Bakke, J., Trachsel, M., Kvisvik, B.C., Nesje, A. and Lysa, A. 2013. Numerical analyses of a multi-proxy data set from a distal glacier-fed lake, Sorsendalsvatn, western Norway.
Quaternary Science Reviews 73: 182-195.
AbstractFrom CO2 Science:
Here we present a Holocene record of glacier variability as documented through physical sediment properties analysed on sediments from the distal glacier-fed Lake Nedre (Nedre = Lower) Sørsendalsvatn (918 m a.s.l.), located 35 km inland from the coast in western Norway. We emphasise comparing different sediment parameters by means of statistical methods as well as integrating chronological uncertainties along with uncertainties of reconstructed glacier variability. A multi-proxy data set consisting of sedimentological, physical, and geochemical data shows one main process, as extracted by means of principal component analysis (88% of the variance explained by the first PC), driving sediment variability in Nedre Sørsendalsvatn. The common signal extracted from the sediment data is indicative of glacial activity in the catchment and is interpreted to vary in concert with the changing glacier equilibrium-line altitude. The reconstruction of former glacier activity is in accordance with glacier variability reconstructed from other sites in western Norway, including the termination of the deglaciation at approximately 10,000 cal yr BP, the 8.2 ka BP (Finse) event, the Holocene thermal optimum between ∼8000 and 5500 cal yr BP, and the onset of the Neoglacial at 5500 cal yr BP. The largest glacial extent during the Neoglacial time period took place during the ‘Little Ice Age’. The combined radiocarbon chronologies from three different sediment cores provide insight into the duration of the “8.2 ka event” in the terrestrial system. The maximum glacier activity at approximately 8.2 cal BP is the culmination of a glacier advance that began around 9 cal BP and accelerated at 8.4 cal BP. The glacier advance ended abruptly at 8.0 cal BP.
Bakke et al. report that their reconstruction accords with "glacier variability reconstructed from other sites in western Norway, including the termination of the deglaciation at approximately 10,000 cal yr BP, the 8.2 ka BP (Finse) event, the Holocene thermal optimum between ~8000 and 5500 cal yr BP, and the onset of the Neoglacial at 5500 cal yr BP," while further noting that "the largest glacial extent during the Neoglacial time period took place during the 'Little Ice Age'." They additionally indicate that these several findings are "in accordance with all glacier reconstructions available for western Norway (e.g., Nesje et al., 2001; Nesje, 2009; Vasskog et al., 2012), northern Norway (e.g., Bakke et al., 2010) and ... with glacier fluctuations in Iceland (Geirsdottir et al., 2009) and in the European Alps (e.g. Holzhauser, 2007)."
These facts clearly demonstrate that the most recent warming of the globe - which brought the earth to its current state of warmth (which is still far less than levels that were reached at earlier times in the Holocene) - began at the very coldest point of the current interglacial. Thus, there is no reason to think it out of the ordinary that the planet would subsequently experience a strong warming, or that the latter portion of that warming would be in any way unusual, unnatural or unprecedented (especially since it actually ceased over a decade and a half ago). In fact, it was no more unnatural than the cooling that had brought the plane's temperature down to that earlier and truly unique cold point in time.