The unpredictability of weather is shaping how each year’s avalanches will occur. “Avalanches are intimately tied to what happens in the weather,” said Brian Lazar, deputy director for the Colorado Avalanche Information Center.
As snowpacks fall later in the season and melt off earlier, there will be a series of uncertain consequences in the backcountry.
Climate change’s broad effects lead to different outcomes, but avalanches can be tied to human-caused global warming through the increase in carbon dioxide emissions. A direct result of this is snowpack occurring earlier or later in the season.
Avalanches in the Mountain West are the most common and deadly natural danger. They can be triggered by recreational use, naturally, or through mitigation. Over the last week alone, 121 avalanches have been triggered, according to the CAIC.
Avalanches occur because of the winter season’s sequence of events. The snow’s layers give us a look into the storms that have occurred throughout the season.
“It’s really the sequence of events that dictates the avalanche hazard,” said Lazar.
Uneasy snowpack presents dangerous conditions for anyone traveling in the backcountry as the snow is unable to fully settle on the mountain’s aspects and angles.
Lazar said that the warming due to climate change causes predictable elements and events such as moving snowlines higher in elevation, more rain on snow, earlier melt events, and the change in timing of avalanche activity. This means that avalanches will occur higher in elevation, and earlier in the season, than what’s been seen in the past.
Lazar spoke about “increased climate variability.” This means, in essence, that the chances of experiencing what has been an average year are going down. For example, if you have a really wet year one year and a drought year the next, you end up with “something in the middle,” but the chances of getting something in the middle are going down.
So, is climate change going to impact avalanches? Yes, says Lazar. “It will, because that means the weather making up the climate will change, but how that’s gonna look on any given season really depends on the sequence of storm events that you get in a given year. … We don’t have that level of precision, yet, in projecting future climate.”
He says that oneof the tools in an avalanche forecaster’s toolbox is comparing observations from today to past years. As past years become different and more variable from one another, that tool becomes less precise.
Climate change is sure to bring more wet avalanches in the middle of the winter, which Lazar says used to be an “exceedingly rare event,” that “it’s hard to call that exceedingly rare anymore.” Also, rain on snow events in the middle of the year used to be rare, but are occurring more often in much higher elevations.
However, compared to last year, which saw 37 backcountry fatalities, “we’re off to a much better start,” because of this year’s sequence of events. However, just last week, a backcountry skier was caught and buried in an avalanche near Fort Collins, resulting in his death.
It’s hard to say if we will experience more years like last year, in terms of fatalities. Because last year’s sequence of events made the snowpack very dangerous, Lazar calls it a “once in a decade” year.
Last year, we saw heavy October snow and then a very long dry spell which made the snowpack weak, widespread and reactive. New snow fell on that weak layer, creating dangerous conditions. And with the increase in backcountry activity, which some experts are saying was tied to the pandemic lockdown, that reactive snow layer brought one of the most dangerous avalanche years in Colorado’s history.
This year is looking good so far. We had warmer temperatures in the high country that melted a large portion of the snow away and left the weak layers at higher elevations on northerly facing slopes.
This last week’s storm, though, is creating highly dangerous conditions. There is a high avalanche warning for most of the state right now. A more comprehensive look at avalanche conditions in our mountain ranges can be found here.