Global Change and a Sustainable Future Chapter 19
Global Change Result of human activities a. placed increased demands on natural resources b. emitted greater amounts of gases (CO 2, N, and S) c. agricultural methods - fertilizers and pesticides d. challenges of waste disposal, sanitation, and disease
Global Change a. “changes that occur in the chemical, biological, and physical properties of the planet” b. natural causes ex) Global temperatures c. anthropogenic ex) emissions from coal-burning power plants and incinerators (release of mercury)
Global Climate Change a. “changes in global climate” b. natural causes ex) El Nino years, alters patterns in temperatures and precipitation c. anthropogenic ex) fossil fuel combustion, deforestation Global Warming * warming of the oceans, landmasses, and atmosphere
The Sun-Earth Heating System
Greenhouse Effect 2 most common gases in atmosphere a. N 2 and O 2 b. not greenhouse gases Global Temperature a. with greenhouse gases (14C) b. without greenhouse gases (-18C) Greenhouse GasGlobal Warming Potential Duration in Atmosphere H 2 O (water vapor) **<19 days CO 2 1Highly variable CH years N 2 O (nitrous oxide) years CFCs (don’t exist naturally) 1,600 to 13,00055 to >500 years
Sources of Greenhouse Gases * natural sources SourceGas Volcanic eruptionsCO 2, ash (absorbing sunlight) Decomposition and digestionCH 4 (wetlands, termites) DenitrificationN 2 O in low oxygen situations EvaporationH 2 O (land) EvapotranspirationH 2 O (plants)
Anthropogenic SourceGas Fossil FuelsCO 2 Agricultural practicesCH 4 and N 2 O DeforestationCO 2 LandfillsCH 4 Industrial production of chemicals CFCs -phased out by Montreal Protocol - HCFCS introduced but still have high Greenhouse Warming Potential
Ranking of Anthropogenic Sources GasTop Sources CH 4 Digestive processes of livestock, landfills, production of natural gas and petroleum N2ON2OSoil receiving synthetic fertilizers, manure, nitrogen- fixing crops (alfalfa) CO 2 Burning of fossil fuels (94%)
Changes in CO 2 and Global Temperatures Increasing CO 2 Concentrations a. Charles David Keeling 1. Mauna Loa Observatory 2. CO 2 levels vary seasonally and increase from year to year - seasonal (photosynthesis) - annual increase (fossil fuels and deforestation)
Developed v. Developing a. consumption of fossil fuel is greatest in developed (leads to greater production of CO 2 ) b. Emitter of CO 2 1. China 2. U.S. c. per capita of CO 2 1. Australia 2. U.S. 3. Canada
Global Temperatures Since 1880 a – increase of 0.8C (1.4F) Global Temperatures the past 400,000 years a. indirect measurements used 1. species composition (foraminifera) 2. chemical analysis of ice b. rapid increase of CO 2 in past 50 years c. CH 4 and N 2 O in addition to CO 2 rose dramatically (Industrial Revolution)
Feedbacks Increasing or Decreasing Impact of Climate Change Positive Feedback Loop a. intensifies change ex) rise in temperatures Negative Feedback Loop a. dampens change ex) plants response to increases in atmospheric carbon
Consequences due to Global Warming Impact of Global WarmingEffect Global Warming has it Polar Ice Caps Large openings in the ice Over next 70 years, Arctic warm by (4C- 7C) Glaciers Melting (lack of reliable water supply) Ex) Glacier National Park Permafrost Melting; Tundra and Boreal Forests Shrinks lakes, unstable surface for structures, release of CH 4 Sea Levels Increase in total volume due to melting of glaciers and ice sheets, ocean becomes warmer and expands Potential flooding of low-lying land Heat Waves* Increased energy demand for cooling, risk of death, damage to crops, increases use of irrigation Precipitation Patterns* Warmer temperatures drive increased evaporation from Earth’s surface Diseases* Warmer temperatures allow for easier spread of disease geographically (ex-West Nile)
Kyoto Protocol Control emissions of greenhouse gases Countries agreed to different levels of emission restrictions Grounded on precautionary principle - reducing emissions - removing CO2 from atmosphere * carbon sequestration U.S. has not yet ratified the agreement