The Science of Global Warming.pdf
- 1. 12.340x Global Warming Science Kerry Emanuel, Daniel Cziczo, and David McGee, Instructors With Introductions by Heidi Cullen
- 2. Purpose of this Course Develop a broad understanding of the earth’s climate system Understand and use some of the basic tools of climate science Develop an awareness of possible consequences of climate change
- 3. What this Course is Not This is not a course about the politics or policies surrounding the issue of global warming
- 4. Prerequisites Calculus, through ordinary differential equations. (Partial differential equations helpful, but not required.) Basic mechanics and electromagnetism Some background in thermodynamics will be helpful
- 6. Global average temperature change from 1850 Mean temperature change between 1950’s and 2000’s The World is Warming. Why?
- 7. Central Questions What is climate? What physical, chemical, and biological processes control climate? How has earth’s climate varied since the formation of the planet, and why? How has climate been varying on human time scales, and why? What tools are used to study climate? How might climate change in the future?
- 8. Definition of “Climate” Popular definitions: Climate is the average weather Climate is what you expect, weather is what you get Technical usage: “Climate” is the statistics of weather This includes not just the average weather, but the statistics of its variability Commonly calculated over periods of one year or more
- 9. Definition of “Climate” Popular definitions: Climate is the average weather Climate is what you expect, weather is what you get Technical usage: “Climate” is the statistics of weather This includes not just the average weather, but the statistics of its variability Commonly calculated over periods of one year or more
- 10. Examples of Climate Variability: El Niño/La Niña (2-4 years) “Little ice age” (100 years) Glacial cycles (20,000-100,000 years) Paleocene-Eocene Thermal Maximum (onset ~20,000 years; decay ~100,000 years) Cooling from Cretaceous to present (~50 million years)
- 11. Climate Change Through Geologic Time
- 13. The Faint Young Sun Paradox: Why didn’t the Earth Freeze?
- 17. Last 450 Thousand Years
- 18. A detailed record of the earth’s climate has emerged over the last few decades, from analyses of ice cores and deep sea sediments
- 19. Ice Cover, Last Glacial Maximum (~18,000 years ago)
- 21. Paleo reconstructions of temperature change over the last 2000 years Year Instrumental Record “Hockey Stick”
- 22. Arctic air temperature change reconstructed (blue), observed (red) The long-term cooling trend in the Arctic was reversed during recent decades. The blue line shows the estimated Arctic average summer temperature over the last 2000 years, based on proxy records from lake sediments, ice cores, and tree rings. The shaded area represents variability among the 23 sites use for the reconstruction. The red line shows the recent warming based on instrumental temperatures. From Kaufman et al. (2009).
- 23. Estimates of Global Mean Surface Temperature from the Instrumental Record
- 24. Climate Science Described by some as the most difficult scientific problem ever faced Draws on all the major scientific disciplines: – Chemistry, geology, atmospheric science, oceanography, solar physics, orbital mechanics, biology – Climate prediction also requires understanding of economics, politics, human psychology Very much a frontier science
- 25. John Tyndall (1820-1893) The Greenhouse Effect Jean Baptiste Joseph Fourier (1768-1830)
- 26. Svante Arrhenius, 1859-1927 “Any doubling of the percentage of carbon dioxide in the air would raise the temperature of the earth's surface by 4°; and if the carbon dioxide were increased fourfold, the temperature would rise by 8°.” – Världarnas utveckling (Worlds in the Making), 1906
- 29. Elements of the Greenhouse Effect
- 30. Climate Elements and Feedbacks
- 31. Feedbacks in Climate Models Water vapor Cloud Surface albedo Lapse rate Water vapor + lapse rate
- 32. Free versus Forced Climate Variability
- 34. It’s getting warmer!.... No, it’s not! Warming stopped at 13! In fact, 13 was warmer than at any time since then! Time
- 35. 0 30 60 90
- 36. Note: We can forecast that summer will be warmer than winter, even though we cannot forecast the weather beyond a few days Average Daily Temperature, Boston, 1995
- 37. Climate Forcing, Natural and Otherwise
- 38. Orbital Forcing and Response
- 39. Black: Time rate of change of ice volume Red: Summer high latitude sunlight Strong Correlation between High Latitude Summer Insolation and Ice Volume P. Huybers, Science, 2006
- 40. Causes of Recent Climate Change
- 44. Recent History of Volcanic Eruptions
- 46. Distribution of temperature change, 1901-2005
- 47. Global Climate Models: How Good Are They, and What Do They Tell Us about The Future?
- 48. Global mean temperature (black) and simulations using many different global models (colors) including all forcings
- 49. Global mean temperature (black) and simulations using many different global models (colors) including all forcings Same as above, but models run with only natural forcings
- 51. Consequences
- 53. 54 Changes in Precipitation EEA 2008 Observations: trend 1961-2006 Model simulation Southern Europe Is drying out
- 54. 55 Heat Stress Kältestress leicht extreme high moderate slight mäßig hoch extrem Mortality and heat stress (8. August 2003, 13 UTC) 15,000 † 7,000 † 4,000 † 2,000 † 2,000 † 4,000 † 1,500 † Mortality data: Earth Policy Institute Heat Stress: Deutscher Wetterdienst Summer 2003, greatest natural disaster in Europe ca. 35.000 fatalities © 2007 Geo Risks Research, Munich Re Heat Waves
- 55. Hurricane Power is Changing in Concert with Tropical Ocean Temperature
- 56. 57 Storm Surge Risk in New York Today: once in 100 years After 1 m rise: once in 3 years
- 57. 58 The Oceans are Turning Sour Acidification through CO2 threatens marine life Plankton Coral Reefs
- 58. Should He Really Be Worried? Stay Tuned....