Cascade glaciers hold secrets of future smoky skies
The wildfire smoke has been around a lot longer this summer and autumn, defiantly longer than anyone anticipated. Some might wonder what effect the smoke – and, more importantly, the ash — might have in terms of the long view of geologic history in the Pacific Northwest.
As it turns out, while the daily effects are pretty harmful to anyone forced to breathe the air outside, the effects it has on Cascade glaciers are even worse and much longer lasting.
Andrew Fountain, Ph.D., is a professor emeritus at Portland State University and a glaciologist who’s studied mountain ice in the Pacific Northwest for more than 40 years. Fountain says that compared with a lot of other areas of scientific study, his field is still relatively young.
“It’s been an area of active study since about the 1950s,” Fountain told KIRO Newsradio. “That’s when it really got going after World War II. Prior to that, people were looking at glaciers every so often [and] the occasional university professor [or] hiking clubs would kind of monitor glaciers, but since World War II and the rise of modern science and the science establishment, that’s when glacier studies really took off.”
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In the Pacific Northwest, the ice in Cascade glaciers is comparatively younger than in higher latitudes, Fountain said.
“Unlike Antarctica and the top of Greenland, the Pacific Northwest gets lots of snow in winter, and in summer, lots of snow and ice melt away such that the throughput of ice (or mass flux into and out of the glacier) is quite high, so the residence time of ice in a Pacific Northwest glacier is quite short,” Fountain wrote in an email. “We wouldn’t expect the oldest ice to exceed about 300 years or [date to] about 1700.”
One of the scientists in the region looking at this relatively young ice record to study changes in the climate is Susan Kaspari, Ph.D., professor of geological sciences at Central Washington University in Ellensburg. She’s on sabbatical in Norway at the Norwegian Polar Institute, which is where KIRO Newsradio reached her earlier this week.
Kaspari studied ice core samples taken from the South Cascade Glacier – west of Stehekin in the North Cascades – by the U.S Geological Survey (USGS) in 1994. She dated the ice at the base of that sample to the 1840s, which is right about when the non-Indigenous population in the Northwest began to grow in large numbers – as settlers came via the Oregon Trail and by ship. The U.S. established ownership of what’s now Washington, Oregon, and Idaho through a treaty with Britain in 1846.
The core sample taken in 1994 is an astounding 158 meters long and 10 cm in diameter – though Kaspari says her team examined just a narrow slice in search of evidence of “black carbon” – a more scientific name for the ash deposited on the surface of the glacier via smoke.
“The record starts in 1840, and concentrations [of black carbon] are quite low,” Kaspari told KIRO Newsradio. “And then, we start to see an increase starting more in the later 1800s that coincides with when you had an expansion of railways into the western United States, and the population in the region started to increase.
“And then, it’s really post-1940, after … World War II, that you really start to see an increase … in general black carbon,” Kaspari continued. “A lot of this is even more so due to industrial and just domestic burning of wood and coal for heating in the region. And then starting in the late 1960s … the black carbon concentration starts to go down, and that’s associated more with a transition in fuel use [and] moving away from coal and that sort of thing.”
Along with clear evidence of the growth in industrial activity, the “record” revealed by the ice, said Kaspari, also shows evidence of wildfires.
“All through the record, it’s punctuated by large peaks of black carbon that are tied to when there have been wildfires,” Kaspari said. “But in the more recent part of the record, we see an increase in black carbon concentration that’s tied to wildfire activity combined with more melt on the glaciers . . . basically, the black carbon is not spread out over as much snow, and so you end up with higher concentrations.”
And it’s these “higher concentrations” of black carbon – from wildfire smoke and ash – that can make disturbing impacts on Cascade glaciers.
“Smoke definitely affects the glaciers,” Fountain said. “The smoke itself – particularly the ash part – the larger particles fall on the surface, and because they’re quite dark – the black carbon – they absorb a lot more solar radiation than regular dust particles do.
“It causes the snow to melt much faster and causes the ice to melt much faster,” Fountain said.
Compounding the effect, Fountain says, is the reality that smoke and ash from one season can end up sticking around for multiple years on the surface and continue to impact the ice.
“Winter comes, the snowpack builds up again,” Fountain continued. “And then, the next summer, as that snowpack melts and reaches, say, the past year’s layer, which occasionally happens, you sometimes lose all your snow cover. Now, you have all this dark material sitting there, so even though the current year isn’t being affected by fires, the snowpack is still being affected by the previous year’s forest fires because the dark particles are sitting there melting the snow much faster.”
Dr. Fountain says, generally speaking, in the distant past, the effects of ash – from naturally caused wildfires before Europeans and Americans came – on snow and glaciers were perhaps only negligible. But, in this more modern epoch, when climate change means glaciers are already receding more rapidly than anyone thought possible, the effects of the ash are compounding and accelerating what’s already underway.
However, it’s not all doom and gloom.
Fountain says that after well-documented temperature increases in the 19th century and early 20th century, it may have been changed in ocean currents in the Pacific Ocean not long after World War II, which resulted in something that sounds like the name of a Miles Davis album or maybe a hipster furniture store: “the mid-century cool period.”
“You hit the 1950s, and the glaciers stopped receding,” Fountain said. “And in fact, in some cases, they advanced slightly, and this is really well documented. You go back to the literature, and people are saying, ‘Hey, the glaciers are advancing’ or ‘Hey, they’re staying pretty steady.’
“That was called ‘the mid-century cool period,’ and the reasons for which they’re not really clear on what happened,” Fountain continued. “But the thing is, this can happen – that things can cool a little bit, and the glaciers can either stabilize or advance a little bit.
“And that’s what we want, right?” Fountain said. “For a lot of different reasons, not just for the glaciers. So this is possible.”
While no one has control over the ocean currents – like those that may have fostered the mid-century cool period – there is, of course, much that can be controlled.
“It’s a matter of whether we have the political will in terms of reducing our carbon emissions [and] methane emissions to bring that scenario back again,” Fountain said.
Which is certainly something to think about this week as you scan the hazy skies while trying to get a better view of the Pacific Northwest – past, present, and future – while also trying to get a breath of fresh air.
You can hear Feliks every Wednesday and Friday morning on Seattle’s Morning News, read more from him here, and subscribe to The Resident Historian Podcast here. If you have a story idea or a question about Northwest history, please email Feliks here.