Aviation and the Environment

Aviation and the Environment......Page 3
Contents......Page 7
Preface......Page 9
Executive Summary......Page 13
Processes that Impact Climate......Page 16
Outstanding Issues......Page 36
Best Way to Assess Uncertainties with Current Knowledge......Page 50
Summary......Page 51
References......Page 52
Executive Summary......Page 65
Introduction......Page 67
Current State of Chemical and Dynamical Issues in the UT/LS......Page 68
Focus on Uncertainties......Page 85
Priorities......Page 92
Recommendations......Page 96
Summary......Page 98
References......Page 99
Annex I: Models with Comprehensive Tropospheric and Stratospheric Chemistry......Page 109
Annex II: Suggested Structure for Each SSWP......Page 110
Annex III: Questions to be Considered in Report......Page 111
Executive Summary......Page 113
Introduction and Background......Page 115
Review......Page 119
Outstanding Limitations, Gaps and Issues Requiring Improvement......Page 143
Prioritization for Tackling Outstanding Issues......Page 151
Recommendations......Page 159
References......Page 161
Executive Summary......Page 173
Review of the Specific Theme......Page 176
Outstanding Limitations, Gaps and Issues that Need Improvement......Page 219
Recommendations and Prioritization for Tackling Outstanding Issues......Page 224
Recommendations from the Current 'Practical' Perspective......Page 227
References......Page 229
Executive Summary......Page 241
Introduction/Background......Page 245
A Review of the Climatic Impacts of Contrail and Contrail Cirrus......Page 250
Outstanding Limitations, Gaps and Issues that Need Improvement......Page 287
Prioritization of Research Needs for Tackling Outstanding Issues......Page 293
Recommendations for Best Use of Current Tools for Modeling and Data Analysis......Page 298
References......Page 299
Executive Summary......Page 315
Introduction and Background......Page 319
Review of Current Knowledge of the Optical Properties and Radiative Forcing of Contrails and Contrail-Induced Cirrus Clouds......Page 320
Outstanding Limitations, Gaps and Issues that Need Improvement......Page 333
Prioritization of Outstanding Issues......Page 352
Recommendations for Best Use of Current Tools for Modeling and Data Analysis......Page 355
References......Page 356
Executive Summary......Page 365
Introduction and Background......Page 368
Review......Page 371
Outstanding Limitations, Gaps and Issues that Need Improvement......Page 399
Prioritization for Tackling Outstanding Issues......Page 408
Recommendations for Best Use of Current Tools for Modeling and Data Analysis......Page 410
References......Page 414
Executive Summary......Page 419
Introduction......Page 422
A Review of Metrics for Climate Impacts......Page 427
Uncertainties, Limitations, Gaps, and Needed Improvements......Page 454
Prioritization for Tackling Outstanding Issues......Page 459
Recommendations for Best Use of Current Tools......Page 462
Summary......Page 463
Appendix A. Discussion of Efficacy Factors......Page 464
References......Page 471
What GAO Found......Page 479
Why GAO Did This Study......Page 480
Summary......Page 482
Aviation's Small but Growing Proportion of Total Emissions Contributes to Health and Environmental Effects......Page 483
Key Federal Efforts to Address Aviation Emissions Include Near-Term Operational Changes and Longer-Term R&D Initiatives......Page 487
Several Steps can be Taken to Help Reduce Aviation Emissions, but Challenges Remain to be Addressed......Page 492
Appendix I: Federal Agency Views on Health and Environmental Effects of Air Pollution......Page 501
Appendix II: Examples of the National Aeronautics and Space Administrations's Research and Development Programs Supporting NextGen......Page 502
Related GAO Products......Page 503
References......Page 504
Index......Page 509