ALPINE GLACIERS IN WESTERN CANADA APPROACH THEIR SMALLEST SIZE OF THE PAST 7000 YEARS

Most alpine glaciers in the Northern Hemisphere reached their maximum extent of the Holocene between AD 1600 and 1850. Since the late 1800s, however, glaciers have thinned and retreated, mainly due to atmospheric warming. Glacier retreat in western Canada and other regions is exposing fossil tree stumps, soils, and plant detritus that, until recently, were beneath tens to hundreds of metres of ice. Dating of these fossils indicates that many of these glaciers are smaller today than they have been at any time in the past 7000 years. This evidence, in turn, suggests that glacier recession in the twentieth century is unprecedented during the past several millennia and that glaciers in western Canada have reached minimum extents only 150 years after they achieved their maximum Holocene extent.