It has been described as “landmark” litigation, “groundbreaking” and “first-of-its-kind.” But behind one of the nation’s most watched climate lawsuits — aimed at demonstrating that Montana’s promotion of fossil fuels violates the state’s constitution — are 16 young people, driven by passionate dread over the places they cherish.

A namesake ecosystem. Miles of treasured hometown hiking trails. Pristine rivers, forests, mountains and national parks they’ve known since childhood.

“This is a case out of love,” said Grace Gibson-Snyder, a 19-year-old plaintiff from Missoula. She then paused, and added: “And a certain amount of fear, for sure. But the fear of loss comes from our love for these places.”

On Aug. 14, Judge Kathy Seeley of the Lewis and Clark County District Court in Helena, ruled in Held v. Montana that the current state law violates the youth plaintiffs’ right to a clean and healthful environment, a right spelled out explicitly in the state’s constitution.

In testimony and court exhibits, the plaintiffs — helped by an environmental legal nonprofit, Our Children’s Trust — argue that climate change will irrevocably alter the natural places that they love.

Part of Montana’s constitution guarantees a right to a “clean and healthful environment,” and the plaintiffs argued state lawmakers violated this right by barring agencies from considering the climate impacts of proposed energy projects.

The case, the first constitutional and first youth-led climate lawsuit to go to trial, could reshape the nation’s climate litigation — and, the plaintiffs say, spur action that would slow the destruction of the places most special to them.

Already, climate change is having a profound impact on Montana, including accelerating the retreat of the glaciers in Glacier National Park, fueling wildfires that have torn through the forests and worsening drought conditions that have left rivers running at historic lows. The land and culture of Indigenous communities are also threatened.

Below are some of the young people who have captured the nation’s attention, by taking the climate to the courts.

Olivia Vesovich, 20

Olivia Vesovich on her favorite hiking trail in Missoula, Mont., on July 11. Photo for The Washington Post by Tailyr Irvine.

From the top of Pattee Canyon, Olivia Vesovich can see her hometown, Missoula, a place she knows like the back of her hand.

She hikes the Barmeyer Trail multiple times a month, often at sunset. As she walks between the trees and the wildflowers that blanket the trail in the spring, she anticipates the view. At the lookout, the grassy plains, mountains and the place she calls home stretch in front of her underneath a pink and orange sky.

She has explored the trail systems in the state since she was a little kid, and while every year looks a bit different, she worries about the impact climate change is having on her favorite hiking spot in Missoula. The fire department has luckily kept wildfires from getting out of control, but she said there are more bark beetles, a tree-killing insect that scientists warn are growing in number and range with climate change.

“This lawsuit means everything to me,” she said. “I want nothing more than to protect my home for myself and for all Montanans who love the land.”

Sariel Sandoval, 20

Sariel Sandoval, who is Bitterroot Salish, Upper Pend d’Oreille, and Diné, is one of 16 young plaintiffs suing the state of Montana over its contributions to climate change. Photo for The Washington Post by Tailyr Irvine

As wildfires advance across the Flathead Indian Reservation, Sariel Sandoval can only watch and worry from hundreds of miles away.

The rising junior is making progress toward her degree at University of California at Berkeley. The fires in Montana, which have already consumed over 20,000 acres, are another reminder of how climate change is threatening the reservation where she grew up.

Sandoval, a member of the Confederated Salish and Kootenai tribes, said her community’s culture and connection to the land could be lost to climate change. For instance, the huckleberries her family picks every year and turns into jams, syrup and traditional foods are smaller and moving farther up the mountains with each passing year. And rising temperatures mean the winter snow she remembers trick-or-treating in sometimes doesn’t arrive until December, which prevents the sharing of traditional coyote stories.

“If there’s no snow on the ground, when do you tell these stories that explain who we are as Salish people?” she said.

Sandoval said it is heartbreaking not to be with her family and community during the fires. Her grandmother lives in Dixon, which is threatened by the blaze. But summer classes put her one step closer to finishing her degree as fast as she can and then soon, being home.

“As Native people, the land has helped sustain us since time immemorial,” she said. “When that is being threatened, it also threatens us.”

Kian Tanner, 18

Kian Tanner in a forested area near his home in Kalispell, Mont., on July 12. Photo for The Washington Post by Tailyr Irvine

A great day for Kian Tanner is one spent fishing. For him, there’s nothing quite like being half submerged in a cool river with the sun on his face while casting for trout.

Tanner said being out on the river is in his DNA, and he’s had a fly rod in his hands as long as he can remember. He’s even participated in two documentaries, including the conservation film “CO2ld Waters,” which was shot in Montana in 2014 and explored how climate change threatens angling.

Tanner once took fly-fishing for granted. But over the years, he’s had trips canceled due to wildfire smoke, and rising river temperatures and drought make it harder for fish to thrive. He’s most worried about the consequences for his future children and grandchildren.

“I want them to experience nature and fly-fishing to its truest form, and they won’t have that opportunity if we don’t fight climate change,” he said.

He hopes a victory in the lawsuit will inspire national change. More immediately, he wants the state to recognize his right to a clean and healthy environment and protect it. The plaintiffs, he said, have “facts and science and common decency, and not to mention the law” on their side.

“My fellow plaintiffs and I live in the state of Montana, while the state lives in the state of denial,” he said.

Grace Gibson-Snyder, 19

Grace Gibson-Snyder on a hiking trail in Missoula, Mont., on July 12. Photo for The Washington Post by Tailyr Irvine

Grace Gibson-Snyder isn’t sure whether her first memory of Yellowstone National Park is truly hers or the result of hearing her parents tell her the story again and again.

But here’s what she thinks she knows: At 3, she woke up in the back of a car, surrounded by a herd of bison on a bridge. Time slowed down as she looked at the large animals with wonder, awe and a bit of fear.

“Animals know nothing about email or college,” said the rising Yale sophomore. “It’s so simple and so natural.”

She has carried the memory with her as she’s grown older and become more aware of climate change. Last year, catastrophic flooding struck Yellowstone and the area around the park, and Gibson-Snyder watched a video of a whole house being swept away. She has also backpacked in wildfire smoke, which made her lungs feel chalky and lingered in her hair for days. And rising temperatures are reducing snowpack, extending summers and shifting animals’ migratory patterns with cascading effects — including making it harder for tourists to find animals like the buffalo she encountered as a child.

“I have been so ridiculously lucky to grow up here,” she said. “I’m lucky to have had these places so accessible, and I want to be able to maintain them.”

Badge and Lander Busse, 15 and 18

Lander Bussy, left, and his brother Badge, in a forested area near their home in Kalispell, Mont., on July 12. Photo for The Washington Post by Tailyr Irvine

Badge and Lander Busse are fans of fishing, hiking, rafting and biking — “all the good Montana stuff,” said Badge Busse, who is named for the Badger-Two Medicine area near Glacier National Park.

Their most treasured tradition is hunting in Montana’s extensive network of forests, plains and other outdoor spaces. Hunting has not only helped keep the family fed but produced some of their favorite memories.

Lander Busse recalls the first time he killed a deer with his father. On the day of the hunt, he woke up “before the crack of dawn” to beat the deer to the top of a hill. From there, they watched the sun rise over the peaks and spread its rays across the valley — it was like seeing the land wake up, he said. Though the hunt was a thrill, the day was ultimately a lesson in preservation and conservation, he said.

The brothers want to protect the forests for themselves and generations to come. Lander Busse said hunting only works if the animals are getting what they need. All that changes when climate change reduces their populations or makes them harder to find.

Badge Busse said they are “doing this for all of Montana and all of Montanans.”

Added his brother: “If the places you love and depend on are being impacted, you stand up and fight.”