Wedgemount and Overlord Glaciers again in full retreat
How did the health of our glaciers fare over the past year? On Sept. 16 and 17 we surveyed the glacier termini to find out; it was not a hopeful result. Several enthusiastic volunteers provided the assistance on two warm days, in glacier-melting temperatures, before the onset of the autumn cooling cycle in the following week. Not much further retraction and meltdown was missed in our surveys.
This year was a "neutral" (a Nada) in the El Niño-La Niña cycle. Significant oceanic cooling in the 1998-99 year brought on higher than normal snow packs (record levels at the coast) and a long summer of melting to take most of it away in the areas above timberline. Nonetheless, snow lingered around the shores of Russet Lake, itself still covered in slush, during our September 1999 survey.
Expectedly, Overlord Glacier advanced in that time period, because the snow cover shielded the underlying ice for much of the summer. For 1999-2000 the La Niña event weakened; less snowfall and less overall protection to the glacier from summer solar radiation, and thus a retreat of 2.8 metres for the time frame.
This past winter was a well-known low snow pack event (especially in eastern B.C.) despite the neutral temperature status of the Pacific Ocean. Snow had disappeared from the high country by early to mid-July, bringing on a fierce melt period on the glacier surface in August to early September. Residual snow of the previous two years about Russet Lake had also disappeared, suggesting that the previous years reserves left on the glacier would also be gone. Expectedly, the snouts of Overlord Glacier retracted 7.0 metres, and it could have been worse.
What is the long-term outlook for Overlord Glacier? Well, it has not yet retracted to its 1951 position, as another 66 metres of recession will be required. Between 1951 and 1986 it had managed to advance 175 metres, but in 9 to 10 years time, we could well see a return to the 1951 position; only then do we begin to panic!
In the meantime there is the puzzle of the extra snow pack on the upper glacier from 1998-99; will it translate into elongation of the glacier over the same time frame, or did last summer swipe it all away? A very barren and heavily crevassed glacier of September, 2001 suggests the latter, although sometimes the onset of extra crevassing signals an advance. The bets are even/steven.
Moving on to the desolate scene at Wedgemount Lake, the betting is recession; the glacier never did muster a significant advance in the last 50 years. This years survey posted another 12-15 metres of recession, in tune with the average annual rate of 13.15 metres since 1900. In 1951 the glacier engulfed the eastern one-third of the lake basin; today its a 110 metre boulder-hopping scramble from lake shore to glacier edge. This edge was a mass of ice 60-70 metre thick in 1977 when the glacier was radio-echo sounded.
The glaciers terminus lies at an elevation of 300 metres higher than that of Overlord; yet the recession rate is doubly higher, suggesting that the glacier is not receiving its just amount of winter nourishment. Has a rain shadow developed at Wedge Mountain? The odds are stacked to more of such retreat over the next 10 to 20 years before a new and higher equilibrium position on the glacier will hopefully stymie further retreat. The terminus is likely to stabilize at the base of the lower ice fall.
This years surveys were assisted by Nina Evans-Locke, Shelly Mathews, and Walter and Sheila Frith.
Upcoming Events :
Sunday, November 18th Return of the Salmon Festival (Squamish). The Squamish Estuary Conservation Society presents the second annual Return of the Salmon Festival, a celebration of the varied traditions, delicious foods, music, arts and recreation associated with the return of the salmon. The Festival begins at 11 a.m. (rain or shine) at the Sunwolf Outdoor Centre located on the Squamish Valley Road, north of the Squamish Airport and the municipal landfill, near the Cheekye bridge. Included are a Squamish Nation traditional salmon BBQ with bannock, live entertainment, art and craft demonstrations, games and face-painting for kids, and educational displays. Theres no admission charge and the salmon BBQ will be budget-priced (under $6). For more information or to participate as a volunteer or sponsor, contact Edith Tobe, Festival Event Director (phone: 604-898-9171; e-mail: email@example.com).
Thursday, November 29th Whistler Naturalists AGM. Our featured speaker for this years AGM is Andrew Bryant, Chief Scientist for the Vancouver Island Marmot Recovery Project. The AGM will be held in the auditorium at Millennium Place and consists of two parts: the business portion of the meeting for members only (starting at 6), and Andrews public talk (starting at 8 p.m.). Please mark November 29th on your calendar and watch this column for more details.
Sightings and Memberships: NatureSpeak is prepared by the Whistler Naturalists. To become a member or to report noteworthy sightings of mammals, birds, or other species, contact Lee Edwards (905-6448; e-mail: firstname.lastname@example.org).