Adaptation Actions for a Changing Arctic: Perspectives from the Barents Area

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Adaptation Actions for a Changing Arctic: Perspectives from the Barents Area

exploited by a range of species. This habitat is listed in the EU Habitats Directive (Council Directive 92/43/EEC) as important for biodiversity in Europe. Permafrost temperature decreases with increasing latitude. In Scandinavia,Svalbard and northwesternRussia the permafrost is warmer than in otherArctic regions.This is due to the warming influence of ocean currents and prevailing winds on climate, while altitude is a modifying factor in the Nordic mountains (Romanovsky et al., 2010; Sato et al., 2014). Permafrost has been thawing since the 1990s (AMAP, 2017). The draining of lakes and wetlands converts aquatic and wetland areas into terrestrial ecosystems (Bring et al., 2016;Wrona et al., 2016). Peatlands in the permafrost zone are important reservoirs of soil organic carbon, particularly where permafrost is extensive and the peat is relatively thick. Disturbance of the peat surface layers in the tundra may lead to irreversible changes, transforming a carbon-sink ecosystem into a carbon-releasing system, either directly through emissions of greenhouse gases or through hydrological flows becoming a subsequent source of emissions (Degteva et al. 2015). For further implications of the ongoing climate change on permafrost see Chapter 4. 2.2.2 Marine ecosystems The Barents Sea is a high-latitude Arctic shelf sea comprising 1.6 million km 2 (Carmack et al., 2006) with a mean depth of 230 m. It is one of two major shallow and highly productive Arctic seas, the other being the Bering Sea in the North Pacific Region.The Barents Sea is bordered by the northernNorwegian andRussian coasts and by theNovaya Zemlya Islands.The 500-m depth contour is often used to delimit the Barents Sea towards the Greenland Sea,Norwegian Sea,andArcticOcean (see Figure 2.1). Ocean circulation in this region is dominated by the Norwegian Atlantic Current, which brings warm saline AtlanticWater into the area from the south (e.g.Loeng,1991).AtlanticWater extends throughout much of the western and central parts of the Barents

raptors and other birds that require large territories.Among the tree-covered areas, nutrient-rich deciduous forests offer more insects and tree holes for breeding birds than uplands forests, and so are more species-rich.Mammals are not represented in high species diversity or numbers in peatlands. Peat moss has a low energy content and small rodents,moose and reindeer tend to be found in wetland areas only in the nutrient-rich swamps and fen-forests. Beaver can inhabit peaty wetlands, depending on the availability of brooks and streams and proximity to food and lodge material such as aspen and birch. Wetlands provide a wide range of key ecosystem services: maintaining permafrost (in northern areas, see next section), regulating and filtering water and storing vast quantities of greenhouse gases, which is critical for global biodiversity. See Box 2.2 for further descriptions of ecosystem services. 2.2.1.4 Discontinuous and continuous permafrost Permafrost (cryotic soils) is defined as soil(s) that remains at or below the freezing point of water for at least two consecutive years. Permafrost can only develop when the mean annual air temperature is low enough and snowfall in winter is limited, to allowheat flux from the ground.Permafrost is often divided into subgroups based on extent (Figure 2.4): continuous (90–100%), discontinuous (50–90%), sporadic (10–50%) and isolated patches (0–10%). On the mainland, continuous permafrost occurs mainly in Russia with extent increasing eastwards. Svalbard and Franz Josef Land have extensive permafrost zones. Within the discontinuous permafrost areas thawing and freezing processes create frost heaves, and where there is a thick enough peat layer a peat hummock with a frozen core will rise above the surface of a mire (Seppälä, 1986).This is referred to as a ‘pals’. Eventually the structure collapses exposing bare soil and often producing a small pond. This dynamic process creates a mosaic on the mire (Figure 2.5) which generates a heterogeneous environment (Luoto et al., 2004) potentially

Sporadic permafrost Discontinuous permafrost Continuous permafrost Isolated permafrost

Figure 2.4 Distribution of permafrost in the circumpolar north (http://maps.grida.no/arctic/).