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Chapter 21: Climate Change

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1 Chapter 21: Climate Change
Global Change Unit

2 Past climates Global cooling and warming occur in cycles
Glacial and interglacial periods Glacial periods last about 100,000 years. Interglacial last about 10,000-12,500 years. Our current interglacial age has lasted about 12,000 years…

3 Glacial and Interglacial Periods
Average temperature over past 900,000 years 17 16 15 14 Average surface temperature (°C) 13 12 11 10 9 900 800 700 600 500 400 300 200 100 Present Thousands of years ago Glacial and Interglacial Periods

4 Temperature change over past 22,000 years
Agriculture established 1 Average temperature over past 10,000 years = 15°C (59°F) -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 Past 22,000 years

5 Temperature change over past 1,000 years Temperature change (°C)
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 Past 1,000 years

6 Past 130 years 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 Past 130 years

7 Ice can tell us WHAT? Past climate information is found through ice cores from Antarctica and Greenland. The ice core (see fig 21.3) can tell us: Greenhouse gas concentrations Solar activity Snowfall Forest fires (layers of soot) Core samples from lakes/ponds bottom tell us: Pollen Fossils Plant life Growth trends

8 Too much information!! What we do with all that information:
IPCC: Intergovernmental Panel on Climate Change 2,000 experts from 70 nations IPCC uses probability to describe trends: Virtually certain: more than 99% probability Very likely: 90-99% probability Likely: 66-90% probability Our current interglacial age is likely to last another 15,000 years

9 Pink vs. Blue Various regions of the world all show warming trends over the past 100 years. These graphs compare the observed changes in temperature (black lines) with model results that include only natural climate forcings like volcanic eruptions and changes in solar energy (blue) and model results that use both natural and human caused climate forcings (pink).

10 Greenhouse Effect

11 What’s happening here? More greenhouse gases in the air, prevents heat moving out of the atmosphere. Added greenhouse gases absorb the heat.

12 Greenhouse Effect                                                  Heat is “trapped” inside the atmosphere much like heat is trapped in a greenhouse. What causes the “trapping”? Carbon Dioxide Methane NOx CFC’s HCFC’s Halons Water vapor (hasn’t changed – closed system) CF4 This animation shows how a carbon dioxide molecule vibrates when it absorbs heat.

13 Greenhouse Effect Heat is “trapped” inside the atmosphere much like heat is trapped in a greenhouse. What causes the “trapping” Carbon Dioxide Methane NOx CFC’s HCFC’s view clip Halons Water vapor (hasn’t changed – closed system) CF4

14 Effects to think about Increased death from heat, malnutrition
Very likely (90-99%) that tree deaths from disease and pests will increase Very likely that wildfires will increase Loss of animals and plants that can’t migrate quickly enough Increase in pest (high tolerance) animals and insects Tree species would move toward polar regions (5 miles per decade now) Increased hurricanes (over warmer water)

15 CO2 effects 380 360 340 320 300 Concentration of carbon dioxide
in the atmosphere (ppm) 280 Carbon dioxide 260 240 +2.5 220 200 Variation of temperature (˚C) from current level 180 –2.5 –5.0 –7.5 Temperature change End of last ice age –10.0 160 120 80 40 Thousands of years before present

16 Where’s all this gas from?
Burning of fossil fuels (CO2 ) Deforestation (CO2) Clearing and burning grasslands (CO2) Larger cattle herds (CH4) Rice paddies/fertilizers (Nox and CH4 ) Automobiles (1 gallon of gas = 20 lbs. of CO2 ; one tank of gas = 360 lbs. of CO2)

17 Dirty, Rotten Americans!
#1 producer of CO2 emissions (24% of world’s emissions) CO2 emissions from our cars is more than the emissions of everything that powers Japan! Each American produces more CO2 than any other nations individuals (per capita). 500 tons of CO2 in your lifetime! Huge amounts of methane from landfills and livestock.

18 The graphs say it all

19 Carbon dioxide (CO2) 410 360 Parts per million 310 260 1800 1900 2000
2100 Year Carbon dioxide (CO2)

20 Methane (CH4) 2.4 1.8 Parts per million 1.2 0.6 1800 1900 2000 2100
Year Methane (CH4)

21 Nitrous oxide (N2O) 320 310 Parts per million 300 290 260 1800 1900
2000 2100 Year Nitrous oxide (N2O)

22 Global Warming vs Climate Change
Global warming: trend towards increasing temperatures. 10 warmest years on record have occurred since 1990. Global climate change: changes in precipitation, temperatures, storm intensity. Global warming can lead to global climate change.

23 Where’s the proof baby?

24 “Proof” of Global Warming
20th century was hottest on record Since 1861, average global temperature has risen between 1o- 1.4o F (most of that has been since 1980) 16 hottest years on record have been since 1980, 10 hottest have been since 1990. Glaciers and sea ice are shrinking. Sea level rising (4 to 8 inches)

25 1979 2003 Arctic Sea Ice Changes

26 Factors Affecting Earth’s Temperature
Oceans can store heat and CO2, but no one knows how much. Cloud cover: can warm by trapping and releasing heat or cool by reflecting heat back to space (albedo effect)!

27 Albedo is measured on a scale from 0-1(or sometimes as a %).
Very dark colors have an albedo close to 0 (or close to 0%). Very light colors have an albedo close to 1 (or close to 100%).

28 Albedo is measured on a scale from 0-1(or sometimes as a %).
Forests have low albedo, near 0.15. Snow and ice, have very high albedo, as high as 0.8 or 0.9, and reflect most of the solar energy that gets to them, absorbing very little

29 Factors Affecting Earth’s Temperature
Oceans can store heat and CO2, but no one knows how much. Cloud cover: can warm by trapping and releasing heat or cool by reflecting heat back to space (albedo effect)! Outdoor air pollution: aerosols can either warm or cool the atmosphere (much like clouds) Stimulate photosynthesis: more CO2 can temporarily cause higher photosynthesis. Temporary because plants will “level off” and die, releasing their CO2 Methane trapped under ice is released when the ice melts.

30 Solutions Global Warming Prevention Cleanup Cut fossil fuel use (especially coal) Remove CO2 from smokestack and vehicle emissions Shift from coal to natural gas Store (sequester) CO2 by planting trees Improve energy efficiency Shift to renewable energy resources Sequester CO2 deep underground Transfer energy efficiency and renewable energy technologies to developing countries Reduce deforestation Sequester CO2 in the deep ocean Use more sustainable agriculture Repair leaky natural gas pipelines and facilities Slow population growth Use feeds that reduce CH4 emissions by belching cows

31 What are things would you be willing to do around your house?

32 What Can You Do? Reducing CO2 Emissions Drive a fuel-efficient car, walk, bike, carpool, and use mass transit Use energy-efficient windows Use energy-efficient appliances and lights Heavily insulate your house and seal all drafts Reduce garbage by recycling and reuse Insulate hot water heater Use compact fluorescent bulbs Plant trees to shade your house during summer Set water heater no higher than 49°C (120°F) Wash laundry in warm or cold water Use low-flow shower head

33 Is this a Review of the Air Pollution Chapter?

34 Ozone Depletion The culprits: The “hole”:
CFC’s: used as coolants (Freon). Are now being phased out. Halons: in fire extinguishers Hydrobromofluorocarbons The “hole”: More of a thinning. August-November (late winter/spring) over Antarctica Why: wind patterns bring pollutants up and polar vortex keeps them there.

35 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 The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO). Cl O Summary of Reactions CCl3F + UV Cl + CCl2F Cl + O3 ClO + O2 Cl + O Cl + O2 Repeated many times O O

36 Spring Ozone Measurements
Year 1970 1975 1990 2000 2005 1985 1955 1960 1965 1980 1995 400 350 300 250 200 150 100 Total ozone (Dobson units) October monthly means Spring Ozone Measurements

37 Ozone Depletion Solar Backscatter Ultraviolet (SBUV)
Total Ozone Mapping Spectrometer (TOMS) instruments

38 Natural Capital Degradation Effects of Ozone Depletion
Human Health Worse sunburn More eye cataracts More skin cancers Immune system suppression Food and Forests Reduced yields for some crops Reduced seafood supplies from reduced phytoplankton Decreased forest productivity for UV-sensitive tree species Wildlife Increased eye cataracts in some species Decreased population of aquatic species sensitive to UV radiation Reduced population of surface phytoplankton Disrupted aquatic food webs from reduced phytoplankton Air Pollution and Materials Increased acid deposition Increased photochemical smog Degradation of outdoor paints and plastics Global Warming Accelerated warming because of decreased ocean uptake of CO2 from atmosphere by phytoplankton and CFCs acting as greenhouse gases

39 Protocols

40 Protocols Kyoto Protocol: 1997; Reduce greenhouse gases. (concern is global warming) Montreal Protocol: 1987; Reduce use of CFC’s (concern is ozone depletion) Copenhagen Protocol: 1992; Reduce ozone depleting chemicals (concern is ozone depletion)

41 Kyoto Protocol International agreement 1997 161 nations
Directs 39 countries to take steps to decrease greenhouse gas emissions. Developing countries were not held to the same standards as developed ones. 2001: G.W. Bush withdrew the US from the agreement because of expense and the fact that developing countries like China and India weren’t held accountable.


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