It was a year into his life alone in Colorado’s Rocky Mountains when Billy Barr began his recordings. It started as a curiosity, a task to busy his mind during the winter. By no means, Barr told me, having skied down from his cabin to use the nearest phone, did he set out to make a vital database for climate change scientists. “Hell no!” he said. “I didn’t know anything about climate change at the time.”

In 1973 Barr had dropped out of college and made his home an abandoned mining shack at the base of Gothic Mountain, a 12,600-foot stone buttress. The cold winds blew through the shack’s wood slat walls as if they didn’t exist; he shared the bare dirt floor with a skunk and pine marten, his only regular company for much of the year. Barr had moved from the East Coast to the Rocky Mountains precisely because of the solitude, but he couldn’t escape boredom. Especially that first winter. So he measured snow levels, animal tracks, and in spring the first jubilant calls of birds returning. He filled a notebook with these observations; then another notebook. This has continued now for 44 years.

Barr’s data would likely have remained the tinkerings of an amateur scientist were he not so close to the Rocky Mountain Biological Laboratory (RMBL), one of the most important phenology research sites in the world. During the last couple decades, scientists at the RMBL have become fascinated with climate change’s impact on plants and animals in the high alpines, hoping to scale their discoveries into broader lessons about life in a warmer earth. But their research suffered from a dearth of long-term records. In Gothic, for example, the spring snow seemed to melt a little earlier. The flowers blossomed a little sooner. But without historical context, these little changes could not be understood for what they really were.

The site of the RMBL was once a silver boomtown in the 1880s, but within a decade it’d been abandoned for richer mines elsewhere. In 1928, a biology professor rediscovered the area and founded what is now a summer pilgrimage of scientists. Researchers at the lab sleep in cabins and university department presidents and lowly students share mess hall tables, working side-by-side on long-term conservation studies. One of the lab’s longest-running studies is a wildflower research project started by ecologist David Inouye.

The same year Barr would become Gothic’s only permanent resident, in 1973, Inouye measured some 30 plots to study wildflowers. By recording when and how long flowers bloomed Inouye and a handful of scientist hoped to draw correlations to the insects and birds that feed upon them. This research has since been used in many studies and is particularly important to understanding how climate change alters flower blooming times, the animals that depend on them, and thus the rest of Gothic Mountain’s ecology. And by extension, to high alpine environments everywhere. The idea for the study arose out of a casual conversation, and that is part of RMBL’s beauty. A similar beautiful fluke would lead Inouye to discover Barr’s 40 years of data.

Barr had intended to spend one summer in Gothic as a research student. In 1972 he was 21 years old, a shy, skinny guy studying environmental science at Rutgers University. The summer before he’d shoveled shit and hay at a dairy farm and he was ready for a change. The field of conservation was still small back then, so even though he had little experience, when he saw the RMBL was looking for help with a water chemistry project, Barr applied.

One of the first newspaper interviews Barr gave—long after he’d become known in the nearby town as the eccentric mountain man—romanticized his escape to Gothic, painting him as Thoreauvian. “He climbed to a nearby mountain peak the day he made that decision and sat in the waning daylight… ” The reality is that he couldn’t hack the regular world.  “I was just getting more and more depressed,” Barr, now 66 years old, told me. “A lot of me moving out there the first few years was just me stabilizing; getting to be around quiet.”

Gothic is about 10 miles from the nearest town. In the winter the road is closed and it's unreachable except by backcountry skis on a trail that cuts through dangerous avalanche territory. His first winter, Barr lived in a tent as long as he could bear. When snow piled up he moved into the abandoned 8-by-10-foot mining shack. It had a wood-burning stove and a bed, but its true value lay in its messy chain of title.

The RMBL seemed to think the cabin belonged to the U.S. Forest Service. And the Forest Service thought it belonged to the RMBL. A local man also claimed to own it, so amid this triangle of confusion Barr found a home. Barr seemed to spend all day that first winter chopping wood. He’d wake before sunrise, eat, ski into the woods, cut down a dead tree, eat, haul it back, then split the logs for a fire. In the hope that it would keep him busy at night, and thinking that it might come in handy next winter, he began to track the snow levels and the wildlife on his treks into the woods. “Under kerosene light you can’t do much,” Barr told me. “And after a few years I had something to compare each winter with.”

The mining shack Billy Barr first lived in / Billy Barr

In the summer he took odd jobs, working on a hotshot crew fighting wildfires, and later washing dishes in the RMBL’s kitchen. Each year, the RMBL seemed to operate on a prayer. No one tracked the bills, and the distracted scientists came and left without much thought for the lab’s upkeep. In the late 1970s Barr became the unofficial caretaker, shutting off the water so the pipes wouldn’t freeze, keeping an eye on the research equipment. In return the lab let him borrow its car parked at the bottom of the mountain so he could drive into town for supplies. Barr always considered himself a numbers guy, and as a kid growing up in Trenton, New Jersey, he kept detailed baseball stats on his favorite players. When the RMBL’s then-director found out, he suggested Barr take an accounting class through the mail. In the early 1980s Barr became the lab’s accountant.

Around this same time Barr built his own home a half mile from the lab. He added solar panels and a greenhouse for vegetables, and a theater room with a projector to watch his favorite Bollywood films. With age he grew more relaxed around people. One year he skied into town to see a play at the local theater, and when he arrived he was the only person in the audience. The play’s director wanted to call it off. But when everyone realized it was Barr seated there—his long beard and string-bean body—they put on the play anyway. As the RMBL’s accountant, Barr became the first person researchers saw as they checked in—as well the primary source of chocolate candy—and in that way he became the lab’s face. All the while he kept his records.

Each stenographer’s notebook lasted for three years of data, and Barr developed his own code. In the morning and night he logged snow levels, weather, and temperatures. For wildlife he invented his own number system, and in red he circled first sightings: the mammals emerging from hibernation, or the first calls for spring from the robins, the flickers, and especially important to Inouye would be the broad-tailed hummingbird.

Having lived in the area nearly three decades, Barr had become good friends with many of the scientists, and because Inouye had visited RMBL as long as Barr had lived there, the two talked often in the summer. Even so, it wasn’t until the late 1990s that Inouye learned of Barr’s priceless trove of data.

Morgan Heim / Day’s Edge Production

It happened during a conversation no one clearly recalls. By the end of it, Barr agreed to send Inouye some of his research.

“I realized right away what a valuable treasure it was,” Inouye told me of the moment he saw Barr’s work. “I knew what type of thing could be done with access to historical records.”

Barr’s notes have now appeared in dozens of research papers focused on climate change science. His notebooks on the first and last snow, the snowpack levels in between, and when hibernating animals wake and when the birds return to the the high alpine environment have provided an unexpected glimpse back into a world scientists never recorded. And from the past, scientists have gained a little more understanding of the the world’s warming future.

Hydrologists like Rosemary Carroll, who works at the Desert Research Institute, use Barr’s snowpack data and other sources to model groundwater flows to the Colorado River. Forty million people rely on the river to pipe water to their faucets, and Carroll’s work—with the help of Barr’s data—will help shape water policy for Southwestern cities.

Inouye has included Barr’s records in several studies, and collectively his work has become some of the most significant indication that climate change is rearranging mountain ecosystems more dramatically and quickly than anyone imagined. In his work with wildflowers Inouye understood that first flowering came about a month earlier now than when he’d begun the project 40 years ago.

He also understood that the male broad-tailed hummingbird’s wings make a whistling sound, and indeed Barr had tracked the bird's return each spring. Together with Barr’s weather and snow melt, Inouye was able to show how climate change’s impact on a single flower might mean the end of broad-tailed hummingbird migration in the region.

The hummingbird relies on nectar from the glacier lily—so much so that it synced its migration to arrive in Gothic just before it blooms. To adjust to warmer springs, however, the lily now flowers 17 days earlier than it did four decades ago. In two more decades it’s likely the broad-tailed hummingbird will completely miss the glacier lily’s nectar. This widening seasonal imbalance is called phenological mismatch, and has become a major concern as scientists learn more about climate change. In Gothic, this will impact not just broad-tailed hummingbirds, but also butterflies, bees, hibernating mammals, and the animals that depend on all those animals. These same dynamics will play out across the Rocky Mountains, and similar alpine ecosystems across the world.

Barr still wakes each day in his cabin before dawn to log the snow levels. He buys his wood now, which has freed up some time, and he has started the dreary process of converting his notebooks into spreadsheets. Sometimes Barr is credited as a contributor on reports that use his data; sometimes not. This year, however, he’s won some much deserved recognition. He is a character in a not-yet-released documentary called End of Snow; and this summer the RMBL named a building after him: The Billy Barr Community Center.

“Some day I’ll die,” Barr said, and people will ask: “Who the hell is it named after—this Billy Barr?”