People who visit the Australian high country know how badly it has been impacted by bushfires over the past decade.
In Victoria, we experienced the Eastern Alps fire of 2003, which burnt 1.3 million hectares, and also in 2006/07 which burnt almost 1.3 million hectares. Then over the summer of 2012/13, the Aberfeldy-Donnellys Creek and Harrietville fires also burnt large areas of the mountains. Some sections have been burnt three times in a decade, with loss of significant stands of Alpine Ash and snow gums.
I have often wondered what the fire impact might mean in terms of snow cover. Obviously where there is the classic open canopy of a mature snow gum woodland, at least half the ground is at least partially shaded from direct sunlight. Often snow will stay in better condition under the trees when its getting sun affected in the open areas. And equally you will often get snow lingering in the forests once it is mostly burnt off in adjacent treeless areas.
The following information is the first science-based assessment of the impacts of wildfire on snow pack that I have seen.
Kelly Gleason is a Postdoctoral Research Ecologist who is using data from NASA to assess how forest fire disturbance affects the loss of snowpack in the Cascade Mountains in Oregon. Her findings are common sense: yes, forest fire impacts on the tree cover, which does impact on how quickly the snow melts. And its consistent with my observations in our mountains:
“Gleason determined that in the winters following forest fires the more open canopy allowed 60% more sunlight to reach the snowpack surface, while the sloughing of charred debris from standing dead trees darkened the snowpack surface and reduced the snow albedo by 40%. These two factors led to a 200% increase in the amount of sunlight absorbed by the snowpack surface, which resulted in faster snowmelt in the burned forest. As a consequence, snow disappearance occurred three weeks earlier in burned areas than in the adjacent unburned forest.”
This is depressing news. Yet I’m reminded of the good advice from the Climate Council from when they released their research into the impacts of climate change on bushfires:
“These trends can be turned around. Australians have an opportunity to rapidly and significantly reduce our CO2 emissions to help stabilise the climate and halt the current trend towards more extreme weather events and hotter average temperatures”.