Global Climate Change

Transcription

1 Global Climate Change

2 Climate Climate is characterized by the statistical properties of the weather over a period of time, including averages of local variables such as temperature, winds, humidity, pressure, and precipitation.

3 Global Climate There's a lot of differing data, but as far as I can gather, over the last hundred years the temperature on this planet has gone up 1.8 degrees. Am I the only one who finds that amazingly stable? I could go back to my hotel room tonight and futz with the thermostat for three to four hours. I could not detect that difference. -Dennis Miller

4 June 12, 2001 Warming Threat Requires Action Now, Scientists Say By ANDREW C. REVKIN In his speech on climate yesterday, President Bush said that a basic problem with the Kyoto Protocol, the proposed international pact for curtailing global warming, was that it laid out a timetable for cutting releases of heat-trapping gases before the threat posed by a buildup of those gases was clearly understood. New York Times

5 The Science of the Greenhouse Effect: Solar Radiation P = Power = FA = 4πr σt 2 4 P sun = 4πr 2 sun σt 4 Wein s Law Radiative Power from the Sun = [4π ( ) 2 ][( )(5800) 4 ] = W F sun = ( ) /(4π ( ) 2 ) = 1389 Wm 2 Power Incident on Earth

6 The Science of the Greenhouse Effect: Solar Radiation solar flux πr 2

7 The Science of the Greenhouse Effect: Solar Radiation F sun 2 earth 2 earth 2 ( πr ) = (1389Wm )( πr ) = W Global energy use by population ~ 1x10 13 W 1 part in % for U.S. Urban Areas

8 The Science of the Greenhouse Effect: Earth Emission F earth = σt 4 F earth = ( Wm 2 K 4 )(288K) 4 = 390Wm 2 Earth Emission 10 8 W 390 W 1 m Sun Emission 1 m 1 m 1 m Earth Emission

9 The Science of the Greenhouse Effect: Radiation Balance F earth = σt 4 earth P earth = 4πr 2 earth σt 4 earth total W emitted from the earth F sun (1 A) πr 2 earth = 4πr 2 earth σt 4 earth balance Fraction Absorbed A: Albedo

10 The Science of the Greenhouse Effect: Radiation Balance T earth = (1 A) F 4σ sun 1/ 4 T earth = (1 0.31) 1398Wm Wm K 2 4 1/ 4 = 254 K = 19 o C Actual is 290 K!

11 Temperature at the Surface of Three planets: = T actual - T calculated Calculated T/K Actual T/K Earth Mars Venus

12 The Science of the Greenhouse Effect

13 Greenhouse Gases and Their Sources Species Source Lifetime CO 2 Fossil fuels, deforestation, soil destruction 500 years CH 4 Cattle, biomass, rice paddies, gas leaks, 7-10 years mining, termites N 2 O Fossil fuels, soil cultivation, deforestation years CFCs Refrigeration, air conditioning,foam blowing, solvents years O 3 Photochemical processes, cars, power plants, solvents Hours to days Source: World Resources Institute, The 1994 Information Please Environmental Almanac (Boston: Houghton Mifflin Co., 1994), 344.

14 Hypotheses: 1. Global Warming is not Occuring 2. Global Warming is Occuring but due to natural cycles 3. Global Warming is Occuring and due in part to human activity

15 Questions regarding data sets: 1. What are the maximum and minimum values presented? 2. How was the data collected? 3. Where was the data collected? 4. How should the data be interpreted? 5. What data appear to be the most significant indicators or Global Warming? Which data appear to be less relevant?

16 Global Warming?: Houston

17 Houston Summer Months and Number of Days at a Temperature >96 o Year June July August September Total

18 Annual Rainfall* in Houston, TX Year Annual Rainfall (Inches) *for years when the annual rainfall exceeded 70 inches

19 Global Warming?: Greenhouse Gases

20 Evolution of Trace Gas Mixing Ratios Preindustrial CO 2 (ppmv) CH 4 (ppbv) N 2 O(ppbv) CFC-11(pptv) CFC-12(pptv) CFC-113(pptv) CFC-114(pptv) CFC-115(pptv) CCl 4 (pptv) CH 3 Cl(pptv)

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24 Global CH4 Levels

25 Global N 2 O Levels

26 Global Warming?: Temperature?

27 Global Temperature

28 The effect of mean and variance increases on temperature

29 Global Warming?: Severe Weather

30 Major Storms in the United States

31 Tornadoes in the United States

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33 Feedback Feedback is the influence of system responses on the operation of greenhouse gas forcing either tending to reinforce the main process (positive feedback) or resisting the main process (negative feedback). Water vapor feedback. Due to greenhouse warming, more water evaporates and more water vapor is present in the atmosphere. But water is a greenhouse gas, so one result of greenhouse gas emissions is to increase the concentration of another greenhouse gas, a positive feedback.