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How quickly is climate changing altering the glacial face of the National Park System?/Rebecca Latson

How quickly is climate change altering the glacial face of the National Park System?/Rebecca Latson

Under The Glaring Sun | National Park Glaciers At Risk

By Rita Beamish

During the blistering heat wave that rocked the Pacific Northwest this summer, triple-digit highs obliterated historical records, and snowmelt poured off the glaciated mountains in Mount Rainier, North Cascades, and Olympic national parks. 

The torrents shed by Mount Rainier – which boasts more glacial ice than the other Cascade-range volcanoes combined -- swelled rivers and washed out trail bridges below. Flooding fed by sped-up melt in North Cascades National Park nearly washed out the roadbed along Cascade River Road in late June, well after the spring floods that the park typically expects. 

Still, at Mount Rainier’s 5,400-foot-elevation Paradise visitor center, “We ended the hot spell with snow still on the ground in spite of all that melting,” said the park’s public information officer Kevin Bacher.  That’s because the faster-than-usual melt came from a deeper-than-usual winter snowpack – more than Bacher had seen in his 19 years with the park. 

That snow piled up like a protective jacket over the glacial ice beneath, leaving the overall result on the region’s glaciers an open question: Which dominated -- the heat-driven melt or the deep snowpack -- in terms of building or shrinking the glaciers? 

A big melt year could well emerge in the end but, this being science, the precise answer has to wait until annual measurements are taken at the parks in the fall --  after all summer melting ends. When glaciers receive more winter snow than melts away in summer, they grow in size, and they shrink when melt exceeds snowfall.   

“While heat waves like we experienced in June exacerbate melt, for glaciers we need to view it in the context of total summer melt,” explained Katy Hooper, North Cascades' deputy chief of interpretation and education.  “It is probably safe to say that any benefit gained from the above average spring snowpack has melted away. Though much of that has melted away, what happens in the remainder of summer will ultimately determine how glaciers fared this year.” 

Added Mount Rainier park geologist Scott Beason: “Glaciers are strange things and sometimes we see less than intuitive changes in the glaciers.” Notably, not all glaciers will experience identical changes in any given year. Mount Rainier’s outlook, for instance, is complicated by the fact that the heavy snowfall occurred mainly at elevations between 5,000 and 7,000 feet -- 5,000 feet being generally at the low-end of glaciers on Rainier. Higher elevations, on the other hand, saw thinner than normal snow accumulation, Beason said. 

“We really won’t know what the glacial volume was like until we get mass balance studies done just before the snow accumulation starts this winter,” he said. Until then, “it’s too early for us to say with certainty about whether this year will be the biggest or not” in a century’s worth of melting glaciers. 

The Fryingpan, Emmons and tiny Inter glaciers at Mount Rainier/Rebecca Latson

While there appears a decent chance of more glacier loss than usual – more hotter-than-normal weather followed the extreme June heat wave -- the experts also caution that the major glaciated parks in the lower 48 -- Glacier in Montana, and Rainier, Olympic, and North Cascades in Washington – all contain glaciers at differing altitudes; they face in different directions; and they experience varied shade and snowfall. All of that influences how and when they may thin or thicken year to year. 

And when glaciers retreat into higher niches that are more shaded, the rate of melting can slow, raising additional research questions about whether that shading may temper the impact of hot temperatures.  

On Mount Rainier, all 25 major glaciers are losing volume, but at different rates, Bacher said, noting the south side of the mountain and the lower-elevation glaciers are shrinking quickest. 

Summer Measurements 

Glaciologist Mauri Pelto, director of the North Cascade Glacier Climate Project, headed to the field with his team early this month for their annual preliminary assessments on 10 glaciers. The team conducts measurements at 100 to 300 locations per glacier, including Lower Curtis Glacier in North Cascades National Park, and is finding evidence of the hot summer.

Pelto, an environmental science professor at Nichols College in Massachusetts, reported from the field that snowpack on Rainbow Glacier on Mount Baker, which lies outside the boundary of North Cascades, was just 70 percent of normal despite the heavy winter snowfall. The heat wave “accelerated loss of snow cover and emergence of bare ice on glaciers,” he said, adding that bare ice melts as much as 40 percent more rapidly than snow surface.

The Lower Curtis Glacier showed a retreat of 13 meters since last year, he reported, which was more than he had earlier suspected he might find. Pelto also is interested in learning the impact of the heat wave at different elevations.

Loss of glaciers carries far-ranging impacts/USGS

For overall volume loss, Pelto thinks the glaciers by end of the melt season will exceed the average annual depth loss of roughly half a meter that’s been occurring over nearly four decades. But he anticipates the loss is not likely to reach the 2.1 meter drop of 2015 after a low snowpack and hot weather combined to wallop the glaciers – “like taking over 2 meters off every glacier and slicing it off the top; it’s gone,” Pelto said.

A big snowmelt early in summer makes it “hard to catch up later,” especially for small glaciers, he said.

“It definitely can be said the relationship between summer daily temperature and glacier melt is generally strong,” explained Caitlyn Florentine, a USGS physical scientist in Glacier National Park and the Northern Rocky Mountain Science Center. She also emphasized, however, “When we talk about the prognosis for the year overall … it’s really about the magnitude rather than the rate. A fast melt in one portion of the summer can be offset by slower melt rates later in the summer. “

“You always have to burn through the seasonal snow first before you start melting glacier ice,” she said.

Glacier National Park saw slightly more snowfall than normal this year, she said, but the park still needs fall data to confirm overall glacier loss for the year.  

The Big Ongoing Trend

What’s not in question is that the massive ice forms are shrinking worldwide, in continual retreat during  decades of human-caused global warming. Year-to-year changes, such as the results of this year’s hot spell, are less important to their shrinkage than is that overall trend, scientists say.

Mountain goats in Glacier National Park rest on snow patches to cool down on hot days. Doing so helps them slow their breathing and conserve energy. Climate change raises temperatures and shrinks snow patches. Researchers worry that these changes could le

Mountain goats in Glacier National Park rest on snow patches to cool down on hot days. Doing so helps them slow their breathing and conserve energy. Climate change raises temperatures and shrinks snow patches. Researchers worry that these changes could lead to greater stress on the park’s cold-adapted goats--National Park Service

Over the past century, glacial coverage has declined about 53 percent in North Cascades, 27 percent in Mount Rainier, and 52 percent in Olympic national parks, according to the National Park Service’s North Coast and Cascades Inventory and Monitoring Network. At Olympic, temperatures at higher elevations are warming the fastest, the Park Service says, and now, precipitation that used to fall as snow, feeding the glacier ice, falls more often as rain.

Officials at Olympic are speculating that the fall measurements could show even greater melt rates up high than at lower park elevations. 

Glacier National Park’s 37 named glaciers declined 68 percent in area between the mid-19th century and 2015, according to U.S. Geological Survey monitoring. The park’s namesake icy features are expected to disappear entirely by the end of this century.

A glacier’s area -- its footprint – can be readily seen in aerial photographs, which often show icy mountain lakes below shrunken glaciers where mighty rivers of ice once dominated the landscape. But observing the area does not reveal the full extent of glacier loss because it does not show the glacier’s thickness and overall mass, experts note. The mass, or volume, is what the parks will learn from their measurements on the glaciers this fall. 

Scientists at Glacier also have started using photogrammetry techniques with satellite imagery to remotely ascertain changes in glacier mass. 

Mass not only reveals how much frozen water is stored in a glacier, with implications for community water supplies below, but can inform issues like stream volume changes in habitat for downstream aquatic species, Florentine noted.  

Disappearing, But Over Time

A single bad melt year conceivably could clobber a glacier that has shrunk to the point that it’s almost “not a glacier” any more, Beason said. On the other hand, people may not notice a big difference on Mount Rainier, for example, from one year of thinner than normal snowpack above 7,000 feet.

“But successive years, or more years than not over a long time, will most certainly lead to visually observable changes in the glaciers,” he said.

Glacial retreat over time certainly affords powerful and dramatic evidence of a warming globe. Still, said Pelto, people often fail to realize that “Glaciers are pretty big and pretty thick. No one year, no one decade, is going to get rid of a glacier that has any size. … They don’t just disappear that quickly.”

Glacier National Park rangers using "repeat photography" images to explain to visitors how the park's glaciers are changing/NPS

Glacier National Park uses "repeat photography" images to explain to visitors how the park's glaciers are changing/NPS

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Comments

Rocky Mountain Park has lost many glaciers also.


I appreciate that you mention the following and acknowledge that there are many factors that can impact the melting:

experts also caution that the major glaciated parks in the lower 48 -- Glacier in Montana, and Rainier, Olympic, and North Cascades in Washington - all contain glaciers at differing altitudes; they face in different directions; and they experience varied shade and snowfall. All of that influences how and when they may thin or thicken year to year. 

I think if you want to actually fully convince people that these glacier melting and retreats are directly correlated to the climate change, you need to show side-by-side pictures of the glacier shrinkage/retreat from decades before (with the date clearly notated on the before/after and being roughly in the same month (not something like March in the "Before" and July in the "After")) and with tabular data that shows the snowfall amount the prior winter, the temperature RANGE (Hi/Low) each week as well as the Average AND Standard Deviation (Averages alone are misleading -- when this is the only thing given, I absolutely distrust the conclusions b/c they can be misleading and manipulated).  Additionally, a table should be provided that shows the concrete glacier measurements -- not only the distance it retreated but its thickness (Average & Std Deviation across many sample points), and an approximation of the ice volume (this is what we really care about, but it must be using the same calculation model for both the past and present).  The glacial ice volume approximation should have a standard deviation  and confidence interval associated with it as well (if it is a calculation using an imperfect statistical/computer model with sparse data points and/or data resolution). The approach used to calculate the ice volume should be described to lend credibility to the approximations and confidence that they are decently accurate.

 

If your analysis of correlation to the weather reasonably proves the fluctuating glacial extent is not simply seasonal and multi-decadal cyclical norms, then I would say you have at least proven 1 point of the climate change argument, namely that "the glaciers are retreating and shrinking due to out-of-the-norm weather anomalies trending beyond the very-recent (on a earth-history time-scale) weather patterns of the last 1 to 2 centuries". 

 

However, I must point out that there is plenty of evidence (on both the hyper-recent last 2 milleniums, and the very long past of 50,000 to several million years) that the Earth's climate fluctuates by many degrees and can change quite rapidly (like the Younger Dryas event).  Very Large Glaciers have completely melted in the past and disappeared across North America. Glaciers are what formed the Great Lakes -- the largest glacial lakes (see https://igws.indiana.edu/FossilsAndTime/LakeMichigan) -- and they used to extend north to south from the Hudson Bay down as far as Indiana, Ohio, Pennsylvania, and from West to East all the way from Minnesota (land of 10000 lakes (smaller glacial recesses)) to the Eastern seaboard in Upper New York, Vermont, New Hampshire, and Massachusetts. https://files.dnr.state.mn.us/mcvmagazine/young_naturalists/young-natura...

 

The warming period that melted these MUCH bigger glaciers and created the resulting lakes and uncovered land all the way up to Ontario, Quebec and the Hudson Bay were not induced by humans (there was no industrial age yet to create greenhouse gases at this time), and therefore lend credibility to the thought that the current warming may have multiple causes, with man's involvement being one of the smaller factors.  

 

Take into account that we have only been monitoring glacial coverage (with precise measurements and weather history) for about 200 years, a relatively small segment of history, questionably not enough time to make such large deductions that Man is entirely responsible for these glacial meltings and temperature increases. When the glaciers existed for many years, the ground beneath the glaciers was frozen continuously and went very deep (many feet down). When the ice melted, the land still remained rather cold because of this cold reservoir where the glacier used to be (and due to the high latitudes, and low average temperatures, especially up in Canada, and especially deep down b/c soil has a lower heat transfer coefficient), so it maintained a permafrost layer that continued to freeze each year (the soil layers deep down never fully thawed so each winter it could refreeze the top layers due to the layers below not providing heat upward to slow the freezing, although over time this effect would gradually deplete the cold reservoir such that eventually the top layer would no longer freeze over each winter).  That layer of deep soil that stays permanently frozen has been getting deeper and deeper over the years. All of this points to an explanation that the Earth has been warming since the Great Lake glaciers started to melt more than 4000 years ago, and since the last remains of ice melted, the permafrost has been retreating northward and deeper down. Now at the higher elevations in mountains, the temperature increase that started thousands of years ago has finally reached a point where it is conquering the effects of combined altitude and latitude that helped to maintain the mountain glaciers longer than the lower sea level areas in the plains and along the Canadaian/US border.

 

 


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