lecture 6: human environment relations Flashcards
Climate is a function of the interaction of many spheres:
atmosphere: gases
* hydrosphere: oceans, large bodies of water
* lithosphere: plate tectonics
* cryosphere: glaciers, ice sheets, snow cover
* biosphere: vegetation, animals, humans
the last glacial period:
all of Canada covered in ice expect for northern yukon
lower sea levels at that time exposed the bering land bridge
causes of climate change:
- variations in solar radiation
- changes in composition of the atmosphere
- changes in earths surface
- variations in earths orbit
variations in solar radiation
the sun tends to emit more energy during periods of high sunspot activity
sunspot:
a cool ration of high magnitude on the sun (dark and black)
* Sunspots occur in cycles and reach a maximum every 11 years
* sunspots are cool areas on the sun that are surrounded by faculae
* solar output changes on the order of 0.1 - 0.2% in relation to sunspot cycles
* more sunspots = increased solar output
faculae:
bright areas with high amounts of energy
Maunder Minimum:
a period with no sunspots; this corresponds to a time known as the little ice age
changes in composition
greenhouse gases
addition of greenhouse gases (CO2, water vapour, methane) increases global temperature
* CO2 has long residence time in the atmosphere – even though we are reducing CO2 effects will not be felt for decades
* A warming climate appears to be inevitable during our lifetimes
Ice cores
- width of an layer provides insight on the temp and snowfall of that year
- Each year a new layer of ice forms
- bubbles of air trapped in the ice
- Ice cores can provide data for up to 600,000 years in the past
denderochronology
- the study of tree rings
- wider rings = warmer or wetter years
- tree rings provide data up to 1000 years in the past
theory of plate tectonics
- the continents have moved over time
the collision of converging plates = an uplift and the creation of mountains - implications: affects wind, temp and precipitation patterns on surrounding landscapes
variations in earths orbit
The greenhouse effect: why does it exist?
greenhouse gasses allow solar radiation to pass through, but they also absorb infrared radiation from earth
* Main greenhouse gases: carbon dioxide, water vapour, methane
Milankovitch theory:
three seperate phenomena relating to earths orbit contirbute to climate change (3 cycles)
1. eccentricity: changes in the shape of the earths orbit from circular to elliptical, 100,000 year cycle (accounts for ice ages)
2. precession: wobble of earths axis, 23,000 year cycle
3. obliquity: changes in the tilt of earths axis, 41,000 year cycle
enhancement of the greenhouse effect:
the greenhouse effect itself is not a concern however the enhancement effect by humans is a concern.. why? - adding greenhouse gas = climate change
* increasing the amount of CO2 enhance the greenhouse effect.. why? Because more infrared radiation from the earth is absorbed in the atmosphere
* CO2 emissions are increasing in China and India as the economies in these countries continue to industrialize
ozone
- gas composed of oxygen with a pungent smell
- forms naturally in the stratoshpere
- forms in the troposphere by chemical reactions with other gases
Ozone in the stratosphere
important because 7% of suns radiation is ultraviolet
* layers protect us from UV rays
* UV rays can cause great damage to unprotected skin
destruction of the ozone layer
chlorofluorocarbons (CFCs) are the major reason for the depleting of the ozone during 1900s
* CFCs were found in inefficient appliances, spray cans, and industrial processes
* Non essential uses of CFCs were banned in north america
* ultraviolet radiation breaks up CFC molecules causing the release of chlorine
* chlorine destroy ozone
* A CFC molecule can remain in the atmosphere for many decades
* through CFCs have declined since 1970, there is little decline recognized in the atmosphere… why? Because of high residence time of CFCs
* decreased amounts of stratospheric ozone have resulted in increased cause of skin cancer (skin cancer rates have doubled since 1950)
montreal protocol (1987)
a highly successful worldwide agreement among countries to reduce CFC concentrations
Acid precipitation
precipitation that combines with pollutants that turn the precipitation acidic
* Main sources: sulfar oxides, nitrogen oxides
* effects of acid precipitation: slow tree growth, reduces fish population in lakes and erodes materials
* 14, 000 lakes in Canada are acidified
* PH scale is a measure of acidity —> 0-14, 7 is neutral and below 7 is acidic
* precipitation is naturally acidic (5.5)
* Most common in eastern north america
* canada - us air quality agreement
* nitrogen and sulfar oxides react with water molecules to form nitric and sulfuric acid
* Aquatic life cannot survive when PH < 4.8
positive feedback
process that encourages the continuation of the original process
Example specific to climate change:
less snow/ice decreases the reflectivity of solar radiation (cause snow is highly reflective)
* after snow/ice melts, more solar radiation is absorbed rather than reflected
* This process leads to warmer conditions
* the reason why polar regions are warming the fastest
loss of sea ice
- by 2050, remaining Arctic sea ice in summer is expected to be around ellesmere island and northern Greenland
- Since 1980, has declined by 30%
How do the climate models work?
- by solving a series of mathematical equations
What do the variables in the equations represent?
greenhouse gases, solar radiation, other climatological components
Kyoto protocol (1997)
a global agreement aiming to slow climate change
* objective: to reduce greenhouse has emissions to 5% below 1990 levels by 2010
Impacts of climate change
polar areas will warm the most
* boreal forests will expand northward, agriculture will shift northward
* precipitation patterns will change affect in habitats
* increased intensity of tropical storms and hurricanes
sea level rise
as sea levels rises, erosion affecting areas inland; some eroding 10m
* Sea level is projected to rise as global climate changes and ice sheets continue to melt
* Vancouver, miami, new york
* 80% of then country is less then 1m above sea level
* Seawalls have built around the islands
impacts on humans
climate change affects food production, tourism and human health
* Most common impact is the speed of malaria
Impacts on biodiversity (warming temps will)
- bleaching corals
- Loss of flora and fauna
- extinction risk for polar bears
what is the relationship between humans and nature?
- humans are simply one component of the natural world
- Humans are separate from nature
our relationship with nature dictates our actions
- living in harmony with nature (sustainable development)
- Exploiting nature for economic growth (ignore the true costs of resource extraction)
The realities of natural resources
- many natural resources are finite
- using resources creates waste products
problem: developed countries have created societies and economies which these realities are neglected
* there is resistance to changing the way resources are extracte
The precautionary principle: examples of its use
- insurance policies
- preventative maintenance (if there is risk we should still act even if their is uncertainty) there is a social responsibility to protect the people and the environment from harm
Applied to environmental change: decide between harm and cost of inaction compared to wasted costs of acting unnecessarily
* the depletion of the ozone layer showed that surprise problems can develop rapidly and unexpectedly
Photovoltaics
convert light directly into electricity
wind energy:
- creates 6MW of power (1000 small buildings)
- renewable and pollution free source of energy
- Viable in areas with constant moderate winds
Issue preventing the growth of wind farms:
- habitat distruption
- appearance
- Noise
hydroelectric energy: implications of large projects
- loss of land due to flooding
- displaced population
- leaching
- destruction of habitats
* smaller generators on smaller rivers are more desirable but can be very costly
