Scientists Predicted Glacier Park's Glaciers Would Be Gone By Now. What Happened?

Last week, Glacier National Park announced that it will be changing signs warning that its signature glaciers would disappear by 2020. The park says the signs, put in more than a decade ago, were based on the best available predictions at the time.

Montana Public Radio’s Aaron Bolton spoke about what changed with Caitlyn Florentine, a research physical scientist with the U.S. Geological Survey’s Northern Rocky Mountain Science Center.

Aaron Bolton Caitlyn, thanks for joining us on MTPR. And I want to start with the news from last week. Glacier National Park is replacing signage saying the park's glaciers would be gone by 2020. Obviously, it's 2020 and glaciers are still there. Why didn't it exactly pan out?

Caitlyn Florentine In 2003 a study was published that considered how the landscape would change both in terms of glacier evolution as well as vegetation change. And that 2003 study showed that one of the glaciers in Glacier National Park would entirely disappear by 2030. And then as time went on, more observations unique to Glacier National Park were collected. So more measurements were made. You know, more scientists started to scrutinize. And as I mentioned, make more observations.

Bolton How many glaciers are in the park today? Do we know historically how many there were?

Florentine Yes. So, [146]* in about the mid 19th century. And then today there are 26 named glaciers in the park.

Bolton What type of information is going into predictions about when a glacier might melt? What goes into a prediction like that?

Florentine You're going to need information about the existing ice volume. So again, not only the footprint of the glacier, but the ice thickness. You also need information about how the glacier flows. You might want to know something about, not just the snow falling from the sky and how warm that ambient temperatures are in the summer, that climate information, you might also want some information about avalanches and the wind drifting of snow. These are the sorts of considerations that would go into a physical treatment of when a glacier disappears by. And again, when this problem was first looked at for Glacier National Park, it was a geospatial model that wasn't as, sort of, anchored in with observations with that information about ice thickness, et cetera. To run the physical model, you really need to know how much ice is there to begin with.

Bolton How should the average person be thinking about predictions on climate change, like when glaciers melt? I mean, is it fair to have this expectation that it's going to be correct most of the time, when in fact, it's a prediction based on the best available science and data that you guys can get a hold of?

Florentine Yeah, absolutely. When a prediction is based on the best available science, then I think it is. I mean, well, even then, it's a personal call, right, where you put your faith. But, you know, I think also the level of scrutiny and faith is going to vary, whether you're somebody walking through a visitor center in a national park versus whether you're the mayor of Miami making decisions about how the city is run and how city planning happens; or if you're a congressperson deciding how money will be allocated based on some other, you know, consideration of where water mass is located.

But I can tell you with a straight face and with confidence that there is, the people that I interact with professionally are earnestly dedicated to using science to connect — both expose and connect — all of us to, you know, as capital 't' truth as we can get. And it's an imperfect process. But the whole process of peer review is that things are honestly poked and prodded and analyzed many different ways, and still seems to be true. That's the information to be trusted in.

Bolton What is the latest and I guess greatest in terms of predicting when we might see some of the major glaciers in the park melt.

Florentine In terms of the predictions, the latest that I've seen actually comes from a group of Swiss researchers. So I would have to look at their results in more detail than is possible from looking at the paper they published to be able to say definitively when all the glaciers are are hosed and no longer present, but certainly by 2100.

Correction: In an earlier version of this story, Florentine incorrectly stated the estimated number of glaciers that were historically in Glacier National Park, and timeframe that estimate was made for. In the mid-nineteenth century, there were estimated to be 146 glaciers in the park.