PowerPoint Chapter 16

PowerPoint Chapter 16 - Climate Change and Ozone Loss...

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Unformatted text preview: Climate Change and Ozone Loss Chapter 16 Key Concepts Changes in the Earth's climate over time How might the Earth's temperature change in the future? Factors affecting the Earth's average temperature Benefits and harmful effects of a warmer Earth Slowing and adapting to rising temperatures Ozone depletion and human influences Slowing and reversing ozone loss Past Climate Changes Past global temperatures Causes of climatic changes Glaciations and warmer interglacial periods Earth's natural greenhouse effect (Fig. 5-5, p. 82) Average Global Temperature over the Past 900,000 Years Average surface temperature (C) 17 16 15 14 13 12 11 10 9 900 800 700 600 500 400 300 Thousands of years ago 200 100 Present Fig. 16-2a, p. 369 Temperature Changes Over Past 22,000 Years 2 Temperature change (C) 1 0 1 2 3 4 5 20,000 Agriculture established End of last ice age Average temperature over past 10,000 years = 15C (59F) 10,000 2,000 1,000 Years ago 200 100 Now Fig. 16-2b, p. 369 Temperature Changes Over Past 1,000 Years 1.0 Temperature change (C) 0.5 0.0 0.5 1.0 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2101 Year Fig. 16-2c, p. 369 Average Global Temperature Over Past 130 Years Average surface temperature (C) 15.0 14.8 14.6 14.4 14.2 14.0 13.8 13.6 1860 1880 1900 1920 1940 Year 1960 1980 2000 2020 Fig. 16-2d, p. 369 Greenhouse Effect (a) Rays of sunlight penetrate the lower atmosphere and warm the earth's surface. (b) The earth's surface absorbs much of the incoming solar radiation and degrades it to longer-wavelength infrared (IR) radiation, which rises into the lower atmosphere. Some of this IR radiation escapes into space as heat and some is absorbed by molecules of greenhouse gases and emitted as even longer wavelength IR radiation, which warms the lower atmosphere. (c) As concentrations of greenhouse gases rise, their molecules absorb and emit more infrared radiation, which adds more heat to the lower atmosphere. Fig. 5-5, p. 82 Major Greenhouse Gases Water vapor Carbon dioxide (CO2) Methane (CH4) Nitrous oxide (N2O) Table 16-1, p. 370 Table 16-1, p. 370 Atmospheric Carbon Dioxide and Global Temperatures 380 360 340 320 300 280 260 240 220 200 180 Concentration of carbon dioxide in the atmosphere (ppm) Carbon dioxide +2.5 0 2.5 5.0 Temperature End of change last ice age 7.5 10.0 160 120 80 40 0 Thousands of years before present Variation of temperature (C) from current level Fig. 16-4, p. 370 Climate Change and Human Activities Human emissions of greenhouse gases US carbon dioxide emissions Troposphere warming 20th century warmest in 1000 years Average global temperatures rising 16 warmest years since 1980 Glaciers and floating sea ice melting Melting permafrost and release of more greenhouse gases Rising sea level Increases in Average Atmospheric Carbon Dioxide Since 1860 410 Parts per million 360 310 260 1800 Year Carbon dioxide (CO2) 1900 2000 2100 Fig. 16-5a, p. 371 Increases in Average Atmospheric Methane Since 1860 2.4 Parts per million 1.8 1.2 0.6 1800 1900 Year Methane (CH4) 2000 2100 Fig. 16-5b, p. 371 Increases in Average Atmospheric Nitrous Oxide Since 1860 320 310 Parts per million 300 290 260 1800 Year Nitrous oxide (N2O) 1900 2000 2100 Fig. 16-5c, p. 371 Shrinking Arctic Sea Ice (1979-2003) Fig. 16-6, p. 372 Scientific Consensus on Future Climate Change Mathematical models Model data and assumptions Predictions of the models Models indicate most recent warming due to human activities Very likely Earth's mean temperature will increase in 21st century Processes that Determine Average Temperature and Greenhouse Gas Content Troposphere Cooling from increase Aerosols Warming from decrease Greenhouse gases CO2 removal by plants and soil organisms CO2 emissions from land cleaning, fires, and decay Heat and CO2 removal Heat and CO2 emissions Ice and snow cover Shallow ocean Land and soil biotoa Natural and human emissions Long-term storage Deep ocean Fig. 16-7, p. 372 Measured Average Temperatures and Future Predictions Fig. 16-8, p. 373 Concerns about a Warmer Earth Droughts Higher sea level and coastal flooding Disrupted ecology Economic and social costs Abrupt changes Severe storms Insects and infectious diseases Factors Affecting the Earth's Temperature Ability of oceans to store carbon dioxide Local global cooling is possible Effects of cloud cover Jet contrails Aerosols: volcanic eruptions and human activities Sulfate and black carbon aerosols Photosynthesis Methane emissions: methane hydrates Shallow and Deep Ocean Currents Fig. 16-9, p. 374 Possible Effects of Global Warming on Beech Trees Beech Future range Overlap Present range Fig. 16-11, p. 377 Why Climate Change is a Difficult Problem Complex causes Global problem: How can we all agree? Long-term problem Harmful and beneficial effects of climate change not spread evenly Can't stop climate change, only slow rate and adapt Solutions are difficult and controversial Options to Deal with Climate Change "Wait and see" strategy: we need more research "Act now" strategy "Act now with no regrets" strategy Government Roles in Reducing the Threat of Climate Change Funding for carbon dioxide removal technologies Carbon taxes Energy taxes Decreasing other taxes Leveling the economic playing field Technology transfer Kyoto Protocol What other countries, cities and businesses are doing Preparing for Climate Changes Develop crops that need less water Waste less water Connect wildlife reserves with corridors Move people away from low-lying coastal areas Move hazardous material storage tanks away from coast Stockpile 1- to 5-year supply of key foods Expand existing wildlife reserves toward poles Prohibit new construction on low-lying coastal areas or build houses on stilts Fig. 16-16, p. 382 Ozone Depletion in the Stratosphere Location and purpose of the ozone layer Seasonal and long-term depletion of ozone Causes: chlorofluorocarbons (CFCs) and other chemicals How CFCs destroy the ozone layer Former Uses of CFCs Coolants in air conditioners and refrigerators Propellants in aerosol cans Cleaning solutions for electronic parts Fumigants Bubbles in plastic packing foam Ozone Thinning Seasonal More severe over Antarctica than the Arctic Consequences Models Protecting the Ozone Layer Slow recovery of the ozone layer Montreal Protocol: Reducing CFC emissions Copenhagen Protocol International cooperation ...
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