The iconic column of water gushes down the cliffside every spring and dries up each fall. One of these years, it won't come back.
We hear the distant, pouring-sand drone of Upper Yosemite Falls long before it is visible. My family has hiked more than a thousand feet uphill under a baking sun, in air more dead than disco, with cumulous clouds of dust rising from our footsteps to crunch in our teeth. At an overlook, we stop for a drink and a snack.
Before us, Yosemite Valley's half-mile-high granite walls frame a richly green forest that, from this height, more closely resembles a supermarket display of broccoli crowns than tall trees. We stand behind a steel railing installed to protect the multitudes of novice hikers from the seemingly obvious hazard of walking off a cliff. The ever-present traffic centipede inches forward far below.
Despite having cruelly wakened my family at seven o'clock this morning, it is noon by the time we drive to The Valley, negotiate the traffic, park in a dusty lot the size of the Caspian Sea, and ride a shuttle bus to the Upper Yosemite Falls Trailhead. We have begun this huge uphill climb during the day's hottest hours.
Now, watching my nine-year-old son, Nate, and seven-year-old daughter, Alex, wilt at this overlook barely more than a third of the way to Upper Yosemite Falls, I'm wondering whether we'll make the top.
I've learned that hiking with kids is a bit like trying to predict the wind; things can seem to be in your favor, or not, and then abruptly reverse direction. I watch them for subtle hints of fatigue or hunger, such as a lagging pace. They lack an adult's self-awareness. They drink when I urge them, but not always enough. They'll complain one moment that hiking embodies the most inhumane form of "torture," and "this is the worst day of my life!" The next, they'll dash ahead, suddenly excited. They are imprecise barometers of their own physical condition.
So I read them like an ancient mariner searching the night sky, trying to anticipate their needs before trouble arises. Parenthood is complicated like that.
Also with us is my 12-year-old nephew, Marco, who shows no signs of tiring but is visibly nervous about the exposure and keeps his distance from the railing; and my mom, Joanne, an active seventy-three-year-old who has hiked in many places with me, among them the Tetons, the Grand Canyon, and the Presidential Range. She has returned to Yosemite Valley to repeat hikes she and I shared fifteen summers ago this month. But even my unflappable mother has already told me, "This feels a lot tougher than it did fifteen years ago." Now she rises slowly to her feet and starts upward.
The trail turns a corner, where a breeze stirs the air. Then Upper Yosemite Falls comes into view, a column of water falling through more than a quarter mile of air.
I ask Marco, Nate, and Alex, "What do you think of that?" But they only stare, saying nothing.
It's easy to be hypnotized by the complex liquid topography of Upper Yosemite Falls. At its apex, a thick, brilliantly white pillar drops perhaps a hundred feet and crashes onto a big ledge, sending a horizontal geyser ricocheting straight outward. This eruption breaks up into a broad curtain raining watery tracer bullets that arc downward. Strong gusts occasionally blow the curtain to the left, a pendulum swing in defiance of gravity. The waterfall blossoms in its earthward plunge, spreading ever wider, the curtain shredding like tissue paper.
Below the falls, the creek drops another 675 feet through the middle cascades, mostly hidden in a gorge. It then pours over 320-foot-tall Lower Yosemite Falls, which is visited by exponentially more people than the upper falls because it's just a short, flat walk from the road. Yosemite Falls drops a total of 2,425 feet, making it the sixth-highest in the world. The upper falls alone ranks among the world's twenty tallest.
While Nate and Marco scurry ahead, Alex continues gazing silently at the waterfall, her brow knitted in thought. Finally, she asks me, "How does the water go up the mountain?"
What a great question.
To the eyes of a seven-year-old, Upper Yosemite Falls appears to materialize inexplicably from the top of this 1,400-foot cliff. So I explain to Alex that up there, beyond sight, a lot of melting snow fills that creek with water. But I don't try to explain, yet, that Yosemite Creek, like many High Sierra streams, is ephemeral--this creek and waterfall dry up by July or August every summer. A rare heavy rain in autumn may temporarily resuscitate the creek. It alternately trickles and freezes through winter. But as spring liquefies the prodigious high-country snowpack, a rejuvenated Yosemite Creek bulks up again, building to a crescendo in May and June.
Nor can I figure out, at the moment, how to describe for her one certain outcome of a warming climate: less snow in Yosemite's future. Snowfall has declined measurably for decades in virtually all parts of the world that receive it. In the Sierra, as across the Mountain West, snow melts out and streams reach peak runoff two to four weeks earlier than a half century ago. The upshot is that this waterfall and every other one in Yosemite will reach peak runoff weeks or months earlier in the year by the time Alex is grown up. The profound effects of this seasonal shift in water flows will reverberate throughout ecosystems across the western United States, the region that's home to many of our big wilderness parks.
Seeing and hearing the upper falls, it's hard to believe it dries up every summer. I remember a late-summer day years ago, when I looked toward Yosemite Falls and it wasn't there. For an instant, I assumed I must have been looking in the wrong spot, but I wasn't. It threw my sense of place off balance because Yosemite Falls is the marker that defines that corner of The Valley. Its absence feels as conspicuous as the Manhattan skyline's gap after 9/11.
Someday, many of us may find ourselves struggling with my seven-year-old's question about how water will get up that mountain.
On the entire planet, probably nowhere else receives as much snow as the mountains that stand like a bulwark along America's West Coast. In California's Sierra, it is not uncommon for a storm to dump six feet or more of snow. The winter of 2010-11 hammered the Sierra and the Cascades, with more than fifty feet of snow at Lake Tahoe's ski resorts and more than seventy-one feet at Mount Baker's ski area.
But viewed from a longer perspective, in the words of Yosemite National Park hydrologist Jim Roche: "Snow is ... an endangered resource." Climate models offer different prognoses for the future of snow, depending largely on what steps society takes in coming years to reduce carbon dioxide emissions. Unfortunately, humanity has steadily emitted more CO2 than even the worst-case scenarios in forecasts from the Intergovernmental Panel on Climate Change (IPCC), the Nobel Peace Prize-winning United Nations body of more than two thousand scientists researching climate change. Predicting outcomes for species gets difficult because of the myriad complex interactions of plants and animals, habitat and topography. But the behavior of water is extremely reliable: it freezes at 32 degrees Fahrenheit, or 0 degrees Celsius, and melts above it. Always has, always will.
Cascades snowpack has already declined by 15 to 30 percent over the past seventy years. Virtually all glaciers in the North Cascades, locus of the most extensive glacier research in the world, are in retreat, according to scientists with the North Cascades Glacier Climate Project and North Cascades National Park. That ice currently holds as much water as all of Washington's lakes, rivers, and reservoirs combined. It provides a buffer against droughts and, in a region that is famously rainy but has dry summers, supplies one-fourth of the summer water supply, according to the North Cascades Glacier Climate Project.
Philip Mote, now director of the Oregon Climate Change Research Institute at Oregon State University, predicted back in 1995 that it is "likely that the losses in snowpack observed to date will continue and even accelerate," especially in already mild, middle-elevation ranges like the northern Sierra and Cascades. Mote added that this decline, "already well under way, will have profound consequences for water use in a region already contending with the clash between rising demands and increasing allocations of water for endangered fish and wildlife."
Fifty-three North Cascades glaciers disappeared between 1971 and 2006. Glaciated area has shrunk 40 percent since 1850, and 13 percent just since 1971. By the time Alex and Nate are my age, researchers expect 70 percent of the glaciers, which have existed for perhaps sixteen thousand years, to be gone.
Adapted from Michael Lanza's Before They're Gone: A Family's Year-Long Quest to Explore America's Most Endangered National Parks (Beacon Press, 2012).