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October 20, 2008
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Yosemite glacier on thin ice
Sacramento
By Tom Knudson, staff writer
ON THE LYELL GLACIER – As melting water gushed off the ice in a tinseled maze of rivulets and tumbled through a gaping chasm, the hikers watched, wondered and worried.
Unlike most backcountry travelers who pitch their tents along the John Muir Trail in the upper reaches of the Lyell Fork of the Tuolumne River, these visitors had not pushed on to scale the summit of Mount Lyell – Yosemite's highest peak.
Instead, they scrambled up a ridge of rose-tinted granite and over a mound of dark, unstable boulders to tromp across this less well-known corner of the national park, a silvery-white sheet of ice fast becoming one of the first
Later in the day, Pete Devine, a veteran glacier observer who manages educational programs for the nonprofit Yosemite Association, sat on a log and opened a notebook. "Gaunt remnant of what I saw 10, 20 years ago," he wrote in his journal. "Lots of large boulders dot the surface. Lots of melt water flow."
As signals of climate change begin to come into focus in the
More of the Sierra's precipitation is falling as rain instead of snow, studies show, and the snow that blankets the range in winter is running off earlier in the spring. And snow in the Sierra touches everything. Take it away and droughts deepen, ski areas go bust and fire seasons rage longer.
Some glaciers already have melted away, including the first Sierra glacier discovered in
"All across the Sierra, glaciers are transitioning into ice patches. Ice patches are transitioning to snow fields. And snow fields are transitioning into bedrock," said Greg Stock, a geologist with Yosemite National Park who joined Devine last month on an annual survey of the Lyell glacier.
While this is not the first time glaciers have receded across the
"We have entered new terrain with what's going on in the atmosphere," he said. "We haven't seen anything like this in tens of millions of years."
Witnesses to a warming planet
Stock and Devine were accompanied by four tourists who came to see the signature of climate change firsthand, to pay their respects to a Sierra sentinel before it slips away. The trip, organized through the Yosemite Association, cost $360 – and the melting glacier put on quite a show.
Amid the whoosh of rushing water and the wind's freight train roar, they looked up at boulders riding on the surface of the ice that not long ago were entombed in the glacier.
They trudged past sofa-sized slabs of granite perched atop thawing pedestals of ice and peered awestruck into the icy abyss and yawning death-trap of a moulin – a water-carved hole in the ice – and scrambled across a widening moat of super-sized stones along the glacier's receding lower edge.
"You don't have to be Al Gore to realize something is changing and we need to do something," said Jerel Steckling, a safety officer at the Hilmar Cheese Co. near
The four tourists were not the only ones to make the pilgrimage. A few days later, 81-year-old Hal Klieforth inched himself up a pale pink ridge below the glacier on a return visit to an ice sheet he last set foot on 58 years ago.
At one spot, he slipped and his walking stick – an old metal broom handle – went flying. A bit later, he lowered himself onto his hands and knees and willed himself up a ladder-steep wall of bedrock.
On Aug. 20, 1950, Klieforth had crossed the glacier on a youthful scramble to the summit of
As he crested a towering wall of rocks at the foot of the glacier and gazed across it, a boyish smile spread across his face. "Oh my goodness, this takes me back," he said.
His joy was tempered by reality, for the ice sheet was a shrunken remnant of the one he knew six decades ago. Gone was the massive, furrowed brow of ice and snow that curved around a ridge of rock, linking the glacier into a mile-wide seamless wall of white. Gone were the scalloped waves of thigh-deep snow that covered much of the glacier in 1950 and made hiking difficult.
Now, the research meteorologist from Bishop looked out across a mostly naked sheet of melting ice.
"It's an historic change," he said, "one of many things that tells us climate change is real and not to be denied."
Glacial history complex
Small in comparison to other ice sheets,
But today's glaciers – including Lyell – are not vestiges of the monoliths that scoured and polished the Sierra so long ago. They were born during a more recent cooling episode known as the Little Ice Age, which began around 1350. "It was a well-documented event," Stock said. "The Vikings were literally run off of
Then, around 1850, the Little Ice Age ended. "That is the year most historians point to as the start of the Industrial Revolution," Stock said. "That signifies the start of the mass consumption of fossil fuels."
Critics of global warming say glaciers have been retreating for more than a century and climate change is caused by natural forces, such as increased sun spot activity. But Stock cites scientific studies that point to a new culprit: rising carbon dioxide levels.
Answers in the ancient ice
Much of that knowledge comes from drilling into Antarctic and
"As far back as we can see in time, we don't see anything like what's happening today," Stock said.
As he tromped around the west lobe of the Lyell glacier, Stock saw signs of warming everywhere. One of the most vivid examples, he pointed out, was the daunting perch at the west end of a "transect line" – a fixed route anchored by two stationary points on bedrock on each side of the glacier – that geologists walk each year to chart changes.
"In the 1930s, you could step right off the bedrock and onto the glacier," Stock said. " Now we have to step off a rock shelf, climb down a series of cliffs for 100 feet. It's not often you see that much change in nature."
On the smaller east lobe, scientists have stopped transect surveys altogether because the route has turned to rock. "The east lobe is just a little flake," said the Yosemite Association's Devine, 50, who has journeyed to the glacier most years since 1985.
In all, the west lobe has shrunk by about 35 percent since 1883 – and the east lobe 70 percent. Today, the rate of loss is so swift it is almost not even glacial.
"It could be a piece of dead ice now," Devine said. "Glaciers are defined by their ability to move" – to creep downhill under their own weight. "It might not have enough mass to keep moving."
Alive or not, time is running out: The east lobe likely will be gone by 2050, scientists say.
In his daypack, Devine carried historic photos of the Lyell glacier, including one taken just four years ago. Even in that short span, the ice sheet has changed. No longer is its icy surface so marshmallow white. Today, parts of it are speckled with rocks. Boulders the size of cars, kayaks and kitchen tables litter the surface of the west lobe – and most are melting out of the shrinking ice sheet, not tumbling down from the cliffs above.
There was so much rock, Devine dredged up a bit of humor. "What's the Lyell glacier's favorite movie?" he asked the tour group. Nobody had a clue.
"Rocky," he said. Some laughed. Others groaned. Still, Devine wasn't finished.
"What's the Lyell glacier's favorite ice cream?" he asked. Someone got that one: Rocky Road. "And what's its favorite band?" That one was easy: the Rolling Stones.
The melting is so swift that even U.S. Geological Survey maps no longer reflect reality.
"All this is gone," Devine said as he kneeled down to look at a 1985 topographical map that one member of the tour group –
The highly detailed Mount Lyell Quadrangle map showed the glacier in the right place – tucked into a gigantic spoon-shaped cirque on the north-facing side of the mountain. But the ice sheet was too large. "Just eyeballing this, a third of it" has vanished, Devine said.
"Maybe 40 percent," Peterson said.
The most dramatic spectacle was not on the map or in the historic photos, though. It was the sight and sound of the water gushing off the glacier. "I don't think I've ever seen that much meltwater before," Stock said.
Clear as vodka, it trickled and tumbled, spilled and splashed. At times, its sound seemed almost musical: steady and sonorous, with a cadence like a chant or a funeral dirge. And with temperatures barely below freezing at night, the music played 24-7 – not a good sign for a glacier.
All glaciers melt naturally. But to remain stable or grow, they must replace meltwater with snowfall. And that's not happening at Lyell or elsewhere. Today, scientists are finding that not only is more precipitation across the region arriving as rain, but less snow overall is falling. The current drought – now heading into a possible third year – could be catastrophic for
"With a healthy glacier, we expect to see the upper half covered in snow and the lower half bare ice," Stock said in base camp one morning. "Instead, virtually all of the glacier is bare ice. It's losing a lot more than it's gaining. It's definitely deteriorating."
That lack of snowfall worries many observers the most. "The most valuable resource in the
"The range is well-named – the
Carrying experience back
Few people are better acquainted with the Sierra snow-pack than Klieforth, the meteorologist from Bishop, who has spent much of his life studying the range's climate, vegetation and weather patterns.
As he sat on a rock, looking up at the receding glacier, his mind wandered back to prehistoric climatic changes that have swept across the Sierra, sometimes suddenly, including two massive droughts that lasted for generations.
"It does get you thinking about what is happening right now," he said. "You wonder if we are in one of those catastrophic times or not."
Willow-thin and wiry, the 81-year-old Klieforth had begun this journey at the Tuolumne Meadows trailhead 13 miles down the canyon with an old World War II Army surplus sleeping bag stuffed inside a plastic grocery bag. His pack included plastic dinnerware he has carried on camping trips for half a century.
This trip, he said, was both professional – he still keeps track of weather patterns – and a personal challenge.
And it was hardly the first. In 1981, he hiked around
Nothing thrills him more "than taking off from my house in Bishop and seeing how far I can go on foot," he said. A dawn-to-dark hike to the bristlecone pine groves of the
"I would hate to stop doing this," he said, as he slowly made his way toward the glacier, stopping frequently to rest. "My mind is energized by being outdoors."
On this journey to the Lyell glacier, Klieforth logged another 30 miles and spent a part of each day looking at grainy, black-and-white photographs he had taken of the glacier back in 1950 – pictures of a much bigger ice sheet than the one he was seeing today.
No global warming skeptic, Klieforth is nonetheless a cautious man, careful about jumping to conclusions. He was moved by his trip to the glacier, calling it a watershed event.
"Climate change is sneaking up on us," he said. "And the rate of the sneaking is going from a slow walk to a sprint."
He wanted to share the visit with some special friends: his old climbing buddies – now in their 80s – who had joined him on the original 1950 trip.
"I'm going to tell them that they can believe in global warming," Klieforth said. They can "take it to the bank." #
http://www.sacbee.com/101/story/1325423.html
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