Iceland

Within the high North Atlantic region, Iceland is the natural nexus between Scandinavia and Greenland. Its location at the meeting point of polar and temperate air masses and cold and warm sea currents makes this island very sensitive to climatic oscillations. The spreading of permafrost and periglacial environments throughout the island began at the first ice-free coastal lowland areas uncovered by the Icelandic Ice Sheet at the onset of the deglaciation following the Last Glacial Maximum (LGM, hereafter). Post-glacial periglacial dynamics varied in intensity and resulted in a wide variety of periglacial phenomena associated to both permafrost and seasonal frost regimes. Today, the lower limit of permafrost ranges between 850–900 m in the north and 950–1000 m in the south. The shifts of the lower permafrost limit and the extent of the seasonal frost areas since the LGM has generated a wide range of periglacial landforms from the coastal areas (<150 m; relict rock glaciers, and sorted polygons) to the highlands of central (>700 m; e.g. palsas, sorted nets, stripes), north-western and northern Iceland (solifluction, relict and active rock glaciers, talus slopes). The current atmospheric warming and the changes in the general weather pattern are leading to the fast retreat of outlet glaciers and the degradation of permafrost and snow cover, contributing also to catastrophic phenomena such as complex landslides, debris slides and slush avalanches. Periglacial dynamics has also been affected by widespread human activities over the last millennia or all the way since the Norse settlement (grazing, deforestation, etc.). In addition, projected warming for the next decades will likely increase the frequency of such events.