The first permafrost cycle in Færdesmyra, eastern Finnmark, Norway?

ABSTRACT

The author studied the causal relationships between palsa formation, the maintenance of palsas, their final thawing, and climate. His main approach was to compare his observations with other researchers’ observations of recent palsa formation and degradation, and the use of relevant palaeoclimatic data. A more than 10 km² large palsa mire complex in Sør-Varanger Municipality, northern Norway, was studied in terms of vegetation and stratigraphy 50 years ago, and then observed between 2005 and 2015, when the final palsa thawing occurred. The decisive climatic factor for the maintenance of existing palsas – annual mean temperatures below -1 °C, stated earlier by researchers – seemed to be valid also in the studied case. However, the results showed that new palsa formation may require a series of consecutive years with temperatures between -1 and -2 °C in annual mean temperatures. There is a possibility of detecting former palsas (i.e. since thawed) by stratigraphic investigations in cases of lateral erosion of palsas. Stratigraphic corings and field observations in the selected study area did not indicate earlier periods of palsa thawing prior to the modern one. The author concludes that the present thawing thus reflects a reversal of the final cooling stage of the present interstadial (Holocene).

EDITORS:

• Ivar Berthling
• Catriona Turner

KEYWORDS:

• Northern Norway
• palsa thawing
• sporadic permafrost

Acknowledgements

I express my gratitude to Dr Øyvind Nordli and Dr Erik Johnsen at The Norwegian Meteorological Institute, Oslo, for meteorological data, and Tove Midtun, University of Tromsø, for producing Figs. 1 and 2, and modifications to other Figures. Additionally, I am grateful to Assistant Professor Geoffrey Corner, Department of Geology, University of Tromsø, for improvements to the English language of an earlier version of this article, and to Bjørn Vorren (in Neiden) and Sigbjørn Sildnes (in Kirkenes) for observations and information on palsa thawing at Færdesmyra. Finally, I thank the editors of Norsk Geografisk Tidsskrift–Norwegian Journal of Geography and referees who reviewed this article.

Notes

1. The online service is part of the Cologne Radiocarbon Calibration & Paleoclimate Research Package.