Heterogeneous Changes in Western North American Glaciers Linked to Decadal Variability in Zonal Wind Strength

Abstract

Western North American (WNA) glaciers outside of Alaska cover 14,384 km2 of mountainous terrain. No comprehensive analysis of recent mass change exists for this region. We generated over 15,000 multisensor digital elevation models from spaceborne optical imagery to provide an assessment of mass change for WNA over the period 2000–2018. These glaciers lost 117 ± 42 gigatons (Gt) of mass, which accounts for up to 0.32 ± 0.11 mm of sea level rise over the full period of study. We observe a fourfold increase in mass loss rates between 2000–2009 [−2.9 ± 3.1 Gt yr−1] and 2009–2018 [−12.3 ± 4.6 Gt yr−1], and we attribute this change to a shift in regional meteorological conditions driven by the location and strength of upper level zonal wind. Our results document decadal‐scale climate variability over WNA that will likely modulate glacier mass change in the future.

Regional influence of ocean–atmosphere teleconnections on the timing and duration of MODIS-derived snow cover in British Columbia, Canada

“…The strongest negative correlation is between ONI and SD DUR (−0.81 ± 0.46, p < 0.001). We conclude that, similar to previous studies (e.g., Fleming and Whitfield, 2010;Moore and McKendry, 1996;Whitfield et al, 2010), El Niño (La Niña) events and positive (negative) PDO events result in earlier (later) melt and shorter (longer) snow duration in BC. When we compare seasonal ONI and PDO values to provincial snow measurements (SD ON , SD OFF , and SD DUR ), we see seasonal variation in the response (Fig.…”

“…Hemispheric-scale circulation patterns, or ocean-atmosphere teleconnections, are known to influence the climatology of western Canada; the most influential patterns include the PDO (Stahl et al, 2006a;Whitfield et al, 2010), ENSO (Moore and McKendry, 1996;Shabbar, 2006), Pacific North American pattern (PNA; Bonsal and Shabbar, 2008;Stahl et al, 2006a), and Arctic Oscillation (AO; Burn, 2008;Fleming et al, 2016). Anthropogenic climate change is also an important influence on snow cover in BC (e.g., White et al, 2016;Foord, 2016;Islam et al, 2017;Najafi et al, 2017;Schnorbus et al, 2014); however, climate change studies require long time series and are complex due to the potential influence of climate change on the ocean-atmosphere teleconnections themselves (e.g., Cai et al, 2018).…”

“…1). Generally mild and dry winters in BC have been identified as important factors in forest insect outbreaks (Stahl et al, 2006b), wildfire activity (Crowley et al, 2019), glacier change (e.g., Menounos et al, 2018), and overall drought conditions (Trishchenko et al, 2016). The winter snowpack differs in timing and duration throughout the province and is influenced by, among other processes, climate change (e.g., Allchin and Déry, 2017;Foord, 2016;Najafi et al, 2017), local geography (e.g., Moore and McKendry, 1996;Schnorbus et al, 2014;Stahl et al, 2006a), land cover change (e.g., Boon, 2012), and ocean-atmosphere teleconnections (e.g., Fleming and Whitfield, 2010;Hsieh and Tang, 2001;Shabbar, 2006;Winkler and Moore, 2006).…”

“…The El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) have been identified as the two most influential ocean-atmosphere teleconnections on snow cover in BC (Moore and McKendry, 1996). This paper investigates the regional effects of ENSO and PDO on the MODIS-derived SD ON and SD OFF and the total duration of snow cover (SD DUR ) in BC.…”

Observations on the May 2019 Joffre Peak landslides, British Columbia

“…The total rock mass lost at the source is 5.2 × 10 6 m 3 , and the accumulated material in the deposit is 4.9 × 10 6 m 3 with respective uncertainties of ± 2.01% and ± 13.65%. The source and deposit uncertainties reflect the standard deviation (± 1σ) of stable terrain following methods described elsewhere (Menounos et al 2019). While there is good agreement between the total source volume estimates from the photogrammetry and Lidar analyses, the deposit volume is smaller than expected considering that bulking and dilation would have occurred.…”