Past and future forcing of Beaufort Sea coastal change

Abstract

Changes to the Beaufort Sea shoreline occur due to the impact of storms and rising relative sea level. During the open-water season (June to October), storm winds predominantly from the north-west generate waves and storm surges which are effective in eroding thawing ice-rich cliffs and causing overwash of gravel beaches. Climate change is expected to be enhanced in Arctic regions relative to the global mean and include accelerated sea-level rise, more frequent extreme storm winds, more frequent and extreme storm surge flooding, decreased sea-ice extent, more frequent and higher waves, and increased temperatures. We investigate historical records of wind speeds and directions, water levels, sea-ice extent and temperature to identify variability in past forcing and use the Canadian Global Coupled Model ensembles 1 and 2 (CGCM1 and CGCM2) climate modelling results to develop a scenario forcing future change of Beaufort Sea shorelines. This scenario and future return periods of peak storm wind speeds and water levels likely indicate increased forcing of coastal change during the next century resulting in increased rates of cliff erosion and beach migration, and more extreme flooding.

Archaeological Site Vulnerability Modelling: The Influence of High Impact Storm Events on Models of Shoreline Erosion in the Western Canadian Arctic

“…In order to determine if high water levels accompanied the open-water wind events, tidal gauge records from offshore buoys near Tuktoyaktuk were obtained from the Fisheries and Oceans Canada -Drifting Buoys website (http://isdm-gdsi.gc.ca/isdm-gdsi/drib-bder/index-eng.htm). Much of the buoy data was missing for the 2013 and 2014 period, but high water levels, defined by an increase of 1.25 m above chart datum over a period of no less than one hour (Manson, Solomon 2007), accompanied all of the 2013 wind events from June through October. Several other high water levels from 2013 appear to correlate with wind events that took place as late as mid-November, possibly hinting at a longer open water duration than usual for 2013.…”

“…Changes through time however are most commonly attributed to long-term fluctuations in storminess and the duration of open water conditions (Solomon 2005). Winds exceeding 50 km/h have been correlated with pronounced periods of shoreline erosion within the study area (Manson, Solomon 2007), while shorefast ice which limits the erosive impact of waves typically persists in the Beaufort Sea from October through to June (Solomon 2005). In order to determine if Toker Point experienced an unusually active storm season during the autumn of 2013, wind speed and directional data from the nearest weather monitoring station at Tuktoyaktuk was obtained from Environment Canada's online climate data archives (http://climate.weather.gc.ca/).…”

“…However, the inclusion of further recent imagery and thereby shorter intervals of analysis can result in more nuanced models of shoreline change in the direct vicinity of known archaeological remains. Current forecasts have predicted changes in the seasonality of erosion forcing mechanisms, such that protracted open water periods coincide more often with strong autumn/winter storm events (Manson, Solomon 2007). Thus, the ability to detect sporadic, high-impact erosion events can be of tremendous use to cultural landscape management initiatives both now and in the future.…”

“…As a result, archaeological sites located there are particularly vulnerable to climate related impacts such as permafrost depletion (Smith et al 2009), backshore thaw slump activation (Lantz, Kokelj 2008), increased severity and frequency of wind events and related storm surges (Pisaric et al 2011, Small et al 2011, and shoreline erosion (Solomon 2005). The region is notorious for its powerful northwesterly wind events, which typically increase in strength and frequency in the late autumn prior to freeze-up (Manson, Solomon 2007, Solomon 2005. Studies have shown that storm surges influenced by the severity of fall storms and the duration of open water conditions can have substantial impacts on the rate of shoreline retreat among permafrost and massive-ice laden coastlines (Solomon 2014).…”

The Arctic Coastal Dynamics Database: A New Classification Scheme and Statistics on Arctic Permafrost Coastlines

“…One of the driving forces behind a potential increase in erosion is the lengthening of the open-water season, which is thought to have a much greater impact on the coasts than the increased fetch associated with disappearing sea ice, at least in the Canadian Beaufort Sea (Manson and Solomon 2007). In that sense, it is legitimate to think that erosion can and will increase where rates of erosion are already substantial, but in light of this study, one can equally assume that some dramatic changes can be expected regionally on coasts where the open water season was virtually nonexistent until now.…”