ENVIR 495C: Ice worms, a legacy of the ice age

The warmest year on record (2015) since 1880 when such records were first recorded  is not the year you would expect to “discover” a glacier and an unusual link to the last ice age. But this is just what happened this year with my class, ENVIR 495C: Landscape Change in the Pacific Northwest. Here is the story.

In this photo, we are posing by a small snowfield on the off-trail traverse from Cedar Lake to Graywolf Pass. The snowfield is labeled 2112:9 in the photo below. On this warm day, we were enjoying the cool blast of air coming out of the stream-carved tunnel from under the snow, an activity I have many times enjoyed in Washington’s mountains. As we stood there enjoying nature’s air conditioning, however, I began to notice some things that told me this was not simply an ephemeral snowfield.

I’ve been hiking the off-trail traverse from Cedar Lake to Graywolf Pass for at least 10 years now. I usually hike it in early to late July, a time of year when the remnants of the previous winter’s snows still blanket most of the route. This summer, however, was perhaps the most anomalous summer in recorded history in the Olympic Mountains. With less than 14% of the normal winter snow pack, the only snow remaining in the mountains, and indeed on the route from Cedar Lake to Graywolf Pass, was snow that has accumulated (and never melted)  in shaded, sheltered pockets in years of much greater than average snow pack. I have always assumed that many of these snow pockets simply melt away during lean snow years, and build up again during strings of above average snow years. Some of these snow pockets, however, take on characteristics of glaciers–that is, they form ice in their interiors as snow compacts and crystals deform, and they start to develop crevasses as they slide downhill under their own weight. In these cases, I’ve always wondered if these were small glaciers that built up during a cooling period 250 years ago, or if they are remnants of the extensive glaciers that covered these mountains 16-17,000 years ago during the last ice age.

Graywolf glaciers

The snowfield depicted in the image above is labeled 2212:9 in this image provided to me by Bill Baccus of Olympic National Park. This snowfield is one of the permanent ice features identified in their recent glacier survey. Unbeknownst to me (until now) this little pocket of snow typically does not melt out even at the end of summer–at least according to aerial surveys that have been done here since the 1980s. I have always assumed that these little pockets of snow probably did melt away completely on strings of dry warm years (of which there were many prior to the Little Ice Age, and a few since the Little Ice Age) and probably reappeared after strings of colder wetter years. Either that, or they were remnants of small glaciers that formed during the “Little Ice Age” 250 years ago, but not remnants of glacial systems that formed during the last major continental-scale ice advance (~17,000 years ago).

 

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As we stood by the mouth of the stream coming out of the snowfield, I noticed some features above that appeared to be crevasses–which would indicate movement of the snowfield. This kind of movement (and crevasse feature) is usually associated with true glaciers, but can sometimes be associated with temporary snowfields. So we went up to check it out. What we found astounded me. The snowfield actually consisted of about a 3 meter thick layer of what appeared to be glacial ice–very dense and blue. Some temporary snow features are underlain by ice snow, but this had the distinct appearance of the dense ice of a glacier. This snowfield, then was actually the remnant of small (and probably stagnant, i.e. no longer very active) glacier, and this feature was the remnant of a crevasse that opened when the glacier was active. But how old could this glacier be? A remnant of the Little Ice Age ice build up 250 years ago? Or a relict of the last true ice age 16,000-20,000 years ago?

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Looking into the crevasse I was astonished to see a little wriggling thread, a little less than an inch long. An ice worm, (Mesenchytraeus solifugus)! I was blown away! I have explored many small snow fields and small glaciers, and it is highly unusual to find ice worms, unless the glacier is (or was recently) connected to a larger glacial system. Ice worms are a species that are unique to the Pacific northwest and Alaska. They live in glacial ice and are only associated with glacial ice. That is, they are not known to migrate away from glacial ice and across temporary snowfields. Finding ice worms here implies that this piece of glacial ice is a remnant not just of the Little Ice Age, but of the last true ice age some 20,000 years ago. Peter Wimberger at the University of Puget Sound has found that ice worms in some of the larger glaciers of the eastern Olympics are identical genetically to Alaskan ice worms, implying that the glaciers of the eastern Olympics were connected to the continental ice sheet that flowed down the Puget Sound from the north 17,000 years ago. Thus, this tiny patch of ice must at one time have been contiguous with the continental ice sheet 17,000 years ago (or at least contiguous with glaciers that had been themselves contiguous with the continental ice sheet). Far across the valley, there is a glacier high on Mount Deception in the Graywolf watershed, that is known to have ice worms–so this tiny fragment of ice must have at one time been contiguous with Deception’s glaciers, which themselves were in contact with the continental ice sheet flowing down the Puget Trough. I don’t see evidence that the Upper Graywolf Glaciers were in contact with Deception’s glaciers in the Little Ice Age, so my guess is that this patch of ice (2112:9) was last connected to Deception’s glaciers thousands of years ago. Simply amazing to think about. And make no mistake about it, ice worms are one of the more endangered organisms in the context of predicted changes in climate for this region. This small population of ice worms we discovered will disappear (if it hasn’t already) if we get another summer or 2 like the summer of 2015.

A close-up view of the worm, alive in a piece of snow, held by a student.

Student Shane Kelly holds an ice worm, a direct descendant of the last ice age, in a small melting snowball.

Life size image of the same ice worm depicted above. With more searching, we found hundreds of ice worms in this mini-glacier. They are known to feed on algae in the snow, and can burrow through ice with an anti-freeze like substance in their body. They burrow their way to the surface at night to feed on algae, thereby avoiding the harmful (to them) warmth of the sunshine, as well as predators (like Rosy Finches–which will also be harmed by loss of glaciers) who eat them. This population of worms, as far as I can see it, is essentially doomed here. If this ice patch didn’t melt out completely this summer, it will be gone within a few more similar summers, and gone with it will be this population of ice worms. A similar fate awaits any small populations of worms left in any of the other small ice patches around the Olympics.

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