At 70-71°N, 30°E the Varanger peninsula harbors the westernmost fringe of the vast continental Eurasian arctic tundra. Bordering the ice-free southern part of the Barents sea, the outer low-lying coastal areas have annual average temperatures above zero (0-2°C). The interior of the peninsula, with highland rising to 600 m above sea level, have below zero annual temperatures (-3 – 0°C) and wide-spread low-arctic permafrost. Annual precipitation is highest in the coastal areas facing the Barents Sea and in the central highlands. The northern and eastern coastal low-lands as well as the interior highlands have mean July temperatures ≤ 10 °C. The south-western low lands with higher July temperatures (11-13°C) are mostly covered with birch Betula pubescens forests. Thus there is an extensive forest-tundra transition zone that cuts through the peninsula mainly in the west-east direction. However, topographic variation creates climatically benign conditions allowing for isolated patches of forest in some of the north-eastern valleys.
Vegetation productivity, expressed as summer NDVI, in low-arctic Varanger peninsula. Full black lines show the fenced border between the two reindeer herding districts on the peninsula.
Human presence, land and resource use
The coasts of the Varanger peninsula were among the first areas in Fennoscandia to be colonized by humans after the last ice age. Thus natural resources have been exploited in this region for millennia. Although marine resources always have provided the bulk of the subsistence, also terrestrial resources were important. Presently, marine fisheries constitute the main industry for several smaller towns and villages along the coast, and the total human population is at present just above 15 000. In 2006 Varanger Peninsula National Park was established. With an area of 1806 km² the national park covers most of the interior of the peninsula as well as coastal tundra, especially in the eastern and northern parts. A key motive for the establishment of the park was to protect the only large area with terrestrial arctic biota and landscape features in mainland Fennoscandia.
Climate change and impacts
During the last three decades mean annual temperature and precipitation patterns have shown significant deviations from 1961-1990 standard normal values. On the Varanger peninsula, only a single year since 1989 has been colder than the 1961-1990 normal. Also, mean monthly precipitation show positive deviations from normal in the majority of years since 1990. The clearest and most extensive ecological effect of climate warming so far in the Varanger region is the eastward spread of the outbreak range of the winter moth Operopthera brumata. This insect pest species has contributed to defoliation and death of large tracts of the birch forest and a comprehensive vegetation state shift throughout the forest-tundra ecotone. Moreover, climate warming appears to have reduced the outbreak amplitude of the Norwegian lemming Lemmus lemmus, which have contributed to dampening of the guild level rodent dynamics, which nevertheless is still cyclic. Cascading impacts of dampened small rodent cycles may have contributed to severe population declines of lemming-dependent predators of which some now are red listed.
Key site-specific assets for COAT
The positioning of the Varanger peninsula at the southern edge of the low arctic tundra provides excellent opportunities for monitoring the changes across and close to the transition zone between sub-arctic forest and arctic tundra. This zone is expected to represent a hot spot for climate change impacts in particular in terms of species range changes and structural aspects of vegetation with feed-backs to the climate system. The Varanger peninsula also harbors other highly climate sensitive vegetation strata within the tundra zone and ‘warm’ low-arctic permafrost in its highlands with low resilience to increasing temperatures.