization, and funding and are organized by the states

crop rotation

- growing different crops from one year to the next

- returns nutrients to soil

- prevents erosion, reduces pests

- wheat or corn and soybeans

contour farming

- plowing perpendicularly across a hill

- furrors slow runoff and capture soil

terracing

- level platforms cut into steep hillsides

- this "staircase" contains rain and irrigation water

alley cropping (intercropping)

- planting different crops in alternating bands

- increases ground cover

- decreases pest and disease

- replenishes soil

shelter belters (wind breaks)

- rows of trees planted along edges of fields

- slows the wind

- can be combined with intercropping

conversation village

- residues of previous crops are left in field to prevent erosion

- soil soaks up more water

- no till farming (ult form of conservation tillage)

no till farming has many benefits

- it increases organic matter and soil biota

- reduces erosion and improves soil quality

- uses less labor, saves time, causes less wear on machinery

May help mitigate climate change

- reduces fossil fuel use due to less use of the tractors

- adds organic matter soils that is kept from the atmosphere

pests

any organism that damages valuable crops

weeds

any plant that competes with crops

pesticides

poisons that target pest organisms

Pollinators are beneficial "bugs" worth preserving

not all insects are pests, some are absolutely vital

- over 800 cultivated plants rely on pollinators

Colony Collapse Disorder

- entire beehives have died

- 1/3 of all U.S. honeybees have died

- causes are unknown but may involve: insecticides, new parasites, a combo of stresses that weaken bees' immune systems and destroy social communication

The Slow Food Movement

promotes local food and traditional cooking

- a global, grassroots org, founded in 1989 to prevent the disappearance of local food cultures and traditions, counteract the rise of fast life and combat people's dwindling interest in the food they eat, where it comes from and how our food choices affect the world around us

- tied to culture, politics, agriculture, and the environment

Energy sources and consumption are unevenly distributed

- industrialized nations use up to 100 times more

- energy per person than dev nations

- half of the world's proven reserves of crude oil lie in the Middle East, which is also rich natural gas

- Russia holds the most natural gas

- The U.S. possesses more coal than any other country

Coal

- fossil fuel extracted from ground (solid)

- solid fossil fuel formed from decaying organic matter exposed to heat and pressure over millions of years

- has been used for thousands of years to cook, heat homes, and fire pottery

- coal is the dirtiest fossil fuel, polluting air and water

Coal: advantages and disadvantages

advantages

- ample supplies in many countries

- medium to high net energy yield

- low cost when environmental costs are not included

disadvantages

- severe land disturbance and water pollution

- fine particle and toxic mercury emissions threaten human health

- emits large amounts of CO2 and other air pollutants when produced and burned

Oil

- fossil fuel extracted from ground (liquid)

- a sludge like liquid mixture of hundreds of different types of hydrocarbon molecules

- used for fuel vehicles and homes (gas, diesel, jet fuel)

- petroleum based products include lubricants, fabrics, pharmaceuticals

Natural gas

- Fossil fuel extracted from ground (gas)

- methane (CH4) and other volatile hydrocarbons

- mixture of gases (50%-90% methane)- provides 28% of energy

- used to generate electricity in power plants, heat and cook in homes

- versatile and clean burning

oil and natural gas

formed when dead organic material was buried in marine sediments and transformed by time, heat, and pressure

- organic material -> kerogen,

the source material for both crude oil and natural gas

if the kerogen is 1.5-3 km (1-2 mi) below the surface, it becomes crude oil

if below 3 km, it becomes natural gas

Anaerobic environment

- little or no oxygen present

- deep lakes, swamps

- produces fossil fuels

it takes energy to make energy

we don't get energy for free

to harness, extract, process, and deliver energy requires substantial inputs of energy

net energy

the difference between costs in energy invested and benefits in energy received

net energy = energy returned - energy invested

Energy returned on investment (EROI)

energy returned/energy invested

- higher ratios mean we receive energy than we invest

- fossil fuels have high EROI

- decline when we extract the easiest deposits first

scientists can look at net energy yield as the best measure for determining long term usefulness of an energy resource

if a new energy yield is 0 or a negative number- the resource cannot compete in the marketplace

(+) humans use fossil fuels because they're easily available and inexpensive to extract and process

(-) using these nonrenewable fuels degrades the environment, causes air and water pollution, and releases greenhouse gases into the atmosphere

Geothermal power

Earth's internal heat rising from core

A great deal of energy emanates from Earth's core

Nuclear power

- Immense amounts of energy reside in an atom's bonds

- little environmental impact and a very low accident risk, but usage is limited due to its low net energy yield

- fear of accidents and the long life of radioactive wastes are also limiting

- nuclear power is only possible because of gov subsidies

Nuclear Power adv and disadv

adv

- no stack emissions

- power plants pose fewer health risks from pollution

- uranium mining damages less land than coal mining

disadv

- nuclear waste is radioactive and difficult to dispose

- if an accident or sabotage occurs, the consequences can be catastrophic

- costs associated with building and decommissioning a plant are very high

Electricity

a secondary form of energy that is easy to transfer and apply to a variety of uses

Developing nations use a greater portion of their energy for subsistence activities

- agriculture, food preparation, and home heating

- less for transportation

- often rely on manual or animal energy, not fossil fuels

Industrialized nations rely more on tech and equipment so use more fossil fuels

fossil fuels supply 82% of the US energy demand

Shale oil

oil found within layers of rock

net energy is low- currently not economically viable/harmful to the environment

tar sands/oil sands

oil mixed with clay, sand, water and bitumen - low net energy yield and harmful to environment

conventional oil adv and disadv

adv

- ample supply for several decades

- net energy is medium but decreasing

- low land disruption

- efficient distribution system

disadv

- water pollution from oil spills and leaks

- environmental costs not included in market price

- releases CO2 and other air pollutants when burned

- vulnerable to international supply interruptions

heavy oil from oil sands adv and disadv

adv

- large potential supplies

- easily transported within and between countries

- efficient distribution system in place

disadv

- low net energy

- expensive

- releases CO2 and other air pollutants

- severe land disruption

- water pollution and high water use

conventional natural gas adv and disadv

adv

- ample supplies

- versatile fuel

- medium net energy yield

- emits less CO2 and other air pollutants than other fossil fuels when burned

disadv

- low new energy yield for LNG

- prod and delivery may emit more CO2 and CH4 per unit of energy produced than coal

- fracking uses and pollutes large volumes of water

- potential groundwater pollution from fracking

Hydraulic Fracturing (hydrofracking or fracking)

- used to extract natural gas trapped in shale deposits

- drilling deep into the earth and then angling the drill horizontally once it meets shale formation

- electric charges create fractures in the shale

- then a slurry of water, sand and chemicals is pumped in

- sand lodges in the fractures and holds them open as some liquid returns to the surface, including natural gas

- expands our access to oil and gas

- debate over environmental impact and health concerns versus increased economic benefits and well paying jobs

Three-Mile Island, Pennsylvania

- most serious accident in the US due to mechanical failure and human error

meltdown

- coolant water drained from the reactor

- temp rose inside the reactor core

- melting the metal surrounding the fuel rods

- releasing radiation

Chernobyl, Ukraine

- most severe nuclear plant accident that has ever occured due to human error and unsafe design

- for 10 days, radiation escaped while crews tried to put out the fires

- 19 miles of surrounding landscape still remain contaminated

- accident killed 31 people directly

Fukushima Daiichi

- 9.0 magnitude earthquake struck Japan, causing an immense tsunami

- killed 23,000 people

- flooded the Fukushima Daiichi nuclear plant

without electricity and the use of the control rods, the uranium fuel overheated

- radiation was released at levels equal to Chernobyl's and trace amounts were detected around the world

- thousands were evacuated

- radioactivity is still being released with unknown long term health effects

- could have been prevented because generators shouldn't be put in basements

what energy does the US generate the most?

nuclear power

Nuclear fission

the splitting apart of atomic nuclei

drives the release of nuclear energy in power plants

nuclear fusion

The process by which two or more small nuclei fuse to make a bigger nucleus

expansion of new renewables has been driven by

-Growing concerns over diminishing fossil fuel supplies

-Environmental and health impacts of burning fossil fuels

-Advances in technology making it easier and cheaper

Why are we not using more renewable energy?

- people think it's diffuse and unreliable (outdates)

- gov financial subsidies for research mush less than those for fossil fuels

- subsidies must be renewed more often- resulting in political pressure possibilities

- free market competition with fossil fuels doesn't include full cost pricing (including harm to environment)

- transitioning from one type of fuel to another takes about 60 years

Solar energy adv and disadv

adv

-easy to install, move around, and expand as needed

- use no fuels, are quiet and safe, contain no moving parts, and require little maintenance

- allow local, decentralized control over power

- dev nations can use solar cookers to replace the gathering of firewood, decreasing environmental/social stress

- most PV owners can sell excess electricity

- green collar jobs are being created

- they reduce the emission of greenhouse gases

disadv

- not all regions are sunny enough

- intermittent source (daily/seasonal variation can limit stand alone systems)

- need storage system or backup

- solar cell power could disrupt desert ecosystems

- most expensive electricity

wind power

energy derived from movement of air

- an indirect form of solar energy

wind turbines

devices that convert wind's kinetic energy into electric energy

wind power adv and disadv

adv

- no emissions once installed

- more efficient

- turbines use less water than conventional power plants

- can be used on many scales

- farmers and ranches can lease their land which produces extra revenue

- advancing tech is also reducing the cost of wind farm construction

- created 85,000 US jobs

- high net energy

- easy to build/expand

disadv

- no control when wind will occur so need to combine it with other generation tech to store energy

- Not in my backyard syndrome (NIMBY)

- turbines threaten birds and bats

- wind sources are not always near pop centers that need energy

- transmission networks need to be expanded to deliver the wind generated power to distant pop centers

Geothermal benefits and limitations

benefits

- medium net energy and high efficiency at accessible sites

- low operating costs at favorable sites

- reduces greenhouse gas emissions

limitations

- not sustainable if the plant withdraws water faster than it can be recharged

- limited to areas where the energy can be trapped

- high cost except at concentrated and accessible sources

- scarcity of suitable sites

- noise and some CO2 emissions

hydroelectric power

- next to biomass, provides more renewable energy than any other sources

- uses the kinetic energy of moving water to turn turbines to generate electricity