Climate-driven landscape development : physical and biogeochemical long-term processes in temperate and periglacial environments
Abstract: Earth has experienced many glacial cycles over the ̴ 2.5 million year long Quaternary period. During the latter part of the Quaternary, roughly the last 800,000 years, each cycle has been of duration ̴ 100,000 years and has included extended periods of glacial conditions, with ice sheets in the northern hemisphere. In-between those periods, intervals with periglacial or temperate conditions in northern latitudes have occurred. Global sea level has, as a response to the formation and melting of ice sheets, fluctuated over 120 meters. Thus, the global climate cycles have been the main driver for the location of continental coastlines, environmental changes in the past as well as the resulting present-day landscapes. Recent human-induced climate change is now also affecting the landscape. In this thesis, I examine the use of global climate models as input to exploring local landscape evolution over glacial cycles. An approach is proposed for landscape description that is designed for use in long-term safety assessments related to landscape development into the far future. The approach is illustrated by results of work that shows methods applied to a site-specific landscape development model using climate and climate-related data. Site-specific data is utilised to gain site understanding from which conceptual ecosystem models are developed for present day conditions, and to inform landscape narratives. Concentrations of elements are used to infer the characteristics of transport processes in the landscape over time. The results from the above studies are discussed in relation to the general hypothesis in this thesis; that by considering a few well-defined climate-related processes and using site understanding on local properties and processes, it is possible to reduce the uncertainties in future landscape developments for a specific site. Uncertainties include the abundance and distribution of ecosystems and associated properties related to processes governing the transport of matter. I conclude that relevant examples of historical and future landscape evolution for specific sites can be given that are useful for long-term assessments.
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