Feb. 20, 2008 -- New research on the timing of deadly avalanches in mountain ski areas such as Aspen, Colo., suggests global warming could start the worst kind of snowy train wrecks earlier in the year in mountains all over the world.
Depending on the rate the climate warms, avalanche season could move up anywhere from 2 to 19 days by the year 2030 and 16 to 45 days earlier by 2100, say researchers who published their findings in the February issue of the journal Cold Regions Science and Technology.
Just as important as the timing, however, is the type of avalanches the warmer temperatures are likely to bring. Snow avalanches come in two flavors: dry and wet.
Dry avalanches occur when the snow is well below freezing temperature. The snow pours down the slopes in dry avalanches but is less weighty than in a warmer, wet avalanche.
"Dry snow packs behave much differently," said Brian Lazar of Stratus Consulting in Colorado and lead author of the new study.
Dry snow packs are more common in colder mountains like the Rockies, and they are much easier to control. The typical technique is to deliberately trigger dry avalanches with explosives, thereby reducing the danger of unexpected avalanches onto skiers or highways.
Wet avalanches, on the other hand, are more common when the air temperature is above freezing -- something that would be more common in many areas and happen earlier in the year as global warming progresses. Unfortunately, the explosive technique doesn't work so well with wet snow packs, Lazar said.
"With a lot of water they are harder to release," said Lazar, referring to the experiences of avalanche control professionals in wetter mountain ranges like the Cascades of the Pacific Northwest and the Sierra Nevada of California.
"We know a lot about controlling dry avalanches and not about wet avalanches," said Ethan Greene, director of the Colorado Avalanche Information Center. "You talk to people who work on big wet avalanches and they say they're different animals."
Greene helps supply ski areas and the Colorado highway department with avalanche forecasts. If wet avalanches become more common, he said, it could very well push ahead the science of avalanche forecasting and control, which is a good thing.
"As they get more wet," said Greene, "we will need to find better ways to deal with them."
As for which type of avalanche is more dangerous, that's a draw, Lazar told Discovery News.
"Hazard has more to do with its size," Lazar said. "Wet avalanches tend to move slower, but they tend to carry more weight."
The effects of global warming on skiing in general will be significant. The snow line will move up the mountains, with ski seasons beginning later and melting happening earlier, he said. It all depends, of course, on what climate model and greenhouse gas emissions scenario you look at, he said.
"There'll still be snow to ski, but avalanches will likely become a problem," Lazar said. "For those of us who are adults now, we'll still be able to ski. But it's a concern for our kids and grandkids."
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