Average residence time
time it takes for a given part of the total reservoir of a particular material to by cycled through the system
Gaia
Greek goddess Mother Earth
Sustainability
the ability to meet humanity's current needs without compromising the ability of future generations to meet their needs
Lag time
time between a stimulus and the response of a system
Volatile Organic Compounds
a variety of organic compounds used as solvents in industrial processes
Positive feedback
when a change in some conditions triggers a response that intensifies the changing condition
negative feedback
when a changing in some condition triggers a response that counteracts the changed condition
true cost/external costs
harmful environmental side effects that are not reflected in a product's cost
First law of thermodynamics
energy is neither created nor destroyed, but may be converted from one form to another
second law of thermodynamics
when energy is changed from one form to another, some useful energy is always degraded into lower quality energy
Ionizing radiation
radiation with enough energy to free electrons from atoms forming ions, may cause cancer
High Quality Energy
organized & concentrated, can perform useful work
Low Quality Energy
disorganized, dispersed
Natural radioactive decay
unstable radioisotopes decay releasing gamma rays, alpha & beta particles
half-life
the time it takes for half the mass of a radioisotope to decay. A radioactive isotope must be stored for approximately 10 half-lives until it decays to a safe level
nuclear fission
nuclei of isotopes split apart when struck by neutrons
nuclear fusion
2 isotopes of light elements forced together at high temperatures till they fuse to form a heavier nucleus. Happens in Sun, very difficult to accomplish on Earth, prohibitively expensive
10 half lives
estimate of how long a radioactive isotope must be stored until it decays to a safe level
ore
a rock that contains a large enough concentration of a mineral making it profitable to mine
mineral reserve
identified deposits currently profitable to extract
surface mining
cheaper, can remove more minerals, less hazardous to workers
organic fertilizer
slow acting long lasting because the organic remains need time to decompose
silviculture
professional growing of trees
shelterwood-cutting
cutting dead and less desirable trees first and after cutting more mature trees
seed-tree cutting
removes all but a few seed trees to promote regeneration
selective cutting
individual trees are marked and cut
humus
organic, dark material remaining after decomposition by microorganisms
leaching
removal of dissolved materials from soil by water moving downwards through soil
illuviation
deposit of leached material in lower soil layers (B)
Conservation
allows use of resources in a responsible manner
Preservation
setting aside areas & protecting them from human activities
loam
perfect agricultural soil with equal portions of sand, silt, clay
soil conservation methods
conservation tillage, crop rotation, contour plowing, organic fertilizers
soil salinization
in arid regions, water evaporates leaving salts behind (ex. Fertile crescent, southwestern US)
water logging
water completely saturates soil, starves plant roots of oxygen, rots roots
Hydrologic cycle components
evaporation, transpiration, runoff, condensation, precipitation, and infiltration
watershed
all of the land that drains into a body of water
aquifer
underground layers of porous rock allow water to move slowly
cone of depression
lowering of the water table around a pumping well
salt water intrusion
near the coast, overpumping of groundwater causes saltwater to move into aquifer
adaptive radiation
occurs when a species enters a new habitat that has unoccupied niches and evolves into a group of new species, each adapted to one of these niches
alpha particle
one of the major types of nuclear radiation, consisting of two protons and two neutrons
beta particle
one of three kinds of nuclear radiation; electrons that are emitted when one of the protons or neutrons in the nucleus of an isotope spontaneously changes
gamma rays
one of three kinds of nuclear radiation; type of EM radiation emitted from the isotope similar to X gays but more energetic and penetrating
ENSO
El Nino Southern Oscillation, trade winds weaken & warm, surface water moves toward South America. Diminished fisheries off S. America, drought in W. Pacific, increased precipitation in southwestern N. America, fewer Atlantic hurricanes
During an El Nino Year
trade winds weaken & warm water sloshed back to S. America
During non El Nino year
Easterly trade winds and ocean currents pool warm water in the western Pacific, allowing upwelling of nutrient rich water off the West coast of S. America
effects of el nino
upwelling decreases disrupting food chains, N. US has mild winters, SW US has increased rainfall, lass Atlantic hurricanes
La Nina
Normal" year, easterly trade winds and ocean currents pool warm water in the W. Pacific, allowing upwelling of nutrient rich water off West coast of S. America
nitrogen fixation
because atmospheric N cannot be used directly by plants, it must be first converted to ammonia by bacteria
ammonification
decomposers convert organic waste into ammonia
nitrification
ammonia is converted to nitrate ions
assimilation
inorganic N is converted into organic molecules such as DNA/amino acids & proteins
denitrification
bacteria convert ammonia back into N
phosphorus
does not exist as a gas; released by weathering of phosphate rocks, it is a major limiting factor for plant growth. Phosphorus cycle is slow, and not atmospheric
excess phosphorus
added to aquatic ecosystems by runoff of animal wastes, fertilizer, sewage discharge
photosynthesis
plants convert CO2 into complex carbs (glucose)
aerobic respiration
oxygen consuming producers, consumers & decomposers break down complex organic compounds and convert C back into CO2
largest reservoirs of Carbon
carbonate rocks first, oceans second
biotic
the living components of an ecosystem
abiotic
the nonliving components of an ecosystem
producer/autotroph
organisms that make their own food--- photosynthetic life
fecal coliform
indicator of sewage contamination
chlorine
good= disinfection of water, bad= forms trihalomethanes
obligate symbiont
relationship between two organisms in which neither by themselves can exist without the other
rangeland
provides food for grazing and browsing animals w/o plowing and planting
pasture
plowed, planted, and harvested to provide forage for animals
igneous rock
formed from solidification of magma
metamorphic rock
formed by heat & pressure
sedimentary rock
formed by weathering & erosion
OAEBCR
soil horizon layers
contour plowing
land is plowed perpendicular to the slopes and as horizontally as possible
no-till agriculture
involves not plowing the land, using herbicides and integrated pest management to keep down weeds, and allowing some weeds to grow
eutrophication
a body of water develops a high concentration of nutrients, causes increase in algae, organisms below deprived of light, large die off, decompose, DO lowers
oligotrophic
referring to bodies of water having low concentration of chemical elements required for life
photodissociation
solar radiation breaks down chemical bonds
trophic levels
producers> primary consumer> secondary consumer> tertiary consumer
energy flow through food web
10% of all usable energy is transferred to the next trophic level. Reason: usable energy lost as heat (2nd law of thermodynamics), not all biomass is digested & absorbed, predators expend energy to catch prey
primary succession
development of communities in a lifeless area not recently inhabited by life
secondary succession
life progresses where soil remains
mutualism
symbiotic relationship where both organisms benefit
commensalism
symbiotic relationship where one organism benefits & the other is unaffected
parasitism
relationship in which one organism obtains nutrients at the expense of the host
carrying capacity
the # of individuals that can be sustained in an area
r-strategist
reproductive strategy in which organisms reproduce early, bear many small, unprotected offspring (insects, mice)
K-strategist
reproductive strategy in which organisms reproduce late, bear few, carerd for offspring (humans, elephants)
wetland
shallow depression that seasonally holds water
natural selection
organisms that possess favorable adaptations pass them onto the next generation
thomas malthus
human population cannot continue to increase. Consequences will be war, famine, and pestilence (disease)
doubling time
(rule of 70) doubling time equals 70 divided by percent growth rate.
replacement level fertility
number of children a couple must have to replace themselves (averages 2.1 in more developed nations, 2.7 in less developed nations)
world population
a little over 6 billion
US population
290 million
Kwashiorkor
lack of sufficient protein in diet, leads to failure of neural development in infants and therefore learning disabilities
marasmus
progressive emaciation caused by lack of protein and calories
undernourishment
lack of calories
preindustrial stage
demographic transitional model stage, birth & death rates high, population grows slowly, infant mortality high
transitional stage
demographic transitional model stage, death rate (infant mortality) lower, birth rate remains high, better health care, population grows fast
industrial stage
demographic transitional model stage, decline in birth rate, population growth slows
postindustrial stage
demographic transitional model stage, low birth & death rates
general fertility rate
number of live births expected in a year per 1,000 women aged 15 to 49 years
total fertility rate
average number of children expected to be born to a woman throughout her childbearing years
incidence rate
number of people contracting a disease during a time period
phosphorus
cycle which does not have a gaseous phase
genetic drift
changes in frequency of a gene in a population due not to mutation, selection, or migration but to chance
age structure diagrams
broad base --> rapid growth; narrow base --> negative growth; uniform shape --> zero growth
most populous nations
1. China, 2. India, 3. US, 4, Indonesia
low status of women
most important factor keeping population growth rates high
methods to decrease birth rates
family planning, contraception, economic rewards & penalties
composition of water on earth
97.5% seawater, 2.5% freshwater
overdraft
groundwater withdrawal when the amount pumped from wells exceeds natural rate of replenishment
ways to conserve water
drip/trickle irrigation, recycling, use gray water, repair leaks, low flow fixtures
aquaculture
farming aquatic species, commonly salmon, shrimp, tilapia, oysters
point source
source from specific location such as pipe or smokestack
non-point source
source spread over an area such as agricultural/feedlot runoff, urban runoff, traffic
primary sewage treatment
first step of sewage treatment; eliminates most particulate material from raw sewage using grates, screens, and gravity (settling)
secondary sewage treatment
second step of sewage treatment; bacteria breakdown organic waste, aeration accelerates process
activated sludge
mass of living bacterial organisms feeding on waste material that has settled, is recycled to aeration tank
BOD
Biological Oxygen Demand, amount of dissolved oxygen needed by aerobic decomposers to break down organic materials
Eutrophication
rapid algal growth caused by an excess of nitrogen & phosphorus, blocks sunlight, causing the death/decomposition of aquatic plants, decreasing dissolved oxygen (DO), suffocating fish
malnourishment
lack of specific components of food (proteins or vitamins)
hypoxia
water with very low dissolved oxygen levels, the end result of eutrophication
Minimata disease
mental impairments caused by mercury
CAFE standards
Corporate Average Fuel Economy standards enacted into law in 1975, established fuel efficiency standards for passenger cars and light trucks. The Fuel economy ratings for a manufacturer's entire line of passenger cars must currently average at least 27.5
primary air pollutants
produced by humans & nature (CO, CO2, SO2, NO, hydrocarbons, particulates)
secondary air pollutants
formed by reaction of primary pollutants
particulate matter
sources include burning fossil fuels and car exhaust. Effects include reduced visibility, respiratory irritation. Mothods of reduction include filtering, electrostatic precipitators, alternative energy
nitrogen oxides
major source is auto exhaust. Primary and secondary effects include acidification of lakes, respiratory irritation, leads to smog and ozone. Reduced using catalytic converters
ozone
secondary pollutant. Causes respiratory irritation and plant damage. Reduced by reducing NO emissions and VOCs
Sultur oxides
primary source is coal burning. Primaryu and secondary effects include acid deposition, respiratory irritation, plant damage. Reduction methods include scrubbers, burn low sulfur fuel
Carbon dioxide
Sources include the combustion of fossil fuels. EEffects: greenhouse gas-contributes to global warming. Reduction accomplished by increased fuel efficiency, mass transit
Carbon Monoxide
Sources include incomplete combustion of fossil fuels. Effects: binds to hemoglobin reducing blood's ability to carry O2. Reduction accomplished by catalytic converters, oxygenated fuel, mass transit
Radon
radioactive gas, formed from the decay of Uranium, causes lung cancer
photochemical smog
formed by chemical reactions involving sunlight
acid deposition
caused by sulfuric and nitric acids resulting in lowered pH of surface waters
acid precipitation
condensed ot frozen water vapor that includes acid rain, acid fog, and acid snow. pH below 5.5. Cause: anthropogenic release of pollutants like SO2 & nitrogen oxides
greenhouse gases
most significant- H2O, CO2, CH4, CFCs. Trap outgoing infrared energy causing Earth to warm
greenhouse effect
a vital process, required for life to exist on Earth. Gases trap outgoing infrared energy causing Earth to warm. If accelerated, bad, leads to global warming
Effects of global warming
rising sea level (due to thermal expansion not melting ice), extreme weather, droughts (famine), and extinctions
Ozone depletion caused by
CFCs, methyl chloroform, carbon tetrachloride, halon, methyl bromide all of which attack stratospheric ozone
effects of ozone depletion
Negative effects include increased UV, skin cancer, cataracts, and decreased plant growth
municipal solid wate
paper and mostly put into landfills
sanitary landfill
problems include leachate, which is solved using a liner with a collection system; methane gas, which may be collected and burned; and the volume of garbage, which may be compacted and/or reduced
incineration advantages
volume of wate reduced by 90% and waste heat can be used
incineration disadvantages
toxic emissions (polyvinyl chloride, dioxin), scrubbers and electrostatic precipitators needed, ash disposal
reduce amount of waste at the source
best solution for waste problem
brownfield
abandoned industrial sites
keystone species
species whose role in an ecosystem is more important than others
indicator species
species that serve as early warnings than an ecosystem is being damaged
In natural ecosystems
50-90% of pest species are kept under control by: predators, diseases, parasites
3 major insecticide groups
chlorinated hydrocarbons (DDT), organophosphates (malathion), carbamates (aldicarb)
integrated pest management
uses a combination of methods, including bological control, certain chemical pesticides, and some methods of planting crops
esticie pros
saves lives from insect transmitted diseases, increases food supply, and increases profits for farmers
pesticide cons
genetic resistance, ecosystem imbalance, pesticide treadmill, persistence, bioaccumulation, and biological magnification
natural pest control
better agricultural practices, genetically resistant plans, natural enemies, and biopesticides, sex attractants
genetically modified organisms (GMOs)
new organisms created by altering the genetic material (DNA) of existing organisms; usually in an attempt to remove undesirable or create desirable characteristics in the new organisms
conservation and increase efficiency
best solution to energy shortage
electricity is generated by
steam, from water boiled, by fossil fuels or nuclear energy, or falling water is used to turn a generator
petroleum formation
microscopic aquatic organisms in sediments converted by heat and pressure into a mixture of hydrocarbons
petroleum pros
cheap, easily transported, high quality energy
Petroleum cons
reserves depleted soon, pollution during drilling, transport and refining, land subsidence, burning oil produces CO2
coal formation
prehistoric plants buried un-decomposed in oxygen-depleted water of swamps/bogs converted by heat and pressure
ranks of coal
peat, lignite, bituminous, anthracite
cogeneration
using waste heat to make electricity
nuclear reactor parts
consists of a core, control rods, moderator, steam generator, turbine, containment building
2 most serious nuclear accidents
Chernobyl, Ukraine, & Three Mile Island, PA
alternate energy sources
wind, solar, waves, biomass, geothermal, fuel cells
remediation
return a contaminated area to its original state
LD-50
amount of a chemical that kills 50% of the animals in a test population
ED-50
amount of a chemical that causes an effect in 50% of the animals in a test population
TD-50
dose that is toxic to 50% of a population
body burden
amount of concentration of a toxic chemical in an individual
threshold
level below which no effect occurs and above which effects begin to occur
acute effect
occurs soon after exposure
chronic effect
takes place over a long period, often as a result of exposure to low levels of a pollutant
persistent organic pollutants (POPs)
are now banned, DDT, PCBs (liquid insulators in electric transformers), and dioxins(byproduct of herbicide production)
troposphere
first layer of atmosphere 0-10 miles above Earth's surface. Contains weather, greenhouse gases (bad ozone)
stratosphere
second layer of atmosphere 10-30 miles above the Earth's surface. Contains protective ozone layer (good ozone)
inversion layer (temperature inversion)
warm layer of air above a cooler layer traps pollutants close to the Earth's surface
mutagen
substances that cause changes in DNA; may result in hereditary changes
teratogen
substances that cause fetus deformities (birth defects)
carcinogen
substances that cause cancer
dioxin
one of the most toxic human-made chemicals. Stable, long-lived, by-product of herbicide production, enters environment as fallout from incineration of municipal and medical waste and persists for many years
PCBs (polychlorinated biphenyls)
stable, long-lived, carcinogenic chlorinated hydrocarbons. Produced by electronics industry
multiple use public lands
National Forest & National Resource lands
Moderately Restricted Use Public Lands
National Wildlife Refuges
Restricted Use Public Lands
National Parks & National Wilderness Preservation System
Divergent Plate Boundaries
tectonic plates spreading apart, new crust being formed (ex. mid-ocean ridges, rift valleys)
convergent plate boundaries
tectonic plates with the oldest crustal material on Earth moving together, one moving under another (ex. mid-ocean trenches). Mineral deposits and volcanoes are most abundant at convergent plate boundaries
transform fault
tectonic plates sliding past one another (San Andres)
most endangered species
have a small range, require large territory, have long generations, have a very specialized niche, or live on an island
atlantic salmon
interbreeding with and competition from escaped farm-raised salmon from the aquaculture industry threaten the wild salmon population
california condor
reasons for decline include shootings, poisoning, lead poisoning, collisions with power lines, egg collecting, pesticides, habitat loss, and decline of large and medium-size native mammals due to encroachments of agriculture and urbanization
delhi sands flower-loving fly
a 1-inch long insect currently restricted to only 12 known populations in San Bernardino and Riverside counties. Estimated 98% of its habitat has been converted to residential, agricultural, and commercial use
florida panther
hunting and development that resulted in habitat loss and fragmentation
gray wolf
subject of predator eradication programs sponsored by the Federal government. Prior to Endangered Species Act(1973), exterminated from lower 48 states except for a few hundred inhabiting extreme northeastern Minnesota and a small number on Isle Royale, Mi
Grizzly Bear
conflict with humans and development that resulted in habitat loss and framentation
Piping plover
predation and human disturbance are thought to be main causes of plover's decline. Listed as endangered in Great Lakes region and as threatened in the Great Plains and on the Atlantic Coast
manatee
initial population decreases resulted from overharvesting for meat, oil, and leather. Today, heavy mortality occurs from accidental collisions with boats and barges, and from canal lock operations
whooping crane
drainage of wetlands, conversion of grasslands to agriculture, and hunting for feathers
American alligator
overhunting and destruction of habitat cuased original listing, removed from list of endangered species by the Fish and Wildlife Service in 1987
bald eagle
ingested DDt by eating contaminated fish. DDT caused shells of the bird's eggs to thin and resulted in nesting failures. Loss of nesting habitat and hunting for feathers also contributed to the population decline. Reclassified from endangered to threatene
peregrine falcon
ingested DDt by eating smaller birds, which had eaten contaminated prey. The presticide caused the shells of the bird's eggs to thin and resulted in nesting failures. Removed from the list of endangered species by the Fish and Wildlife Service in August 1
Gray whale
eastern North Pacific stock of gray whale has the distinction of being the first population of a marine mammal species to be removed from the List of Endangered and Threatened Species
biome
large distinct terrestrial region having similar climate, soil, plants & animals
tropical rain forests
characterized by the greatest diversity of species, believed to include many undiscovered species. Occur near the equator. Soils tend to be low in nutrients. Distinct seasonality: winter is absent, and only two seasons are present (rainy and dry)
temperate forests
occur in eastern North America, Japan, northeatern Asia, and western and central Europe. Dominated by tall deciduous trees. Well-defined seaons include a distinct winter. Logged extensively, only scattered remnants of original temperate forests remain
boreal forests or Taiga
represent the largest terrestrial biome. Dominated by needleleaf, coniferous trees. Found in the cold climates of Eurasia and North America: two-thirds in Siberia with the rest in Scandinavia, Alaska, and Canada. Seasons are divided into short, moist, and
temperate shrub lands
occurs along the coast of Southern California and the Mediterranean region. Characterized by areas of Chaparral-miniature woodlands dominated by dense stands of shrubs
savannas
grassland with scattered individual trees. Cover almost half the surface of Africa and large areas of Australia, South America, and India. Warm or hot climates where the annual rainfall is 20-50 inches per year. The rainfall is concentrated in six or eigh
temperate grasslands
dominated by grasses, trees and large shrubs are absent. Temperatures vary more from summer to winter, and the amount of rainfall is less than in savannas. Temperate grasslands have hot summers and cold iwnters. Occur in South Africa, Hungary, Argentina,
deserts
covers about 1/5 of Earth's surface and occur where rainfall is less than 50 cm/year. Most deserts occur at low latitudesm have a considerable amount of specialized vegetation, as well as specialized animals. Soils have abundant nutrients, need only water
tundra
treeless plains that are the coldest of all the biomes. Occur in the arctic and Antarctica. Dominated by lichens, mosses, sedges, and dwarfed shrubs. Characterized by extremely cold climate, permanently frozen grounnd (permafrost) low biotic diversity, si
wetlands
areas of standing water wet all or most of the year that support aquatic plants including marshes, swamps, and bogs. Species diversity is very high. Includes bogs, swamps, sloughs, and marshes
fresh water
defined as having a low salt concentration (less than 1%). Plants and animals are adjusted to the low salt content and would not be able to survive in areas of high salt concentration ( ex. ocean). There are different types of freshwater regions: ponds an
oceans
the largest of all the ecosystems. The ocean regions are separated into separate zones: intertidal, pelagic, abyssal, and benthic. All four zones have a great diversity of species
chernobyl, Ukraine
April 26, 1986, unauthorized safety test, leads to fire and explosion at nuclear power plant--- millions exposed to unsafe levels of radiation
Three-Mile Island, Pennsylvania
March 29, 1979, nuclear power plant loses cooling water, 50% of core melts, radioactgive materials escape into atmosphere, near meltdown
Yucca Mountain, Nevada
controversial as proposed site for permanent storage of high-level nuclear waste, 70-miles northwest of Las Vegas, near volcano and earthquake faults
Aral Sea, Uzbekistan/Kazakhstan
large inland sea is drying up as a result of water diversion
love canal, NY
chemicals buried in old canal, school and homes built over it led to birth defectrs and cancers
aswan high dam, Egypt
the silt that made the Nile region fertile fills the reservoir. Lack of irrigation controls causes waterlogging and salinization. The parasitic disease schistosomiasis thrives in the stagnant water of the reservoir.
Three Gorges Dam, China
world's largest dam on Yangtze River. Will drown ecosystems, cities, archeological sites, fragment habitats, and displace 2 million people
ogallala aquifer
world's largest aquifer; under part of Wyoming, South Dakota, Nebraska, Kansas, Colorado, Oklahoma, New Mexico, and Texas. Holds enough water to cover the US with 1.5 feet of water. Being depleted for agricultural and urban use
Minimata, Japan
mental impairments, birth defects, and deaths were caused by mercury dumped in Minimata Bay by factory. Mercury entered humans through their diet
Bhopal, India
December 2, 1984m methyl isocyanate released accidentally by Union Carbide pesticide plant kills over 5,000
Valdez, Alaska
March 24, 1989, tanker Exxon Valdez hits submerged rocks in Prince William Sound- worst oil spill in US waters
surface mining control & reclamation act
requires coal strip mines to reclaim land
madrid protocol
moratorium on mineral exploration for 50 years in Antarctica
Safe drinking water act
set maximum contaminant levels for pollutants that may have adverse effects on human health
Clean Water Act
set maximum permissible amounts of water pollutants that can be discharged into waterways...aim to make surface waters swimmable and fishable
Water Quality Act
attempt to reduce non-point source pollution
Ocean Dumping Ban Act
bans ocean dumping of sewage sludge & industrial waste in the ocean
Clean Air Act
set emission standards for cars, and limits for release of air pollutants
Kyoto Protocol
controlling global warming by setting greenhouse gas emissions targets for developed countries
Montreal Protocol
phaseout of ozone deleting substances
Resource Conservation & Recovery Act
controls hazardous waste with a cradle to grave system
Comprehensive Environmental Response, Compensation & Liability Act
designed to identify and clean up abandoned hazardous waste dump sites
low level radioactive policy act
all states must have facilities to handle low level radioactive wastes
Nuclear Waste policy Act
US government must develop a high level nuclear waste site by 2015 (Yucca Mountain)
Endangered Species Act
identifies threatened and endangered species in the US, and puts their protection ahead of economic considerations
Convention on International Trade in Endangered Species (CITES)
lists species that cannot be commercially traded as live specimens or wildlife products
Federal Insecticide, Fungicide, Rodenticide Act
regulates effectiveness of pesticides
Food Quality Protection Act
set pesticide limits in food, & all active and inactive ingredients must be screened for estrogenic/endocrine effects
national environmental policy act
Environmental Impact Statements must be done before any project affecting federal lands can be started
National wild and scenic rivers Act
protects rivers with due to aesthetic, recreational, wildlife, historical, or cultural reasons
US Marine Mammal Protection Act
prohibits taking marine mammals in US wasters and by US citizens, and the importing of marine mammals and marine mammal products into the US
Rachel Carson
published Silent Spring in 1962; documented the environmental damage done by DDT and other pesticides. Heightened public awareness at start of the modern environmental movement
John Muir
founded Sierra Club in 1892; fought unsuccessfully to prevent the damming of the Hetch Hetchy Valley in Yosemite National Park
Gifford Pinchot
first chief of the US Forest Service; advocated managing resources for multiple use using principles of sustainable yield
Garret Hardin
published "The Tragedy of the Commons" in the journal Science in 1968; argued that rational people will exploit shared resources
Aldo Leopold
wrote A Sand County Almanac published a year after his death in 1948; promoted a "Land Ethic" in which humans are ethically responsible for serving as the protectors of nature
Sherwood Rowland & Mario Molina
in 1974, determined that CFCs destroy stratospheric ozone