This post is a follow-up on a previous post in this series, more specifically the post of Wikipedia rewriting history by suggesting that the 2030 prediction was a “later estimate”, following the 2020 prediction. Contrary to the reality that the 2020 estimate was an update of the 2030 estimate and the 2030 estimate was in fact rehashed after the 2020 claim was abandoned (probably because it became clear that the 2020 estimate would fail).
My take was that the Wikipedia contributor found that the 2030 estimate was made in an later snapshot of a National Park Service webpage and didn’t look at the estimates in the snapshots before 2010, therefor went from the assumption that the 2030 prediction was a later estimate. I think that this still holds, but that there is more to it than that.
There was another thing that drew my attention when writing that post. Beside the switch from “2020” to “2030”, another statement was added:
Based on the warming rates of the early 2000s, the park’s remaining glaciers will be gone by 2020
That “based on the warming rates of the early 2000s” was absent in the source. I then wondered where these changes could come from and the search for this inconsistency finally culminated into writing this post. I changed the title of the post that preceded this one, to reflect that this post is an update of it.
The first edit (from “2020” to “2030” without it reflecting the source) was made by Wikipedia contributor “MONGO”. Looking for this handle, I soon found the 2019 archive of the talk page of this user. There is an interesting discussion on that page under the heading “Undesired Revert”. It contains, among others, this statement:
I don’t think the issue of a change from 2020 to 2030 is reflected in reliable sources. I have even seen sources that say 2050.–MONGO (talk) 20:14, 27 September 2019 (UTC)
I recognized the two years and wondered whether this was about the same thing (when glaciers in Glacier National Park would be gone). It was about the glaciers in Glacier National Park all right, but about a similar statement on a different Wikipedia page. The dispute was that MONGO reverted an edit done by user “Valid Validity” and there was a link that pointed to an edit on August 20, 2019 at 15:17 of the List of glaciers in Glacier National Park (U.S.) Wikipedia page
This conversation confirmed that MONGO indeed had no source for the claim that the 2020 estimate was made in the 2000s, nor that the 2030 prediction was a later estimate.
This is the similar statement that is currently on the “List of glaciers in Glacier National Park” entry (my emphasis):
Though believed in the early 2000s that most of the glaciers in the park would disappear by the year 2020, more recent studies now give the year 2030 as a more likely date for this disappearance. A study done in 2003 on two glaciers indicated they would be completely gone by the year 2030, though some other glaciers may remain as small isolated ice bodies for a longer duration.
Besides the “in the early 2000s” statement, it also has the same suggestion that the most recent study gave the 2030 estimate. Link  goes to the “Melting Glaciers” page from the National Park Service (retrieved on June 27, 2019). This page links to the 2003 paper to justify the 2030 estimate. No link is given for the “early 2000s” claim to justify the 2020 estimate (which is no wonder considering the conversation on the talk page).
Looking into the edit history, this was the statement until August 16, 2014:
It is estimated that if current warming trends continue, there will be no glaciers left in the park by 2020.
Link  goes to “Glaciers / Glacial Features” page of the National Park Service (currently inactive). Information on this link shows that the contributor retrieved that page on February 12, 2010. The earliest snapshot that I could get with that date is the February 28, 2010 version. There was no snapshot from August 30, 2009 until February 28, 2010, so the version with the 2020 end date most probably came online somewhere between August 30 and February 12. This is what the archived version on the WayBackMachine (February 28, 2010) says about the end date:
If the current warming trend continues in Glacier National Park, there will be no glaciers left here in the year 2020.
Which is pretty close to what the Wikipedia page stated. Nevertheless, it was changed on August 16, 2014 at 20:09 (the blue color again indicates the change with previous version of the Wikipedia edit history):
It is estimated that if current warming trends continue, there will be no glaciers left in the park by 2030.
The end date suddenly changes from 2020 to 2030, yet the link stayed the same. It goes to the same 2010 snapshot of a glacial features webpage of the National Park Service webpage stating that the end date is 2020. That is exactly the same that we saw in that previous post: the source didn’t claim what the Wikipedia contributor wrote. This specific discrepancy was online for the next … five years. That is similar to the 4.5 years of nobody noticing the discrepancy with the linked source on the “Glacier National Park (US)” page.
The next edit by user Valid Validity was on August 20, 2019 at 14:40, reintroducing the 2020 end date and suggesting the wrong sequence:
It was predicted, under the expected conditions, that there would be no glaciers left by 2020, although this has been changed to 2030.
Link  now goes to the “Glaciers” page of the National Park Service, retrieved on that same day (August 20, 2019). Going to that page on the WayBackMachine on that exact date, gives me information on the Blackfoot and Jackson glacier between 1914 and 2009. It doesn’t say anything that the contributor claims. Not sure why this link is provided. Link  goes to the snapshot of the archived Glaciers / Glacial Features page at WebCite (archived 7 May 2011). This archive page indeed shows the 2020 end data, but not how it is related to the 2030 end date.
The next edit (August 20, 2019 at 15:17) goes a bit further, it gives the suggestion that the 2030 estimate is an update of the 2020 estimate (when it is in fact the reverse):
It was predicted under the warming conditions, that there would be no glaciers left by 2020, although it has been updated to 2030.
The statement was then removed altogether from August 20, 2019 at 22:44 and replaced by:
The glaciers in the park have been in a general state of retreat for at least 150 years 
However the statement disappeared, the two references stayed. This was the disappearance trick that was documented in the talk-page (see above).
The statement reappeared in a slightly different form on September 27, 2019 at 20:22 by user MONGO:
The glaciers in the park have been in a general state of retreat for at least 150 years. A study done in 2003 on two glaciers indicated they would be completely gone by the year 2030, though some other glaciers may remain as small isolated ice bodies for a longer duration..
Notice that now the 2020 estimate was again omitted.
Link  goes to “Glaciers – Glacier National Park”. National Park Service (retrieved August 20, 2019) and link  goes to “Melting Glaciers” (National Park Service. Retrieved June 27, 2019), which indeed mentions the 2003 paper and its 2030 estimate.
The last change was on September 27, 2019 at 22:38 again by contributor MONGO:
The glaciers in the park have been in a general state of retreat since at least the year 1850, which is oftentimes cited as the end of the Little Ice Age, when midlatitude glaciers reached their largest historical maximum. Though believed in the early 2000s that most of the glaciers in the park would disappear by the year 2020, more recent studies now give the year 2030 as a more likely date for this disappearance. A study done in 2003 on two glaciers indicated they would be completely gone by the year 2030, though some other glaciers may remain as small isolated ice bodies for a longer duration.
The 2020 estimate reappears, but the link doesn’t reappear with it.
Link  now goes to “Glaciers – Glacier National Park”. National Park Service. Retrieved 20 August 2019. Link  goes to “Retreat of Glaciers in Glacier National Park” (United States Geological Survey. Retrieved June 27, 2019). Link  goes to “Melting Glaciers” (National Park Service. Retrieved June 27, 2019), which indeed mentions the Hall & Fagre, 2003 paper with its 2030 estimate, but link  also mentions the Brown et al, 2010 paper with a estimate of … 2080. For some reason not mentioned by the Wikipedia contributor.
This last edit is when the “early 2000s” claim slipped in. Taken all the previous into account, I think it is now rather simple to understand where that claim comes from. The 2020 estimate was found on a webapage in 2010 and the 2030 estimate on the same webpage in 2011 and thereafter, therefor it was assumed that the 2030 estimate came after the 2020 estimate. That is the part that I figured out already. The “early 2000s” however gives it another dimension. Because the contributor knew that the 2030 claim was originally from 2003, the 2020 claim then, logically speaking, must come before 2003, which brings us to the vague “early 2000s”…
The contributors seemed to have no clue. They linked to sources that didn’t confirm their statements and were making assumptions while editing that statement over time. They were basically making things up as they went along.
But then, would you say, isn’t it possible that the estimate of 2020 was made somewhere in the 2000s, just before the 2030 estimate in 2003? Maybe, but it is unlikely to explain the sequence on the Glacier / Glacier Features web page that was used as the source for the evolution of both estimates over time.
Let’s assume for the sake of the argument that the 2020 estimate came before the 2030 date and that it was made somewhere in the 2000s. In that case, one has to explain why the 2020 estimate only popped up around 2010 on the National Park Service website when it allegedly originated from before 2003 and how that alleged pre-2003 prediction got on that website in a time frame when the 2003 prediction would be the most recent estimate? Also, why did this 2030 estimate from 2003 made a sudden reappearance after the 2020 estimate was abandoned around 2014?
The timeline tells us a different story. When one take a look at the history of that “glacier / glacier features” page of the National Park Service, then one would see that the 2030 estimate was used until the end of 2009/beginning 2010 and at the end of 2013/beginning 2014 it was used back again.
The misunderstanding came from the cherry picking of just a few snapshots of a webpage, neglecting what came before. The first snapshot was taken in 2010 (just after the switch from 2030 to 2020), the second in 2019 (in the preceding post an October 2014 snapshot was used, just shortly after the switch back to 2030). If they would have been looking also before that date, then they would have realized that the 2020 estimate was only used a few years, sandwiched between the 2030 estimate.
I tried to visualize this in an info graphic:
That also fits exactly what Daniel Fagre told the public via the media. He was very open to the media between 2009 and 2011, confirming that the 2020 estimate was the update of the 2030 estimate, not vice versa as Wikipedia wants us to believe. If it would be true that the 2020 estimate came before the 2030 estimate, then he wasn’t telling the truth to the media back then.
These are the reasons why I think that Wikipedia has it backwards and is rewriting history by claiming that the 2030 prediction was based on a more recent study than the 2020 prediction, without any justification for their claim.