10,000 years of glacier history in Garibaldi Provincial Park
By: Johannes Koch
The alpine environment of Garibaldi Provincial Park has changed dramatically over the last century. The most obvious changes have been to glaciers in the park, such as Sphinx Glacier on the north side of Garibaldi Lake and Helm Glacier, whose ice caves have been lost due to recession of the glaciers. Less obvious are changes to the meadows near Black Tusk and at treeline on Panorama Ridge above Garibaldi Lake. The changes have attracted the interest of researchers at Simon Fraser University, the University of Victoria, and the University of Northern British Columbia.
Glaciers and treeline are sensitive indicators of climate change. Scientists gain important information on past environmental change in alpine regions by studying glacier and treeline fluctuations. This information, in turn, may help us predict the effects of climate warming, which is anticipated in coming years, in these regions. In a year that brought devastating fires to the Interior and flooding to the Sea to Sky corridor, we were reminded that climate and weather have major impacts on our lives.
Nearly all glaciers in Garibaldi Park were much more extensive during the Little Ice Age, a period of cool wet climate that culminated in the park in the first half of the 18th century and ended in the late 19th century. Fossil wood found in the barren terrain (“glacier forefield”) that has been freed of ice since about 1900 gives insight into the history of glaciers in the park. Glaciers have advanced into forest and killed trees several times during the last 10,000 years. We can conclude from this observation that glaciers have advanced and retreated repeatedly throughout this period. However, the large and rapid recession of most glaciers from their extended Little Ice Age positions in just one century is unprecedented. Ice cover in Garibaldi Park is only about 60 per cent of what it was 150 years ago. Some glaciers, such as Helm Glacier, may even vanish within the next several decades. As glaciers recede and, in some cases, disappear, stream flow will decrease, affecting fish populations, power generation, and water supply. Glaciers are eye-catchers and a major reason that hikers visit Garibaldi Park. The park would be a very different place if its glaciers were to disappear.
Photographs taken over the last 75 years show that tree cover has become more extensive in Black Tusk Meadows and on Panorama Ridge. Trees have filled in islands in the former open parkland, and they have become established farther upslope. These changes indicate that climate became more favourable for tree growth in the subalpine zone in the 20th century. These vegetation changes can adversely impact some wildlife, which depend on open parkland, as well as outdoor recreation because people are drawn to the showy flower displays in alpine meadows in summer.