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

phenomenon considered a hazard (Loeng, 2008). It becomes more severe with strong wind and higher waves,and is therefore also connected to storminess. To know whether such storms will become more common or more severe in the Arctic in future is important for adaptation planning. However, it is difficult to predict the atmospheric circulation response to global warming owing to natural climate variability, in space and time. This natural variability generates substantial uncertainty in the model projections of future atmospheric circulation patterns, especially for the next 30 to 50 years. It should also be noted that most GCMs simulate storm tracks that are too weak and display equatorward biases in their latitude (Zappa et al., 2014), and these biases also affect their projections. At present, there is no clear signal for future changes in storm statistics. Chang et al.(2012) analyzed a proxy for stormactivity and found a reduction over the Barents area in the future for the CMIP5 results but little change using the CMIP3 results. Other model projections have also shown a decrease in cyclones over the Norwegian, Barents and Greenland seas during the cold season (Ulbrich et al., 2013; Roshydromet, 2014; Akperov et al., 2015). Projections of North Atlantic and European cyclones from multi-model studies (CMIP5 RCP4.5 and RCP8.5) indicate a tripole pattern with decreasing cyclones in the Norwegian Sea in winter and in summer with fewer and weaker cyclones along the southern flank of theNorthAtlantic storm track (Zappa et al., 2013). Catto et al. (2014) analyzed climate projections based on a multi-model ensemble (CMIP5 RCP8.5) and found overall decreases in future weather front frequency, but a poleward shift in maximum frequency. Another study of extreme Arctic cyclones based on a multi-model ensemble (CMIP5 historical period) found a modest historic increase in storminess in some regions (including southeast of Iceland) compared to future projections (Vavrus, 2013). Catto et al. (2014) suggested that future changes in frontal disturbances were likely to be associated with storm tracks, and that front strength could decrease at higher latitudes due to amplified surface warming in the Arctic and a reduced temperature gradient. They found little change in storm frequency for the Barents area, but strong indications that storm intensity will decrease. The simulated storm tracks were linked to sea ice is such a way that they both influenced and were influenced by the sea ice.According to Bengtsson et al. (2009), most models agree that a poleward shift in storm tracks is inevitable over the long-term under a warming climate, along with a general weakening of the global cyclonic activity. In contrast, a recent study which used the dependency of storm track statistics on mean sea-level pressure to show a slight increase in the frequency of deep cyclones over the Barents Sea under a warming scenario (Benestad et al., 2016).This finding is consistent with an analysis of past trends, which suggests there has been a northward shift in the storm tracks as well as increased cyclonic activity in the Arctic in recent decades (e.g. Zhang et al., 2004; Inoue et al., 2012; Sato et al., 2014; Rutgersson et al., 2015). Recent RCM data project an increase in the maximum daily wind speed (Figure 4.7), especially in winter, in the northeastern part of the Barents Sea including the northeastern coast of Svalbard (Dobler et al., 2016). The projections show increases in wind speed of more than 3 m/s in winter between the two blue lines on the graphic (i.e. the

DJF

MAM

Change in wind speed, m/s

JJA

3

2

1

0

-1

SON

-2

-3

Figure 4.7 Projected seasonal change in daily maximum 10-mwind speed over the Barents and Scandinavian region using the regional climate model COSMO-CLM driven by the global MPI-ESM-LR earth system model under the RCP8.5 scenario for the period 2071–2100 against a 1971–2000 baseline.The green lines indicate the northern extent of an area that is ice- free sea for at least 20% of the time in the future (dark green) and historical period (light green) (Dobler et al., 2016).

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