Naturespeak 

Hot summer for our local glaciers

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No surprises, this past summer's series of heat waves was not nice to our glaciers.

Meltwater discharge was high from all throughout the season - initially clear and cold while snow cover was melting away, but by August that snow was gone and the solar radiation attacked the underlying ice to generate the grey-milky discharge. Green Lake became green due to the reflection of specific solar rays off the silt suspended in the water and the lake level remained high into September.

To the south the influx of silty discharge pushed a greenish-grey plume of freshwater several kilometres out into Howe Sound, often beyond Defence Islets and Anvil Island. This disruption of light penetration creates difficult angling conditions for the fishermen and osprey alike, and locally the kingfishers went elsewhere to forage for food.

The extreme melt conditions stripped out glaciers of snow to higher than usual elevations, creating a ghastly, if not ghostly, blackened smudge on the exposed ice surfaces. Such a scene was only too obvious on a ride up the Peak chairlift on Whistler. Whistler Glacier and the ice in Whistler Bowl were smeared with rubble and blackened "soot." Crevasses widened on the latter to make this writer shy of skiing the bowl until at least late winter, when they might become safely filled in.

Thankfully, our glacier monitoring program has not been on these two glacierets, because there isn't much left to measure!

The surveys of Wedgemount and Overlord Glaciers this September yielded the expected recession on each. The amounts were not healthy but not brutal either: Wedgemount at (-)28.4 metres, and Overlord at (-)20.2 metres.

Historically, it has been worse for both: Wedgemount had (-)34.0 metres for 1949-50 and 1950-51 and a record (-)36.7 metres average per year for 1969-1972.

Overlord averaged (-)31.0 metres per year in the recession dust-bowl period of 1928-1951 and (-)25.0 metres in 1993-94 and 1994-95.

And so the curious will ask, what did the record snowpack of 1998-99 do to the glaciers? This event generated a slowdown to (-)2.5 metres for 2006-07 on Wedgemount and a disappointing (-)6.4 metres for 2007-08 on Overlord.  For the latter, I had unwisely predicted an advance! I'll await a prolonged La Niña signal from our Pacific oceanic currents before making any more predictions.

 

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