Lecture 6 Natural Resources

10 Pages
Unlock Document

Western University
Environmental Science
Environmental Science 1021F/G
Marnie Branfireun

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 ES1021F Lecture 6 (Week 7) – October 26, 2011 • Damage to aquatic biodiversity • Degradation of ecological services associated with hydrology Economic growth vs economic development; the nature of a sustainable economy • Economic growth is achieved by increases in both population and per-capita resource consumption • Sustainable development refers to an economy that uses natural resources in ways that do not deplete them or otherwise compromise their availability to future generations • Ecologically sustainable development additionally ensures that the human economy does not cause other species or natural ecosystems to become extinct or endangered The human economy is clearly non-sustainable • It is aggressively depleting the stocks of both non-renewable and renewable resources • Awful damage is being caused to biodiversity and to ecological services Consider, for example, the Canadian economy: Non-renewables are the major source of commercial energy and of materials • • The exploitable stocks of non-renewables are being rapidly depleted • The stocks of many renewables are being depleted • Much of our native biodiversity is at risk E
More Less

Related notes for Environmental Science 1021F/G

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.