Environmental Science 1021F/G Lecture Notes - Lecture 6: Sustainable Development, Potash, Candu Reactor
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Published on 9 Nov 2011
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ES1021F Lecture 6 (Week 7) – October 26
Freedman Chapters 12 & 13
Renewable vs non-renewable natural resources
Non-renewable resources are finite, and do not regenerate – they can only be ‘mined’
•As they are used, they are used up
•Their stocks are determined by the rates of discovery and of mining, and economic
factors affecting profit
•However, the lifespan of some non-renewables can be extended by recycling
•Time scales (Ex. Trees, oil)
Examples of non-renewable resources:
•Metals
•Fossil fuels
•Petroleum
•Natural gas
•Coal
•Oil-sand
Renewable resources have the ability to regenerate after they are harvested
•Potentially, they can be harvested forever without depletion
•The key is to not harvest them faster than their regeneration, or to otherwise
mismanage them
Examples of renewable resources:
•Forest biomass
•Fish, deer, and other ‘hunted’ animals
•Sunlight in all of its manifestations
•Flowing water
•Wind
•Biomass
•Photovoltaics
•Passive solar
•Renewable resources can regenerate, thus they are the fundamental basis of a
sustainable economy; one that can run forever without depleting its resource base.
•Non-renewables also have a role in a sustainable economy, but only if their depleted
stocks are made up by equivalent increases of renewable resources:
•For example, consider a power plant that generates electricity by burning coal
•The depleted potential energy of coal can be offset by fostering an equivalent net
increase of forest biomass
ES1021F Lecture 6 (Week 7) – October 26, 2011
•Emitted CO2 can be offset by a net increase in organic-carbon in tree biomass
Appropriate management can increase the potential harvest of biological
resources
•Biological resources include forest biomass, hunted animals, and agricultural crops
•Biological resources can be enhanced by various kinds of management actions, which
increase productivity, conserve existing biomass, or enhance quality
***How do you determine the yield/stock of a biological/renewable resource?
Management can increase biological resources
•Selective breeding and domestication can develop crop varieties that are much
‘improved’ in cultivation over their wild progenitors
ES1021F Lecture 6 (Week 7) – October 26
•Post-harvest regeneration can be enhanced by planting young stock, growing
perennial crops, and fostering good conditions for recruitment
•Growth rate can be increased by reducing competition, adding fertilizer or water, and
controlling pests
•Natural predators of livestock can be controlled
Degradation of renewable resources
Deforestation is a widespread problem
•Half of Earth’s original forest cover is now gone
•Another half may disappear in the next 50 years
•Deforestation is mostly caused by the conversion of forest to agricultural land
•Timber harvesting and urban conversion are also important
Deforestation is a terrible problem:
•Loss of a renewable resource – timber
•Damage to forest biodiversity
•Loss of ecological services (e.g., erosion control)
Severe depletion of fish stocks has become common throughout the world’s oceans
•Loss of cod stocks in Atlantic Canada
•Depletion of salmon runs in British Columbia
•This damage is caused by several factors:
•Over-fishing – catch rates that exceed regeneration
•Damage caused to breeding rivers of salmon
Depletion of fish stocks is a terrible problem:
•Loss of a renewable resource – fish as food
•Damage to biodiversity – by-catch and other problems
•Degradation of ecological services (e.g., salmon bring oceanic nutrients to the land)
Same format as deforestation, fishstocks
Excessive water withdrawals are depleting fresh water in many areas
•Groundwater is being rapidly ‘mined’ in arid regions
•The flow of some rivers is being reduced, or the hydrology modified, or the water
polluted
•This damage is caused by several factors:
•Excessive withdrawals for irrigated agriculture
•Use for cities and industry is also important
•Pollution by agricultural and industrial chemicals
Depletion of water reserves is a terrible problem:
•Loss of a renewable resource – water is crucial