At 74-81°N, 15-30 °E the archipelago of Svalbard harbors one of the northernmost terrestrial ecosystems of the world. The archipelago consist of numerous islands, whereof the largest is Spitsbergen (37 700 km²). The North Atlantic Current has a strong effect on Svalbard’s climate. While the sea north and east of Svalbard in general is ice covered for at least 8 months of the year, the warm North Atlantic Current keep the west coast of Svalbard ice free for most of the winter. This warm seawater results in up to 20 °C higher average winter temperatures compared to similar northern latitudes elsewhere. Permafrost is still found in all non-glaciated areas. Long-term meteorological records are mainly available from the west coast of Spitsbergen where the annual average temperature was -6.7 °C for the period 1961-1990 (Longyearbyen Airport). Precipitation is low (on average 190-525 mm annually), and tends to decrease from the outer parts of the fjords on the west coast (~500 mm annually) to the inner eastern parts of these fjords.
After the discovery of Svalbard at the end of the 16th Century, whaling, sealing and trapping were the main activities in Svalbard for three centuries. Thus, the terrestrial ecosystem in Svalbard has been exploited by humans for the last four centuries. Today, the economy on the archipelago is based on mining, tourism and research. There are only two towns in the archipelago, both located on the Nordenskiold Land peninsula on Spitsbergen. The main town Longyearbyen is the administrative center and hosts about 2000 people out of the total population of 2400 people in Svalbard.
During the last three decades the mean annual temperature in Svalbard has shown a significant increase. In the period 1981-2010 the annual temperature was, depending on the location of the weather station, on average 1-2 °C higher than the 1961-1990 standard normal values. Since 1989, no year has been colder than the 1961-1990 normal. The increase in temperature has been particularly prominent in the autumn and winter temperatures. Annual mean monthly precipitation has not shown a similar strong increasing trend over the last three decades. However, the seasonal pattern of precipitation seems to have changed with less precipitation in the spring and summer, and more precipitation in the autumn and winter when compared with the 1961-1990 normal. The combination of milder winters and more precipitation in the winter has also resulted in an increasing amount of precipitation falling as rain in the winter period the last three decades.
The clearest ecological effect of climate warming so far in Svalbard is due to the increase in the frequency of rain-on-snow events during the winter. Rain-on-snow cause ground ice, which has significant negative effects on the population growth of Svalbard reindeer, and may become a threat to the viability of Svalbard reindeer populations. Ground ice leads to elevated reindeer mortality and the carcasses improve food availability for arctic foxes in the winter with subsequent positive effects on arctic fox reproductive rates.
The position of Svalbard provides excellent opportunities for monitoring climate change effects in a high Arctic ecosystem. The close proximity between vegetation communities ranging from the middle Arctic type to arctic desert type will allow vegetation transitions to be monitored at local to regional spatial scales, and imply that transitions between these vegetation communities may respond quickly without a need for stochastic immigration events.
Vegetation productivity expressed as summer NDVI on Nordenskiöldland (left) and Brøggerhalvøya (top right) in high-arctic Svalbard.
Photo: Jennifer Stien
Photo: Eva Fuglei