Rebutting myths about climate change is an endless game of whack-a-mole. But one side-effect is that each dose of misinformation can prompt a look at the real science, and offer a reason to share credible, up-to-date information that might not have gotten much attention were it not for the myth.

After encountering several social media references that glaciers are growing in my home state of Montana, I dug in to find the origin of the myth, and check in with scientists for an update on the status of Glacier National Park’s namesake features.

This alluring falsehood appeared in a denialist blog earlier this summer (June 2019) and quickly spread to several others. The “government is quietly seeking to conceal some of its hysterical claims,” reads one claim. “It appears that the National Park Service is trying to hide the fact that the glaciers are growing!”

The myth states that Montana’s cold, snowy winters and “extreme amounts of snowfall” have not only halted the decades-long trend of glacier retreat, but in fact, have caused glaciers to expand. If true, that would be welcome news. Alas, it isn’t. The U.S. Geological Survey spells it out in plain language: “Despite occasional big winters or frigid weeks that occur, the glaciers of GNP, like most glaciers worldwide, are melting as long-term average temperatures increase.”

While Montana’s winters often are impressively cold, the state is warming at nearly twice the rate of the globe on average. Since 1895, NOAA data show the two counties that comprise Glacier National Park have warmed nearly 3 degrees F, a trend that is taking a heavy toll on the glaciers.

Caitlyn Florentine, a glaciologist with the U.S. Geological Survey’s Northern Rocky Mountain Science Center, is one of several scientists charged with keeping an eye on the park’s glaciers. She described the methods used to keep track of the glaciers, from analysis of aerial photography and satellite imagery, to boots-on-the-ice measurements of glacial ice volume. “It’s measurement-intensive,” she said in a video call from her West Glacier office.

Despite recent cold winters, warmer-than-average summer temperatures have been erasing all the wintertime gains, and then some. Florentine noted that she and other scientists, comparing measurements from benchmark glaciers in the Northern Rockies, Cascades, and Alaska, found all the glaciers to be losing mass, even though they are at different elevations, latitudes, and climate regimes. Florentine summarized the findings as an “overall, consistent trend of mass loss” which she described as “pretty striking, considering that the benchmark glaciers are in such different climate settings.”

Echoing USGS, the National Park Service is unequivocal on its website: “the park’s glaciers are all getting smaller,” explains the park’s webpage about glaciers. The page about climate change bears a stark headline: “This rapid rate of warming is melting the park’s glaciers, increasing the severity and likelihood of wildfires, and shifting wildlife habitat.” The caption on a graph of CO2 and temperature over the past 400,000 years leaves no doubt about the cause of warming: “In the past century, human activities have emitted a significant amount of CO2, which is causing the Earth to heat up – and glaciers to melt – at an alarming rate.”

The Park Service changed three signs to reflect updated scientific projections about glacier behavior.

One element of deliberate misinformation is that it often contains a grain of truth. That’s the case with this myth, too. This story appears to have been triggered when the Park Service changed three signs about projected dates when the glaciers might melt completely. These signs said that the glaciers could be gone by 2020. We now know that’s not the case. The signs have been updated to say, “When they will completely disappear, however, depends on how and when we act.”

Another sign that used to have the 2020 date now reads, “Some glaciers melt faster than others, but one thing is consistent: the glaciers in the park are shrinking.”

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.

Updated signs portrayed as evidence of government conspiracy.

Loathe to let actual science get in the way of a good story, some climate contrarians have played up the idea that the updated signs are evidence that the government had been withholding the truth from the public.

As the myth was repeated across multiple denier websites, the situation was described as the Park Service’s being “forced to admit” it had been wrong and “scrambling to remove the signs without their visitors noticing.”

“National park officials quietly remove climate change alarmist signs after cold winters sink narrative,” announced a headline on a website that describes itself as a source for “conservative ideas that are not available from traditional media outlets.” “They used all this to ramp up tourism and try to get more people in there before there wasn’t a glacier anymore!” wrote a right-wing talk show host.

Contrarians claim that the glaciers are growing – based on their observations at a roadside overlook.

The myth gets even more strange. A fake “university” claims to have sent a “delegation” of volunteers to check up on the glaciers and see for themselves.

The so-called university reported that in 2018 “it quickly became clear that the glaciers have grown substantially in recent years.” Various blog posts make claims of the expansion of the Grinnell and Jackson glaciers by 25 or 30 percent or more since 2009. The evidence presented is a single, blurry photograph snapped from an overlook along a popular park road, and a video that compares a cell phone photo to an image of Grinnell Glacier on a park recycling bin.

When asked if these assertions are true, Florentine was resolute: “No,” she said, shaking her head. “That’s why we turn to science.” Florentine described the work of the USGS as “systematic and reproducible,” a far cry from snapping a photo from the side of the road.

The site that made these claims turns out to be mostly that of a single person who writes a blog espousing libertarian themes, while crediting himself as “the only research institution challenging the government’s Glacier Park climate hysteria.”

The blog post goes on to chastise the media for ignoring its assertions: “No mainstream news outlet has done any meaningful reporting regarding the apparent stabilization and recovery of the glaciers in GNP over the past decade.”

Evidence of glacial retreat comes from decades of measurements.

Fortunately, the topic is getting due attention from legitimate scientists. Extensive measurements of Glacier’s glaciers were made in 1966, 1998, 2005, and 2015. Furthermore, Sperry Glacier is monitored in size and volume twice a year. The cumulative dataset spanning 50 years of glacier monitoring was released in 2017 and is freely available to the public. No need for imaginary secrecy.

As for reports that Grinnell and Jackson glaciers are growing, data clearly show that’s not the case. Both glaciers have gotten progressively smaller, and their overall footprints shrank by 8.4% and 5.8% respectively, in the 10-year period between 2005 and 2015. Were it true that Jackson glacier had grown by 30% since 2009, the glacier would be larger now than it was in the 1990s. If that were actually happening, it would be welcome news, and as the blog author hints, it would indeed be newsworthy. But – and this bears repeating – the claim is false.

Glaciers worldwide are shrinking.

While contrarians often use cherry-picked data to distract from the overall stark trends of ice loss around the world, it’s worth keeping in mind that glaciers are not dwindling just in Glacier National Park. Glaciers are receding rapidly all around the world: in the Himalayas, Greenland, the Alps, Africa, South America, and Antarctica.

Reflecting on the worldwide loss of glaciers, Florentine underscores “how critical this science is,” particularly when informing policymakers about responses to climate change. “It’s really important to have scientific information so we get the numbers right,” she said.