From their vantage point high above the glacier, it was readily apparent that the ice sheet was waning, even in its death throes.

While standing upon that peak overlooking the terrain above the rim wall, we got the thrill of thrills, for there lay the glacier, shriveled and shrunken from its former size, almost senile, with its back against the mountain walls to the east of it, putting up its last fight for life. It was still what seemed to be a lusty giant, but it was dying, dying, dying, every score of years as it receded, it was spewing at its mouth the accumulations buried within its bosom for centuries.

Albert Sperry, the nephew of Lyman Beecher Sperry, jotted down those thoughts after their first visit, in 1894, to the river of ice that took his uncle's surname. Of course, more than a century later Sperry Glacier is still alive, its glacial melt spilling in long, wispy tendrils into Avalanche Lake in Glacier National Park. But whereas the size of Sperry in 1901 has been estimated by the U.S. Geological Survey at 3,237,485 square meters, today the mass has been shrunken to about 874,229 square meters; more than two-thirds of that behemoth that Albert Sperry described as "dying, dying, dying" having been lost to a warmer climate.

Against that history, and against recent years' predictions that Glacier would be glacier-less by 2030, last week's news that two of the park's glaciers, Shepard and Miche Wabun, had had their "glacier" status removed by the USGS because estimates of their masses had dwindled below 25 acres, was not earthshaking. It was eye-catching, though, as perhaps no other national park is so strongly connected with a single aspect of its contents as Glacier is with its glaciers.

"You know, it’s funny," Jack Potter, Glacier's chief of science and resources management, said in the wake of the flood of news reports about the two delisted glaciers, "just yesterday I had somebody call up and say, ‘What are you going to do about my melting glaciers?’ Well, the answer is nothing. There’s nothing that we can do about that.

"...It's not so big a deal," he said a few minutes later. "It's going to happen, so you might as well get ready for it."

Placed side-by-side, Albert Sperry's notes and the latest USGS findings deliver the same message, that Glacier's glaciers are in retreat. Though not as dramatic in description, the USGS news was more expansive, for in its finding that Shepard and Miche Uban no longer should qualify as glaciers, the agency also found that of the 37 named glaciers in the park, only 25 remain large enough to still be considered glaciers. Of the 12 that have melted away, 11 have done so since 1966, according to the USGS.

Things appear even more daunting when you consider that "it has been estimated that there were approximately 150 glaciers present in 1850, and most glaciers were still present in 1910 when the park was established," the latest USGS analysis points out.

* * * * *

Glacier National Park is suffering from heat stroke, a malady that could melt all of its rivers of ice not by 2030, but by 2020. Such a prospect would send shudders not only across the park's landscape and through its plant and wildlife resources, but also deliver a jolt to Montana's economy. That message was rekindled last week by the Rocky Mountain Climate Organization, which released a 35-page report that, while not breaking new ground when you consider all the clamor that's been raised in recent years over a changing climate and its impact across the National Park System, does cohesively present both on-the-ground impacts and projected threats that will sweep across the 1-million-acre park and the resulting fallout, both biologically and economically.

Glacier National Park in Peril: The Threats of Climate Disruption is the first comprehensive assessment of climate change on not just Glacier, but on any national park, says Stephen Saunders, a former deputy assistant Interior secretary over the National Park Service and U.S. Fish and Wildlife Service who now heads the climate organization.

“We hope to raise awareness, in Montana in particular, but across the country as well, that climate change is not just something happening to the polar ice caps and something that is distant from people’s everyday lives," Mr. Saunders replied when asked about the report's purpose. “It is affecting and threatens to really affect places that are really special to the American people, so we wanted to lay out that information. We hope that it helps to build public support for taking decisive actions that need to be taken to protect Glacier and other special places.”

Data assembled in the report examine various impacts climate change is exacting on the park:

* Within the last decade alone the increase in temperatures at the park huddled along the Montana-Canada border has been twice that experienced anywhere else on Earth. "...at the one weather station in the park with relatively long-term records, a West Glacier station at park headquarters, the average temperature for the decade just completed (2000-2009) was 2.0 F degrees hotter than the station's 1950-1979 average," the report states. "That is exactly double the average global temperature increase of 1.0 F degrees in the past decade..."

* A loss of wildlife in Glacier could result from human-caused climate change. This could disrupt the unique mix of natural wildlife the park now supports, which offers Americans the best chance they have in the lower 48 states to see the full range of mammal predators present at the time of European settlement of the continent, including grizzly and black bears, wolves, lynx, wolverines, mountain lions, and more, as well as other large mammals including mountain goats, bighorn sheep, and elk. The park's staff is concerned that climate change could lead to "wholesale changes in species composition."

* According to a recent study updated by RMCO for the report, western Montana in 2000-2008 experienced "eight days more per year of 90-degree Fahrenheit or higher and eight fewer days a year of 0-degree Fahrenheit or lower, compared to 1900 through 1979."

* Seven years ago, "scientists projected that even modestly hotter summers could eliminate by 2030 all glaciers in one basin in the park. Since this study was published, the glaciers in the basin have melted faster than projected. Now, one of the study's authors believes they might be gone in just 10 years."

* "A hotter climate is also expected to reduce snowfall and snowpack accumulation in the park. One recent study projects that near the end of this century, peak snowpack levels in the park may be reached 41 days earlier than in mid-20th century, and that snow could cover the ground for about 70 fewer days a winter. With mountains not snow-capped as much or as long into the summer, the scenery that draws most visitors to Glacier would be affected."

If these projections play out, the ramifications to Glacier National Park will go beyond the disappearance of the park's glaciers. There likely will be potentially severe hydrological shifts, vegetative transformations, and even species upheavals.

“The whole thing about hydrology is a huge issue," said Chief Potter. "When you talk about precipitation, not runoff, the models don’t clearly say you’re going to get more or less precipitation, but what you can always say is there’s going to be less snow, your hydrology is going to be altered, and you’re going to get a lot more transpiration and evaporation, so things are going to dry out. And of course, if you green up months earlier, fires seasons could be starting in June.”

Not only could the fire season be moved up earlier in the season, but without the slow release of snowmelt that glaciers now produce, vegetation in the park could change, fisheries could be disrupted, forests in some areas could be replaced by grasslands, while meadows elsewhere could see incursions of forest, the RMCO report says. Torrential rainstorms, such as the one that flooded the park in November 2006, could become more frequent and devastating. That November 2006 storm, which arrived at Glacier after raking both Olympic and Mount Rainier national parks in Washington state, dumped 6 inches of rain on Glacier in 24 hours, the report notes.

"The flooding washed away all or parts of the Going-to-the-Sun highway at several points, necessitated $7 million in emergency repairs, and delayed the opening of the highway the following year until July," noted the report's authors. "The 28-mile Inside North Fork Road on the park's west side was also closed from the flooding and did not fully reopen until July 2009, a full two-and-a-half years later."

Economically, the predicted warming could deal a devastating blow to nearby communities, according to Glacier National Park in Peril. Currently, 63 percent of the park's visitors come primarily to see the snow-capped landscape, the report notes, adding that Glacier's drawing power could be fueling as much as $1 billion worth of Montana's tourism economy, a prize that could melt away along with the glaciers.

* * * * *

Despite its icy landscape, Glacier is warming faster than many other areas because of its location, said Mr. Saunders. Research has shown that the interior West has heated up more than most of North America, he said, and there are some studies that claim that higher elevations are warming faster than lower elevations.

While there are those who maintain that the outcome of climate change over the next five decades is settled, that nothing that is done now will alter those impacts, Mr. Saunders is not one. He believes the impacts can be muted by slowing climate change.

"We are going to have further warming, for sure," he said. "How much depends on how much we continue to do. One of the things we do in this report is try to present that information. We lay out where the information exists, what are lower emission scenarios and what are higher emission scenarios, and which way we go will really tell the tale. Which way we go in the sense, do we continue to pollute at the rate we’re going, or do we begin to reduce emissions?"

While recent polling points to a decline in the number of Americans who believe society is accelerating climate change, and while Congress and the Obama administration of late have been consumed with steadying the country's shaky financial system and grappling over health care, Mr. Saunders is optimistic that, in the long-run, the country will tackle anthropogenic climate change.

"I think the scientific evidence is mounting so quickly, and in particular the evidence of changes occurring on the ground that people can witness will change attitudes," he said. "And once we change attitudes, the good news is the things we can do are mostly things that save us money. Not all of them, but most of them, a lot of them. And it is not going to be a wrenching economic transformation to protect the climate. In fact, we will have a huge wrenching transformation if we don’t protect the climate.

"So in the long term I am very optimistic that we are going to get what we should be doing to protect the climate and ourselves," said Mr. Saunders. "In the short-term I am certainly frustrated. I’m frustrated that we have not done more yet, but I am very optimistic that we will soon do so.”