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

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Figure 4.2 Projected change in a typical warm winter mean temperature (DJF; left) and annual total precipitation (right) for a typical wet year between 2015 and 2080 based on empirical-statistical downscaling of the 95-percentile of CMIP5 ensemble following the RCP4.5 emissions scenario.The results are based on Benestad et al. (2016).

to have a range of effects with consequences for other parts of the cryosphere (Førland et al., 2011; Hansen et al., 2014; Vikhamar-Schuler et al., 2016).Winter warming may increase the risk of ROS events. Projections for future warming in theArctic were also generated for the fifthassessment of the Intergovernmental Panel onClimate Change (IPCCAR5), with the extent of warming dependent on time horizon and emission scenario.Changes in temperature are projected with higher confidence than for many other aspects of the climate system (such as precipitation and wind), even at high latitudes. However, the IPCC AR5 also pointed to the increased spread in model projections for temperature in the polar regions.“ The zonal means ... show good agreement of models and scenarios over low and mid-latitudes for temperature, but higher spread across models and especially across scenarios for the areas subject to polar amplification... ” (Collins et al., 2013).This increased spread in model results for high latitudes may be a bit deceptive, as explained by Benestad (2005), because the polar regions involve smaller surface areas with different geometry to the latitude bands at lower latitudes, and so represent a smaller statistical sample and fewer real degrees of freedom. Projections of future temperature suggest that model spread does not change much over time (Hansen et al., 2014). On the other hand, the presence of additional factors in the Arctic (such as sea ice) and different representation in the models, also gives rise to a wider range of results (Stramler et al., 2011). It is important to note that pronounced natural variations, associated with shifts in ocean currents, sea ice, storm tracks, and wind can diminish or amplify the estimates of future temperature by roughly 5°C (Benestad et al., 2016). The Arctic climate responds to changes in ice and snow, heat transport through ocean currents and storms, and heat loss to space, but is also characterized by its marine environment; especially the strong Coriolis effect, frontal systems, energy and moisture

increase by 3–10°Cover the period 2015–2080 under the RCP4.5 scenario (Figure 4.2).Thewarming shows regional variability,with the greatest warming expected to occur over Svalbard and the HighArctic. Temperatures are projected to be even higher under a regional climate model (RCM) that downscaled data from four GCMs (CMIP5) and the RCP8.5 scenario (Koenigk et al., 2015). According to these results, warming over the Barents Sea may be 8–15°C by mid-century and up to 20°C by the end of the century in winter, largely driven by the disappearance of sea ice from the Baltic Sea.Warming over the Barents Sea in summer is projected to be 3–4°C by mid-century and 6–8°C by the end of the century under RCP8.5, with a warming over the adjacent land of 4–6°C by the end of the century.The drawback to this study is the small number of GCMsimulations onwhich the regional data are based. However, these data are comparable with an atlas based on 81 RCP8.5 simulations, and corresponding results from empirical- statistical downscalingof larger ensembles indicates a similar range, albeit with strongest warming in the western part of the Barents area (Benestad et al., 2016). Recent analysis of projections from anotherRCM(COSMO-CLM,Steppeler et al.,2003),downscaling RCP2.6,RCP4.5 andRCP8.5 scenario runs fromthe Earth System ModelMPI-ESM-LR to a resolutionof about 25 kmin the Barents and Scandinavian region, are in agreement with results reported by Koenigk et al. (2015) (Figure 4.3). There was little difference between the projected summer temperatures for the different emission scenarios (i.e. the patterns were similar), although a temperature increase of several degrees is expected to bring the winter conditions closer to freezing over theNordic countries,where winter temperatures already are moderate. Present winters are extremely cold in northern Russia and are expected to remain well below freezing even by the end of the century (Benestad, 2011). Future winters on Svalbard, however, are more likely to rise above freezing, and extreme high winter temperatures in the future are expected