The top of Mount Rainier is no longer the top of Mount Rainier.
The frozen ice cap on top of Washington’s iconic mountain — recognized for generations as the tippy top — is melting as the atmosphere warms. Now, that frozen dome has sunk below a rocky patch on the mountain’s southwest rim, crowning that spot as the new highest point.
Eric Gilbertson, a mountaineer and mechanical engineer, summited Rainier in August and September, taking measurements along the way to confirm the change. He’s collecting a series of data points across the Cascades, and the general conclusion is that Washington’s perpetually ice-capped mountains are shrinking.
Federal officials are now considering what to do with Gilbertson’s measurements, which would chop about 10 feet off the long-standing height of Rainier, taking the mountain from 14,410 feet above sea level down to 14,399.6 feet.
The phenomenon isn’t limited to Washington, which has more glaciers than any other state in the Lower 48. It’s happening in California and Sweden, among other places. A warming atmosphere, caused by an ongoing reliance on fossil fuels, is chipping away at snow and ice around the world.
Since 1984, which is when Mauri Pelto began collecting annual measurements, glaciers across Washington have lost on average perhaps 40% of their volume, he said.
“And obviously, we’ve watched a lot of them disappear,” said Pelto, who teaches at Nichols College in Massachusetts, returning to Washington for his work every year.
The bulk of that melting has come in the past 24 years, Pelto said, meaning the process has sped up.
“We’ll still have mountains; we’ll still have snow in the winter,” he said. “But without the glaciers, you’ve lost an important dynamic, and the mountains will be poorer for it.”
The mountaineer
You could say mountaineering is in Gilbertson’s blood at this point. The 38-year-old first learned the trade as he studied at the Massachusetts Institute of Technology and has since summited the highest points in each of the 50 states and in 143 of the world’s 196 countries. He summited K2 without oxygen and reached about 27,887 feet on Mount Everest without oxygen, short of the summit at 29,032 feet but still well within the so-called death zone.
Gilbertson now teaches at Seattle University. Two years ago, he decided to climb each of Washington’s highest 100 peaks again, a challenge he first completed back in 2018.
This time around, he began to notice a few discrepancies with which mountains actually qualified, so he started bringing his own equipment to measure them. Soon, he began measuring his position using a differential GPS system borrowed from the university. The device compares multiple fixed positions on the ground to satellite data to determine a person’s location or, in this case, elevation.
“That’s as accurate as it gets,” Gilbertson said. “Down to the nearest inch.”
This August, Gilbertson noticed Rainier wasn’t as high as advertised.
The traditional peak of the mountain is an ice cap called the Columbia Crest. Gilbertson said the crest was down 22 feet from the long-standing 14,410 feet above sea level. That change makes the new highest point a rocky spot on the southwest rim of the volcano.
Just to be sure, Gilbertson climbed Rainier again in September, stopping at multiple well-known points, called monuments, along the way. He compared his measurements with past data to make sure his summit elevation would be accurate. The numbers all matched, he said, and the elevation at the top mirrored his findings from the month before. It confirmed that Rainier isn’t as tall as it once was.
Gilbertson’s findings are sound, said Larry Signani, who headed the first survey of the mountain using GPS in 1988 for the Army Corps of Engineers and again several times in the subsequent decades.
The original elevation of 14,410 came from the first-ever survey of the mountain in 1956, Signani said. And while the following measurements varied slightly as the techniques changed throughout the years, the elevation remained pretty much unchanged.
But a survey in 2010 started to show that the Columbia Crest had sunk several feet, Signani said. The formation has clearly melted away even more in the years since, which Gilbertson’s findings confirm, he said.
If the warming climate is melting the top of Rainier, Gilbertson thought, then what about the other three perpetually ice-capped summits in Washington?
The next, Liberty Cap, wasn’t too far away. It’s just on the north slope of Rainier. So he swung by. What’s a few more hours? Turns out Liberty Cap is down too, Gilbertson said. It had melted about 26.3 feet since the last LIDAR measurement in 2007.
Gilbertson summited Colfax Peak next, off the western slope of Mount Baker. And while its elevation is holding steady, the saddle between Colfax and Baker has melted down 16 feet in the past two years, he said.
Finally came Eldorado Peak, just south of Diablo Lake. That one’s down 20 feet, Gilbertson said. Like Rainier, the ice cap is no longer the highest point on the mountain, and a rocky spot now marks the top at 8,873 feet above sea level.
The snowy caps and glaciers across Washington’s mountaintops fluctuate throughout the year as snow builds up in the winter and melts again in the summer. The best way to compare one year to another, Gilbertson said, is to take measurements during the lowest part of the year, which is why August and September are good months for such an analysis.
Melting around the world
Scientists are observing the same results, shrinking ice caps and receding glaciers, all across the world, Pelto said. Sweden’s tallest mountain, Kebnekaise, has shrunk nearly 9 feet since the 1940s.
Or take a look at Svalbard, a Norwegian archipelago, Pelto said. The area is warming several times faster than the rest of the planet, causing its glaciers to melt away more aggressively.
While glaciers on Everest are also melting faster than before, other geologic factors like tectonic shifting and ongoing erosion are actually helping that mountain gain elevation.
Closer to home, the glaciers on California’s Mount Shasta are diminishing as well, Pelto said.
And the phenomenon is speeding up, he said.
A collection of 45 glaciers around the globe provides insight into the trend, Pelto said. They’re called world-reference glaciers, and Pelto has studied three of them in the North Cascades over the past 40 years and half of their losses have come in the last decade.
Greenhouse gases emitted by people burning fossil fuels like gas, oil and coal are warming the atmosphere. Not only was this summer the warmest in the Earth’s 175-year record but we’ve also seen month after month heat records around the world. At our current rate, average surface warming on Earth could hit an increase of 1.5 degrees Celsius by 2040, surpassing what many scientists believe to be a critical climate threshold, beyond which point the danger for our way of life increases sharply.
That warming trend is sure to include further melting of the icy and snowy peaks across the world, Pelto said.
“There aren’t very many glaciers in the North Cascades that can survive the next 30 years,” Pelto said.
On the slopes of Rainier, the melting is something Justin Sackett has noticed over his five years as a guide.
Climbing season on the mountain generally runs from April to late September, Sackett said. But warming weather in recent years has brought those windows to an early close. The company for which Sackett works, International Mountain Guides, stopped its guided trips in August last year. And this year, as a preemptive measure, it stopped booking trips after the middle of September, he said.
Not only does the melting snow and ice create deep crevasses, too wide to cross, but it also increases the risk of rockfalls, Sackett said.
“It’s just too dangerous to climb,” he said.
The changes, season after season, are sad to see, Sackett said.
“But also, in a way, it kind of makes me appreciate it more,” he said, “knowing the mountain won’t be the way it is forever.”
As for the official elevation of Mount Rainier, the jury’s still out.
Scott Beason, geologist for Mount Rainier National Park, said he has received Gilbertson’s measurements and they’re under consideration. The next steps, whether they might include an entirely new survey of the mountain or adopting Gilbertson’s findings, remain unclear, he said.
Ten feet of elevation loss wouldn’t change Rainier’s ranking among the tallest mountains in the contiguous United States; it sits at No. 5, according to the U.S. Geological Survey. Across the rest of the world, hundreds more mountains lay claim to a higher elevation than Washington’s tallest.
As park officials consider the new measurements, Gilbertson said he’s hooked on surveying mountains and plans to keep at it. The work is a perfect intersection of science, mountaineering and engineering. He has a few more mountains to survey in Washington, and next summer he’s eyeing Greenland. Maybe Antarctica after that.
