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

key climate-related fluxes of carbon dioxide, methane, energy, and water (Wrona et al., 2016), and there is an emerging need to establish the spatial extent of ecosystem transformations. Palsas are frost heaves that contain permanently frozen ice lenses. Norway started monitoring palsa peatlands in 2004 (Hofgaard andMyklebost, 2015), in response to concerns about the consequences of reduced palsas on the ecosystem. The permafrost is thawing because the Arctic is warming, and is expected to continue to thaw under the projected increases in future temperature. Long-term records at a selection of sites providing good spatial coverage across the Barents area show the permafrost has warmed since the 1990s (Romanovsky et al., 2017).The greatest warming has occurred in the cold permafrost of Svalbard and Russia (Figure 4.15). In northern Russia and in the western Siberian Arctic, temperatures at 10 m depth at cold permafrost sites have increased by ~0.4–0.6°C per decade since the late 1980s, with less warming at warmer permafrost sites (Figure 4.15).The European permafrost is thawing and there has beenanorthward retreat of the southernboundary of near-surface permafrost in European Russia (Rasmus et al., 2015). Records from Abisko in northern Sweden show the period over which the ground remains frozen each year is decreasing,driven by later freeze-up and earlier spring thaw.Meanmonthly air temperature is highly correlated with ground temperature to 100 cm depth, and the warming is correlated with soil surface movement due to freezing and thawing.Rasmus et al.(2015) found the southern limit of patchy near-surface permafrost retreated northward by 20–50 km in European Russia between 1974 and 2008.

1993; Hansen et al., 2014; Vikhamar-Schuler et al., 2016) as well as for small rodents living below the snow (Kausrud et al., 2008). Soil temperature and thus permafrost are also affected by rain-on-snow induced changes in snow properties (Westermann et al., 2011). There are indications that ground ice formation has become more common at the lichen layer in Finland (Rasmus et al., 2015). Using climate model results (2081–2090 and RCP8.5), English et al. (2015) estimated that future net downward short-wave radiation at the top of the atmosphere may increase by 8 W/m 2 over the Arctic basin due to a decline in surface albedo resulting from a decline in snow and ice cover. Examples of ecological and societal consequences of rain-on- snow events were reported from Svalbard during and after an extreme event in February 2012 (Hansen et al., 2014). This resulted in a thick ice layer on the ground, increased permafrost temperatures to 5 m depth, and triggered slush avalanches with major impacts on infrastructure (airport closure, restricted traveling in the terrain, closed roads) and wildlife (reindeer starved because they could not access forage). Future warming may bring more frequent rain-on- snow events (Hansen et al., 2014). The processes leading to hard layers or ground-ice layers occur on daily rather than monthly timescales, and whether specific conditions are problematic depends on the general conditions during winter, not just those on particular days. 4.4.2 Permafrost The changes taking place in permafrost areas under a warming climate are having various impacts. Thawing permafrost has major consequences for buildings, infrastructure and transport networks designed to be supported by frozen ground. For example, roads can be badly damaged when ice within the soil melts and the land subsides. Another effect of thawing permafrost is the release of methane and the reinforcement of the global greenhouse effect. Thawing permafrost can also increase the risk of erosion and landslides if the frozen water in the soil has been acting as a glue. More details about the present state of the permafrost and its effect on hydrology and vegetation can be found in Chapters 2 and 6.According to the recent SWIPA update, the combination of climate-cryospheric- hydrologic change and multiple ecological feedback processes may cause unpredictable reorganization of ecosystem structure and function, and hence trigger ecosystem shifts or give rise to novel ecosystems (Romanovsky et al., 2017).This tendency has already been observed with vegetation shifts and conversions between terrestrial and aquatic ecosystems. For example, thermokarst lakes and wetlands in ice-rich permafrost environments may drain as the permafrost thaws, resulting in their conversion from aquatic to terrestrial ecosystems (Wrona et al., 2016). Projecting the geographic extent and magnitude of such shifts carries great uncertainty, however. According to Bring et al. (2016) and Wrona et al. (2016), the aquatic and terrestrial landscapes of theArctic have experienced many changes in successional patterns and the spatial extent of biomes where tundra has become shrubland and forest.These changes have largely been driven by climate change and changes in hydrology, especially in relation to permafrost thaw and related flow pathways. Such changes are important in terms of

Ground temperature, °C

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KT-16a (15.0m)

Iskoras Is-B-2 (20.0m)

Bolvansky #56 (10.0m)

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Urengoy #15-06 (10.0m)

Bolvansky #65 (10.0m)

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Bolvansky #59 (10.0m)

ZS-124 (10.0m)

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Juvvasshøe P30 (20.0m)

Tarfalaryggen P20 (20.0m)

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Urengoy #15-10 (10.0m)

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Janssonhaugen P10 (20.0m)

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1975

1985

1995

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2015

Figure 4.15 Time series of ground temperature at depths of 10 to 20 m below the surface at selected measurement sites that fall roughly within the continuous to discontinuous and warm permafrost zones in the Barents area, including Scandinavia, Svalbard, and Russia. Data updated from Christiansen et al. (2010) and Romanovsky et al. (2014, 2015).

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