Temporal and spatial dynamics of Arctic coastal changes and the resulting impacts: Yukon Territory, Canada

• Main Author: Irrgang, Anna
• Format: Thesis
• Language: unknown
• Published: 2018
• Subjects: Arctic; Beaufort Sea; Ice; permafrost; Yukon
• Online Access: https://epic.awi.de/id/eprint/52108/; https://epic.awi.de/id/eprint/52108/1/AMIrrgang_Dissertation.pdf; https://hdl.handle.net/10013/epic.7a068403-107f-48fa-8481-a2a3c40c77bf

In the Arctic, temperatures are rising twice as fast as the global mean. Since most of the terrestrial Arctic is underlain by permafrost it is particularly vulnerable to rising air temperatures. Permafrost holds vast amounts of carbon which upon release can considerably impact the Earth climate system. Studying processes which lead to permafrost degradation and carbon mobilization is thus important for quantifying this impact. The erosion of permafrost coasts is one of these processes and results in the mobilization of previously frozen carbon from the cliff, as well as from the hinterland. Since 34% of the World’s coasts are characterized by the presence of permafrost, the net effect is substantial and leads to the release of large amounts of organic matter. Yet, little data on rates of shoreline change and fluxes of organic matter are available for the Arctic. This thesis fills a gap by providing new baseline data on the temporal and spatial variability of shoreline changes along the ice-rich Yukon coast in the western Canadian Arctic, as well as on subsequent impacts on the natural and human environment. Shoreline change rates were obtained from geocoded aerial images from the 1950s, 1970s and 1990s, as well as from satellite images from 2011. Differential global positioning system (DGPS) measurements of shore zone and cliff profiles along seven field sites were analyzed. Based on this data, shoreline changes were estimated for several time periods. Even though acceleration in shoreline retreat was not reflected in the mean shoreline change rates for the whole coast, analyses along six shorter sections of the coast revealed that coastal erosion is accelerating since the mid-1990s. DGPS field site measurements also indicate a rapid acceleration in shoreline retreat since 2006. Based on the shoreline change rates, sediment and soil organic carbon (SOC) fluxes to the Beaufort Sea were quantified. The SOC fluxes were calculated accounting for ground ice, which reduced the total flux rates by 19%. Sampling of the ...