Does a warmer climate lead to more bumpy flights in the tropics? Insights from a global km-scale global model

Aviation turbulence leads to safety, comfort, and economic risks. For example, a recent high-profile event of a severe turbulence encountered by Singapore Airlines flight SQ321 in 2024 led to a large number of injured passengers, showing the challenge of anticipating hazardous conditions in the tropics.

Multiple studies suggest that turbulence has already increased and will continue to intensify in a warming climate, particularly over the midlatitudes, driven by changes in upper-tropospheric wind shear. However, evidence for the tropics is inconclusive and largely based on climate models with a horizontal resolution of approximately 100 km, which cannot directly resolve key atmospheric processes. Basic theory indicates that the tropical upper troposphere becomes more stable on average as the climate warms, which could suppress clear‑air turbulence. At the same time, the most extreme thunderstorm updrafts are expected to strengthen, potentially increasing turbulence in and around storms and their outflow. Together, these opposing signals leave the net impact on tropical aviation uncertain.

We address this gap using a set of global simulations at 5 km horizontal resolution, which explicitly resolve many upper-tropospheric updrafts in both convective and nearby clear-air environments. We use 40-day long simulations for present-day conditions for uniform sea-surface temperature warming of +2 °C and +4 °C. Additional simulations isolate the impact of CO₂ radiative forcing independent of SST warming, motivated by recent findings that CO₂ direct radiative effects can strengthen upper-tropospheric updrafts and reduce the upper tropospheric static stability. We focus on altitudes of 9-13 km along major flight corridors in tropics and subtropics, where most commercial aviation occurs.

Our analysis examines how the distribution and extremes of vertical velocity change both near and far from deep convection. We use updraft probability density functions and exceedance fractions for aviation-relevant thresholds, together with shear and stability diagnostics. With a global, storm‑resolving framework, we clarify how tropical upper‑tropospheric turbulence is changing and provide evidence that can guide future forecasting and route‑planning decisions in a warming climate.