1. Global Warming Is Human-Induced Climate Change Going To Destroy The World? Ok… that’s a bit dramatic. But, good questions are: 1)What is the evidence for recent climate change? 2)Do we need to worry about it – what are the consequences? 3)What can we do about it? Data and diagrams from Richard Deem, Michael Mann, Lee Kump and the Intergovermental Panel on Climate Change

2. History of Earth’s Atmosphere/Climate Earth formed ~4.6 billion years ago Originally very hot, probably molten, early impact forming the moon Any early atmosphere removed by initiation of sun’s fusion reactions and solar wind Granitic crust and liquid water was present by ~4.3 billion years ago (zircon dating) However, much of Earth’s early history was erased during late heavy bombardment (~3.9 billion years ago)

3. First life appeared by ~3.8 Ga Photosynthesis began 3.5-2.5 Ga, clear evidence for significant oxygen in the atmosphere by 2.0 Ga Photosynthesis introduced oxygen and removed carbon dioxide and methane (greenhouse gases) Earth began current cycles of glacial and interglacial periods ~3 Ma History of Earth’s Atmosphere/Climate

4. Sun Earth’s Temperature Solar Energy

5. Sun Earth’s Temperature Solar Energy Solar Energy Radiative Cooling Radiative Cooling

6. Sun Earth’s Temperature Solar Energy Solar Energy Radiative Cooling Radiative Cooling

7. Sun Earth’s Temperature Solar Energy Solar Energy Radiative Cooling Radiative Cooling

8. Greenhouse Effect Sun

9. Earth’s Atmospheric Gases Nitrogen (N 2 ) Oxygen (O 2 ) Water (H 2 O) Carbon Dioxide (CO 2 ) 99% Methane (CH 4 ) 1% Non- Greenhouse Gases Greenhouse Gases

10. Sun Runaway Greenhouse Effect 97% CO 2 3% N 2 Water & sulfuric acid clouds Temperature: 860°F (hotter than Mercury which is nearest to the sun) Venus

11. 170 220 270 320 370 420 200000400000600000 Time (YBP) CO 2 (ppm) Vostok Ice CoreDome Concordia Carbon Dioxide Levels 0 Muana Loa Readings CO 2 Levels Since 1958 310 330 350 370 10203040 CO 2 (ppm) 0

12. Worldwide Carbon Emissions Carbon (10 9 metric tons) 0 1 2 3 4 5 6 7 8 175018001850190019502000 Year Liquid fuel Total Gas fuel Solid fuel

13. Annual Carbon Emissions Annual carbon emissions Atmospheric CO 2 Atmospheric CO 2 average 195519651975198519952005 0 4 6 8 2 Year Carbon (10 9 metric tons)

14. Future Atmospheric CO 2 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)

15. Kyoto Protocol Adopted in 1997 Cut CO 2 emissions by 5% from 1990 levels for 2008-2012 Really is symbolic only, since such levels of reduction will likely not significantly impact global warming

16. -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1880190019201940196019802000 Year  Mean Temperature (°C) Recorded Worldwide Temperatures

17. -3-2.5-1.5-.5-.1.1.511.52.53.4 2007 Temperature Changes Compared to 1951-1980

18. Past Temperatures Measurement Proxy – a method that approximates a particular measurement (e.g., temperature) Ice cores Pollen records Plant macrofossils Sr/Ca isotope data Oxygen isotopes from speleothem calcite (stalactites and stalagmites)

19. Temperature History of the Earth Little ice age (1400-1840) – 1°C cooler Medieval warm period (800-1300) – 1°C warmer than today Cool/warm cycles occur over ~1,500 years Mostly due to changes in thermohaline circulation system of the ocean

20. Temperature History of the Earth For the past 3 Ma, the Earth has been experiencing ~100 ka cycles of glaciation followed by ~10 ka interglacial periods These climate periods are largely the result of cycles in the earth’s orbit – precession, obliquity, and eccentricity

21. Orbital Parameters & Earth’s Climate Age (ka) 10009008007006005004003002001000 Eccentricity (100 ka) Temperature Obliquity (41 ka) Precession (22 ka)

22. Temperature History of the Earth For the past 3 Ma the earth has been experiencing ~100 ka cycles of glaciation followed by ~10 ka interglacial periods Last ice age began ending 15,000 years ago, but was interrupted by the “Younger Dryas” event 12,900 years ago

23. “Hockey Stick” Controversey 100012001400160018002000 -0.8 Year -0.6 -0.4 -0.2 0 0.2 0.4 0.6 Temperature Change (°C) Direct temperature measurements Mann et al. 1999

24. 170 220 270 320 370 0 0 200000 400000 600000 Time (YBP) CO 2 (ppm) Antarctica 25 26 27 28 29 30 31 SST (°C) Tropical Pacific CO 2 Concentration Vs. Temperature

25. Consequences of Global Warming: Primarily Impacts the Northern Hemisphere and Land Masses -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 192019602000 Year Temperature Change (°C) 192019602000 Year Northern vs. Southern LatitudeLand vs. Ocean Northern Hemisphere Southern Hemisphere Land Ocean

26. 2007 Temperature Changes Compared to 1951-1980 -3-2.5-1.5-.5-.1.1.511.52.53.4

27. Consqeuences of Global Warming: Ice Sheets Melting? GRACE (gravity measured by satellite) found melting in Antarctica equivalent to sea level rise of 0.4 mm/year (2 in/century) Zwally, 2005 (satellite radar altimetry) confirmed Antarctica melting Greenland ice melting on exterior, accumulating inland (higher precipitation) And - Glaciers are retreating all over the world.

28. Consqeuences of Global Warming: Rise in Sea Levels? Present rate is 1.8 ± 0.3 mm/yr (7.4 in/century) Accelerating at a rate of 0.013 ± 0.006 mm/yr 2 If acceleration continues, could result in 12 in/century sea level rise Scenarios claiming 1 meter or more rise are probably unrealistic

29. Consqeuences of Global Warming: How Much Temperature Increase? Some models propose up to 9°C increase this century Two studies put the minimum at 1.5°C and maximum at 4.5°C or 6.2°C Another study puts the minimum at 2.5°C Summary – most studies suggest ~4°C over the next century

30. Potential Worldwide Precipitation Changes -50-20-10-55102050

31. Mitigation of Global Warming? Conservation Reduce energy needs Recycling Alternate energy sources Nuclear Wind Geothermal Hydroelectric Solar Fusion?

32. Conclusions Global warming is happening Most warming is probably the result of human activities – but this is still under debate There will be positive and negative (mostly) repercussions from global warming The costs to mitigate global warming will be high – are they worthwhile?

33. Extra slides 2010 beyond this point

34. Winter Temperatures 10 11 12 13 14 15 16 17 1880190019201940196019802000 Year Summer Temperatures 18 19 20 21 22 23 24 25 1880190019201940196019802000 Year Annual Temperatures 15 16 17 18 19 20 21 22 1880190019201940196019802000 Year Temperature (°C) Historic Los Angeles Temperatures

35. Main Ocean Currents Adapted from IPCC SYR Figure 4-2

36. Younger Dryas Younger Dryas Event – Greenland Data -55 -50 -45 -40 -35 -30 -25 05101520 Age (ka) Temperature (°C) 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Snow Accumulation (m/yr) Little Ice Age Ice Age Medieval Warm

37. Mann et al. 1999 Esper et al. 2002 80010001200140016001800 -2 0 1 2 Temperature Change (°C) 2000 Year Is the Hockey Stick Correct?

38. -1.2 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0400800120016002000 Year Temperature Change (°C) Mann et al. 1999 Esper et al. 2002 Moberg et al. 2005 Mann et al. 2008

39. U.S. National Academy of Sciences: June 2006 100012001400160018002000 -0.8 Year -0.6 -0.4 -0.2 0 0.2 0.4 0.6 Temperature Change (°C) “high level of confidence”“2:1 chance of being right”

40. Changing Sea Levels 1700175018001850190019502000 -20 -10 0 10 20 Relative Sea Level (cm) Adapted from IPCC SYR Figure 2-5 Amsterdam, Netherlands Brest, France Swinoujscie, Poland Global Temperature Change

41. Time (Ka) Sea Level (m) 20 0 0 -20 -40 -60 -80 -100 -120 Sea Levels for 450,000 Years 450 400 350 300 250 200 150 100 50 0 0 25 26 27 28 29 30 31 SST (°C) Tropical Pacific