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Opening Remarks by Ross McKitrick Professor of Economics University of Guelph

ASA Joint Statistical Meetings 2011 Panel Discussion Addressing the Evidence for Anthropogenic Climate Change. Opening Remarks by Ross McKitrick Professor of Economics University of Guelph Guelph Ontario, Canada Miami Florida, August 3 2011. Outline. 3 areas of interest:

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Opening Remarks by Ross McKitrick Professor of Economics University of Guelph

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  1. ASA Joint Statistical Meetings2011 Panel DiscussionAddressing the Evidence for Anthropogenic Climate Change Opening Remarks by Ross McKitrick Professor of Economics University of Guelph Guelph Ontario, Canada Miami Florida, August 3 2011

  2. Outline • 3 areas of interest: • Testing for contamination of surface temperature data • How robust is the hockey stick? • Do climate models get the tropical troposphere right? rossmckitrick.weebly.com

  3. Is warming in surface temperature data independent of the spatial pattern of socioeconomic activity? • Raw surface data biased due to urbanization, regional land use change, equipment discontinuities, data quality problems etc. • Climate data products (CRU, GISS, NOAA) go through “adjustments” to remove these influences • Are the adjustments adequate? rossmckitrick.weebly.com

  4. Is warming in surface temperature data independent of the spatial pattern of socioeconomic activity? • Raw surface data biased due to urbanization, regional land use change, equipment discontinuities, data quality problems etc. • Climate data products (CRU, GISS, NOAA) go through “adjustments” to remove these influences • Are the adjustments adequate? rossmckitrick.weebly.com

  5. Is warming in surface temperature data independent of the spatial pattern of socioeconomic activity? • Raw surface data biased due to urbanization, regional land use change, equipment discontinuities, data quality problems etc. • Climate data products (CRU, GISS, NOAA) go through “adjustments” to remove these influences • Are the adjustments adequate? rossmckitrick.weebly.com

  6. Testing the claim of independence qi = f (climatici) + g(geogi) + h(econi) + ei • Dependent variable: • qi = surface trend in grid cell i, 440 land boxes • Independent variables: • Climatic: mean air pressure, trop trend • Geographic: latitude, coastline, dry • Economic: population, gdp, income, education, coal use rossmckitrick.weebly.com

  7. Modeling & Testing • Series of papers (2004-2011) covering: • Linear spec issues: RESET, clustering, bootstrap, random cross-validation, endogeneity • Spatial autocorrelation • Alternative surface/troposphere data sets • Addition of atmos circulation variables • Attempts to simulate with GCM data rossmckitrick.weebly.com

  8. Findings to date • Socioeconomic variables are highly significant (p<0.01) • Robust finding across countless specifications/data sets • Pattern not predicted in GCMs, which typically predict the opposite • Not accounted for by natural circulation patterns • Add up to net warming bias over land • Explains ~1/3 of global land trend over 1979-2002 rossmckitrick.weebly.com

  9. The Hockey Stick • 2 major claims: • Large library of proxies • New statistical method that yields much smaller uncertainty bands • Heavily promoted by IPCC in 2001 Report rossmckitrick.weebly.com

  10. McIntyre & McKitrick work • Hockey stick shape not feature of most input data • Tied to one small class of proxies (bristlecones) • Overweighted due to PCA/regression method • Unsuitable for temperature reconstructions • Statistical method contained erroneous steps that underestimated the uncertainties rossmckitrick.weebly.com

  11. Model-data comparisons in Tropical Troposphere • Models say GHG-induced warming should be strongest in troposphere over tropics • Should be apparent since 1950s rossmckitrick.weebly.com

  12. Data don’t seem to show it rossmckitrick.weebly.com

  13. Statistical comparisons • Douglass et al. (2009): trends in weather balloons & satellite systems are significantly lower than in models • Santer et al. (2010): applying approximate AR1 correction the differences are not significant over 1979-1999 interval rossmckitrick.weebly.com

  14. McKitrick, McIntyre and Herman(Atmos Sci Lett 2010) • Panel regression (AR1) and Vogelsang-Franses nonparametric method • adaptation of Newey-West HAC for multivariate trend systems • Updated model, balloon and satellite data to 2009 and added in all GCMs rossmckitrick.weebly.com

  15. McKitrick, McIntyre and Herman(Atmos Sci Lett 2010) • Models warm 2-4x faster than obs and differences are significant • Balloons and satellites agree with each other, but not with models rossmckitrick.weebly.com

  16. Ongoing work… • Surf temperatures: • (w/Lise Tole) Explaining surface trend patterns using GCM/Socioecon combo in BMA framework • Trend comparisons: • (w/Tim Vogelsang) Extending VF method to include mean shifts, applying to balloon record 1958-2010 • Model/obs discrepancy in tropics highly significant • with 1977 mean shift due to PCS the trend term is + but insignificant rossmckitrick.weebly.com

  17. Final thoughts • Warming (compared to 1800s)? • Yes • Significance (p<0.05)? • Troposphere – barely/no (where most expected) • Surface data are contaminated and climate research community needs to deal with this before computing climatic trends • Attribution to GHG? • Nontrivial spatial and TS discrepancies between observations and model predictions based on standard GHG sensitivity lead me to believe this case is weaker than IPCC claims rossmckitrick.weebly.com

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