On March 31, Julie Carles defended her PhD thesis entitled “Study of the Radiative Effects of Contrails and Thin Cirrus Clouds, with a Particular Focus on 3D Effects,” conducted within the EMC3 team under the supervision of Jean-Louis Dufresne and Nicolas Bellouin.

The aviation sector is rapidly expanding and contributes significantly to climate change. While the impact of aviation-related CO₂ emissions is well quantified, the ‘non-CO₂’ impacts — such as the formation of contrails — remain poorly constrained, even though they could account for up to two-thirds of the sector’s total radiative forcing. Part of this uncertainty arises from the radiative transfer schemes typically used in calculations, which often neglect three-dimensional effects at cloud edges. Accounting more accurately for these effects would help refine estimates of aviation’s true climate impact.

By performing radiative effect calculations along typical flight trajectories, Julie demonstrated that the differences between 3D and 1D approaches remain substantial, reaching several tens of percent. Her studies under idealized conditions provide valuable insights for analyzing the evolution of radiative effects and 3D processes across broader spatial and temporal scales. This work paves the way for more comprehensive calculations, ultimately aiming to better quantify aviation’s global climate impact.