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

have some connection with low-pressure systems and storm tracks. The risk associated with these events for society and ecosystems can be determined froma climatological description of a region, because climate is based on weather statistics and describes the probabilities connected to the weather events.The following sections examine the different types of hazard in the context of these extreme weather phenomena. Synoptic activity and storm tracks Mid-latitude storms, also referred to as synoptic storms , are associated with low surface pressure, high winds, and ocean surface waves. They may also generate heavy precipitation, and are considered weather hazards in relation to health, offshore activities, transport and infrastructure (avalanches and rockslides; Hov et al., 2013). In 2012, parts of Svalbard were covered in ice after a rain-on-snow event (Hansen et al., 2014), with severe implications for wildlife and tourism.The event itself was associated with a low-pressure systemmoving northwards that brought a combination of extreme warm spells and heavy precipitation, followed by sub-zero temperatures.The incident increased permafrost temperature, triggered slush avalanches, and left a significant ground-ice cover. Rain-on-snow events may become more frequent with higher temperatures in the future, which would have far-reaching implications for Arctic ecosystems and societies through the associated changes in snow-pack and permafrost properties. On 19 December 2015, an avalanche responsible for two fatalities and the destruction of ten houses in Longyearbyen was triggered by a blizzard on the previous day with strong easterly winds that had generated a pile-up of snow on the hillside.This was connected to a low-pressure system from the Norwegian Sea,south of Iceland,that moved northeastward and combined with a temporarily stationary low-pressure system southwest of Svalbard (Figure 4.5 and 4.6). Fast icing at sea, caused by sea spray in sub-zero conditions is another winter

Pithan and Mauritsen (2014) analyzed results from state- of-the-art GCM simulations (CMIP5) and found the largest contribution toArctic amplification was made by temperature feedbacks. Their reasoning was that more energy is radiated back to space at lower latitudes than higher latitudes when the surface warms.They concluded that the surface albedo feedback was the second largest contributor to Arctic amplification. Graversen et al. (2014) found changes in the mean vertical temperature profile associated with a stronger greenhouse effect (the lapse-rate feedback ) tomake a significant contribution to the polar amplification, and their analysis showed this to account for 15% of the amplification in the Arctic. In comparison, they found melting snow and ice to account for 40% of the Arctic amplification.Another type of feedback involves changes in the vertical temperature profile, andWoods and Caballero (2016) suggested that this may be connected with southerly moisture injections as these may influence both temperature and sea ice. Other phenomena and processes which link different parts of the Arctic climate system include storm tracks and ocean currents and their importance for moving heat around. Left to their own devices, these interconnections, which allow changes in some aspects of the climate to feed back to others, sometimes even in circles, lead to natural variability.The question as to how these different feedback processes may change in the future can be rephrased to ask more specifically: Howwill the character of these important natural phenomena be affected by continued global warming? 4.2.3.2 Natural hazards Natural hazards in the Arctic result from weather phenomena such as storms (strong winds, high waves), avalanches, rockslides, floods, wildfires, and harmful effects of freezing rain and rain-on-snow events. The hazards presented here are connected with physical phenomena and processes in the atmosphere, ocean and land. Many of these phenomena may

Christian Jaedicke

Figure 4.5 Avalanche in Longyearbyen, Svalbard on 19 December 2015.