Analysis of Thermal Properties of Permafrost, and Modeling
Permafrost thaw has a potentially large impact on the global climate system through release of carbon gas that has been stored as organic carbon for up to 400,000 years. System feedbacks between permafrost carbon content, microbial decomposition rates, ground temperature, and greenhouse gas radiativ...
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SCARAB
2018
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| Online Access: | https://scarab.bates.edu/geology_theses/41 https://scarab.bates.edu/cgi/viewcontent.cgi?article=1043&context=geology_theses |
| Summary: | Permafrost thaw has a potentially large impact on the global climate system through release of carbon gas that has been stored as organic carbon for up to 400,000 years. System feedbacks between permafrost carbon content, microbial decomposition rates, ground temperature, and greenhouse gas radiative forcing make the permfrost system susceptible to rate induced tipping. Individual components of the permafrost system are examined to contribute to understanding of the timing and behavior of system tipping. A Permafrost Bomb model is created to evaluate the long term decomposition ground temperature feedback behavior. Results showed several system tippings with decreasing successive amplitude under a constant atmospheric temperature forcing. This resembles the global temperature behavior of the PETM hyperthermals, supporting evidence of permafrost thaw influence on paleoclimate events. Six years of ground temperature data from a Kapp Linne borehole was analyzed for the thermal diffusivity through time and depth. Increasing atmospheric temperature is associated with greater thermal diffusivity and more effects from latent heat transfer, which were observed far below the active layer. Considering the results directly from this study and previously published research, a more complete model for permafrost is proposed. This model considers ground and atmospheric conditions for temperature and carbon content. Overall, these findings are applicable in permafrost and climate modeling for the purpose of understanding how the permafrost system may change and impact the global climate on both the geologic time scale and human lifespan. |
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