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Climate Change

Climate Change. Chapter 18. Global Change. Population growth Distribution of water Distribution of food Climate change. Climate Change. Earth’s average surface temperature Distribution of rainfall Patterns of temperature change and global conveyor belt .

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Climate Change

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  1. Climate Change Chapter 18

  2. Global Change • Population growth • Distribution of water • Distribution of food • Climate change

  3. Climate Change • Earth’s average surface temperature • Distribution of rainfall • Patterns of temperature change and global conveyor belt

  4. Factors Affecting Global Climate Change • Relationship of Earth to Sun • Anthropogenic causes

  5. Anthropogenic Causes • Atmospheric change due to carbon dioxide emissions, methane emissions, destruction of ozone by providing more surfaces-free radicals for reactions to occur in stratosphere (SOX, NOX, CO2, CH4), changes in vegetative cover, water pollution - eutrophication

  6. Average temperature over past 900,000 years 17 16 15 14 13 Average surface temperature (°C) 12 11 10 9 900 800 700 600 500 400 300 200 100 Present Thousands of years ago Fig. 18.2a, p. 447

  7. Agriculture established Average temperature over past 10,000 years = 15°C (59°F) Temperature change over past 22,000 years 2 1 0 -1 End of last ice age Temperature change (°C) -2 -3 -4 -5 20,000 10,000 2,000 1,000 200 100 Now Years ago Fig. 18.2b, p. 447

  8. Temperature change over past 1,000 years 1.0 0.5 0.0 Temperature change (°C) -0.5 -1.0 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2101 Year Fig. 18.2c, p. 447

  9. Average temperature over past 130 years 15.0 14.8 14.6 14.4 Average surface temperature (°C) 14.2 14.0 13.8 13.6 1860 1880 1900 1920 1940 1960 1980 2000 2020 Year Fig. 18.2d, p. 447

  10. How do we know? • Recent history-have sufficient data from a variety of sources (hot air balloons, buoys, satellite data, pollen records, coral...) • Ancient history- ice cores (Vostock), rocks, tree rings ) • Geologic history-, deep ocean sampling(plankton & radioisotopes), rocks(fossils & radioisotopes)

  11. Evidence of Global Change

  12. How is this information processed? • Modeling • # factors, depth of data, period of time

  13. Global cooling and warming cycles • Global cooling, Ice Ages, last about 100,000 years • Global warming, interglacial periods, last about 10,000 to 13,000 years • Currently, we are living in an interglacial period

  14. Climate and global warming • Climate is statistics of meteorological conditions, temperature, precipitation, winds, over a long period of time-at least 30 years • 0.5C of warming has occurred in last 130 years with the 1980s the warmest during that period • Pattern parallels that of fossil fuel use and injection into the atmosphere of gases that can absorb radiation and lead to global warming

  15. Greenhouse Effect • Molecules of atmospheric gases vibrate and transform the absorbed energy into longer wavelength infrared radiation in the troposphere • Convection currents distribute the heat

  16. l of greenhouse gases • Atmosphere is good absorber of infrared radiation (7.5 mm) • CO2 and H2O vapor limit transmission to space at many l

  17. Variation of Temperature, pressure, and altitude above Earth’s surface

  18. Global Energy Balance for Atmosphere Numbers are %energy from incoming solar radiation

  19. Greenhouse Effect • Half of solar heat goes into latent heat, absorbed by water changing to water vapor • Of 47% of initial solar energy absorbed at Earth’s surface, only 18% lost by radiation • The remainder is captured by atmosphere-surface cycling which causes Earth to be 33C warmer than is would be without an atmosphere

  20. Tropospheric heating effect • Arrhenius !!!!! 1896 • Not a guess, data supports • Is THEORY in atmospheric science

  21. Average Surface Temperature is about 15C (60F) • Due to combination of greenhouse and global cooling processes • Cooling processes: heat absorbed by evaporation of water, and water vapor stores heat in upper atmosphere (thermosphere)

  22. Greenhouse Gas • CO2 fossil fuel burning (75%), biomass burning • CH4 rice, cows, landfills, coal production, coal seams, natural gas leaks, oil production • N2O fossil fuel burning, fertilizers, livestock wastes, nylon prod • CFCs air conditioners, refrigerators, foams • HCFCs-” “ • Halons- fire extinguishers • CCl4 cleaning solvent

  23. 380 360 Correlation between CO2 and Temp Change 340 320 300 Concentration of carbon dioxide in the atmosphere (ppm) 280 Carbon dioxide 260 240 +2.5 220 0 200 Variation of temperature (˚C) from current level –2.5 180 –5.0 –7.5 Temperature change –10.0 End of last ice age 160 120 80 40 0 Fig. 18.3, p. 449 Thousands of years before present

  24. Surface Ozone:Top is Preindustrial and Lower frame is current (2002)

  25. Changes in atmosphere, geosphere, & biosphere from glacial to interglacial periods

  26. Ozone over Antarctica 1979 to 1990

  27. Measurement of Air pollution from satellite

  28. Drought from June to August in global climate model

  29. Global Ocean Temp at depth of 160 m (vol transport stream)

  30. Carbon dioxide Projected emissions Methane Nitrous oxide 250 200 Index (1900 = 100) 150 100 1990 2000 2025 2050 2075 2100 Fig. 18.5, p. 451 Year

  31. Global warming is cyclical; the rate is not • The rate of global warming is greater than past interglacial periods • The CO2 in troposphere is higher than probably the last 20 million years • 75% of CO2 since 1980 is due to fossil fuel burning; remainder is human changes in land use • Average global temp has >0.6C mostly since 1946 • Since 1861 9 of 10 warmest years have occurred since 1990 with the hottest in 1998 and 2001 • Ice caps and glaciers shrinking • Global sea level rise of 10-20 cm in 100 years • Plants and animals are migrating north to meet optimum temperatures

  32. Global Change • Affect the availability of water resources by altering rates of evaporation and precipitation • Shift areas where crops can be grown • Change average sea levels • Alter the structure and location of the world’s biomes

  33. Positive feedback • More product results in more production-eg. “nothing succeeds like success” • Greater temp, more melting of snow, loss of albedo effect results in greater temp and still more melting of snow • Thawing soil results in more microbial activity; more microbial activity results in more CO2 and more thawing soil • Arctic circle, Greenland, and Antarctica all have thinning ice sheets, particularly Greenland • The influx of freshwater from melting glaciers on Greenland could stop the global conveyor belt in the Atlantic

  34. Greenland Greenland Cold water melting from Antarctica's ice cap and icebergs falls to the ocean floor and surges northward, affecting worldwide circulation. Cold water melting from Antarctica's ice cap and icebergs falls to the ocean floor and surges northward, affecting worldwide circulation. Global conveyor belt Antarctica Fig. 18.10, p. 456

  35. 1.2 Observed 1.0 Model of greenhouse gases + aerosols + solar output 0.8 0.6 Temperature change (°C) from 1980–99 mean 0.4 0.2 0.0 -0.2 1860 1880 1900 1920 1940 1960 1980 2000 2010 Year Fig. 18.7, p. 453

  36. Climate Models and IPCC • IPCC: Intergovernmental Panel on Climate Change 2,000 climate scientists • 90-95% chance that earth’s mean surface temp will >1.4-5.8C between 2000 and 2100; change btwn 2000 and 2030 will equal that of entire 20th century • Many greenhouse gases show increases due to anthropogenic activities • Bush administration 2002 says climate changes anthropogenic and then reject Kyoto Treaty! • Climate models are only models & have limitations

  37. Building models • Transect atmosphere mathematically • Assign initial boundary condition for each variable to each cell in layer (solar radiation, precipitation, heat radiated by earth, cloudiness, interactions btwn atmosphere and oceans, greenhouse gases, & air pollutants) • Develop equations that connect cells so vary together • Run model to simulate changes that can be verified and then run to project future changes • Reliability tied to accuracy of data inputs and magnification of errors over time, & chaos

  38. 6.0 5.5 Measured vs predicted temperature changes 5.0 4.5 4.0 3.5 3.0 Change in temperature (ºC) 2.5 2.0 1.5 1.0 0.5 0 Fig. 18.8, p. 453 1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 2100 Year

  39. Change will not be evenly distributed • Temp increases higher over land than over oceans • Greater in high latitudes near earth’s poles than in lower latitude equatorial regions • Much higher in inland regions in the northern latitudes

  40. Agriculture Water Resources Forests • Shifts in food-growing areas • Changes in crop yields • Increased irrigation demands • Increased pests, crop diseases, and weeds in warmer areas • Changes in forest composition and locations • Disappearance of some forests • Increased fires from drying • Loss of wildlife habitat and species • Changes in water supply • Decreased water quality • Increased drought • Increased flooding Biodiversity Sea Level and Coastal Areas • Rising sea levels • Flooding of low-lying islands and coastal cities • Flooding of coastal estuaries, wetlands, and coral reefs • Beach erosion • Disruption of coastal fisheries • Contamination of coastal aquifiers with salt water • Extinction of some plant and animal species • Loss of habitats • Disruption of aquatic life Weather Extremes Human Health Human Population • Increased deaths from heat and disease • Disruption of food and water supplies • Spread of tropical diseases to temperate areas • Increased respiratory disease • Increased water pollution from coastal flooding • Prolonged heat waves and droughts • Increased flooding • More intense hurricanes, typhoons, tornadoes, and violent storms • Increased deaths • More environmental refugees • Increased migration Fig. 18.12, p. 458

  41. Summary of Reactions CCl3F + UV Cl + CCl2F Cl + O3 ClO + O2 Cl + O Cl + O2 Repeated many times Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breaking off a chlorine atom and leaving CFCl2. Sun Cl Cl C Once free, the chlorine atom is off to attack another ozone molecule and begin the cycle again. Cl F UV radiation Cl Cl O O A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O2. The chlorine atom attacks an ozone (O3) molecule, pulling an oxygen atom off it and leaving an oxygen molecule (O2). Cl Cl O O O O O Cl The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO). O O Fig. 18.16, p. 466 O

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