Little Ice Age investigations in Strathcona Provincial Park, Vancouver Island, B.C.
Date
2001
Authors
Lewis, David Harris
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Abstract
Dendroglaciological and lichenometric techniques were used to establish the Little Ice Age glacial history of two glaciers (Septimus and Colonel Foster) in Strathcona Provincial Park, Vancouver Island, British Columbia. This record was placed in the context of the regional Little Ice Age record of the Pacific North American Cordillera, and evaluated in the context of proxy mass balance and climatic records from 1600 to 1994 AD.
The Strathcona Little Ice Age chronology compares well with regional moraine records from coastal British Columbia, Washington, Alaska, and the Canadian Rocky Mountains. Three generally synchronous episodes of glacier activity are noted: late 1600's to early 1700s, and late 1800s, and mid 1930' s. Dating results suggest two levels of glacier response: (i) asynchronous responses to local factors such as microclimate, topography, and glacier geometry, and (ii) synchronous responses to larger-scale climatic forcing.
Dendroclimatological analysis indicates that ice-proximal mountain hemlock are also responding synchronously, albeit inversely with mass balance, to regional climate variability. A proxy glacier mass balance (MB) record was constructed from a mountain hemlock ring-width chronology derived from climate-sensitive trees growing adjacent to each site. A good comparison between the proxy and regional mass balance records for Pacific Northwest glaciers (1966-1994: R2 = 50%) allowed for the reconstruction of MB anomalies from 1600 - 1994 AD. In addition, a significant relationship was revealed between the mass balance history of glaciers on Vancouver Island and large-scale climatic variability shown to be associated with the Pacific Decadal Oscillation.