Clear-Air Turbulence in a Changing Climate: Past Trends, Future Projections, and Aviation Impacts

Clear-Air Turbulence (CAT) is a major aviation hazard that occurs in cloudless regions, primarily near jet streams at upper tropospheric levels. It is responsible for the majority of weather-related aircraft incidents, posing risks to both passenger safety and airline operations. As the climate warms, jet streams are projected to intensify, potentially leading to more frequent and severe CAT events. This study assesses historical and projected changes in CAT frequency over the Northern Hemisphere using a combination of atmospheric reanalysis datasets and climate model simulations from coupled model experiments.We apply several well-established CAT diagnostics to evaluate the sensitivity of the results to different representations of turbulence. The reanalysis data for the period 1980–2021 reveal significant positive trends in CAT frequency, particularly over North Africa, East Asia, and the Middle East. Signal-to-noise analysis indicates that these trends are likely attributable to anthropogenic climate forcing. In contrast, over the North Atlantic and North Pacific, internal climate variability dominates, obscuring the response to external forcing.Projections from climate models show that CAT will continue to intensify throughout the 21st century, with a high level of model agreement across multiple emission scenarios and diagnostic methods. The most pronounced increases are projected over East Asia, reinforcing this region as a future hotspot for turbulence-related flight risks. However, over the North Atlantic, uncertainty remains high due to inter-model discrepancies and diagnostic sensitivity.These findings highlight the emergence of CAT as a climate-driven risk that is already detectable in recent decades and projected to worsen in the future. Improved turbulence forecasting and adaptation strategies will be essential to mitigate the increasing threat CAT poses to global aviation safety in a warming world.