Project Report
The Faraday Discussion on Atmospheric Chemistry in Cold Environments highlighted progress and emerging challenges in understanding chemical processes in Earth’s cold regions—including the polar areas, upper troposphere, and stratosphere. This workshop brought together expertise spanning physical, analytical, and theoretical chemistry. This Faraday Discussion was distinctive because it successfully bridged multiple disciplines and scales - from molecular-level interfacial chemistry to global atmospheric modeling. In its vivid discussions, it connected scientists from the US, UK, and Europe. The meeting specifically focused on understanding the chemistry of cold environments, linking it to meteorological and physical processes.
The integration of cutting-edge analytical methods (surface-sensitive spectroscopy, neutron reflectivity, advanced mass spectrometry) with theoretical tools (electronic structure calculations, graph theory) and field campaign data from major recent expeditions like MOSAiC and ALPACA created a uniquely comprehensive scientific discussion.
The discussions addressed the main research questions in the field, such as
- Advances in Analytical Methods: The meeting showcased graph theory applications to understand ice nucleation mechanisms, specifically using connectivity analysis of hydrogen bonding networks to understand how alcohol groups influence water molecule ordering during freezing.
- Halogen Chemistry: A new understanding of halogen chemistry in the cold has addressed the chemistry for iodine in Arctic haze formation, the interplay of pollution transport and chemistry and complex chemistry between pollution, halogens, and ozone in populated and economically active areas of the Arctic.
- Geoengineering Science: Was addressed by presenting and discussing the fundamentals and current understanding of ozone depletion and the prediction of its recovery in the stratosphere.
- Major Research Campaigns: Insights were drawn from recent high-profile field campaigns (e.g., MOSAiC, ALPACA, CHACHA) and long-term observations at polar and high-altitude research stations. The discussions covered both local and regional perspectives.
The discussion pointed to several challenges and the need for further research in
- Understanding Multiphase Chemistry: There remain significant uncertainties around interfacial chemistry (e.g., at the ice surface or in snowpacks) and the role of biological materials as ice-nucleating particles.
- Changing Human and Environmental Contexts: The Arctic and Antarctic face increasing pressure from human activities and climate warming, with complex impacts on air quality, ecosystems, and atmospheric composition. Urbanization in cold regions is a growing concern.
- Policy-Relevant Science: The discussion also touched on geoengineering proposals such as stratospheric aerosol injection and their implications for the ozone layer—areas demanding sound scientific foundation before policy decisions.
- Future Directions:The session provided a basis for the upcoming International Polar Year 2032–2033 and highlighted the need to sustain and expand observation, measurement, and modeling efforts in these vulnerable environments
This Faraday Discussion underscored the need for chemistry-focused, multidisciplinary, and integrative research to address the complex, evolving challenges of atmospheric chemistry in cold environments. The meeting’s unique format, with its vivid discussions during and between the sessions, was ideal. The venue and overall organization made the discussions and scientific exchange very productive. A main motivation was to link the aerosol research community with that of polar atmospheric researchers. Atmospheric haze and wintertime pollution are a major research focus; however, the particular aspects of “cold chemistry” as explored in polar research over the last decades were new to this community.
Highlights
- Biogenic ice nucleating particles (INPs) are key over the Arctic Ocean. Significant links between marine biogenic activity, aerosolization, and INP abundance are highlighted, advancing our understanding of ice nucleation for Arctic clouds. (https://doi.org/10.1039/D4FD00160E)
- Tropospheric ozone is frequently depleted in the springtime Arctic, influencing atmospheric oxidation on large spatial scales. Anthropogenic pollution causes more local, intermittent depletion year-round. This paper highlights how chemistry in snow releasing reactive halogens and polluted air masses act together on ozone The interplay between snow and polluted air masses in cold urban environments has also been shown in a novel modelling work, highlighting the role of brine in snow for chemistry.( https://doi.org/10.1039/D4FD00166D https://doi.org/10.1039/D4FD00176A)
- Photolysis of iodide in surface snow is a plausible mechanism for supplying reactive volatile iodine to the Arctic atmosphere. This study addresses the question whether trace gases originate from biological activity in sea ice being transported to the snow, or from snow chemistry. https://doi.org/10.1039/D4FD00178H)
Additional material
All presentations are published as peer reviewed articles:
https://pubs.rsc.org/en/journals/journalissues/fd#!issueid=fd025258&type=current&issnprint=1359-6640
Date and Location
17-19 February 2025, London, UK
IASC Working Group funding the Project:
AWG
Project Leaders:
Thorsten Bartels-Rausch (PSI Center for Energy and Environmental Sciences, Switzerland) (contact: thorsten.bartels-rausch@psi.ch)
Year funded by IASC:
2024