Jon Riedel and I stand at a trailhead that leads to Washington's Mount Baker with nine high school students who have come to the Pacific Northwest for a month to learn about climate change. Jon, a geologist at North Cascades National Park, is here to talk about his glacier monitoring program, and I'm along for the ride. We readjust pack straps and scrounge for water bottles as clouds swirl and settle in tall trees. At last we make our introductions and head out.

If you want to stand on a glacier, there are plenty to choose from in the North Cascades. In fact, if I were to start walking from my front porch in tiny Stehekin, 100 miles to the southeast of us, I could stand on one before dark. Ditto for my friend Jon from his home in Marblemount, 40 miles to the east. It'd be a long walk for me -- five miles on a gravel road, seven by trail, gaining 7,000 feet, then the dicey part, up and over the ridge to stand on the Sandalee -- and a slightly longer one for Jon. He'd have to trudge 20 road miles to a trailhead. Once he got there, though, he could choose from several glaciers -- including Sahale, the one his oldest daughter is named after.

Still, whenever Jon and I tried to make a plan to visit a glacier together, our complicated middle-aged lives got in the way. This roundabout journey was the only way it could work. Yesterday I took a three-hour boat ride, then a four-hour drive, to Jon's house. For the chance to learn about climate change, I've left a carbon footprint the size of Yellowstone. Add up the flights the kids took -- plus the two group leaders, two documentary filmmakers and one journalist -- and that footprint might be the size of Connecticut. I wonder: Is it worth it? Today's plan was to hike to the Easton Glacier, but it's clear from the crummy weather and the inadequate gear the kids have (some are in tennis shoes) that the group will not make it. Jon stashes our ice axes and we set off, hiking through forest and meadow, hemlock and cedar, huckleberries and valerian. We can at least get within sight of our goal.

The first time I saw a glacier up close, I followed a trail out of a book. Encounters with the Archdruid, John McPhee's classic triptych featuring David Brower, devotes one section to a hike near Lyman Lake in Glacier Peak Wilderness. One weekend, I backpacked up a long river valley just to camp there. The lake was lovely, of course, but a short walk farther, through a lime green meadow, all heather and wildflowers and patches of snow, I came upon a second lake. Upper Lyman, a translucent jewel-like blue, nestled up against the jaggedy granite peaks, and right there at the inlet -- right there! -- sat a glacier: vertical slabs of ice, moving imperceptibly like the colliding continents of the past, protruding over the water, breaking off in loud ka-splashes, floating white on the blue.

That's when I started to fall hard in love with this place. My partner and I bought land and built a cabin, and from there the changes grew harder to pinpoint. For the next 15 years, I worked on trail crew and spent most August days clearing brush -- waist-high ferns, head-high nettles -- within view of a glacier, one or more, white against gray granite and blue sky, hanging out over green valleys, and dripping, always dripping. When did it become clear that they were shrinking? Right away. There was less ice farther up, less ice everywhere. Even though I knew about global warming, even though I tried to make conscious choices -- about what car I drove, say, or where my lettuce came from or who I voted for -- I still considered climate change just a concept, a vague threat, something that loomed like nuclear annihilation or a meteor striking the earth, only more thwart-able. It seemed so wrong to see it happen with my own bare ignorant eyes.

Jon took a more empirical tack. While I was hacking at brush and notching logs for bridges, he was measuring glaciers, four of them: Noisy, Silver, North Klawatti and Sandalee. The results were unsurprising: They're all shrinking. I'd have been happier to know my eyes were deceiving me.