COMBINING THE ROLE OF SULFUR AND CARBON IN LONG-DURATION MODELS TO ASSESS THE CLIMATIC IMPACT OF LARGE IGNEOUS PROVINCES

Large Igneous Provinces (LIPs) release both carbon and sulfur into the Earth system and can lead to significant global climate and environmental change. Key to understanding the impact of volcanic gases on climate is the tempo and rate of volatile release into the atmosphere. Modeling a range of volcanogenic outgassing scenarios can determine what LIP eruptive conditions cause major climate changes and thus may cause mass extinction events. We use a multi-box Earth System model, LOSCAR (Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir), which models the carbon cycle perturbations in the oceans, atmosphere, and ocean sediments (Zeebe, 2012). Although LOSCAR has been used to test the climate and environmental impacts of volatile release from LIPs (e.g. Zeebe et al., 2010; Hull et al., 2020), these studies only focused on the carbon cycle and are limited in modeling the sulfur cycle. To assess the combined effect of carbon and sulfur from LIPs over the full eruptive durations (~1 Ma), we modified the LOSCAR model to include sulfate aerosol driven cooling. Thus, we can simulate the effect of 100s of eruptions on the climate as opposed to more detailed studies modeling sulfur and carbon from individual LIP eruptions over < 10 kyr (e.g. Black et al., 2019; Landwehrs et al., 2020). In our analysis, we generate multiple eruption histories by adjusting parameters including: mass of eruption, the number of eruptions, duration of eruption, time between eruption, and duration of eruptive episode with model runs with and without sulfur emissions. For a given eruption scenario, the output related to carbon cycle and climate change (e.g. temperature, pH, pCO₂, total alkalinity, CCD, δ¹³C) is assessed over time. Our model results show very different responses between carbon-only model and combined carbon and sulfur model, especially on the sub 10kyr timescales. We find a clear effect of sulfur not only on the temperature (i.e. cooling effect) but also on the carbon system (e.g. pH, pCO₂, total alkalinity, dissolved inorganic carbon, etc.). We will present the results of these new models over a large parameter space to assess what LIP eruptive rates are required for major environmental perturbations and how these rates compare with various geochronological, paleo-magnetic, and mercury proxy-based constraints.