This study presents the results of dendrochronological and dendroclimatological research of Betula pubescens from four sites in northern Norway (Kvaløya Island, Tromsøya Island and Storelva Valley), which provided a 193-year chronology. Our results highlight the importance of the site selection in dendroclimatological studies. We demonstrated that activity of geomorphic processes connected with local topography could led to reduced strength of climatic signal embedded in tree-ring data. Negative pointer years, triggered mainly by unfavourable climatic conditions and insect outbreaks, were common for all site chronologies in 1945, 1955, 1965, 1975, 1986, 2004. However, some site-specific differences were also distinguished. Response function analysis confirmed that June, July and August temperatures were positively correlated with tree-ring widths. This climate-growth relationship was stable throughout the years 1925-2000. From summer temperature reconstruction back to AD 1820, two colder (c. 1835-1850 and 1890-1920) and two warmer (c. 1825-1835 and 1920-1940) periods were identified. The tree-ring record from the Tromsø Region, well correlated between series, sites and climate variables, is an important element of a large-scale reconstruction of pre-instrumental climate variation in the northeastern part of the Atlantic Ocean. Our dendroclimatic reconstruction corresponds well with other climate proxy data, like fluctuations of mountain glaciers in Scandinavia or sea ice extent.

An analysis of a suite of climatological indices was undertaken on the basis of long-term (1979–2019) climatological data from the Polish Polar Station in Hornsund, SW Spitsbergen. It was followed by an attempt to assess the scale of their impact on the local environment. The temperature and precipitation indices were based on percentiles of the variables calculated for a population of daily values from the climate normals for 1981–2010. A greater share of both cyclonic and anticyclonic circulations from the S and SW sectors, forcing the advection of warm air masses from the south, was decisive for the trends of change in comparison with the long-term mean. Both extreme precipitation and drought events depend on the 500 hPa geopotential height and precipitable water anomalies, determined by the baric field over the North Atlantic. Climate changes impact on the dynamics of local geoecosystems by causing faster glacier ablation and retreat, permafrost degradation, intensification of the hydrological cycle in glaciated and unglaciated catchments, and changes in the condition and growth of tundra vegetation.