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Global Warming: we’re on thin ice!

Global Warming: we’re on thin ice!. Compton Tucker NASA/Goddard Space Flight Center & Climate Change Science Program Office. Evidence of global warming Denial of global warming Convergence of evidence. Measured Surface Temperature the past 150 years.

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Global Warming: we’re on thin ice!

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  1. Global Warming: we’re on thin ice! Compton Tucker NASA/Goddard Space Flight Center & Climate Change Science Program Office • Evidence of global warming • Denial of global warming • Convergence of evidence

  2. Measured Surface Temperature the past 150 years 5 warmest years: 1998, 2002, 2003, 2004, 2005

  3. Warming greatest at high latitudes Amplification of warming due to decrease of albedo (melting of snow and ice)

  4. Mann, Bradley, & Hughes (1998):The “hockey stick” surface temperature

  5. Proxy data used by Mann et al. 1998

  6. Tree Ring Dendrochronology

  7. Tree Ring Dendrochronology

  8. Tree Ring Temperature Reconstructions ~40% tree ring variation is due to temperature Best tree ring chronology is bristlecone pine series from US west that grows >3,000 m & extends >4,000 years Much of the controversy over surface temperature reconstructions has been associated with tree ring proxy temperature

  9. Some ring-width series Cook, 1989 Four red spruce ring-width series from the same stand – different trends related to competition and disturbance.

  10. Coral d18O/16O TemperatureReconstruction

  11. Proxy Surface Temperaturesfrom corals, sediments, and ice cores using 18O/16O • d18O = (18O/16O)sample - (18O/16O)SMOW x 103 ‰ (18O/16O)SMOW • SMOW = Standard Mean Ocean Water The vapor pressure of H216O is > than that of H218O; converselyH218O passes into the liquid state more readily. Because condensation is the result of cooling, the greater the fall in temperature the lower the 18O concentration in H2O will be. Isotope concentration can thus be considered a function of temperature. 18O: 0.20% 17O: 0.04% 16O: 99.76%

  12. Greenland ice core: high resolution/distinct layers

  13. Greenland ice core--yearly layers

  14. McIntyre and McKitrick 2003a reanalysis with a subset of Mann et al. 1998’s data 15th century the warmest time in the past 1000 to 2000 years? Same result as Mann et al. 1998 Same result as Mann et al. 1998 when 5 PCs are used for 15th century

  15. Proxy data used by Mann et al. 1998

  16. Total Solar Irradiance

  17. Arctic Sea Ice Trends 2005 summer minima 1979 summer minima

  18. Warmer Earth Greener NorthArctic Sea Ice Extent 1979 to 1999 Claire Parkinson et al. 2002

  19. Majority of Glaciers are receding

  20. Receding Glaciers

  21. Holgate Glacier July 24, 1909 Holgate Glacier August 13, 2004

  22. Sea Level Rise from thermal expansion & input of water from melting glaciers 20 cm (7 inches) in a century

  23. Bore Hole Temperature Reconstructions

  24. Bore Hole Locationsdifferent physics (thermal diffusivity) & 10s of years time steps

  25. Bore Hole Temp. Reconstructions ~500 years

  26. Subsurface Annual Temperature12.8 m depth @ North Dakota

  27. Bore Hole Data for Eastern & Western North America (Huang & Pollack)

  28. Pollack & Huang Bore Hole Data

  29. Bore Hole Cumulative Temperature Figure 6 from pollack and huang p. 365

  30. National Research Council’s June 2006 Report

  31. Data density circa 1000 AD

  32. Data density circa 1500 AD

  33. Equilibrium Climate from Ice Core Data • Estimate climate forcing (W/m2) from atmospheric composition changes • Regress Temperature anomalies against climate forcing J. Hansen

  34. Data

  35. c8 = ~ 10k year periodicity

  36. c12 = ~ 400,000 year periodicity

  37. S modes 10 to 13 : 20k, 40k, 100k, & 400k years

  38. Equilibrium Climate from Ice Core Data • Estimate climate forcing (W/m2) from atmospheric composition changes • Regress Temperature anomalies against climate forcing J. Hansen

  39. Atmospheric CO2 measurements

  40. Atmospheric CO2 since 1740 Different dCO2/dtime slopes reflect techno-economic conditions

  41. Climate Forcing: expressed as a change in radiative heating (W/m2) at surface for a given change in trace gas composition or other change external to the climate system

  42. Where the rubber hits the road Surface melt on Greenland ice sheet descending into moulin, a vertical shaft carrying the water to base of ice sheet. Source: Roger Braithwaite

  43. 12 mi http://svs.gsfc.nasa.gov/vis/a000000/a002400/a002421/index.html 20 km January 31, 2002

  44. 12 mi http://svs.gsfc.nasa.gov/vis/a000000/a002400/a002421/index.html 20 km March 7, 2002

  45. Gravity Recovery & Climate Experiment 500 km orbit 220 km separation Distance accuracy 0.001 mm

  46. Greenland Mass Loss from GRACE

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