ENV200 Midterm Flashcards
1
Q
Science
A
- An approach for understanding the world (how things work)
- Scientific assumptions, scientific method, scientific uncertainty
- Hypothesis: temporary explanation for a scientific question -> evolve and change
- Scientific theory: used in identifying a grand scheme backed by evidence
- Basis for environmental action
- Highlights the interconnectedness of the natural world
- Scientifically literate society is better positioned to confront problems
- Promotes critical thinking
Vital to ensure the recognition and scope of a problem
2
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Environmental Science
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- Environment: circumstances and conditions that surround an organism
- Science: derived from knowing; process for knowledge production
3
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Challenges of Environmental Science
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Is science unbiased? money/power determine value? Demographics affect subject interest
4
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Science in Society
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Action on environmental issues must begin with examination of relevant scientific information
5
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Recent scientific debates:
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- Evolution v. Intelligent Design: natural selection/adaptation v. god created perfect creatures
- Climate Change: science misrepresented by parties
6
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Science and Media
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Media dramaticizes news; uneven coverage
7
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Human Population
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- How many people live on earth and how many humans can earth’s resources support?
- Variables such as: consumption, economic growth, comfort, livability, etc.
8
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Current world population
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8B
9
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J - shaped curve of population growth
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initial slow growth, then rapid and exponential increase -> due to industrial revolution
10
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Rich and Poor: Global North Economies
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- Use 20% of human population
- slow/negative population growth; higher rates of consumption/resource use
- Higher life expectancy, wealth, resource use, and waste
- Use majority of world’s aluminum, timber, energy, meat eaten, water
11
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Rich and Poor: Global South Economies
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- 80% of human population
- high population growth; high levels of resource use
- Lesser life expectancy, wealth, resource use, and waste
- 8% lives in extreme poverty
12
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Natural Resources: Nonrenewable
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limited supply (ex. Fossil fuels, coal, oil, nuclear power)
13
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Population and Resources
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- Economic growth is tied to resource exploitation
- Overpopulation = too many people, not enough resources
- Consumption overpopulation: use far more than necessary
- Culture of consumption is becoming a trend
14
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Natural Resources: Renewable
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virtually unlimited (ex. Solar power, wind power, hydropower)
15
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Sustainability
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Earth’s natural income: solar capital and natural capital provided by earth
16
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Living sustainability
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living off the earth’s natural income without depleting or degrading it; Implies environment will function indefinitely
17
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Measuring Sustainability: Ecological Footprint
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amount of productive land and ocean needed to provide a person with food, energy, materials, water, and waste disposal
- US has the biggest footprint (per capita and total)
18
Q
What footprint can earth support?
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- Area of earth / population = 11.4B hectares / 8B people = 1.4 hectares pp
- Current average footprint = 2.7 hectares pp
19
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Environmental Impact Formula
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= population x affluence per person x technology used and its environmental effects
20
Q
Sustainable Development
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Economic growth that meets the needs of the present, but does not compromise future generations, and can occur within the earth’s capacity
21
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Growth Rate
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= (birth rate + immigration rate) - (death rate + emigration rate)
22
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Exponential Population Growth
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Constant reproductive rate that occurs under optimal conditions (J shaped curve)
- Ex. Post Industrial Revolution
23
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Environmental Resistance
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Unfavorable environmental conditions that control population growth rate
24
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Carrying capacity
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- Largest population that can be sustained indefinitely
- Always changing; if too high, can crash
- Earth’s carrying capacity: 4-16B people
- Why such a large range? Depends on consumption levels/ENV resources
25
Human Population
Why such a large increase?
- Modern technology = longer/better lives
- Thomas Malthus: hypothesized that population would be kept in check
- Limits to Growth: 1972 book exploring economic and population growth
25
Projecting Future Population
- World growth rate has declined slightly
- At the end of the 21st century, there will be 0 population growth
- The birth rate will = death rate
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Demographics
Study of populations
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Highly Developed Economies Demographics
Low birth rates/low infant mortality/long life expectancy/high gross national income and purchasing power parity
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Less Developed Economies Demographics
high birth rates/high infant mortality/ short life expectancy/ low gross national income and purchasing power parity
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Demographic Transition
Country moves from high birth and death rates to low birth and death rates
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Demographic Transition: Stages
- Preindustrial: women have many children but infant mortality rate is high, so population grows slowly
- Transitional: lower death rates due to technology improvements; birth rate is high and population grows rapidly
- Industrial: decline in birth rate slows population growth despite low death rate
- Postindustrial: people desire smaller families; population grows slowly or not at all
30
Age Structure
Number and proportion of people in each age group in a population
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Age Structure Diagrams
- Pyramid shape diagram: rapid growth (ex. Nigeria)
- Tapered base diagram: slow growth (ex. USA) or decline in growth (ex. Germany)
- These diagrams explain population momentum: why a population grows even if fertility rates decline
32
Diagram Momentum
oldest people die and eventually leave diagram, short bar at the top is replaced by a longer bar below and so on down, the population continues to grow as long as young cohorts contain more individuals
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Future Population Growth
Determined by pre reproductive individuals
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Dependency ratio
- measures size of dependent population (old/can’t work) in relation to working population
- Sum of people <15 and >65 divided by # between 15 and 65
- The larger the ratio: greater potential social support requirements
- Developed vs. Developing Economies (south america, africa, asia)
35
Planet Earth Through the Ages
Earth is 4.5 Billion years old
- Has had many phases, and many names (hadean, archean, paleozoic, mesozoic, etc.)
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Earth’s Life Cycle
- Earth is a molten mass, but then starts to cool enough for rocks to form
- After some time, oceans accumulate and sets up the hydrologic cycle
- Primitive lifeforms begin to appear (earth still has no oxygen at this point)
- Primitive plants create enough oxygen to allow the formation of the ozone layer
- At 50% of earth’s lifetime, Precambrian era begins
- At cambrian era, prehistoric creatures like: fishes, land plants, amphibians, insects, and reptiles appear
- Dinosaurs appear
- Humans appear
- Common period
- Industrial Revolution
37
Current Era
holocene epoch of the quaternary period
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Anthropocene
Period of history dominated by human activity
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The Earth: Crust
0-100 km deep; surface of the earth
- part of lithosphere
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The Earth: Mantle
malleable ‘flesh’ of the earth
- part of lithosphere
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The Earth: Core
solid iron/molten core
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Convection Currents
earth’s internal heat drives convection currents that push the mantle’s soft rocks upwards and it warms and downwards as it cools
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Plate Tectonics
- As the mantle moves, it drags large plates of crust along with it
- Earth’s surface is NOT solid, and is composed of 12-15 plates that move
- Move 2-15cm a year
- Continents are passengers on plates (african, eurasian, arabian plates, etc)
44
Plate Tectonics: Influence on Climate
- Changing location of continents, changing topography, determines global biogeography, influences atmospheric chemistry and transparency
- Global Biogeography: N/S hemisphere flora and fauna are distinct (NH more modern, SH more ancient)
- Island biotas are peculiar and vulnerable; usually volcanic and occur over hotspots
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Why and How are the plates moving?
- Convergent, divergent plate boundaries; transform plate boundary; continental rift zone
- Plate boundaries marked by: Earthquake Fault Lines, Ring of Fire, Mountain Belts
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Systems
- Complex network of interlinked systems make up environment
- Network of relationships among parts that interact and influence one another
- ENV solutions depend on understanding systems
- Often illustrated with boxes and arrows that show: inflow, pools, outflows, and fluxes
- Earth Systems are usually: cyclic, hierarchical, have no human interference
47
Residence Time
- Average amount of time that a particle spends in a system
- = capacity of system / rate of flow of particles through the system
- Reciprocal of residence time = turnover rate = 1 / R
48
Positive Feedback Loops
- change becomes more pronounced over time (ex. Exponential population growth)
- Means that the system is changing: not necessarily good or bad
49
Negative Feedback Loops
- change becomes inhibited over time/returns to original (ex. Pendulum, predator-prey population, body temperature)
- Change is reduced which leads to stability
50
Energy
- Capacity or ability to do work
- Flows through ecosystems
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Thermodynamics
rules by which energy is transformed from states
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First Law of Thermodynamics : Conservation of energy
- Energy cannot be created or destroyed, but it can change forms
- Totality is constant in the universe (never added/subtracted)
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Photosynthesis
light/solar energy utilized by plants -> they trap energy and convert it into chemical energy -> eventually transferred into humans through eating
54
Second Law of Thermodynamics: Heat Energy
- When energy changes forms, some of that energy will be converted into heat energy
- Heat is a less usable form of energy
55
Biogeochemical Cycles
- Involves biological, geological, and chemical interactions
- Matter cycles through ecosystems -> one ecosystem to another and one organism to another
- Living organism -> abiotic organism (Ex. CO2 in coal is absorbed by plants which is then consumed by humans)
- Cycles indefinitely throughout time and space (elements/units: carbon, hydrologic, nitrogen, phosphorus)
- Can a carbon atom that existed in a dinosaur be in my body right now? YES
56
Carbon Cycle
- Essential component for life: forms proteins and carbs; exists in gas, solid, and liquid forms
- Can stay in 1 form for a very long time (ex. Fossil Fuels residence time)
- Cyclic: C02 -> Photosynthesis -> sugar -> cellular respiration -> CO2
57
Hydrologic Cycle
Ocean -> atmosphere -> land -> atmosphere
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Nitrogen Cycle
- Forms proteins and DNA
- Atmosphere is 78% nitrogen (N2), but this form is unusable because it is bonded too tightly
59
Nitrogen Cycle Steps
- Nitrogen fixation: N2 converted into ammonia or nitrate by nitrogen fixing bacteria in legume roots
- Nitrification: ammonia is converted into nitrate, which is the preferred nitrogen form for plant uptake
- Assimilation: plants absorb nitrate from soil and incorporate it into proteins/acids which transfer nitrogen into the food chain
- Ammonification: decomposers break down dead organisms into ammonia which goes back into the soil for reuse
- Denitrification: nitrate is converted back into nitrogen gas which is released back into the atmosphere
60
Phosphorus Cycle
- No atmospheric pool; phosphates are found in earth (mined from sea beds)
- Phosphates used in DNA and ATP as chemical energy
- Affects plant growth and the food chain
- Land -> Organism -> Organism -> Land
- Phosphorus tied to decomposition of lifeforms
61
Atmosphere
- Gaseous envelope covering earth; mostly oxygen and nitrogen
- It took 2-3B years to form the atmosphere and ozone layer -> this made the earth temperate enough for biodiversity to flourish
- Atmosphere is very thin and vital in protecting earth
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Atmosphere Layers
- Troposphere: closest to humans
- Stratosphere: ozone resides; commercial jets fly here; absorbs most UV rays
- Mesosphere: coldest layer where meteors burn out
- Thermosphere: low atmospheric density with varying temperatures; reflects radio waves
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Atmosphere Temperature
Temperature differences: each layer has different and fluctuating temperature (not linear)
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Atmosphere Composition
nitrogen (78%), oxygen (21%), Argon (0.93%), C02 (0.04%), Other Gases (0.03%)
65
Ecosystem Services from Atmosphere
- Atmosphere protects earth from UV rays
- Allows light (sunlight) and some infrared (heat) to penetrate and keep life sustained
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Oxygen Balance from Atmosphere
atmosphere -> sunlight -> photosynthesis -> oxygen -> life
67
Sun’s Energy Output
- Based on sun’s energy output and distance from sun, earth’s average temperature without atmosphere should be -18C
- But it is actually 15C
- Why the 33C gap?
- Atmosphere is a blanket that traps radiation
- Planet Temperature depends on: distance from sun, density, atmospheric conditions, etc
68
Solar Radiation
Atmosphere blocks most harm, lets in small and necessary amounts of infrared rays
69
Electromagnetic Spectrum
Gamma, UV, X-Ray, Ultraviolet, Visible, Infrared, etc.
- On one end of the spectrum: Gamma and X-Rays which are high energy, very harmful, and has short wavelengths
- On the other end of the spectrum: Infrared and Radio rays are less energy, less harmful, and have long wavelengths
- Visible light passes through the atmosphere undiminished
- Ultraviolet light is absorbed by ozone in the stratosphere
- Infrared radiation is absorbed by carbon dioxide and water in the troposphere
70
Electromagnetic Radiation
When a wavelength of EMR moves out of the vacuum of space and enters the atmosphere; the ff could happen
- Nothing: passes through the clear atmosphere
- Reflected: by the earth and atmosphere
- Absorbed: by the earth’s surface and warms it / absorbed and re-emitted by GHG
- Absorption of high-energy wavelengths = re-emission of low-energy wavelengths + heat
- Numerous substances can absorb EMR: land masses, water, atmospheric gases
71
Earth Atmosphere Energy Balance
- 45 units of warming on earth comes from solar radiation (sun only gives ½)
- Majority of warming is due to the trapping of infrared radiation from the atmosphere
- GHG are needed in the atmosphere, but too much is harmful
- Infrared radiation is more impactful than solar radiation
72
The Sun and Latitude
- The sun does not reach all places uniformly
- Because earth is round / on a tilt, so temperatures vary locally
- It is the same intensity of radiation, but different levels of dispersion
- Tilt of Earth’s Axis: heat is absorbed more at equator, less at poles
- At high latitudes, sun rays are dispersed + wintertime light is more dispersed
- Earth orbit changes proximity to sun = summertime light is concentrated
- At equator, proximity to sun rarely changes + always hot and sunny
- Axial Tilt is the best explanation for seasonality
- Earth is closest to sun in January (Perihelion) and farthest in July (Aphelion)
- Conditional to tilt, not distance
73
Hadley Cell
- Temperature differences drive circulation: atmospheric circulation moderates surface temperatures
- As air cools and condenses, its density increases and it falls back to earth
74
Hadley Cell Process
Sun heats surface of earth -> warm ground heats air -> warm air rises and carries heat upwards -> air cools as it rises -> heat from air is radiated into the atmosphere -> warm air condenses into clouds/rain/snow -> drops back down in the form of weather
75
Weather patterns around earth
wet and dry zones at different latitudes due to moisture movement/cycling
76
Hadley Cell circulation consequences
creates major wind systems, creates differential pressure and precipitation patterns
77
Atmospheric Circulation: Coriolis Effect
- Earth’s rotation from W -> E
- Moving air or water is deflected
- Northern Hemisphere is deflected to the Right
- Southern Hemisphere is deflected to the Left
- Influences wind direction
78
Atmospheric Circulation: Winds
- Small scale, horizontal movements
- Result of atmospheric pressure and earth’s rotation
- Prevailing winds: major surface winds that blow continuously
(Polar easterlies, westerlies, trade winds)
79
Atmospheric Circulation: Polar Vortex
- Prevailing wind pattern that circles the arctic all the way around earth
- Normally keeps extremely cold air bottled up towards the north pole
- But vortex can weaken and allow cold air to extend across regions
80
Atmospheric Circulation: Oceanic Conveyor Belt (Thermohaline Circulation)
- Transfer of warm water from pacific ocean to atlantic ocean as a surface current
- Cold dense water sinks and slowly floats from atlantic ocean to pacific ocean as a deep water current
81
Atmospheric Circulation: Why do countries at the same latitude have different temperatures?
- Due to ocean circulation: oceanic conveyor belt/thermohaline circulation
- Temperature and salinity (mixing fresh and sea water affects density) move water
- Hot and Cool water currents sink and rise as they move around the continents
- Transfer of warm water from the pacific -> atlantic ocean as surface currents
- Cold dense water sinks and flows from the atlantic -> pacific ocean as a deep water current
82
Ozone: Essential protection in Stratosphere
- Naturally produced and shields earth from radiation; essential for life on earth
83
Effects of Ozone Depletion
- More UV reaches earth; damage to ecosystem; human health issues (cancer, cataract, etc)
84
Ozone: Pollutant in Troposphere
- Ground level ozone: unnatural and consequence of secondary reactions (burning of fuels, smog, etc)
- Affect respiratory health of humans, plant/animal wellbeing
- Made up of: NOx + VOCs as a result of burning/combustion
- When exposed to sunlight, they turn to ozone (sun and heat is a trigger)
85
Causes of Ozone Thinning
- Production of chlorofluorocarbons (CFCs); chemicals that leak out of appliances
- Eventually banned
86
Recovery of Ozone Layer
- 1987 Montreal Protocol: phase out CFCs
- Industry substitutes of CFCs like hydrofluorocarbons did not harm CFCs, but they are GHG
- Ozone still being depleted because CFCs have long residence time in the atmosphere
