Climate Change Chapter 22 Atmosphere • The atmosphere the thin layers of gases surrounding the plant earth. • If Earth was the size of an apple, the atmosphere will be the skin. Atmospheric Layers • Troposphere (0-10km) • Where weather occurs • Temperature decreases with altitude • Stratosphere (10-45km) • Temperature increases with altitude- very stable • Ozone layer absorbs UV • Mesosphere (45-80km) • Temperature decreases with altitude • Thermosphere (80-500km) • Gases in thin air absorb x-rays and short-wave UV radiation = very hot • Source of aurora • Exosphere (500km and up) • Outermost layer • Atmosphere continues to thin until converges with interplanetary space Weather vs. Climate • Weather – A description of short term physical conditions of atmosphere. • Climate – A description of long term weather pattern of a particular area. • Temperature • Humidity • Wind • Rainfall What changes climate? • Changes in: • Sun ’ s output • Earth ’ s orbit • Drifting continents • Volcanic eruptions • Greenhouse gases Measuring Carbon Dioxide in the Atmosphere • There is a carbon dioxide detector in Mauna Loa in Hawaii.
• This allows measurements far away from cities and forests. • The winds over Mauna Loa have come thousands of miles across the Pacific Ocean, swirling and mixing as they traveled. • Keeling ’ s first measurement, in March of 1958, was 0.0314 percent. • Slightly higher in the winter. • Slightly lower in the summer. • Why? • These levels have rose steadily over the last 50 years. Future Carbon Dioxide Levels • Increasing CO 2 emissions, especially in China and developing countries • Likely to double within 150 years: • Increased coal usage • Increased natural gas usage • Decreased petroleum usage (increased cost and decreasing supply) Past Temperatures Measurement • Proxy – a method that approximates a particular measurement (e.g., temperature) • Tree rings • Ice cores • Pollen records • Plant macrofossils • Sr/Ca isotope data • Oxygen isotopes from speleothem calcite (stalactites and stalagmites) How Does Global Temperature Affect Rain? • The amount of heat in the atmosphere directly affects the movement of water. • Warm air containing evaporated water rises higher into the atmosphere. • Warm air is less dense than cool air. • As warm air rises, heat is released into the atmosphere and the water vapor condenses. • The condensed water then falls as rain or snow. Sea-level Rise Projections: A Few Inches to a Few Feet • 2 ft: U.S. would lose 10,000 square miles • 3 ft: Would inundate Miami • Affects erosion, loss of wetlands, freshwater supplies • Half of the world ’ s population lives along coasts 2007 Conclusions • Warming of the climate system is unequivocal • Very high confidence that global average net effect of human activities since 1750 one
of warming • Human-caused warming over last 30 years has likely had a visible influence on many physical and biological systems • Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21 st century that would very likely be larger than those observed during the 20 th century. ” What Can We Do? • Produce more fuel-efficient vehicles • Reduce vehicle use • Improve energy-efficiency in buildings • Develop carbon capture and storage processes • Triple nuclear power • Increase solar power • Decrease deforestation/plant forests • Improve soil carbon management strategies Legislation • Cap-and-Trade System • A limit on the amount of carbon dioxide any specific factory or power plant can produce. • Permits (or credits) are required depending on how much carbon dioxide is emitted. • An organization can purchase additional credits from other organizations that do not need them.
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