4. Environmental and Landscape Changes

Climate changes in western Sørkapp Land mirror global fluctuations. The Little Ice Age ended with a cold period in the 1890s. A warm contemporary period began in the early twentieth century. Afterwards, secondary cold and warm climate fluctuations occurred. The most recent fluctuation, since the 1980s, shows a significant warming trend. The mean annual temperature increased by almost 2 °C and the mean annual total precipitation increased by about 60 mm since the 1980s (according to data of the station located 10 km from the study area). Almost all the snow patches melt during the warmest and sunniest summer seasons. The so-called active layer of permafrost had doubled at sites below 100 m of altitude from the 1980s to 2008. Almost all Sørkapp Land glaciers have undergone a continuous recession since the beginning of the twentieth century. Two processes are important for glacier recession: decrease in snow accumulation in firn fields due to the summer thawing of a larger snow mass, and summer thawing of ice on the surface of glacier tongues, which results in a decrease in ice thickness. Thus, the equilibrium-line altitude of a glacier shifts upward, reducing the accumulation zone. Hence, the entire surface of the glaciers undergoes lowering each year, which results in a decrease in their volume and their overall retreat. Since the 1980s, an acceleration of the glaciers’ recession has occurred, causing great changes in landforms and Quaternary. New accumulation landforms appeared in the front of glaciers and around glacier tongues in their marginal zones, that is, on lowlands and valley floors abandoned by glaciers and in their forefields situated below the marginal zones (i.e., beyond the former extent of the glaciers). New erosion landforms, apart from proglacial river incisions, prevail on the steep slopes of valleys and mountain massifs. The cliffs of tidewater glaciers undergo the quickest retreat. Karst processes have intensified due to higher air temperatures and larger quantities of flowing water. Surface and underground streams carry much more water today than in the 1980s. However, the soil is generally drier on the lowlands between the streams today due to the deepening of the active layer above the permafrost. The river and lake network changed the most due to glacier recession. Ice-dammed lakes disappeared due to the recession of glaciers. On the basis of repeated vegetation mapping, significant changes in composition and extent of several plant communities were documented. Decrease in species diversity, leading to a more uniform vegetation, has been observed mainly in dry habitats. In some cases boundaries between plant communities that were clear in the 1980s have now vanished. Fruticose epigeic lichens, such as Flavocetraria nivalis, Cladonia rangiferina, and other species of Cladonia have disappeared from the most part of the study area and their extent is now limited to steep rocky slopes. In some communities increase in abundance of Salix polaris was recorded. The main cause of vegetation changes in Sørkapp Land is the rapidly growing reindeer population in the area.