Chapter 13 – sea ice hazards, risks and implications for disasters

Chapter 13 – sea ice hazards, risks, and implications for disasters Chapter 13 – sea ice hazards, risks, and implications for disasters Chapter 13 – sea ice hazards, risks, and implications for disasters Chapter 13 – sea ice hazards, risks, and implications for disasters Chapter 13 – sea ice hazards, risks, and implications for disasters Chapter 13 – sea ice hazards, risks, and implications for disasters Chapter 13 – sea ice hazards, risks, and implications for disasters

Chapter 13 Sea Ice: Hazards, Risks, and Implications for Disasters Hajo Eicken and Andrew R Mahoney Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA ABSTRACT The role of sea ice as a natural hazard is discussed with a focus on Arctic and subArctic regions where risks associated with human activities and ice processes are the greatest Hazard assessment and emergency response need to consider a range of controlling factors that can lead to events initiating an accident, failure, or full-scale disaster These factors include environmental hazards, equipment, procedures and settings, and people Quantifying risks associated with the presence of sea ice requires the joint consideration of the probability of specific hazards and the magnitude of their impacts Both of these also depend on the type and level of human activity, such that disaster risks are substantially higher in the Arctic than in the Antarctic We identify three types of sea-ice hazards: (1) broad, long-term hazards and associated risks associated with a rapid reduction in summer ice extent; (2) nearterm hazards resulting from changes in sea-ice extent and dynamics such as increased coastal erosion and threats to coastal infrastructure; and (3) immediate risks and the potential for disasters derived from the combination of sea-ice hazards and human activities such as shipping or offshore resource development A review of key properties and processes governing the role of sea ice as a hazard focuses on recent rapid changes in ice extent and concentration in the Arctic and resulting threats to coastal systems Other key factors include the distribution of old perennial ice that has a greater thickness and higher mechanical strength than seasonal ice, patterns of ice movement that determine advection of ice hazards, and the degree of ice deformation that can generate thick, rough ice and represent a hazard in its own right These factors are examined in the context of a case study for the Beaufort and Chukchi Seas in the North American Arctic Linking specific environmental hazards to the geospatial distribution of human activities and vulnerable ecosystems allows for an integrated Arctic hazards assessment, currently still in its infancy The need for coordinated environmental observations in informing hazard assessments and emergency response is discussed in the context of recent increases in maritime activities in the Arctic Coastal and Marine Hazards, Risks, and Disasters http://dx.doi.org/10.1016/B978-0-12-396483-0.00013-3 Copyright © 2015 Elsevier Inc All rights reserved 381 382 Coastal and Marine Hazards, Risks, and Disasters 13.1 INTRODUCTION: ENVIRONMENTAL HAZARDS, DISASTERS AND SEA ICE The presence of sea ice in polar and subpolar oceans is a defining environmental factor that governs weather and climate, ecology, and human activities in these regions Sea ice is also a significant natural hazard, both through direct interaction with assets and infrastructure and through the indirect impacts of variability and rapid changes in its distribution, in particular in Arctic and sub-Arctic regions Although the former type of threat is clearly defined and falls well within the scope of classic hazard analysis (e.g., Ogorodov et al., 2005; Zhang et al., 2013), the latter aspect relates to the broader problem of threats to benefits or services provided by sea ice For example, delayed formation of coastal ice as a result of climate change can expose shorelines to erosive action of fall storms and enhance thermal subsidence of coastal permafrost, over time greatly accelerating rates of coastal retreat (Overeem et al., 2011) Nevertheless, both types of threats or hazards, rapid and slow onset, can be understood in the context of sea-ice system services, which describe and potentially quantify the benefits and threats that socialeenvironmental systems derive from sea ice over a range of scales (Eicken et al., 2009) This contribution considers both types of hazards and hence direct and indirect effects of sea ice that can lead to harm or disasters Sea ice is an integral part of socialeenvironmental systems, in particular in the northern hemispheredhence, ice hazards and their potential role in disasters cannot be considered in isolation This broader perspective is summarized in Figure 13.1, which outlines the combination of factors initiating a sequence of events that may culminate in failure of structures, loss of life and property, or escalate into a large-scale disaster Hazard mitigation and disaster prevention aim to curb or eliminate initiating events that can potentially escalate with negative consequences for human activities or ecosystems (Vinnem, 2007) It is important to recognize that in such a context, natural or environmental hazards, including sea ice, are part of a combination of factors that can lead to disasters Other factors include the design or hardware of infrastructure implicated in an event, human judgment, or error as well as procedures in place to ensure safety and reliability of an organizational structure (Figure 13.1) The entire complex of factors, initiating events, prevention, escalation, and disasters can be understood in terms of risks associated with specific consequences (Schneider et al., 2007) Typically, risk is evaluated in terms of a convolution of the probability of occurrence of a particular event and the magnitude of its consequences The concept of risk provides some guidance to the scope and thrust of this contribution By mapping the distribution of sea-ice processes and properties that represent threats and hazards, we can help constrain the probability of occurrence of a disaster or loss event By evaluating harmful impacts through Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters 383 Hazards & controlling factors Equipment Environmental hazards People Procedures Design/ setting Risk: Prevention Initiating events Escalation probability of occurrence × magnitude of consequences Consequences: e.g., failure of structures, damage to life & property, disasters FIGURE 13.1 Key concepts relevant to the study of sea ice as a natural or environmental hazard, building on research in maritime risk assessment (Vinnem, 2007) Environmental hazards are one of the several controlling factors that may lead to a sequence of events culminating in damage to life and property or a potential disaster The risk associated with such a chain of events is characterized by the convolution of probability of occurrence and the magnitude of the resulting consequences direct (e.g., damage to offshore structures or vessels along shipping lanes) and indirect actions (e.g., enhanced coastal erosion or loss of climate regulation through reduced sea ice), we can assess both the probability and the magnitude of consequences in a geospatial context In combination, such an evaluation provides guidance on both the relevant processes that need to be considered and the specific regions to focus on The following section concentrates on a limited range of sea-ice processes and properties relevant for our understanding of sea ice as a natural hazard in both polar regions At the same time, for geospatially explicit discussions of consequences, the focus is on the Arctic where both the nature of sea-ice hazards and the probability of occurrence of events impacting human activities are more substantial than in the Antarctic In Antarctica, human activity and vessel traffic are concentrated into a small subregion of the Antarctic Peninsula region, where research bases and tourism account for roughly 100 vessel passages per year (based on 2007/2008 season; Lynch et al., 2010) In the Arctic, such vessel densities are typical of the entire circum-Arctic with, for example, roughly 140 vessels passing through the Canadian Arctic maritime region in 2012 with close to half of these vessels consisting of bulk carriers, tankers, and cargo ships (Pizzolato et al., 2014) Moreover, in contrast with the Antarctic, (sub-)Arctic sea-ice hazards play a prominent role in offshore resource development and associated coastal infrastructure 384 Coastal and Marine Hazards, Risks, and Disasters 13.2 GEOGRAPHIC DISTRIBUTION OF SEA ICE AND KEY PROCESSES AND PROPERTIES Polar sea ice waxes and wanes with the seasons Ice fills the Arctic basin and occupies roughly 15  106 km2 at its maximum winter extent in March, shrinking to a seasonal minimum in September of 10 percent and may not detect ice during summer months at low concentrations (Meier and Stroeve, 2008) Hence, Arctic shelf seas and coastal regions, such as those highlighted in Figure 13.2, undergoing longer open water periods may still see lingering ice that can represent a hazard but is not captured at a sufficient spatial and temporal resolution (Eicken et al., 2011) Reductions in ice concentration over the course of summer in the North American and Siberian Arctic (Figure 13.2, right) and a longer open water period have resulted in substantial increases in the amount of solar heating of these waters (Perovich et al., 2007) Further, increased fetch during the fall storm season has resulted in increases in wave amplitudes in fall (Overeem et al., 2011) Thinner, more dynamic ice also appears to be associated with increases in wave heights and deeper propagation of swell into the ice pack in spring (Francis and Atkinson, 2012) These changes work in concert to increase erosive action, thermal subrosion of coastal permafrost, and thereby accelerate rates of coastal retreat with potentially negative impacts on coastal communities and infrastructure A key property of relevance from a natural-hazard perspective is the mechanical strength of sea ice Typically, ice strength varies disproportionately with age since desalination of sea ice during the first and subsequent melt seasons greatly reduces the porosity of the bulk of the ice cover, thereby increasing bending and compressive ice strength by between one half to as much as a factor of three to four (Timco and Weeks, 2010) Similarly, brackish or freshwater ice formed in coastal lagoons or estuaries as well as glacial ice in the form of icebergs will exhibit greater strength than sea ice Mapping the Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters FIGURE 13.2 Monthly Arctic sea-ice concentration trends derived from passive microwave satellite data for the time period 1979e2013 (left: March; right: September) National Snow and Ice Data Center Sea Ice Index; Fetterer et al., 2013 385 386 Coastal and Marine Hazards, Risks, and Disasters FIGURE 13.3 Mean sea-ice age for the time period 2005e2010 The map is based on ice age fields derived by tracking regions of ice as they drift around the Arctic (Maslanik et al., 2007) distribution of sea-ice age, using a combination of remote-sensing and drifting buoy data, provides a large-scale measure of the probability of encountering older, stronger ice (Maslanik et al., 2007) For the period 2005e2010, the North American half of the Arctic basin was filled with ice three years or older (Figure 13.3), though the mean age of Arctic sea ice continues to drop substantially as a result of reductions in the extent of perennial ice surviving at least one summer’s melt Here, ice age can also serve as a proxy for level-ice thickness (Maslanik et al., 2007) First-year ice rarely exceeds m and typically ranges between and 1.5 m in thickness across the (sub)Arctic shelf seas in late spring In the Arctic basin, second-year ice ranges in thickness between and m, and only the oldest level ice is likely to exceed a thickness of 4e5 m However, the Canadian Archipelago generates much older ice that can exceed a 10-m thickness even in level, undeformed areas and which may enter the Arctic Ocean through some of the straits exiting the Archipelago (Johnston et al., 2009; Barber et al., 2014) The prevailing patterns of ice motion, largely driven by surface wind forcing anddon time scales of months to yearsdby sea surface tilt, transport Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters 387 FIGURE 13.4 Mean Arctic sea-ice velocity field for winter (OctobereMay; left) and summer (JuneeSeptember; right) for the time period 1982e2009 as derived by Kwok et al (2013) The color scale indicates whether ice velocities are exhibiting a trend toward higher (red) or lower (blue) velocities older ice from the high Canadian Arctic into the Pacific Arctic sector and waters off Alaska (Figures 13.3 and 13.4) Along the North American and East Siberian coastlines, ice motion is mostly shore parallel, directed toward the West with the anticyclonic Beaufort Gyre In central and western Siberia, ice motion is directed away from the shore, whereas north of Greenland and the High Canadian Arctic, it is toward the shore As a result, some of the oldest, thickest ice is found in the latter regions, whereas some of the youngest ice prevails in the former (Figures 13.3 and 13.4) Recent studies have found an increase in both ice speed and deformation rate (the latter by roughly 50 percent per decade since 1979), likely a result of changes in surface forcing and reduced ice thickness that foster increased ice mobility (Rampal et al., 2009) As is evident in Figure 13.4, regions with the highest mean ice velocities also appear to experience the greatest increase in ice speed Moreover, recent work by Barber et al (2014) demonstrates that as a result of the combination of these changes, the complexity of ice motion patterns and hence the challenge to predict ice movement on short time scales has greatly increased A measure of the geographic distribution of ice deformation processes can be obtained from an analysis of winter ice movement obtained from radar remote-sensing imagery over the time period 1996e2008 (Figure 13.5; Herman and Glowacki, 2012) Here, the distribution of cells that fall into the top 5-percentile of the mean total deformation rate provides an indication of areas where shear or repeated divergent/convergent deformation events have the potential to produce highly deformed ice As is apparent from Figure 13.5, 388 Coastal and Marine Hazards, Risks, and Disasters FIGURE 13.5 Occurrence probability of very strong Arctic sea-ice deformation events, corresponding to the top 5-percentile of total deformation rates for the entire Arctic, as derived by Herman and Glowacki (2012) Data cover the winter (NovembereApril) from 1996 to 2008 Rectangle (solid black line) delineates the approximate extent of the data shown in Figure 13.8 the high deformation regions are confined to the Arctic Ocean marginal seas and are likely the result of iceeland interaction in combination with strong surface forcing by winds (reflected in the mean fields shown in Figure 13.4) and tidal currents (Lyard, 1997) North of the Canadian Archipelago, where some of the oldest ice in the Arctic resides, deformation rates are not as high This is explained in part by the high strength and compactness of multiyear ice in this region that does not accommodate significant strain Ice deformation can result in ice thickness multiple times that of thick-level ice, by piling ice floe fragments into ridges or rubble piles An example of such deformation processes and the resulting features is shown in Figure 13.6 for rafted and ridged ice forced onshore by motion converging on the coastline at Barrow, Alaska A case study below provides further insight into these processes The coastal topography and prevailing ice motion (Figures 13.4 and 13.5) favor such iceecoast interaction with potentially significant implications for coastal processes and hazards In the Southern Ocean, sea ice girdles the Antarctic continent with a winter maximum extent of roughly 18  106 km2, decreasing to  106 km2 in the Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters 389 FIGURE 13.6 Sea ice forced onshore at Barrow, Alaska in an ice-push event in spring of 2001 (Mahoney et al., 2004) Such events require a compact ice cover offshore and wind or ocean forcing acting over a sufficient fetch of ice Note how the parent ice sheet of a roughly 1.5-m thickness has been rafted onto the beach at right, while failing in a buckling mode, resulting in an ice pressure ridge at left Coastal infrastructure, such as powerlines, harbor installations, or buildings (visible in the distance at the right) can be threatened by such ice-push events austral summer (Comiso, 2010) Due to higher ocean-to-ice heat fluxes and lack of old multiyear ice, Antarctic sea ice is typically much thinner (maximum level-ice thickness well below m in most regions) than Arctic sea ice Also, multiyear ice does not undergo the same degree of desalination as in the Arctic, such that the bulk strength of Antarctic multiyear ice is typically of the same magnitude as that of first-year ice Deformation processes and sea-ice circulation are driven by a similar combination of factors as in the Arctic, creating similar hazards for vessel entrapment in regions of persistent deformation and convergence Interaction between the sea-ice cover and the Antarctic coastline is substantially different, however, from that of the Arctic because of the prevalence of either ice shelves or rocky shores throughout Antarctica 13.3 SEA ICE AS NATURAL HAZARD Building on an understanding of the services sea ice provides to people and ecosystems (Eicken et al., 2009), and taking into consideration in particular the Arctic ice cover’s recent transformation, we can evaluate the role of sea ice as a natural hazard As illustrated in Figure 13.1, this problem cannot be treated as an assessment of, for example, geophysical processes in isolation from the broader setting Therefore, we recognize three principal aspects of the problem: (1) broad, long-term hazards and associated risks associated with a rapid reduction in summer ice extent, such as geographic shifts in marine ecosystems and warming of submarine permafrost and adjacent land; (2) nearterm hazards resulting from changes in sea-ice extent and dynamics such as 390 Coastal and Marine Hazards, Risks, and Disasters increased coastal erosion and broad threats to coastal infrastructure; and (3) immediate risks and the potential for disasters derived from the combination of sea-ice hazards and human activities such as shipping or offshore resource development that involve specific, localized assets The first type of hazard can be thought of in terms of slow-onset events, typically at regional to hemispheric scale, that require a response in the form of mitigation and adaptation (e.g., IPCC, 2012) Hazards of type are associated with rapidonset events at the local scale (though with regional to global repercussions, e.g., in the case of the threat to major infrastructure or the potential of an oil spill of national or international significance), while type hazards can fall somewhere in between Type hazards can be considered in the context of services provided by the sea-ice cover, such as the regulation of global climate and its central role in ice-albedo feedback (Eicken et al., 2009) Rapid changes in ice extent and feedback processes may then have significant impacts, ranging from changes in the Earth’s heat budget, to impacts on midlatitude weather to threats to key species of global significance With the science, for example, on potential linkages between Arctic summer sea-ice reduction and extreme weather events still emerging (e.g., Francis and Vavrus, 2012; Screen and Simmonds, 2013), causal attribution and identification of specific hazards are challenging at this broader scale Nevertheless, initial model-based attempts have been made to estimate the economic impacts of such hazards (Euskirchen et al., 2013) Future research will have to establish whether hazard mitigation can be directly translated into specific reductions in the risk of, for example, extreme weather events or associated disasters For type hazards, the link between sea-ice processes and their variability and change is better established Thus, the potential for greater significant wave heights and a longer open water period with potential for wave action and coastal flooding has been identified in a number of regions, with major impacts in particular in the Siberian and Pacific Arctic sector (Atkinson, 2005; Overeem et al., 2011; Asplin et al., 2012; Francis and Atkinson, 2012) Under conditions of a more mobile ice cover (Rampal et al., 2009; Barber et al., 2014), this recent development also increases the probability for iceecoastal interaction during the open water and shoulder seasons For example, in coastal Alaska, revetments put in place to protect the shoreline from wave action have been damaged by storm-induced ice action during the fall freezeup period It is not clear whether to expect more frequent occurrence of icepush and similar events (Figure 13.6) as a result of a changing ice cover Anecdotal evidence suggests that reductions in the amount of well-anchored, stable shorefast ice have led to an increase in such events in northern and Western Alaska Impacts of reduced sea ice on coastal permafrost exacerbate the vulnerability to flooding and coastal retreat Thus, wave action and warming of surface waters promote the thermal subrosion of both terrestrial and marine Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters 391 permafrost along the coast (Ravens et al., 2012) As a result, rates of coastal retreat and subsidence increase Sea-ice hazards of type involve the direct interaction between ice and artificial structures or vessels at the local scale An assessment of the distribution of human activities that are vulnerable to sea-ice hazards is provided in Figure 13.7 Of particular relevance are the distribution of major shipping lanes, regions of intensifying offshore oil and gas exploration and production, mines accessible only by sea as well as areas frequented by tourist cruise ships At present, the vast majority of vessel traffic in the Arctic is destinational traffic in support of coastal communities or resource development With a FIGURE 13.7 Map of marine activity in the Arctic Sources: Grid-Arendal, Arctic Council, 2009; Arctic Marine Shipping Assessment 2009 Report Original by H Ahlenius Shipping Lines from Arctic Data Portal Adapted by NordRegio (2011) Design by J Sterling 392 Coastal and Marine Hazards, Risks, and Disasters typical lifetime of mines or offshore oil and gas fields on the order of one to three decades, and with offshore resource exploration efforts underway in all Arctic coastal states, the picture of potential areas of increased risk is likely to persist and evolve gradually over the coming years Transarctic shipping, along the Northern Sea Route or through the Northwest Arctic Passage (Figure 13.7) is currently of little economic importance, but may increase in significance over coming decades (Brigham, 2010) In terms of risks emanating from human activities in the Arctic, the infrastructure and activity map shown in Figure 13.7 represents a coarse measure of both the probability of occurrence and the magnitude of the consequences of failure or disaster initiating and escalating events, following the concepts laid out in the Introduction and in Figure 13.1 However, it is only in combination with the key sea-ice processes and properties governing its role as a hazard that a full measure of the regional distribution of hazards and risks can be obtained The distributions of these latter controlling factors are represented by the maps shown in Figures 13.2e13.5 Most importantly, they include a measure of the probability of encountering sea ice, implicit in the ice concentration trend and ice age distribution maps Even traces of ice can constitute a major shipping hazard if conditions prevent visual or ship-radar detection However, as discussed above, the satellite data entering into Figures 13.2 and 13.3 are not of a sufficient resolution and accuracy to provide information on the distribution of such sparse ice (Meier and Stroeve, 2008; Eicken et al., 2011) Thus, areas shown in blue in Figure 13.2 on the right can be considered to contain significant amounts of potential ice hazards throughout much of the open water season Secondary factors that determine the severity of a sea-ice hazard as encountered by a vessel or impacting offshore structures relate to the distribution of old ice of high mechanical strength and greater thickness (Figure 13.3) A further measure of the distribution or origin of very thick, deformed ice is the deformation map shown in Figure 13.5 Thick ice, both level old ice and deformed younger ice, is likely to linger long into the melt season In conjunction with the ice velocity maps shown in Figure 13.4, this accounts for the increased risk associated with massive ice floes or remnants of ice ridges drifting into regions of active offshore oil and gas exploration, such as in the northwestern Alaska Arctic In the summer of 2012, such older ice remnants required suspension of drilling operations at a borehole late in the season (U.S Department of Interior, 2013) The western Canadian and Alaskan Arctic emerges as a region of higher risk with respect to sea-ice hazards, as illustrated by the band of high deformation comparatively close to the coast (Figure 13.5), the potential for advection of strong, thick multiyear ice even in recent years (Figure 13.3), and the high ice velocities observed over the shelf (Figure 13.4) To be sure, these risks are tempered by greatly reduced ice concentration during the open water season, diminished ice velocities in the summer months, and an overall Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters 393 reduction in the thickness and age of ice in the region Outside of the Arctic proper, the Bohai Sea, a semienclosed body of water along China’s northeastern coast emerges as another region of substantial risk There, a large fishing fleet, offshore oil and gas production platforms, and substantial maritime traffic operate in a region with seasonal sea ice that can reach level-ice thicknesses of up to m and experiences substantial deformation as the result of strong tidal currents and wind forcing (Yue and Li, 2003; Zhang et al., 2013) Moreover, in recent years ice conditions have become more severe, possibly as a result of summer sea-ice loss in the Arctic and its impact on midlatitude weather patterns Another type of human activity that is potentially threatened by sea-ice hazards is the use of the coastal ice cover by the indigenous peoples of the Arctic and other northern residents (Eicken et al., 2009) In particular, the shorefast ice serves as a platform and natural extension of the land to provide access to marine waters for subsistence hunting and fishing, as well as an effective transportation corridor between different communities (Krupnik et al., 2010) In addition, ice roads across shorefast ice represent seasonal infrastructure used by the oil industry for nearshore operations (Masterson, 2009) A less stable, less predictable and less trafficable ice cover presents coastal communities with substantial challenges and risks, including the potential to drift out to sea with poorly anchored shorefast ice or for increased dangers of falls through ice (George et al., 2004; Ford et al., 2008) Northern communities have adapted to such changes, and their responses may hold lessons that are relevant in the broader context of addressing sea-ice hazards In the Antarctic, at present, the most substantial risk associated with sea ice as a natural hazard is its impact on tourist and research vessel activity The sinking of a Canadian cruise ship in 2007 as a result of ice damage to the hull illustrates the level of risk associated with high-traffic areas near the Antarctic Peninsula where most of the tourist traffic converges, and where sea ice and icebergs can linger into late summer (Lynch et al., 2010) The temporary trapping of a charter vessel and a research icebreaker in East Antarctica (in late December 2013; J Turner, theGuardian.com, January 3, 2014) occurred in a region where prevailing patterns of ice movement and deformation (similar to the deformation zones highlighted in Figure 13.5) had resulted in besetting of vessels by ice in the past Although thick ice and icebergs represent the greatest risk for structural damage to vessels and other marine assets, it is important to recognize that any ice can be problematic for systems that are designed only for open water For example, although slush ice may represent no hazard for ice-strengthened structures, it can swamp boats or clog intake ports leading to mechanical failures Indeed the earliest onset of freeze-up is what defines the end of the offshore drilling season in the Alaska Arctic Capabilities for predicting and tracking the onset of freeze-up are not currently well developed, which reduces our ability to mitigate the associated risks 394 Coastal and Marine Hazards, Risks, and Disasters 13.4 CASE STUDY: ICE HAZARDS IN THE BEAUFORT AND CHUKCHI SEAS The Beaufort and Chukchi Seas, comprising Canadian and US waters, provide important sea-ice habitat to a range of organisms, from ice algae to marine mammals The indigenous population of coastal communities relies on the ice cover as a platform for transportation and subsistence hunting The region has also seen substantial increases in maritime traffic and offshore oil and gas exploration in recent years, in particular north of the Northwest Territories and on the Northwest Alaskan shelf (areas shown in red in Figure 13.7) Industry may rely on coastal landfast ice as a platform for wintertime exploration and supply of nearshore production platforms In the summer months and shoulder seasons, sea ice presents a potential hazard to offshore activities In evaluating marine ice hazards in this region, it is important to recognize that the use of landfast ice by coastal communities and industry as well as the ecological significance of drifting and landfast sea ice as a habitat benefit from the very types of processes and ice features that represent a hazard to coastal and offshore infrastructure and shipping (see also the summary in Table 13.1) Specifically, the advection of thick multiyear ice from the High Canadian Arctic TABLE 13.1 Ice-Associated Threats to Maritime Activities in Beaufort and Chukchi Seas (modified from Eicken et al., 2011) Activity or Asset Hazard or Threat Relevant Variable Setting/Scale Shipping Ice contact & damage Ice concentration, ice type Marginal ice zone, 10e100 s km Use of ice as platform Ice breakout or breaking through of personnel & equipment Landfast ice stability/ anchoring strength, thickness, morphology Landfast ice, 20 m along a short profile section of a few kilometers’ length flown across Hanna Shoal Much of this ice is heavily deformed and grounded at water depths of 15 m can also be found north of Barrow in a zone that corresponds roughly to the band of strong deformation evident in Figure 13.5 This band corresponds to strong shear deformation resulting in the ridging and rubbling of ice as the main body of the pack ice moves past the northernmost tip of the Alaska landmass (Figure 13.4) We interpret the annual grounding of ice at Hanna Shoal to imply that the probability of producing deep-draft ice in this region of strong shear is high enough to result in initial grounding of a pressure ridge at Hanna Shoal every year This grounded piece of ice then forms the nucleus for further deformation and subduction of strongly deformed ice, resulting in the scalloped, deep-draft features shown in Figure 13.8 Such a local source of deep-draft ice that is known to linger in the region into summer is a potential Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters 397 threat to summer operations as well as buried pipelines that are part of one scenario for potential development of offshore Chukchi oil and gas fields The probability of encountering lingering deep-draft and multiyear ice later in summer is still significant, even with observed reductions in summer ice concentration In 2012, during exploratory drilling near Hanna Shoal in the first half of September, a field of sea ice several tens of kilometers in size drifted into the region and threatened operations Based on ice forecasting and remote-sensing data analysis by the operator, a potential threat was identified and the drill vessel pulled offsite for a period of approximately two weeks (U.S Department of Interior, 2013) It is likely that such lingering ice included thick multiyear ice entering the region from the East (Figure 13.3) and persisting well into summer due to greater thickness and reduced melt rates compared to darker, thinner first-year ice Changes in ice conditions upstream of the region are projected to continue and local deformation patterns seem likely to persist in coming decades Thus, the Beaufort and Chukchi Seas are likely to retain a full array of ice hazards (Table 13.1) Moreover, factors such as substantial swell or fine-scale ice drift patterns that are not captured by remote-sensing products are likely to increase the overall risk to maritime operations in the region At the same time, ice use by marine mammals and subsistence hunters will be concentrated into smaller areas and shorter time periods, further affecting key risk factors as outlined in Section 13.1 13.5 SEA-ICE HAZARDS AND DISASTERS: PREVENTION, MITIGATION, AND RESPONSE With a variety of controlling factors playing into the potential occurrence and escalation of initiating events (Figure 13.1), prevention of disasters and mitigation of hazards require comprehensive approaches that address a multitude of factors Here, we briefly discuss the importance of collecting and providing sea-ice information relevant to disaster prevention and response As a first step, the compilation of hazard and risk maps may help in long-term planning and optimal coordination of emergency response assets At present, we are not aware of such products being available for broader sectors of the Arctic, although national ice forecasting services may generate local maps that indicate, for example, ice severity as a hazard indicator (e.g., the Chinese Marine Environmental Forecasting Center’s Ice Severity Zones, Zhang et al., 2013; or the Barnett Ice Severity Index used in the United States, Eicken et al., 2009) The information summarized in Figures 13.2e13.5, however, would likely figure prominently in the development of such an index Since such maps can be assembled based largely on satellite-remote sensing and some surface-based measurements, they are of value both as indicators of “normal” hazard conditions and to track specific conditions in a particular year or vulnerable region At the same time, the type of human activity, infrastructure, or ecosystem service that is potentially impacted also figures 398 Coastal and Marine Hazards, Risks, and Disasters into the evaluation of hazard magnitudes Thus, while old, thick ice constitutes a major hazard for ship traffic and offshore structures, it actually helps stabilize shorefast ice in nearshore regions and thus reduces the risk of catastrophic ice breakout events Hence, the intertwining of the different controlling factors shown in Figure 13.1 needs to be taken into account when developing hazard maps or ice severity indices At present, there is the potential for converging interests and activities related to tracking of environmental variables relevant from a hazards perspective and action by response agencies to address emergency response in the maritime sector across the Arctic Thus, the International Polar Year 2007e2008 resulted in a major push toward distributed polar environmental observing networks (Krupnik et al., 2011) In the Arctic, this effort has culminated in a number of sustained national and international observing programs, such as the US interagency Arctic Observing Network (IARPC, 2007) While these networks typically comprise a strong academic research component as well as agencyedriven activities, they represent a repository of data and information that is critical in the context of environmental security and emergency response The Arctic coastal states and other nations engaged in Arctic research recognized the importance of such observing efforts and have taken steps toward sustaining such activities at the Arctic Council working group level At the same time, through the Arctic Council, the coastal states recently have reached agreements on Cooperation on Aeronautical and Maritime Search and Rescue in the Arctic as well as on Cooperation on Marine Oil Pollution Preparedness in the Arctic (www.arctic-council.org/eppr/) Further work is required to ensure that these efforts result in coordinated hazard tracking and response capabilities that are effective in preventing accidents or disasters The scientific community has an important role to play in this context, since at present much of the observing capacity in the marine sector of the Arctic is driven by research projects as much as by operational activities While ocean observing systems developed for lower latitudes have addressed a number of issues central to this challenge (e.g., Schofield et al., 2002), the Arcticdmore so than any other regiondrequires a hybrid approach that meets information needs of the scientific community, Arctic residents and other stakeholders In this context, two aspects of the problem are deserving of particular notice First, as discussed in the context of the satellite data shown in Figures 13.2 and 13.3, climate data records and other scientific data products often fail to meet the requirements of operational products meant to inform hazard assessments and emergency response These issues can be addressed by combining in situ and remote-sensing measurements at the appropriate spatial and temporal scale, such as explored by Barber et al (2014) in the Canadian Arctic In a demonstration project for a coastal ice observatory at Barrow, Alaska, we have explored how the combination of ice-based autonomous sensors, marine radar, and remote sensing can serve the needs of multiple ice Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters 399 users and stakeholders (Druckenmiller et al., 2009; Eicken et al., 2011) An important component of this approach is the inclusion of local and indigenous knowledge, in particular since local experts often have considerable expertise and insight into the evaluation of environmental hazards For example, local observations by Inupiaq ice experts have demonstrated how certain types of coastal ice formations, so-called ice berms, can serve as a natural buffer that can help mitigate some of the wave and ice 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Coastal and Marine Hazards, Risks, and Disasters 13. 2 GEOGRAPHIC DISTRIBUTION OF SEA ICE AND KEY PROCESSES AND PROPERTIES Polar sea ice waxes and wanes with the seasons Ice fills the Arctic basin and. .. decreasing to  106 km2 in the Chapter j 13 Sea Ice: Hazards, Risks, and Implications for Disasters 389 FIGURE 13. 6 Sea ice forced onshore at Barrow, Alaska in an ice- push event in spring of 2001... Coastal and Marine Hazards, Risks, and Disasters 13. 4 CASE STUDY: ICE HAZARDS IN THE BEAUFORT AND CHUKCHI SEAS The Beaufort and Chukchi Seas, comprising Canadian and US waters, provide important sea- ice