Developing a Research Agenda on Contrails and Their Climate Impacts (2025)
Chapter: Front Matter
Developing a Research Agenda on Contrails and Their Climate Impacts
_______
Committee on the Research Agenda for Reducing the Climate Impact of Aviation-Induced Cloudiness and Persistent Contrails from Commercial Aviation
Aeronautics and Space Engineering Board
Space Studies Board
Division on Engineering and Physical Sciences
Consensus Study Report
NATIONAL ACADEMIES PRESS 500 Fifth Street, NW Washington, DC 20001
This activity was supported by a contract between the National Academy of Sciences and the National Aeronautics and Space Administration. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.
International Standard Book Number-13: 978-0-309-73551-3
Digital Object Identifier: https://doi.org/10.17226/29073
This publication is available from the National Academies Press, 500 Fifth Street, NW, Keck 360, Washington, DC 20001; (800) 624-6242; http://nap.nationalacademies.org.
The manufacturer’s authorized representative in the European Union for product safety is Authorised Rep Compliance Ltd., Ground Floor, 71 Lower Baggot Street, Dublin D02 P593 Ireland; www.arccompliance.com.
Copyright 2025 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and National Academies Press and the graphical logos for each are all trademarks of the National Academy of Sciences. All rights reserved.
Printed in the United States of America.
Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2025.
Developing a Research Agenda on Contrails and Their Climate Impacts. Washington, DC: National Academies Press. https://doi.org/10.17226/29073.
The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president.
The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president.
The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president.
The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine.
Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org.
Consensus Study Reports published by the National Academies of Sciences, Engineering, and Medicine document the evidence-based consensus on the study’s statement of task by an authoring committee of experts. Reports typically include findings, conclusions, and recommendations based on information gathered by the committee and the committee’s deliberations. Each report has been subjected to a rigorous and independent peer-review process and it represents the position of the National Academies on the statement of task.
Proceedings published by the National Academies of Sciences, Engineering, and Medicine chronicle the presentations and discussions at a workshop, symposium, or other event convened by the National Academies. The statements and opinions contained in proceedings are those of the participants and are not endorsed by other participants, the planning committee, or the National Academies.
Rapid Expert Consultations published by the National Academies of Sciences, Engineering, and Medicine are authored by subject-matter experts on narrowly focused topics that can be supported by a body of evidence. The discussions contained in rapid expert consultations are considered those of the authors and do not contain policy recommendations. Rapid expert consultations are reviewed by the institution before release.
For information about other products and activities of the National Academies, please visit www.nationalacademies.org/about/whatwedo.
COMMITTEE ON THE RESEARCH AGENDA FOR REDUCING THE CLIMATE IMPACT OF AVIATION-INDUCED CLOUDINESS AND PERSISTENT CONTRAILS FROM COMMERCIAL AVIATION
TIMOTHY C. LIEUWEN (NAE), Georgia Institute of Technology, Chair
STEVE BARRETT, Cambridge University
SEAN BRADSHAW, Pratt & Whitney
LETICIA CUELLAR-HENGARTNER, Los Alamos National Laboratory
ERIC H. DUCHARME (NAE), Martlet Engineering, LLC
ANDREW GETTELMAN, Pacific Northwest National Laboratory
ROBERT J. HANSMAN, JR. (NAE), Massachusetts Institute of Technology
RICHARD H. MOORE, NASA Langley Research Center
JOYCE E. PENNER, University of Michigan
MICHAEL J. PRATHER, University of California, Irvine
Staff
DWAYNE A. DAY, Senior Program Officer, Aeronautics and Space Engineering Board
LINDA M. WALKER, Program Coordinator, Aeronautics and Space Engineering Board, Board on Physics and Astronomy, and Space Studies Board
DIONNA WISE, Program Coordinator, Space Studies Board
COLLEEN N. HARTMAN, Senior Board Director, Space Studies Board, Aeronautics and Space Engineering Board, and Board on Physics and Astronomy (through May 15, 2025)
AERONAUTICS AND SPACE ENGINEERING BOARD
ILAN KROO (NAE), Stanford University, Chair
SEAN BRADSHAW, Pratt & Whitney
ROBERT D. BRAUN (NAE), Johns Hopkins University Applied Physics Laboratory
EDWARD F. CRAWLEY (NAE), Massachusetts Institute of Technology
SHANA L. DALE, National Aeronautics and Space Administration
ERIC H. DUCHARME (NAE), Martlet Engineering, LLC
WILLIAM R. GRAY, U.S. Air Force
MORIBA K. JAH, University of Texas at Austin
JOHN C. KARAS, Lockheed Martin Space Systems Company
TIMOTHY C. LIEUWEN (NAE), Georgia Institute of Technology
GEORGE T. LIGLER (NAE), Texas A&M University
GENERAL LESTER L. LYLES (NAE), U.S. Air Force (retired)
ELLEN OCHOA (NAE), NASA Johnson Space Center
TOM G. REYNOLDS, MIT Lincoln Laboratory
WANDA A. SIGUR (NAE), Lockheed Martin Corporation
MICHAEL K. SINNETT (NAE), Boeing Commercial Airplanes
ANTHONY M. WAAS, Arizona State University
Staff
COLLEEN N. HARTMAN, Senior Board Director, Space Studies Board, Aeronautics and Space Engineering Board, and Board on Physics and Astronomy (through May 15, 2025)
ARUL MOZHI, Associate Board Director (Acting Board Director from May 16, 2025)
TANJA PILZAK, Manager, Program Operations
ANDREA REBHOLZ, Program Coordinator
SPACE STUDIES BOARD
MARGARET G. KIVELSON (NAS), University of California, Los Angeles, Chair
JAMES H. CROCKER (NAE), Lockheed Martin Corporation, Vice Chair
DANIELA CALZETTI (NAS), University of Massachusetts Amherst
ROBIN M. CANUP (NAS), Southwest Research Institute
DEEPTO CHAKRABARTY, Massachusetts Institute of Technology
JEFF DOZIER, University of California, Santa Barbara
MELINDA D. DYAR, Mount Holyoke College
ANTONIO L. ELIAS (NAE), Orbital ATK Inc.
STEPHEN J. MACKWELL, National Science Foundation
PETER I. MESZAROS (NAS), Pennsylvania State University, University Park
RICHARD M. OBERMANN, National Research Council
NELSON PEDREIRO (NAE), Lockheed Martin Space Systems Company
CHRISTA D. PETERS-LIDARD (NAE), NASA Goddard Space Flight Center
MARK P. SAUNDERS, Independent Consultant
HOWARD J. SINGER, National Oceanic and Atmospheric Administration
KEIVAN G. STASSUN, Vanderbilt University
ERIKA B. WAGNER, Blue Origin, LLC
PAUL D. WOOSTER, SpaceX
ENDAWOKE YIZENGAW, The Aerospace Corporation
GARY P. ZANK (NAS), University of Alabama in Huntsville
Staff
COLLEEN N. HARTMAN, Senior Board Director, Space Studies Board, Aeronautics and Space Engineering Board, and Board on Physics and Astronomy (through May 15, 2025)
ARUL MOZHI, Associate Board Director (Acting Board Director from May 16, 2025)
TANJA PILZAK, Manager, Program Operations
ANDREA REBHOLZ, Program Coordinator
This page intentionally left blank.
Reviewers
This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process.
We thank the following individuals for their review of this report:
IRENE C. DEDOUSSI, University of Cambridge
BRANDON GRAVER, Airlines for America
JIM HILEMAN, Boeing
GEORGE T. LIGLER (NAE), Texas A&M University
RICK MIAKE-LYE, Aerodyne Research Inc.
ANDREW ROLLINS, National Oceanic and Atmospheric Administration
MARC SHAPIRO, Breakthrough Energy
LAURENCE VIGEANT-LANGLOIS, AE Industrial Partners
CHRISTIANE VOIGT, German Aerospace Center (DLR)
DONALD WUEBBLES, University of Illinois Urbana-Champaign
Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of this report nor did they see the final draft before its release. The review of this report was overseen by BRADLEY COLMAN, Bayer Corporation (retired), and CHRIS FIELD (NAS), Stanford University. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.
This page intentionally left blank.
Preface
In early 2024, NASA requested that the National Academies of Sciences, Engineering, and Medicine conduct a study to develop a national research agenda to better understand, quantify, and support the development of technical and operational solutions to significantly reduce the global climate impact of aviation-induced cloudiness and persistent contrails from commercial aviation. Under the auspices of the Aeronautics and Space Engineering Board and the Space Studies Board, the National Academies created the Committee on the Research Agenda for Reducing the Climate Impact of Aviation-Induced Cloudiness and Persistent Contrails from Commercial Aviation to undertake this task. The committee began meeting in summer 2024, holding multiple virtual meetings to gather data from a wide range of experts in government, industry, and academia, as well as international perspectives. The committee heard from representatives of airlines and aircraft manufacturers as well as atmospheric scientists and propulsion engineers. By fall 2024, the committee began writing its report and held in-person and virtual meetings to generate findings and recommendations, guided by its statement of task (see Appendix A).
