Chapter 13 Human Impacts on Natural Systems Climates and biomas: global warming, acid rain, and ozone Abuses of land and vegetation: deforestation, desertification, and soil erosion Problems of water supply and water quality Disposal of solid and toxic wastes. http://www.usatoday.com –accessed date: 4/21/08
Physical Environments and Cultural Impacts • Modest and substantial modifications of of nature (13.1), shopping mall/office buildings - new cultural creations • Biosphere: atmosphere, hydrosphere and lithosphere. Climate, Biomes, and Change • Global climate patterns - determined by solar energy (13.2a and b), land and water distribution, ocean/atm. currents - controls biomes (major communities of plants and animals occupying extensive areas of the earth’s surface in response to climatic conditions). • Ecosystems - self-regulating adapted to local combinations of climate, topography, soil, and drainage conditions.
Global Cooling/Warming.. • Icebox effect - Global Cooling? - aerosols reradiate incoming solar energy back to space. Aerosols from dust storms, forest fires, or volcanoes. Two cool summer cases 1) 1815 due to Tambora, Indonesia, volcano eruption and 2) Mt. Pinatubo, Philippines, in 1991. Aerosols also produced from human activities (power plants, vehicles, factories). global cooling became noticeable in 1940. • Cooling trends found in large industrial cities in China. • This fear was replaced by other concerns in 80s 1) Global Warming, 2) Acid Rain, and 3) Ozone depletion
Global Warming • Started in Industrial Revolution, burning coal, petroleum, gas, vehicle emission produce CO2 and water vapor. Deforestation cause less trees to trap CO2 • “Greenhouse Effect” - is needed, but it is too much with increased CO2. (13.5) • 2.5 - 10.4 oF increase in temperature predicted in this century. Climate prediction is not an exact science. • Current CO2 level – 388.79 ppmv • Arctic ice melt (might disappear by the middle of 21st century) • Continental ice melt will cause sea level rise 0.5 to 3 meters, (Maldives - 80% of land are less than 1 meter above sea level), http://www.guardian.co.uk/environment/2008/nov/10/maldives-climate-change
Global Warming? • Carbon can be reduced by “sinks” - forest, soils and oceans. • A 40% decrease of precipitation in corn belt is predicted, reducing productivity. Such reduction of precip will have water supply disasters in western states. • Beneficial effects to northern countries, such as parts of Russia, Scandinavia, and Canada. Longer growing season in the north (12 days longer in 45oN), latitudinal temperature difference is reduced. • Impact on developing countries is high but uncertain. Global productivity could increase by up to 30% due to the doubling of CO2, in terms of fertilization effect. But, lower latitude developing countries have higher impact due to increased heat and higher evaporation rates. Impact of climate change on diversified developed countries are likely to be small. • Kyoto Protocol - two goals 1) clean development credits 2) emissions trading. If fully implemented, would not slow warming trend too much, according to Climate Change Panel • Increased precipitation in upper-latitude (recorded in Antarctica) would increase fresh water flux to sea water which, then dilute the density of seawater. This will affect the circulation of heat globally. Polar temperature can drop dramatically. • Greenhouse Gases and Health – EPA’s report
Idaho wind power map: http://www.inl.gov/wind/idaho/i/idaho_map.jpg
Acid Rain • The average pH of normal rainfall is 5.6. • The taller chimneys only creates more problems of acid rain (13.7) - Sulfur dioxide and nitrogen oxides mixed with water creates sulfuric and nitric acid carried to distant areas • Mostly in developed countries. Its corrosive effects on marble and limestone buildings and metals (13.8). Trees at higher elevations, disappearing fish, increased heavy metals in drinking water supplies, loss of aquatic life • Crop damage decrease yields of food production, death of soil microorganism • US and Canada, 2,000 lakes totally dead to fish life and another 15,000 in danger (13.9)
Ozone Depletion • Ozone in troposphere block UV reaching earth, destruction in higher atmosphere will cause DNA and other skin cancers. • 1986, ozone hole was found in Antarctica. (occur in late August and October), Hole spread to S America and Australia. Mostly from CFC (winter in Antarctic lack of sunlight, CFC destroying O3 easily • 1987 Montreal Protocol- developed country stopped using CFC and 2010 for developing countries. • Surface Ozone - accumulation of ozone, harm to plants, reduced wheat yield - produced in photochemical smog by sunshine and vehicles emission. Destruction of forest in Europe caused by surface ozone.
Land Use and Land Cover • Minor LULC change - Methane gas increased by rice paddy, and increasing herds of cattle, fertilizer applications increase nitrous oxide, affecting the algae growth and water reflectivity and evaporation rates. • Major LULC changes from deforestation and loss of grassland to farmland - alter temperature and water balance - increasing release of CO2 to the atmosphere. • Growing pop. more agr. land needed, expanded demand for fuel and commercial wood, and midlatitude market for beef - cause loss of tropical rain forest in Asia, Africa and Latin America. • 45% of original forest land was lost in these area. every year a size of Missouri are lost. Three global concerns are raised:
Tropical Deforestation • Three global impacts: • 1) Forest act as carbon storage and oxygen replenishers • 2) forest destruction change surface and air temperature, moisture content, and reflectivity. Estimated 3 to 5o C increase due to the clearing of S American forest. • 3) loss of biodiversity of the planet. Food sources in rainforest and storehouse of drug-yielding plants and insects will be limited. • Cutting trees in local area will increase flooding and soil erosion (13.11)
Desertification - the expansion or intensification of areas of degraded or destroyed soil and vegetation cover. • Climate variation, rather than human abuse of the land, is thought to be the major influence on dryland ecology and the shifting margins of deserts. • 1/4 of the earth’s surface is qualified as degraded semi-desert • 40% of the non-desert land is in danger of human-induced desertification. • Food production drop 50% between 1950 and 1990 in area with most extensive desertification - Algeria, Ethiopia, Iraq, Jordan, Lebanon, Mali and Niger. Mali may be the first country in the world rendered uninhabitable by environmental destruction (13.14). • Deforestation,farming, and grazing cause desertification
Soil Erosion • Soil - the top 1 ft of surface, is complex mixture of inorg/org matters, living organism, water and air; formed from phy/chem decomposition of rock material and the decay of organic matter • Under natural conditions, the rate of soil formation equals or exceeds the rate of soil erosion. • Farmers practice to keep top soils: • Rotation to preserve fertility or to provide cover to protect soil • Fallowing leaves a field idle in one year, a) in tropical wet regions, to renew soil fertility of the swidden plot, b) in semiarid areas , to accumulate soil moisture for next year. • Terracing provide layers for cropland, and breaking speed of water flow
Soil Erosion • 40% of the world’s agr. land is seriously degraded - caused decreased yields of cultivated fields and in increased stream sediment loads and downstream deposition of silt. • 15-17 million acres of existing arable land are lost to erosion each year. • The most sediment-laden of any waterway on earth - Huang River in China - 50% silt by weight.(Yellow River) • Terracingreduces soil erosion, but if farm on a 15% slope, soil cover will be lost in 10 years. • US lost 2 billion tons of soil each year to erosion. 1/3 land is in danger. 24 billion tons of sediments washed to the oceans each year. (fig 13.15) • Soil retention techniques: contour plowing, terracing, strip cropping and crop rotation, construction of water diversion channels, erecting windbreaks, practicing no-till or minimum tillage • Tennessee’s soil loss tolerance level – 5 tons/acre/year. Factors: slope, rainfall, land cover…. • Quiet Crisis - Agricultural soil depletion due to soil erosion, salt accumulation, and desertification.
Water Problems • Problems in water distribution, availability, and its quality. • Water is renewable resources, seen in hydrologic cycle (13.17) • 13.18 Precipitation distribution, 13.19 Water supplies in relation to the demands of the vegetation cover. • Irrigation accounts for 73% of freshwater use, 90% in poorest countries. 21% industrial use. recreational and domestic use account for the remainder. • Untreated sewer water pollute water in 90% of developing urban area. • 70% surface water in India are polluted. China’s 80% river are polluted, untreated water will be the source of impounded water in Three Gorges Dam (not too many WWTP systems in China)
Garbage Heaps and Toxic Wastes • “Middens” - refuse piles containing the kitchen wastes, broken tools and other debris of human settlement. (Lebanese Garbage Mountain) • Modern cultures differ in volume and character of their wastes, the more developed, the greater the volume and diversity of garbage. • US produce 2 kg/person/day garbage and rate is increasing. • Sanitary landfill site (13.24) - 75% of country’s municipal waste is disposed of. • Incineration - reduce volume of waste, produce electricity and air pollution - burn out 1/6 of US garbage from 110 incinerators. Dioxin toxic release in Japan is 3 times higher than in the US • Dioxin is formed by burning chlorine-based chemical compounds with hydrocarbons. (sources: paper mills, PVC, pesticides manufactures..)
Toxic /Hazardous Waste • EPA classified more than 400 substance as hazardous. • Groundwater is the most at risk of contamination from hazardous waste. 2% of US groundwater is polluted from hazardous wastes. • e-Waste: China, EU (not U.S.) proposed laws. • U.S. Ship E-Waste • China’ E-Waste • E-waste –youtube1, 2 • Facts and Figures on E-Waste and Recycling • Radioactive Wastes (Yucca Mountain, pg.521) • Half of low-level waste produced from nuclear power plants. (decay to safety level in < 100 years). Most in landfills. • High-level waste - remain radioactive for 10,000 years. Mostly from nuclear power plants’ “spent fuel” • Major toxic waste exporters: U.S., Germany, Australia, Britain, and Netherlands. • In 2005, estimated 50-80% recyclable waste was shipped to China, India and Pakistan • European waste to Baltic countries, Eastern and Central Europe • U.S. waste to Latin America • Britain waste to Asia
Yucca Mountain • In 1982, DOE (department of energy) was ordered to construct a permanent repository for spent fuel by 1998. Can it be open by 2010? • Three concerns: • Volcano and earthquake may cause groundwater to flood the repository. • Rainwater penetrate and dissolve waste which seep down to water table. • Too close to air force bombing range.