Holocene glacier fluctuations in Garibaldi Provincial Park, southern coast mountains, British Columbia

Glacier fluctuations of the last 10,000 years have been reconstructed in Garibaldi Provincial Park in the southern Coast Mountains, British Columbia, from historical documents, dendrochronologic and lichenometric dating of moraines, and radiocarbon dating of fossil wood in glacier forefields. Six major periods of glacier advance are recognized: 7700-7300,6400-5100,4300,4100-2900,1600-1100 14c years BP, and the last millennium. Evidence for each of these six periods was found in the forefield of Sphinx Glacier, the only glacier in western North America with so complete a record. Evidence for each period, except the 4300 14c years BP event, was found at two or more sites, showing the regional sigmficance of the advances. The data demonstrate that the Little Ice Age in Garibaldi Park began as early as AD 1000. The earliest maximum was achieved in the lYh century, followed by recession until sometime in the 14'~ century. Several glaciers advanced into forests in the 14'1~ century, culminating with the construction of moraines in the late early lath, lgth, and early 2oth centuries. Helm Glacier provides a near complete record of fluctuations since the 14'~ century. Glaciers receded between the 1930s and 1960s at average annual rates of about 30 m. Between the 1960s and 1980s, glaciers advanced up to 300 m, but since then they have receded at annual rates of 5-10 m. Ice cover has decreased by about 240 km2 since the Little Ice Age maximum, with most of this loss occurring after the 19;!0s. Some small glaciers in the park have already vanished, and more are likely to disappear if the current trend continues. The record from Garibaldi Park is broadly synchronous with records of glaciers throughout the wlorld, suggesting a global forcing mechanism. Hemispheric temperature change can explain glacier behaviour during the last millennium. The Garibaldi record shows a relation to reconstructed Holocene sunspot activity, suggesting that changes in solar activity probably play an important role in global climate change.