Ulrike Lohmann
Atmospheric Physicist
Institute for Atmospheric and Climate Science, ETH Zurich
The Role of Clouds and Aerosol Particles in the Current and Warmer Climate

Clouds are not only fascinating to observe for their myriad of shapes, but are also scientifically challenging because their formation requires both knowledge about the large-scale meteorological environment as well as knowledge about the details of cloud droplet and ice crystal formation on the micro-scale.

Aerosol particles scatter and absorb radiation and with that cause a cooling, that partly offsets the warming due to anthropogenic greenhouse gases. Aerosol particles also influence the microphysics of clouds by acting as cloud condensation nuclei and ice nucleating particles. The magnitude and geographical distribution of the cooling caused by aerosol particles themselves and by aerosol-cloud interactions is much more uncertain than the greenhouse gas warming because aerosol particles have localized sources and sinks and only have an atmospheric residence time of days to weeks.

An additional uncertainty related to clouds is that it is not yet clear how clouds change in a warmer climate. In this lecture, I will discuss the role of clouds and aerosols in the current climate and in climate projections.

Ulrike Lohmann is Full Professor for Experimental Atmospheric Physics in the Institute for Atmospheric and Climate Science since October 2004. She was born in 1966 in Berlin (Germany) and studied from 1988 to 1993 Meteorology at the Universities of Mainz and Hamburg. In 1996, she obtained her PhD in climate modelling from the Max Planck Institute for Meteorology. She was a post-doctoral fellow at the Canadian Centre for Climate (1996–97) and Assistant and Associate Professor at Dalhousie University in Halifax (Canada) (1997–2004). Ulrike Lohmann was awarded a Canada Research Chair in 2002, received the AMS Henry G. Houghton Award in 2007, was elected as a fellow of the American Geophysical Union in 2008 and of the German National Academy of Sciences, Leopoldina in 2014. She was a lead author for the Fourth and Fifth Assessment Reports of the Intergovernmental Panel for Climate Change (IPCC). She was the coordinator of the EU FP7 project BACCHUS (2013–2018). At ETH, she was the head of the Institute for Atmospheric and Climate Science from 2006–2014, is a delegate of the ETH president for heading search committees and vice president of the Lecturer’s conference. Since 2018 she is a member of the Research Council of the Swiss National Research Council and was awarded a honorary doctorate from Stockholm University. Her research focuses on the role of aerosol particles and clouds in the climate system. She combines laboratory work and field measurements on cloud and aerosol microphysics with their representation in different numerical models.