Review

3.6 Water Resources 2.5% of the Earth’s water is fresh water. – 70% of that is ice caps and glaciers – Almost 30% is ground water – Remainder is lakes, rivers, soil water, atmospheric water vapor, and biota – Direct access to only 0.3% of the total. – Atmospheric water vapor is only.001% – All together referred to as the HYDROSPHERE

Turnover Time Time it takes for a water molecule to traverse the water cycle (hydrologic cycle) – Longest turnover time: a molecule in the polar ice caps – Shortest turnover time: biological water – If water is turned-over within a year, it is a renewable resource. – Ground water is not renewable – Drilling wells in Aquifers, while producing a lot of water, leads to depletion of a non-renewable resource.

Sustainable water use: Cities: – More efficient buildings—use of recycled rain water for showers and sanitation – Water efficient appliances – More meters to help people use it more efficiently Rural areas: – Drought resistant crops – Use organic fertilizer to prevent eutrophication of the water

How water is used: 1=domestic 2=industrial 3=agricultural

Think about how Ecocentric vs Technocentric philosophies are involved in water usage projects.

Supply and Demand Irrigation Industry Increase population Global warming

Aquifer loss US: Kansas High Plains Aquifer Other countries using the water for irrigation of agriculture: Australia, Mexico, Spain and US France: loss of water to new agriculture Saudia Arabia over pumps water India—lots of loss for agriculture

3.7 Limits to Growth 1.population 2.natural resources 3.pollution 4.agricultural production 5.industrial production

Limits to Growth Model Food induced output and population grow exponentially until diminishing resources slow industrial growth. Population and pollution continue. Population growth is halted by increased death due to lack of resources. If present trends continue, limit to growth in 100 years.

Limits to Growth Model BUT: this is world wide. Ignores spatial distribution of population, resources, etc. Alternative: SUSTAINABLE LIMITS TO GROWTH

Sustainable Limits to Growth Model

Carrying Capacity For large populations, Stops once it hits the cc Small pops, short lifespans, high Fertility.

Can’t determine Human CC The range of resources is great Humans can substitute resources Lifestyle can change Technology Importing of resources

Malthus Population grows exponentially Food increases linearly but will not be enough.

Boserup In preindustrial society, new technology will lead to increased food production. Shifting cultivation— land only last 100 years Multi cropping—more than one crop per year. (more advanced too)

Increased food producition Drained marshes Reclaimed land from sea Cross bred cattle High yield plants Terracing Greenhouses Irrigation improvements New foods Artificial fertilizers Farming native species Fish farming

3.8 Environmental demands on human populations Ecological Footprints --an area of land and water required to support an individual or population. Opposite of Carrying Capacity

Increased Footprint Fossil fuels Technology dependence Imported resources Per capita food consumption high Meat rich diets Reduced resource use Recycling Reusing Improved efficiency of resource use Decreased pollution Export of wastes Increased CC due to technology Import of resources Using technology to increase land use Decreased Footprint

Calculating Footprints 1.Per capita food consumption (kg yr -1 ) Mean food production of local arable land (kg ha -1 yr -1 ) Large meat consumption causes higher grain consumption (food) 1.Per capita CO 2 emission (kg C yr -1 ) Net carbon fixation of local vegetation (kg C ha -1 yr -1 ) TOTAL LAND REQUIREMENT = sum of both equations.

Does not include: Aquatic or atmospheric resources Wastes other than CO2 Land in other countries for imports Replacement of productive land for cities