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The Modeling of Climate and Climate Change; can we trust model predictions

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The Modeling of Climate and Climate Change; can we trust model predictions

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    1. The Modeling of Climate and Climate Change; can we trust model predictions? University of California, Irvine 21 February 2003 by John Houghton

    2. Outline Introduction Cloud Radiation Feedback Ocean Interactions The Carbon Cycle The Climate of the 20th Century Climate Projections for the 21st Century Regional Climate Modeling Patterns of Climate Response

    4. Spectra of outgoing radiation from Earth observed by IRIS on Nimbus 3

    6. The Enhanced Greenhouse Effect Solar (S) and longwave (L) radiation in Wm-2 at the top of the atmosphere

    7. The climate system

    8. The Development of Climate models, Past, Present and Future

    9. Predicting impacts of climate change Emissions Concentrations CO2, methane, sulphates, etc. Global climate change Temperature, rainfall, sea level, etc. Regional detail Mountain effects, islands, extreme weather, etc. Impacts Flooding, food supply, etc.

    14. Physical Feedbacks Water vapour Ice albedo Clouds Oceans Ice sheets

    15. Cloud Radiation Feedback

    16. Cloud radiation feedback

    17. Global average change in T /C

    18. Model Estimates of Cloud Radiative Forcing with CO2 Doubling

    19. Effect of cloud feedback formulation on climate prediction Feedback scheme Global Av Temp change,C for doubled CO2 RH 5.3 CW 2.8 CWRP 1.9 after Senior & Mitchell, Hadley Centre

    20. Net cloud forcing: January to July Hadley Centre

    21. SHIP TRACKS UNDER CLOUD

    22. Ocean Interactions

    26. Projected changes in annual temperatures for the 2050s The projected change in annual temperatures for the 2050s compared with the present day, when the climate model is driven with an increase in greenhouse gas concentrations equivalent to about 1% increase per year in CO2

    29. The Carbon Cycle

    32. Human Perturbation of the Carbon Cycle

    33. Partitioning of CO2 uptake using O2 measurements

    34. Global CO2 budgets in GtC per year

    35. Carbon cycle feedbacks

    40. Constraint from ENSO Sensitivity Model with q10=2 has realistic sensitivity to ENSO. Reconstructions for range of q10. Infer q10=2.1±0.7.

    41. Constraint from Sensitivity to Volcanoes Model with q10=2 has realistic sensitivity to Pinatubo. Reconstructions for range of q10. Infer q10=1.9±0.4

    42. ENSO and Pinatubo Variations as a constraint on climate-carbon cycle feedback

    45. NET EFFECT OF PLANTING TREES expressed as equivalent carbon uptake

    46. EMISSIONS AND CONCENTRATIONS OF CO2 from unmitigated and stabilising emission scenarios

    47. The Climate of the 20th Century

    48. Global mean surface air temperature anomalies from 1,000 year control simulations with three different climate models, - Hadley, GFDL and Hamburg, compared to the recent instrumental record. No model control simulation shows a trend in surface air temperature as large as the observed trend. If internal variability is correct in these models, the recent warming is likely not due to variability produced within the climate system alone.

    49. Simulated annual global mean surface temperatures Natural forcing

    50. Simulated annual global mean surface temperatures

    51. IPCC statements on Detection “The balance of evidence suggests a discernible human influence on global climate” 1995 Report “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities” 2001 Report

    52. Climate Projections for the 21st century

    54. SRES scenario familys More economic

    58. Observed and projected changes in extremes Confidence in observed changes (latter half of the 20th century) Likely Very likely Very likely Likely, over many areas Likely, over many Northern Hemisphere mid- to high-latitude land areas Likely, in a few areas Not observed in the few analyses available Insufficient data for assessment

    59. Simulated temperature rise and thermal expansion for the 4xCO2 experiment

    60. Regional Climate Modelling

    62. Regional Climate Model High resolution (50km) over limited area (Europe, Indian subcontinent) Embedded in global model, so subject to same uncertainties Takes account of local characteristics, e.g. mountains, coasts Better regional detail, better prediction of extremes in weather (eg flooding) Everybody wants one!

    69. Is the Climate Chaotic?

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