The Lathrop Glacier has disappeared from southern Oregon within the past decade. What does this mean for the Cascade Range? Will it ever come back? Andrew Fountain is a professor of geology and geography at Portland State University. He joins us to talk about what it means when a glacier is gone.
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Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. Oregon’s southernmost glacier, the Lathrop Glacier, used to be on Mount Thielsen in Douglas County. But at some point in the last five years, it disappeared, and it’s not alone. Andrew Fountain is a glaciologist at Portland State University. He says that more glaciers are likely to follow. Andrew Fountain joins us now with the details. Welcome back to Think Out Loud.
Andrew Fountain: Thank you very much. Glad to be here.
Dave Miller: Let’s start with the size here. Lathrop Glacier, it was about the size of half a football field. How does that compare to other glaciers in the northwest or to truly large glaciers in other parts of the world?
Andrew Fountain: It’s actually a little worse than that. The Lathrop actually has two arms, the east and west arm. If you put those together, they are about half a football field. So, each arm is about a quarter of a football field. That’s really small compared to what we would normally consider glaciers. Frankly, it’s kind of on the edge of whether it’s a glacier or not. Most people, most scientists who do glacier inventories, stop looking at these kind of features that are below .01 square kilometers, which is about a football field by a football field in area. So the Lathrop on most inventories would not even be included as a glacier.
Dave Miller: Just because of size, even if it was ice moving on rock or land over time?
Andrew Fountain: That’s right. I mean you have to draw the line someplace. Otherwise it just takes a huge amount of time to inventory all the glaciers everywhere.
Dave Miller: This glacier did not calve into an ocean. There’s no ocean at the bottom of it. So, what’s the best understanding for what happened to it?
Andrew Fountain: These glaciers in general are retreating and shrinking just due to warmer air temperatures. We see that all over the world, frankly, and certainly here in the western US.
Dave Miller: So, it just melted?
Andrew Fountain: Yeah, it just melted. This glacier in particular is very thin. It’s on a steep slope and it doesn’t have the thickness to mechanically hold it together and every so often it kind of breaks away, leaving a remnant piece and the rest of it is kind of avalanched downslope to the bottom. So, this has an extra mask loss because of that breakage. That’s not unusual for really small glaciers.
Dave Miller: This particular glacier wasn’t named until the 1960s. Do you have an estimate for how old it would have been?
Andrew Fountain: Man, who knows? It’s really hard to tell the age of these glaciers. It would be impossible for me to say.
Dave Miller: But potentially thousands of years old?
Andrew Fountain: Oh yeah, yeah. Now, having said that, there is evidence, particularly in California, of glaciers disappearing 3-4,000 years ago. The small ones, not the big ones, the small ones disappearing 2 or 3,000 years ago and then reforming again as the climate began to cool. For all I know, this could have happened to the Lathrop Glacier as well. So it might not be more than a couple of thousand years old.
Dave Miller: What’s lost locally when a glacier melts? I mean, what did this glacier mean for the local ecosystem and the land below it?
Andrew Fountain: What a lot of people don’t appreciate are these glaciers act as frozen reservoirs after the seasonal snow has melted and we have these really dry summers. The main source of water, because there’s no rainfall, is glacier melt. So these glaciers melt like crazy during the hot, dry summers and don’t melt much at all during the cool wet summers. They buffer the stream flow by providing a relatively constant stream flow to high alpine ecosystems, buffering them against drought. That’s one of the major contributions that glaciers make.
Dave Miller: So below that glacier, it could have enabled an ecosystem that otherwise would have been impossible?
Andrew Fountain: Yeah, it would be impossible. Or let’s just say, very different.
Dave Miller: You noted that it’s not unusual for smaller glaciers, a couple of thousands of years ago, to disappear and then to reform. How likely is that, though, going forward for the Lathrop Glacier given warming?
Andrew Fountain: There’s no reason that any of our glaciers will reform for the foreseeable future. Certainly through 2,100 there’s no expectation that they’ll reform.
Dave Miller: Can you give us a sense for the scale of the glacial loss that we’re seeing in the northwest and what you’re expecting for the rest of the century?
Andrew Fountain: Since the 1950s, Oregon has lost more than about half of its glacier area and up in Washington, because they get more snow up there [and] they’re a little higher elevation, their loss since the 1950s is somewhere around a quarter to 30%. There’s no reason to think that this won’t continue. While I was waiting for this interview, I was trying to put the finishing touches on a paper for a submission to a journal that predicts that the glaciers of the Olympic Peninsula, for example, will disappear by about 2070. They’re relatively low elevation glaciers and a relatively warm climate right on the edge of the Pacific Ocean. So they would be the first ones to go before others in the western US would go.
Dave Miller: And the estimate there is just to go completely. The Olympic Peninsula would lose its glaciers?
Andrew Fountain: That’s hard to say because these glaciers, as they retreat, they retreat upslope to a cooler environment. They can be protected by the bedrock headwalls. They can get more of their nourishment from avalanching of snow. So, they tend to hang in there. They wouldn’t be glaciers anymore because they wouldn’t move, but they might be just these ice patches, kind of like what we see today in the Wallowas.
Dave Miller: In order for it to qualify as a glacier, it’s not just it has to be a certain size as you noted earlier, but it has to be mobile.
Andrew Fountain: Yeah, that’s the definition. The scientific definition is perennial snow or ice that moves and the squishiness of that is how do you define perennial? And there’s no fixed definition of that.
Dave Miller: As I noted, you have been studying glaciers for four decades now. When you started, did you realize that the things you’re devoting your professional life to were disappearing? Was it obvious even then?
Andrew Fountain: Yeah. You know, that’s an interesting question. And I’ve thought about that. When we first started out, the glaciers were in a relatively advanced position. They were smaller than they were, say 100 years ago, but they were definitely seeming to do okay. And then, the next year I was employed, I saw the glaciers had retreated a little bit, meaning like 10 ft. or something. Then the year after that it kind of retreated a little more and then after about five or six years you get the impression, ‘hey, wait a minute. These things are getting smaller,’ but it takes a while for this to happen. Where we used to have this hut on this glacier, we used to be able to walk onto the glacier and by the time I ended my studies there, you had to jump down about 5 or 6 feet from the bedrock onto the glacier. So that was very material, very tangible, the feeling of the retreat of this glacier.
Dave Miller: Is it fair to say that all the glaciers in the northwest are disappearing right now?
Andrew Fountain: Yeah, that’s right. That’s right. We don’t have any evidence of any glaciers advancing other than the Crater Glacier. And that’s because Mt. Saint Helens exploded creating this perfect precipitation gauge, north facing, so it’s shaded from the sun. So, if you’re going to create a glacier, that’s the place to do it.
Dave Miller: That’s the one place where a glacier is actually growing right now.
Andrew Fountain: Yeah. Right. But you need a volcanic explosion to do that.
Dave Miller: Okay, Andrew Fountain, thanks for your time today. I really appreciate it.
Andrew Fountain: Okay, take care.
Dave Miller: Andrew Fountain is a Professor of Geology and Geography at Portland State University.