Arctic Loess as an Environmental Archive: Holocene Dust and Wildfire Record in West Greenland

• Main Author: Hällberg, Lars Petter
• Format: Bachelor Thesis
• Language: English
• Published: Uppsala universitet, Institutionen för geovetenskaper 2018
• Subjects: aeolian dust; IRSL; luminescence dating; charcoal analysis; magnetic susceptibility; wildfire; Physical Geography; Naturgeografi; Arctic; Greenland; Västra; albedo; Arktis*; Grönland; Ice; Ice Sheet; Magnetic susceptibility; permafrost; Tundra
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-367767

The largest wildfire ever observed in Greenland raged through its tundra during august 2017, and it is unknown if there have been similar wildfires in the area before satellite monitoring began in 1999. Arctic wildfires affect permafrost degradation, carbon storage of soils and the surface albedo of the Greenland Ice sheet – despite this, local fires have previously been ignored by researchers. Here, aeolian dust deposits are independently dated by radiocarbon and luminescence techniques and paleoenvironmental proxies and macrocharcoal contents reflecting local fires are analyzed. The dating results indicate that the onset of aeolian deposition coincides with the deglaciation of the area, suggesting that paleoenvironmental proxy records from aeolian dust deposits may extend the entire ice-free period of the area until approximately 8 ka BP. Luminescence signals are generally partially bleached, resulting in age over-estimation of several samples. This effect is quantified using the pIRIR/IR ratio and different integration limit intervals. No evidence for previous wildfires were found during the charcoal analysis, suggesting that the area around the assessed profile has never been burnt since its deglaciation. These first results show promise for the method, and in order to expand this to a regional estimate of the wildfire activity through the Holocene, analysis of more material is needed.