EPA’s Response to the Petitions to Reconsider the Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act Volume 1: Climate Science and Data Issues Raised by Petitioners U.S. Environmental Protection Agency Office of Atmospheric Programs Climate Change Division Washington, D.C. 1 TABLE OF CONTENTS Page 1.0 Climate Science and Data Issues Raised by Petitioners ...................................................6 1.1. Validity of Paleoclimate Temperature Reconstructions and Related Issues ....................6 1.1.1 The “Divergence Issue” in Paleoclimate Reconstructions .....................................6 1.1.2 Background..............................................................................................................7 1.1.3 Assessment of the Evidence Provided by Petitioners Regarding the Climate Reconstructions ..........................................................................................9 1.1.4 Assessment of the Evidence Provided by the Petitioners of Intentional Data Manipulation Regarding Tree Ring Data and the MWP..............................22 1.1.5 Assessment of Petitioners’ Argument That the MWP May Have Been Warmer Than Present Temperatures.....................................................................24 1.1.6 Assessment of the Petitioners’ Argument that Questions About the MWP and Paleoclimate Reconstructions Limit Current Ability to Attribute Present Warming to Humans.................................................................................26 1.1.7 Summary .............................................................................................................31 1.2 Attribution of Recent Temperature Trends and Models.................................................32 1.2.1 The Validity of the Human “Fingerprint” in the Vertical Temperature Structure of the Atmosphere Over the Tropics...............................................................32 1.2.1.1 Background............................................................................................................32 1.2.1.2 Assessment of the Arguments Regarding the Vertical Temperature Structure Over the Tropics.........................................................................33 1.2.2 Global Temperature Trends Over the Last Decade and Implications for Attribution of These Trends to GHGs ....................................................................35 1.2.2.1 Background................................................................................................35 1.2.2.2 Assessment of Arguments Regarding Global Temperature Trends Over the Last Decade and Implications for Attribution of These Trends to GHGs .........................................................................................36 1.2.3 Climate Model Issues Raised by Petitions.............................................................50 1.2.4 Summary ................................................................................................................58 1.3. Validity of the HadCRUT Temperature Record.............................................................59 1.3.1 Overview ................................................................................................................59 1.3.2 Scientific Background on Surface Temperature Records and Underlying Datasets..................................................................................................................60 1.3.3 Responses to Petitioners’ Arguments Regarding the Validity of CRU Data.........65 1.3.3.1 Alleged Destruction of Raw Data ..............................................................66 1.3.3.2 Alleged Data Manipulation.......................................................................70 1.3.3.3 “Harry Read Me” file and other code.......................................................73 1.3.3.4 Claims of Selective Use of Data From Russian Weather Stations.............89 1.3.4 Claims of Flawed Approach to Correct for Urban Heat Island (UHI) Effects.....................................................................................................................90 1.3.5 Alleged Dependence of IPCC Conclusions on the HadCRUT temperature record.....................................................................................................................92 1.3.6 Summary ................................................................................................................96 2 1.4 Validity of NOAA and NASA Temperature Records ....................................................97 1.4.1 Overview ................................................................................................................97 1.4.2 Background on the Collection and Analysis of Surface Temperature Data..........97 1.4.3 The Petitioners’ Arguments and EPA Responses ..................................................99 1.4.3.1 Assessment of Issues Related to Alleged Station Dropout and Inappropriate Extrapolation......................................................................99 1.4.3.2 Issues Raised With Respect to Adjustments for the UHI Effect ...............106 1.4.3.3 Issues Raised in Additional Literature Provided by Petitioners..............116 1.4.3.4 Petitioners’ Allegations Regarding Data Adjustments at Specific Stations.....................................................................................................118 1.4.3.5 Allegations Regarding the Independence of NOAA, NASA, and HadCRUT Temperature Records.............................................................127 1.4.3.6 Additional Issues Regarding Allegations of Manipulation of Data........131 1.4.4 Summary ..............................................................................................................133 1.5 Implications of New Studies and Data Submitted by the Petitioners ...........................135 1.5.1 Overview ..............................................................................................................135 1.5.2 Implications of a New Study on Stratospheric Water Vapor ............................135 1.5.3 Implications of Material Indicating That CO2 Is Not Well Mixed in the Atmosphere and That the Airborne Fraction of CO2 Has Not Changed .............136 1.5.4 Implications of New Tropical Cyclone Studies....................................................142 1.5.5 Implications of New Studies on the Statistical Significance of Increases in Antarctic Sea Ice..................................................................................................144 1.5.6 Implications of Recent Data on Observational Snow Cover Trends ...................146 1.5.7 Petitioners Claim That EPA Ignored a Satellite Dataset ....................................151 1.5.8 Summary ..............................................................................................................152 References....................................................................................................................................153 3 ACRONYMS °C degrees Celsius °F degrees Fahrenheit AIRS Atmospheric Infrared Sounder AMS American Meteorological Society AOGCM Atmosphere-Ocean General Circulation Models AR4 IPCC Fourth Assessment Report BOM Australian Bureau of Meteorology CCSP U.S. Climate Change Science Program CH4 methane cm centimeter CDIAC Carbon Dioxide Information Analysis Center CMIP Coupled Model Intercomparison Project CO2 carbon dioxide CRU Climatic Research Unit EPA U.S. Environmental Protection Agency FOIA Freedom of Information Act GHCN Global Historical Climatology Network GHG greenhouse gases GISS Goddard Institute for Space Studies (NASA) GSL Global Snow Laboratory (Rutgers Universitry) IAC InterAcademy Council IEA Institute of Economic Analysis IISD International Institute for Sustainable Development IJC International Journal of Climatology IPCC Intergovernmental Panel on Climate Change IQA Information Quality Act LIA Little Ice Age MET United Kingdom Meteorological Office MWP Medieval Warm Period NASA National Aeronautics and Space Administration NCAR National Center for Atmospheric Research NCDC National Climatic Data Center NIWA National Institute of Water & Atmospheric Research NMS National Meteorological Station NOAA National Oceanic and Atmospheric Administration NRC National Research Council NSIDC U.S. National and Snow and Ice Data Center ORNL Oak Ridge National Laboratory PBL Netherlands Environmental Assessment Agency RTC Response to Comments RTP Response to Petitions SAB Scientific Advisory Board SALR saturated adiabatic lapse rate TSD Technical Support Document 4 UAH University of Alabama–Huntsville UCAR University Corporation for Atmospheric Research UHI urban heat island UK United Kingdom USGCRP U.S. Global Change Research Program USHCN United States Historical Climatology Network W/m2 watts per meter squared WMO World Meteorological Organization WWR World Weather Reports 5 1.0 Climate Science and Data Issues Raised by Petitioners 1.1. Validity of Paleoclimate Temperature Reconstructions and Related Issues 1.1.1 The “Divergence Issue” in Paleoclimate Reconstructions A number of petitioners (the Coalition for Responsible Regulation, Peabody Energy, the Southeastern Legal Foundation, the State of Texas, and the Competitive Enterprise Institute) challenge the validity of the paleoclimate reconstructions of the temperatures of the past 1,000 and 10,000 years, as summarized in the assessment literature.1 Many of the issues they raise are similar to comments EPA