Medium Answers Flashcards
The Agricultural Revolution
10,000BP - 250BP
Slow, complex process of change - not simple linear
progression
By 1,500AD 95% had become farmers
Domestication (hunting, farming)
- selection and cross-breeding
Shifting cultivation
- slash & burn
Sedentary agriculture
- Sedentary sawahor wet rice cultivation emerged in China.
- -Irrigation vital to increase productivity in dry valleys.
The Agricultural Revolution heralded major change in human lifestyles, & in our relationship with the ‘natural’ environment.
Living sustainably
Population Increase vs Urbanisation With New Technologies means new ‘things’ in the environment ‘become’ resources. Increased speed of resource extraction Increased scale of exploitation Shift from reliance on renewable resources to non-renewable resources Expansion of Cash Economy Increase in Wealth Globalisation Two major concerns for future: • environmental degradation • resource scarcity Sustainable resource management is: • the practice of managing resources in a way that ensures continuing supply. - managing our use of the environment & resources to safeguard the life supporting capacity of the environment & the potential of resources to meet the needs of future generations. Environmental Law International Environmental Law We can aim to live sustainably… 1) reduce our carbon footprint 2) cut waste, & 3) be critical consumers.
Renewable energy sources
Preindustrial: energy sources mostly renewable e.g.: wood, flowing water, wind, animal
new sustainable energy sources e.g.:
-Renewable: Hydroelectricity (HEP)
• Provides 11% of NZ’s energy
• Water flow critical to HEP generation: drought a problem.
• HEP can be controversial: river diversions, reduced
recreational use of rivers, effect on forest/wildlife etc.
-Renewable: Wind
• Only provides c.1% of NZ energy generation
• Turbines need to be 30-130 m tall to harness higher wind speeds
• Must be in open country to be efficient/economic
• Visual impact (on ridgelines) & noise pollution
-Renewable: Tidal
• Need sites with high tidal ranges & fast flow
• First emerged in France in 1960s. May be more competitive in future. Expensive.
-Renewable: Solar
• Solar energy not yet extensively used in NZ (2013: 1.6% of NZ homes)
• Needs regular sunlight to be effective.
Earthquakes
Plate Tectonics
§ Tectonic plates move slowly around, ‘carrying’ continents.
§ Earth’s crust is divided into 8 main large tectonic plates.
Tectonic plates are driven by large convection currents in semi-soft mantle.
- Convection currents sink at subduction zones (along ocean trenches) & plates push towards each other.
Plate boundaries are areas of very high stress in Earth’s crust.
Sometimes pressure builds until there is sudden, massive fracturing & movement of rock along faults (zones of weakness), causing earthquakes.
Most earthquakes are shallow (5-15km), where rock is brittle.
§ When shockwaves reach Earth’s surface, they spread out as ripples across water & land.
§ Land may bulge, crack & then close again. Land can be uplifted or may sink.
- Direct e.g.: collapse buildings, powerlines, bridges etc., rupture dams, pipelines etc., cause rock falls, landslides, avalanches etc. Often cause injury/death.
- Indirect e.g.: gas leaks/falling power lines may start fires, burst dams may cause flooding, disrupted water supplies may lead to disease outbreaks.
Floods
Floods occur when the flow of a river cannot be
accommodated within the margins of its normal
channel
• As a result, the water spreads over the adjoining
ground
• Dissipates energy, Replenishes topsoil, Spreads seeds
• Erodes and deposits sediment
Discharge
• Quantity of water flowing at a given point
intensity × area × time
Catchment shape + Catchment steepness
High tide -Controlled by gravity of sun and moon Spring tide - At alignment of earth, moon, sun King tide - Alignment + lunar perigee Storm surge • Rise in water level in presence of a storm caused by two factors: Pressure set-up • Low pressure air allows water to expand Wind set-up • High winds pushing against water surface • Further raised by Large waves - Floods account for about 1/3 of all natural disasters - Cause more than 1/2 of fatalities due to natural disasters throughout the world - Are responsible for 1/3 of the overall economic loss Direct impacts • Injury/Loss of life • Damage to infrastructure and buildings • Electricity • Water supply • Business/Income disruption • Erosion/Deposition Indirect impacts • Cleanup and reconstruction costs • Destruction of crops/agriculture • Water-borne diseases • Malnutrition/Thirst/Hunger
Ozone depletion
Ozone depletion are caused by air pollution
Concentration of ozone (less than 10 parts per
million by volume), mainly 25-40km above Earth
• 90% of Earth’s ozone is located in the ozone layer.
• Mainly forms in tropics, when oxygen molecules are
bombarded by high energy UV radiation & are converted to O3.
Ozone layer naturally maintained through a delicately balanced cycle of ozone creation & destruction.
• Wind currents carry O3 from tropics towards poles à spreads around the Earth.
• In cool regions O3 is converted back to O2.
• Some natural O3 destruction also occurs due to volcanic eruptions & cosmic rays.
The ozone layer filters the sun’s ultraviolet (UV) radiation.
Two chemists (Rowland & Molina) theorised human emissions of chlorofluorocarbons (CFCs) could destroy
ozone, & increase UV-B reaching Earth’s surface.
CFCs: nontoxic, nonflammable chemicals containing atoms of chlorine, fluorine & carbon.
Ozone hole over Antarctica is worst in Southern hemisphere spring. (after winter)
- Consequences of ozone depletion
Increased penetration of UV radiation àproblems for:
Animals (including humans) e.g.
• higher risk of sunburn
• more skin cancer
• eye cataracts
• suppression of immune systems
• death of fish larvae
Plant life e.g.
• damages chlorophyll & slows photosynthesis
• reduces plant immunity to disease
Materials e.g.
• paints & plastics break down
