All gone by the year 2020: some justifications for why the prediction failed

This is part 2 in the series on the prediction that glaciers in Glacier National Park will be gone by 2020. You might want to see to part 1 if you haven’t already

There are some efforts to explain the failed “gone by the year 2020” prediction. These are however more difficult to find because they are so sparsely distributed and not to be found in the media, this contrary to the emotional “gone by the year 2020” claim that was broadcast and shared widely.

I found two justifications for the failed prediction. The first one is a paragraph on a webpage of the National Park Service dedicated to melting glaciers (emphasis by the National Park Service):

When will all the park’s glaciers be gone? A geospatial model, published in 2003, predicted that two of the park’s largest glaciers would become inactive by 2030 if carbon dioxide levels continued to rise. For several years, those glaciers actually melted faster than the rate predicted by the model, prompting researchers to refine analysis of glacier retreat with more physical detail. These recent studies have revealed the real world complexity of mountain landscape change. Though the park’s glaciers are all getting smaller, variations in snow avalanches, ice flow dynamics, and ice thickness cause some glaciers to shrink faster than others. Sometimes a glacier will retreat very quickly where it was thinly and widely spread, only to shrink much more slowly when only the shaded, high elevation ice remains. Some small remnant ice may persist late into the 21st century or even beyond, depending on how and when we act.

It says roughly the same as Fagre told Thinkprogress, that there was a 2003 model that had put the end date to 2030, but when new information became available, a new, much earlier, end date was put forward. The only difference is the different parameter (temperature versus melt), but more about that later in this post.

Nice that there is the admission that the shrinking of the glaciers is more complex than thought, yet no attempt to make a new prediction (beside the wide ranging “remnant of ice may persist in the 21^th century”).

That last part of the last sentence got it to the diorama sign, so apparently it is the official National Park position.

The second justification is the Fact check: No, the glaciers are not growing in Glacier National Park. It is not exactly clear what this fact check is all about, there is no link to the actual claim they want to fact check. It seems a rather biased article, larded with mentions of “denier”, “denialist” and “contrarian”.

Whatever the controversy the article wants to react to, the author (Karin Kirk) ask Caitlyn Florentine (a glaciologist with the U.S. Geological Survey) to explain the conditions of the glaciers. The altering of the diorama signs at the St. Mary visitor center was also mentioned and there is also a picture of the sign as it is currently displayed, so we are talking about the same thing:

We also learn from the article that there is another sign that used to have the 2020 date and that now reads:

Some glaciers melt faster than others, but one thing is consistent: the glaciers in the park are shrinking.

These are the reasons why these signs were changed (emphasis by the yaleclimateconnections author)

Why were the predictions revised?
The original estimates of the timing of glacier melt were based on two things: modeled projections of the glaciers’ response to warming, and direct observations of glacial retreat. A 2003 report was based on modeling a scenario of doubling pre-industrial atmospheric CO2 levels by 2030, which would have melted the park’s major glaciers – and presumably the minor ones, too – by 2030.

After publication of that report, field observations showed glacier melt to be years ahead of the projections, causing scientists in 2010 to revise their “end date” to 2020.

This 2020 date was then put on signs in the park, educating visitors about the observations of rapid ice loss resulting from global warming.

New science means new signs.
The death throes of glaciers are an urgent research topic, as streamflow, water supplies, aquatic habitat, and albedo feedback all hinge on the presence of glaciers. Thus, new research continues to shed light on the subject. A 2017 USGS report suggests that as glaciers retreat upward in elevation, they become more resistant to melting. The residual parts of the glaciers are higher, more shaded, and receive more snow deposition from avalanches and windblown snow. Because of these factors, these glacier remnants appear more capable of withstanding higher temperatures, compared to the thinner, lower-elevation parts of the glaciers that underwent rapid melt.

Glaciers are “dynamic and flowing landforms,” explained Florentine, and new understanding of the intricacies of glacier retreat can help clarify why the remaining glaciers are more persistent than once thought. This is just one of many examples where interpretive signs in the national parks are updated to reflect emerging science.

The 2010 revision date seems a bit odd, it doesn’t seem to match reality. The 2020 deadline was already broadcast in the media at the beginning of 2009. I might be a innocuous memory recall issue though.

The quote also confirms the two predictions: first there was the 2003 model prediction resulting in the 2030 end date, which was later revised to 2020 by on-site observations. As seen in the previous example, Florentine claims that these observations were of actual glacier melt. This is contrary to what Daniel Fagre told Thinkprogress. According to Fagre, the temperature predictions of the IPCC were used as input in the model. He then observed that the local temperature rise was twice that of the IPCC projections and when he used the local temperature rise as input into their model, it gave 2020 as the new output.

I am not sure which version is true. I am tempted to believe Fagre though. He is the one who has first-hand information about the issue and, having read the 2003 paper, his explanation makes the most sense. According to the paper, Hall and Fagre indeed used the IPCC projection of (worldwide) temperature increase in their model, so it is plausible that they would recalculate their model after realizing that the local temperature increase was twice as high as the worldwide temperature increase used in their model.

It also doesn’t seem to match the reality that the actual melt went much slower than projected. Remember, according to the prediction the glaciers would be gone by the year 2020… If accelerated melt was really observed between 2003 and 2009, then this would mean that the melt slowed down considerably between 2009 and 2020 (after having accelerated between 2003 and 2009 in such a way that it became necessary to recalculate the projection and getting an end date of ten years earlier).

Fagre did a risky prediction based on the then available information and it didn’t pan out well for that prediction. If they really entered the more correct data (that came available in 2009) into the model yet the resulting end date was worse than when the model was fed the original data (which was outdated or incorrect), then, in my humble opinion, there is something seriously wrong with that model. It doesn’t even matter whether that new data was the local temperature data (replacing the IPCC data) or an accelerated melt between 2003 and 2009 or both.

Just as in the first justification, Florentine mentioned some uncertainties that were not known at the time and that help explaining the failed 2020 prediction. So, would you say, if new insights becomes available, shouldn’t it be the most logical thing to change the signs according to the current knowledge?

That is certainly true. Personally, I have no problem with correcting signs using factual information when new understanding of how glacier melt works emerges. I don’t think that is the case here. As I explained in previous post, the “gone by the year 2020” prediction was replaced by:

When they will completely disappear, however, depends on how and when we act.

There is nothing wrong with “new understanding of the intricacies of glacier retreat” that “can help clarify why the remaining glaciers are more persistent than once thought” just being “just one of many examples where interpretive signs in the national parks are updated to reflect emerging science”. However, that is not what happened. The outdated prediction was not replaced by “new intricacies of glacier retreat” that “can help clarify why the remaining glaciers are more persistent than once thought”. None of the reasons the glaciologist gave to justify the outdated prediction got it to that sign and now the public gets the perception that human action is the one variable that determines the end date of the glaciers in Glacier National Park…

Go to Part 1 | Part 2 | Part 3 | part 4 | part 5 | part 6 | part 7

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