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IPCC Climate Change Report

IPCC Climate Change Report. Moving Towards Consensus Based on real world data. IPCC Consensus process is Conservative by Nature. IPCC Consensus Evolution. FAR: 1990: The unequivocal detection of the enhanced greenhouse gas effect from observations is not likely for a decade or more

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IPCC Climate Change Report

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  1. IPCC Climate Change Report Moving Towards Consensus Based on real world data

  2. IPCC Consensus process is Conservative by Nature

  3. IPCC Consensus Evolution • FAR: 1990: The unequivocal detection of the enhanced greenhouse gas effect from observations is not likely for a decade or more • SAR: 1995: The balance of evidence suggestions a discernible human influence on global climate

  4. Getting Stronger • TAR: 2001: There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities • AT4: 2007: Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the increase in anthropogenic greenhouse gas concentrations.

  5. Climate Modeling Evolution

  6. Better Grid Resolution

  7. Basic Approach • Coefficient of doubling CO2

  8. Leads to CO2 Stabilization Scenarios

  9. Basic Future Predictions • A 2°C rise from today's temperatures produces 30% species extinction • A 3°C warming will lead to widespread coral deaths • Water availability in the moist tropics and in the high latitudes will increase, but will drop in the semi-arid low latitudes • A 1°C warming will decrease agricultural yields in the low-latitudes; 2°C increases yields at high latitudes

  10. Preponderance of Evidence • Want to find indicators of climate change • Requires a) a robust definition and measure of what constitutes climate and b) an instrumental precision sufficient to measure change • No one indicator (e.g. smoking gun) exists; aggregate of all data then forms the preponderance

  11. Reinforced with 2D Representation

  12. Winter Signal is Strongest

  13. Central Europe Summer Signal • Huge statistical signal via baseline/area test

  14. Record Events depend on wave form evolution

  15. Global Aerosols – leads to dimming • Mostly Industrial; African Source is pyrogenic and biogenic in nature (drought related)

  16. Convolution of positive and negative forcings are what we observe. • GHG produces the net positive here

  17. And all is superimposed on El Nino Cycle

  18. Putting it altogether

  19. Other indicators • Sea Ice • Glacial retreats and glacial mass balance • Permafrost • Droughts • Water vapor feedback • Cloud cover • Ocean wave heights • Sea surface temperature anamolies

  20. Sea Ice – opening of the NW Passage 2007 2006

  21. Glacial Retreat and Mass Balance 1941 - 2005

  22. Wholesale Change in Mass Balance

  23. Permafrost indicators

  24. Summary of the Cyrosphere (frozen land) observations

  25. Droughts

  26. Water vapor increases?

  27. Cloud Cover • Extremely difficult to really measure with any accuracy • Extant data are inconclusive and noisy

  28. Wave height data shows something!

  29. Ocean Sea Surface Temperature Response • Its important to realize that virtually all of the extra (heat) flux goes into the oceans

  30. Big reservoir of heat • 0.1 degree C increase transferred (instantly) to the atmosphere produces 100 degree C increase. • Ocean circulation and redistribution of excess heat is (fortunately) a slow process • But that is where the “pipeline” warming is even if CO2 was stablized today!

  31. Sea Level Rising • Sea Level measured at San Francisco

  32. Known SST oscillations increasing in amplitude • North Atlantic Oscillation (notice the post 1995 slope):

  33. Future predictions remain uncertain

  34. Physics of Atmospheric Energy Transport is difficult • Potential energy • Internal energy • Kinetic energy • Latent heat • Latitude dependent; vertical dependence

  35. Complete Feedback Models too Difficult to reliably construct

  36. Source of Uncertainties • Roles of clouds and aerosols in radiative transfer models? (e.g. scattering!) • Role of tropical convection and the water vapor feedback loop? • How well do observations constrain the input climate parameters? • How to weight the inputs for best fit statistical model? • Contributions of other greenhouse gases specifically methane from permafrost release

  37. Global Warming Potential • TH = Time Horizon (20 or 100 years) • Ax = increased forcing from X (Watts m^2 kg) • x(t) = decay following some hypothetical instantaneous release of X • Denominator is relevant quantities for CO2 • Nominal value for Methane is 21

  38. Do Tipping Points Exist in Climate? • Does the system have critical phenomena? Or do the various and somewhat unknown feedback mechanisms serve to counter this?

  39. The Next Level of Physics in Climate Science • More strongly incorporates the role of various feedbacks particularly water vapor • Identifying critical points (or lack thereof) is essential in future models • Improved modeling of aerosols and their scattering properties • Improved modeling of tropical convection to better understand ocean/atmosphere heat exchange

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