Developing a Research Agenda on Contrails and Their Climate Impacts

Contrails are visible lines in the sky behind aircraft that occur when warm jet engine exhaust meets the colder surrounding atmosphere, forming small ice crystals. Most contrails dissipate within about 10 minutes, but they can last for hours under certain conditions. Persistent contrails can contribute to atmospheric warming and are estimated to have a climate impact on par with carbon dioxide emissions from aviation.

In early 2024, NASA requested that the National Academies develop a national research agenda to better understand, quantify, and develop technical and operational solutions to reduce the global climate impact of aviation-induced cloudiness and persistent contrails. This report presents priorities for a national contrails research strategy and provides a vision for how this research could eventually support operational contrails mitigation. This research would support the global economic competitiveness of the U.S. civil aviation industry in the context of emerging international aviation regulations.

Table of Contents

Front Matter Summary 1 Overview 2 Aircraft Engine Emissions 3 Atmospheric Measurements 4 Contrail Modeling Systems 5 Contrail Forecast and Verification 6 Operational Concepts Appendixes Appendix A: Statement of Task Appendix B: Committee and Staff Biographical Information Appendix C: Recommendations