Ulrike Lohmann receives Vilhelm Bjerknes Medal 2025

Clouds play an important role in the Earth's radiation budget and the distribution of precipitation. Ulrike Lohmann's research focuses on the interactions between aerosols, clouds and climate. This is a long-standing challenge in atmospheric science. "My approach has been to focus on developing and improving the physical understanding of the system and using this to improve the representation and quantification of the effects," she explains.

A cloud and aerosol pioneer

Lohmann's contributions include the first comprehensive uncertainty estimate of the cloud-mediated forcing of anthropogenic aerosol emissions. Early in her career, she developed a cloud microphysics scheme for the ECHAM climate model, the basis of which is still widely used today. She was one of the first to use satellite-based remote sensing of clouds to constrain the global model representation of their radiative effects. "I recognised the importance of aerosol modification of ice clouds in the climate system and realised that there was a lack of microscale observations and process-based knowledge that was preventing improvements in global models being made," says the Berlin-born scientist..

Tracing cloud icing

Lohmann initiated an integrated research programme that brought together laboratory studies, advances in instrumentation and field observations to improve knowledge of the ice nucleating particles, responsible for glaciating many clouds. Lohmann led several major research programmes. As well as making numerous contributions to her field, she has also played an important role in the assessment cycles of the Intergovernmental Panel on Climate Change (IPCC), seeking to ensure that her work and that of others is used to inform policy at various levels.

A holistic approach

Ulrike Lohmann receives the 2025 Vilhelm Bjerknes Medal for her contributions to the field of aerosol-cloud-climate interactions and the development of the fundamental physical knowledge that underpins them. "This holistic approach has been exceptional and has inspired a new generation of researchers in what remains one of the great challenges of atmospheric sciences," writes the European Geosciences Union (EGU). The award ceremony will take place on 30 April in Vienna, Austria.