COEUR d’ALENE, Idaho – Jakob Namson peered up at the towering ponderosa pine before him. He looked at his notebook, which was full of calculations scribbled in pencil. Then he looked back at the pine. If his math was right – and it nearly always is – he would need to plant 36 trees just like this one to offset the 831 pounds of carbon dioxide that his drive to school emits each year.

Namson, 17, gazed around at his classmates, who were all examining their own pines in northern Idaho’s Farragut State Park. He considered the 76 people in this grove, the 49,000 people in his home town of Coeur d’Alene, the millions of people in the United States driving billions of miles a year – and approached his teacher, Jamie Esler, with a solemn look on his face.

“I think I’m beginning to understand the enormity of the problem,” the teenager said – a revelation that Esler later described as “one of the most inspirational moments of my entire career.”

The phrase “climate change” evokes deep skepticism in northern Idaho. Fewer than half of adults in Kootenai County think that human activities contribute to global warming, surveys show. In February, the state legislature urged the state board of education to rewrite the science curriculum to eliminate what one lawmaker called “an over emphasis on human caused factors.”

On Thursday, President Trump’s decision to withdraw the United States from a landmark global climate agreement touched off a new round of combustible debate. But here in Idaho, Esler has managed to nurture a growing cadre of budding environmentalists by eschewing politics and focusing on tangible changes in the natural landscape, changes that affect the crystalline water, the ancient trees, the once-abundant snow.

“Esler is kind of a genius,” said Annika Jacobson, 17. “He teaches things in a way that doesn’t mold your brain to his, so you almost don’t notice that you’re learning all these things. Until someone on the street says they don’t believe in climate change and then you’re like, ‘Wait a minute,’ and you have all these stats and graphs and factual things.”

An athletic 32-year-old in a down vest and a ponytail, Esler has been teaching science in Idaho for almost a decade, helping establish his school’s Outdoor Studies Program, a year-long interdisciplinary program for juniors.

In 2014, he was named Idaho’s Teacher of the Year. He finds the state’s skepticism about human-caused climate change ironic, he says, because the effects are increasingly evident here.

Two years ago, the devastating drought that hit most of the West sparked huge wildfires. Last summer, warmer weather contributed to an algae bloom in Fernan Lake, making the local spot too toxic for swimming. Lately, even Esler’s youngest students remark on the number of winter days when the city gets rain instead of snow.

Esler prods students to investigate and reach their own conclusions about people’s impact on the environment. Instead of lecturing about the perils of warmer winters, he takes his class into the surrounding Bitterroot Mountains to measure declining snowpack. Instead of telling them to use energy-efficient LED bulbs, he has them test the efficiency of four varieties of lightbulbs and then write about which they prefer and why.

On the trip to Farragut State Park, students take pencil-thin core samples from their trees. They count the rings to get each sampled tree’s age, then do some math to determine how much carbon the tree pulls out of the atmosphere through photosynthesis.

The teenagers marveled at the delicate rings on their samples. One girl breathed in the spicy pine scent and said, “Whoa, it’s like Bath and Body Works but better.”

“We could do this in the classroom,” Esler said. “I could just give them the numbers and show them a PowerPoint. But now I have kids smelling the inside of a tree. That’s a tangible connection. . . . I hope it makes them think about what happens to that carbon when it comes out of their tail pipe.”

The Outdoor Studies Program has 76 energetic students who are conversant in subjects such as “eutrophication” and “water snow equivalency” and will earnestly say that they “want to save the world.”

After learning about the persistence of plastic in the environment, Lenna Reardon talked her boss at the local ice cream parlor into installing a recycling bin. Connor Brooks’s family now composts. Jordan Lo, the vice president of the Environmental Club, is on a crusade to get his classmates to ditch bottled water for reusable containers.

Jacobson helped organize an “environmental health week” on campus this spring. “Most kids here honestly don’t really believe in climate change because their parents don’t,” she said. Even her boyfriend was skeptical. “What’s so important about climate literacy?” he asked her.

Jacobson made a face. When she encounters this attitude, she said, “You really just have to hit them with facts.”

And what are those facts?

Her eyes lit up.

“Do you want to see a graph?”

Jacobson whipped out her cellphone and pulled up a NASA graph of global temperature records going back hundreds of thousands of years. With her pinkie, she traced the zigzagging line through the centuries, then pointed to where it shoots up sharply in the 1950s – right when humans started adding greenhouse gases to the atmosphere at a perilously fast rate.

“Once you see it,” she said, “it’s really hard to deny.”

Most of Esler’s students say they rarely thought about climate change before taking his class. Craig Cooper, a state water researcher who leads a local climate action group, acknowledges that outreach is a problem.

“The single biggest failure of the climate movement is that it hasn’t done a good enough job building relationships,” Cooper said. To most people, climate change is “a political argument they don’t want to get into.”

That’s true for Chuck Morris, 53. In the 13 years he’s been hunting and hiking in Idaho, the machinist has seen winters shortening and summers drying out. He believes that humans play a role in the changes. But he is put off by the way scientists “stand up there and speak to you in jargon.” And he is skeptical of politicians who propose regulations to address it.

“Basically, the opinion I drew on it is: It’s there, but I can’t find anything that shows it’s getting worse, really,” Morris said.

Since Morris’s daughter Sarah joined Esler’s class, father and daughter have been having what he calls “discussions” – and what she calls “arguments” – about the issue.

“It’s kind of scary” to challenge a parent, she said, “but he’s respecting it.”

“She suggests things, and I don’t blow it off,” Morris agreed, adding that he wants to encourage his daughter in her favorite class. “Who knows? Maybe Sarah gets looking into [an environmental problem] and she comes up with the solution.”

The ongoing debate over the state’s public school science standards has raised awareness of the issue. In February, the legislature struck five paragraphs related to climate change and urged the standards committee to rewrite them. The standards help determine what appears in public school textbooks, statewide texts and teacher training materials.

It was the third time in three years the section on climate change had been scrutinized. Lawmakers decided that the standards should be “more balanced between human and natural causes,” state Rep. Ryan Kerby (R) wrote in an email to The Washington Post.

Esler serves on Idaho’s science standards committee. Ultimately, the group offered minor changes, which will go before the board of education in August. A paragraph that said, “Human activities have altered the biosphere, sometimes damaging or destroying natural habitats and causing the extinction of other species,” now reads: “Human activities can have consequences (positive and negative) on the biosphere, sometimes altering natural habitats and causing the extinction of other species.” A line that instructed teachers to emphasize the major role that human activities play in causing the rise in global temperature was deleted.

“It’s essentially the same science worded in a way that may be received as less abrasive,” Esler said. “The bulk of our work” was figuring out “how do we take the same science and use the English language to state it without triggering defensive, dismissive reactions?”

Esler has received teacher training through the University of Washington, NASA and the National Science Foundation (NSF). Many of the projects in which his students participate rely on federal education funds. Such support could be increasingly scarce: Trump’s 2018 budget request would eliminate the NASA education office and cut funding for the NSF by more than 10 percent.

Back among the ponderosa pines at Farragut State Park, Esler and his students ate lunch and discussed the results of their experiment.

“Do you feel like there’s something you can do after this lab?” Esler asked. “Yes, yell at my parents,” one student responded. There was a wave of laughter. “Plant more trees!” shouted another. “Do we even have space on Earth to plant that many trees?” wondered a third.

Namson remained quiet, considering the gravity of the issue. “Mr. Esler basically just said he agreed with me,” Namson recalled later. But his teacher couldn’t tell him what to do about it. That was up to him.