University of Cambridge > > AI4ER Seminar Series > The role of sulphur from human emissions in driving climate change

The role of sulphur from human emissions in driving climate change

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If you have a question about this talk, please contact Annabelle Scott.

To aid climate policy decisions, robust, accurate and comprehensive Earth system models are needed. Earth system models are large numerical models of the atmosphere, ocean and other components which describe different environments of our planet such as the atmosphere, ocean, etc. These models provide quantitative treatment of the interactions within the climate system and give the necessary understanding of both the drivers and responses to future climate change. Modelling aerosol as part of the Earth system has been identified as the largest source of uncertainty in Earth’s energy budget calculation due to the complex chemical reactions they undergo and their interaction with clouds. This work investigates how aerosols affect the climate under changing human emissions. This is important because human emissions change the atmosphere constituents, modifying aerosol production, which in turn affects the climate.

Understanding the link between anthropogenic emissions and radiative forcing remains a challenge in climate research. Linkages arise between emissions, atmospheric chemistry and climate through the formation of secondary aerosols such as sulfate, nitrate and organic aerosols. Sulfur dioxide (SO2) is an important aerosol precursor with the largest sources coming from anthropogenic activity. The lifetime of SO2 is short, and a principal sink is the conversion to sulfate via oxidation. Unlike well-mixed greenhouse gases, anthropogenic aerosols are heterogeneously distributed because of localised emissions and the short atmospheric residence time. Thus SO2 conversion to aerosol is important to aerosol distribution reflecting both its emission location and the locally available oxidants; both of which are changing rapidly and disparately with time.

This work uses the UKESM1 to investigate the modelled response of sulfate aerosol properties and cloud properties to emissions increases and oxidant changes over the period 1850-2014. From an analysis of the CMIP6 and AerChemMIP experiments, we show that there have been significant changes in the atmospheric oxidation processes of SO2 over this period with consequences for the calculated radiative forcing. Ultimately, this work contributes to the improvement of our process-level understanding of Earth system models that interactively simulate aerosol from precursors and aims to improve the accuracy of aerosol radiative forcing predictions.

This talk is part of the AI4ER Seminar Series series.

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