The arctic environment is changing: air temperatures, major river discharges and open water season length have increased, and storm intensities and tracks are changing. Thirteen quantitative studies of the rates of coastline position change throughout the Arctic show that recently observed environmental changes have not led to ubiquitously or continuously increasing coastal erosion rates, which currently range between 0 and 2 m/yr when averaged for the arctic shelf seas. Current data is probably insufficient, both spatially and temporally, however, to capture change at decadal to sub-decadal time scales. In this context, we describe the current understanding of arctic coastal geomorphodynamics with an emphasis on erosional regimes of coasts with ice-rich sedimentary deposits in the Laptev, East Siberian and Beaufort seas, where local coastal erosion can exceed 20 m/yr. We also examine coasts with lithified (rocky) substrates where geomorphodynamics are intensified by rapid glacial retreat. Coastlines of Svalbard, Greenland and the Canadian Archipelago are less frequently studied than ice-rich continental coasts of North America and Siberia, and studies often focus on coastal sections composed of unlithified material. As air temperature and sea ice duration and extent change, longer thaw and wave seasons will intensify coastal dynamics in the Arctic.

ABStRACt. this study investigates whether raised beach sequences preserved on emergent coasts of the central Canadian Arctic Archipelago contain a proxy record of past sea-ice conditions and wave intensity. We hypothesize that periods of reduced sea ice (increased open water) expose shorelines to more prolonged and higher wave energy, leading to better-developed beach ridges. Surveys of raised beach sequences on Lowther Island revealed the following patterns: a) high, wide, single-to multicrested barriers backed by deep swales or lagoons characterize both the active and lowest relict shorelines; b) small, narrow, discontinuous ridges of poorly sorted gravel extend from 1.0 to 7.5 m asl, except from 4.5 to 5.0 m asl; c) ridge morphology is similar to the active and first relict ridges between 7.5 and 11 m asl; d) a near-featureless zone with minor terraces and ridges above 11 m extends to above 30 m asl. these distinct morphological and sedimentary units are interpreted as a function of wave climate and thus of summer sea-ice conditions. this model suggests periods

ST-HILAIRE-GRAVEL, D.; FORBES, D.L., and BELL, T., 2012. Multitemporal analysis of a gravel-dominated coastline in the central Canadian Arctic Archipelago. Journal of Coastal Research, 28(2), 421-441. West Palm Beach (Florida), ISSN 0749-0208.This study assesses the stability of Arctic gravel coasts across a range of timescales, based on field and remote-sensing studies of three coastal sites near Resolute Bay, Nunavut. It considers shore-zone sensitivity to ice, wind, and wave forcing at storm-event and annual timescales within a longer-term context, including coastal emergence resulting from postglacial isostatic uplift partially counteracted by accelerating sea-level rise. Another long-term factor associated with climate change is the potential for increased seasonal depth of thaw in the beachface and nearshore. The coast in this area is ice bound on average for 10 months of the year, but the annual duration of ice cover has decreased over the past 30 years (1979-2009) by 0.95 d/y. A longer open-water season has implications for the number and timing of storm-wave events, with increased probability of storms impacting the coast later in the season when the seasonal thaw layer is approaching maximum thickness. Overall, shoreline progradation surpassed erosion in the Resolute area between 1958 and 2006, reflecting a combination of sediment supply and emergence. The coastal impacts of storms were found to be short lived and not necessarily indicative of longer-term trends. Gravel shorelines can be resilient in the face of intermittent storm impacts, but thresholds of stability in this high-latitude setting are poorly understood. If current trends of rising sea level, increasing open-water duration, and more frequent effective wave events continue, there is a heightened potential for more rapid coastal change in the region.

No abstract

Landward retreat (marine transgression) is a common response of coastal systems to rising relative sea level. However, given sufficient sediment supply, the coast may advance seaward. The latter response of gravel barriers has been recorded in parts of southeastern and northwestern Canada, where seaward‐rising sets of beach ridges are observed in areas of Holocene RSL rise. Cape Charles Yorke, northern Baffin Island, is a 5 km long gravel foreland characterized by seaward‐rising beach‐ridge crest elevations. The prograded morphology of the Cape Charles Yorke foreland is a prime example of coastal response to a combination of rising RSL and abundant sediment supply, an unusual and little‐documented pattern in the Canadian Arctic. The main gravel supply to Cape Charles Yorke is likely from eroding bedrock and raised marine deposits southwest of the foreland. Although not the dominant sediment source, the Cape Charles Yorke delta contributed to the formation of the foreland by sheltering it from easterly storm waves and providing an anchor point for the prograding ridges. The truncation of relict ridges by the modern shoreline suggests a recent regime shift from continuous deposition to predominant erosion. The cause and timing of this shift are unknown but could result from a recent dwindling in sediment supply, increased accommodation space, increased wave energy, and/or an accelerated rise of relative sea level.