Stratospheric Aerosol Injection from Near-Field to Climate Impact: The Evolution of Aerosol Size Distributions and Agglomerates

In a world with steadily increasing atmospheric CO2 concentrations, we will soon have to drastically reduce our emissions to avoid dangerous climate change. If we fail to do so, one of the proposals to prevent a critical rise in temperature is stratospheric aerosol injection (SAI), which reflects sunlight that would otherwise warm Earth back to space. In addition to pressing governance issues, many scientific questions remain unanswered, particularly regarding processes in the turbulent near field. Through an unprecedented combination of state-of-the-art experimental and modeling work, this project aims to enable the comprehensive account of the atmospheric processes relevant to SAI across scales, i.e., directly from particle injection all the way to tropospheric re-entry. This will improve the representation of SAI scenarios using novel solid aerosols (such as calcite and alumina) to ultimately improve assessments of their environmental impact and associated uncertainties and risks. This will allow to compare SAI scenarios with these solid aerosols or aqueous sulfuric acid droplets with scenarios without SAI under conditions of continued CO2 emissions.

Beiping Luo received his Ph.D. in physical chemistry at Free University of Berlin, with his thesis finished at the Fritz Haber Institute of the Max Planck Society in 1991. He is now a senior scientist at the Institute for Climate and Atmospheric Sciences of ETH Zürich. He is an expert in aerosol microphysics and aerosol optical properties, liquid, cirrus and polar stratospheric cloud formation and nucleation, heterogeneous aerosol chemistry and aerosol-radiation interaction. He was responsible for generating the stratospheric aerosol forcing data for the Coupled Model Intercomparison Project Phase 6 (CMIP6) and Chemistry-Climate Model Initiative (CCMI) model intercomparisons. He is the principal developer of ZOMM (Zürich Optical and Microphysical Model), of ReSAM (Respiratory Aerosol Model) and contributed significantly to the implementation of the size-resolved (sectional, 40 bins) aerosol microphysics module in Solar Climate Ozone Links, version 4 (SOCOLv4), a unique feature of this Earth system model (ESM).

Martin Gysel-Beer obtained his Ph.D. in 2003 from ETH Zürich in environmental sciences. After a postdoctoral stay at the University of Manchester, he joined the Laboratory of Atmospheric Chemistry at Paul Scherrer Institute, Switzerland, and was appointed as a group leader of the Aerosol Physics and Optics group in the department of Energy and Environment in 2014. His main research interests include long-term observations of atmospheric aerosols, including process studies on their interaction with solar radiation and clouds. A recent focus is on aerosol optics and algorithms for aerosol property retrievals from angle-resolved light scattering measurements. Gysel-Beer has been a lecturer at ETH Zürich since 2013, a scientific organization committee member of the ETH Nanoparticles Conference since 2015, and he coordinates the Swiss consortium of the Aerosol, Clouds and Traces Gases Research Infrastructure.

Steven Hulshoff holds M.Sc. and Ph.D. degrees from the department of aerospace engineering at the University of Toronto. He is currently an assistant professor in aerodynamics for the Faculty of Aerospace Engineering at Delft University of Technology. His research interests include the analysis of vortical and entropic noise, the development of multiscale and goal-oriented methods for large-eddy simulation, the application of machine learning and adjoint-based mesh optimization to large-eddy simulation and the development of detailed analysis techniques for stratospheric aerosol injection.

Zamin Kanji obtained his Ph.D. in 2009 from the University of Toronto in atmospheric chemistry. After a postdoctoral stay at ETH Zürich and Environment and Climate Change Canada, he was appointed as a group leader of the experimental atmospheric physics group in the Department of Environmental System Sciences at ETH Zürich in 2013. His main research interests include studying the properties of aerosols on liquid and ice cloud formation both via laboratory and field observations with a recent focus on black carbon and aviation soot–cirrus interactions. Kanji was elected to the International Commission on Cloud and Precipitation in 2021 and the committee on Nucleation and Atmospheric Aerosols in 2023 and serves on the departmental diversity, equity and inclusion committee at ETH Zürich.

Heri Kuswanto is a professor in statistics at the Faculty of Science and Data Analytics, Institut Teknologi Sepuluh Nopember (ITS) Indonesia. He is also an active researcher at the Center for Disaster Mitigation and Climate Change ITS. He obtained his Ph.D. in 2009 from Leibniz Hannover University-Germany in statistics and worked as a postdoctoral research associate in 2010 at Laval University, Canada. Kuswanto has been appointed as the director of the graduate program and academic development at ITS since 2020. He is also a fellow of the Indonesian Young Science Academy. His main research interests include statistical downscaling, computational statistics (machine learning), time series econometrics, weather forecasting and solar radiation management. His current works include of investigating solar radiation management’s impact on extreme climate over the Indonesian Maritime Continent and Southeast Asia.

Roxann Stennett-Brown graduated from the University of the West Indies (UWI) at Mona in 2020 with a Ph.D. in physics. She is a lecturer in physics, cryogenic engineering and thermodynamics in the Faculty of Engineering at UWI and serves as its deputy dean of teaching learning and student matters. Stennett-Brown is a member of the Climate Studies Group at UWI and her current research interests include radiation management, heatwave analysis, statistical downscaling and climate extremes for the Caribbean. Some published work during her graduate years included “Future Caribbean temperature and rainfall extremes from statistical downscaling” and “Caribbean climate change vulnerability: Lessons from an aggregate index approach,” which won the 2020 Principal’s Research Award for best research publication from the Faculty of Engineering.