Americans should embrace their national parks as symbols of the planet’s beauty and history—and help protect them from the ravages of climate change, President Barack Obama said Saturday during an exclusive interview with National Geographic in Yosemite National Park.

Strolling through a forested stretch of Yosemite’s lush valley, below towering granite cliffs and North America's tallest waterfall, the president spoke wistfully about how parks can inspire young minds, bring families together and be a reminder of the need to respond to climate change. The Hawaii-born president recounted one of his favorite childhood memories—a trip to the mainland with his mother and grandmother when he was 11 that included a trip to Yellowstone National Park—and said he was envious of nature-lover Teddy Roosevelt, who frequently disappeared into the woods during his presidency more than a century ago, and became a leader in protecting America’s wild places.

“One of the things that binds us together is we only have one planet and climate change is probably the biggest threat – not only to natural wonders like this—but to the well-being of billions of people, coastal cities, agricultural communities that can be displaced in the span of a few decades by changes in temperatures that mean more drought, more wildfires,” said Obama, who was one of the driving forces behind a new international agreement that seeks to curb the growth of greenhouse gas emissions.

“Part of why it’s so important for us to raise awareness (about climate change) with the general public is: This is a solvable problem,” he added.

View Images U.S. President Barack Obama walks through a forest at the base of Yosemite Falls inside Yosemite National Park on Saturday. Obama visited the park ahead of the National Park Service's centennial, which is August 25. Photograph by David Guttenfelder, National Geographic

During his conversation with journalist and author Richard Bacon, host of National Geographic Channel's signature franchise EXPLORER, the president also turned again and again to the idea that parks can be a salve – a stress reliever, a way for families to reconnect, and a place to feel more connected to the world.

"I think that the way a place like this imprints itself in you, especially when you’re young, and carries on for the rest of your life, is remarkable," Obama told Bacon. “I do believe that when we get kids, families, out in open spaces, it changes them. It roots you. It gives you a sense that there's something bigger and grander than you. It gives you a sense of order.”

Two days after visiting Orlando in the wake of the nation’s worst mass-shooting, the president took his own family to Yosemite this weekend, in part to draw attention to a summer-long celebration of the 100th anniversary of the National Park Service. Obama hiked with Bacon through forests of black oak and ponderosa pine, in a region that first ignited the passions of naturalist John Muir, one of the nation’s most forceful voices for preservation. The president took in some of the iconic vistas that National Geographic magazine's first fulltime editor, Gilbert Grosvenor, urged Congress to protect as part of a 1916 campaign that helped create the Park Service.

"First of all, National Geographic helped open up the eyes of people across the country about the wonders of the natural world, and cultures and traditions and societies that people might never have visited,” Obama said. “It sparked people's imaginations, and it still does. And that’s critically important.”

Obama spoke fondly of his journey to Yellowstone as a child, saying that at the time it was “the greatest experience of my life.”

“I still have unbelievably vivid memories of the first time I spotted a moose, or seeing a group of bison, or elk, or a bear,” he said.

View Images President Barack Obama and First Lady Michelle Obama surprised a group of fourth graders on a visit to Yosemite Saturday. The president gave each student an annual pass to the U.S. National Parks. Photograph by David Guttenfelder, National Geographic

Obama also joked that he’s noticed when he visits national parks that rangers, in particular, are “a happy bunch.” And he bemoaned how much more difficult it is for him than for Roosevelt to slip away into the wild, but agreed with Roosevelt’s assessment that places like Yosemite are sacred cathedrals.

“Nothing like trees to make you feel better,” he said.

Bacon's full interview with the president will air as part of National Geographic Channel’s special programming on the parks, which begins August 23. Two days later, August 25, will mark the centennial of President Woodrow Wilson's signing of the Organic Act, which created the Park Service. National Geographic, Facebook and its Oculus team, and Felix & Paul Studios also shot the White House's first 360 virtual reality video experience, capturing the president's Yosemite visit. That also will air in August.

View Images U.S. Marines stand guard next to the presidential helicopter after landing near Yosemite National Park's iconic Half Dome on Friday. Photograph by David Guttenfelder, National Geographic

A Weekend in the Parks

Obama's Father's Day weekend began Friday with a trip to Carlsbad Caverns in New Mexico, where he, First Lady Michelle Obama and their daughters Malia and Sasha toured a massive section of cave called the Big Room. After landing Friday night in breathtaking fashion in Yosemite—dropping into a valley meadow at dusk in Marine One as the setting sun glinted off the ancient granite of Half Dome – the president and Michelle Obama on Saturday morning surprised a group of 4th-grade students who were visiting Yosemite as part of a White House program that offers free access to national parks for 4th graders and their families.

From there the president walked with Bacon and chatted with Yosemite Superintendent Don Neubacher near Yosemite Creek, below the massive falls. In that conversation, they spoke about the challenges the park faces from rising temperatures, such as increasing droughts that are leading to dead trees and more fires.

Later on Saturday, in public remarks, Obama would point out that climate change’s impact was affecting Yosemite in other ways. “Meadows are drying out,” he said. “Bird ranges are shifting farther northward. Alpine mammals like pikas are being forced farther upslope to escape higher temperatures. Yosemite’s largest glacier—once a mile wide—is now almost gone.”

During their discussion, Neubacher told Obama. “I would hope people would realize that Yosemite, 50 years from now, could be dramatically different, and I don’t think anybody wants that.”

“We sure don’t,” Obama replied.

‘There Is Such a Thing as Being Too Late’

As Obama’s January departure from the presidency approaches, the president and his administration increasingly are focused on leaving an environmental legacy. In recent months the president has spoken more frequently about the need for conservation – especially in light of rising global temperatures from fossil fuel emissions.

On Saturday, Obama again called on Americans to push leaders in Washington, D.C., to do more to reduce fossil fuel emissions, rather than—as some Republican Party leaders have urged—ditch the hard-fought Paris climate agreement.

“The idea that these iconic places could be marred or lost to history shouldn’t be treated as a hoax—it should spur us to action,” Obama said. “It shouldn’t lead to careless suggestions that we might scrap the most advanced climate treaty the world has ever signed—it should make us set our sights even higher, and more ambitious.”

Obama added that, “on this issue, of all issues, there is such a thing as being too late.”

In part as a buffer against changes in nature, Obama is increasingly talking about land and water preservation. A White House Facebook video this week ticked through a list of land monuments and marine areas the president has protected by using the Antiquities Act. On Saturday, he declared that his administration had conserved some 265 million acres – "more land and water than any president in history."

In 2014, he expanded the 83,000-square-mile Pacific Remote Islands Marine National Monument to more than 490,000 square miles. This week, U.S. Senator Brian Schatz, D-Hawaii, urged Obama to dramatically expand the Papahanaumokuakea Marine National Monument in the waters northwest of Obama’s home state.

“We’re restoring vulnerable ecosystems like your Mariposa grove of giant sequoias,” Obama told reporters in Yosemite.

But he also has designated monuments to important people and moments in American history, such as the labor leader who pushed for protections for farm workers, or the early efforts to employ African Americans on sleeper trains in Chicago, which offered some of the first opportunities for them to attain middle-class jobs.

“We’ve designated new monuments and historic sites that better reflect the story of all our people, with monuments to Cesar Chavez, to the Pullman porters in Chicago, and more,” Obama said. “And we’ve got more work to do to preserve our lands, culture, and history.”

View Images Fourth graders and their families play on a boulder in a forest before President Obama and the First Lady arrived to surprise them. Photograph by David Guttenfelder, National Geographic

In his interview with Bacon, Obama said “we still have some designations that we’ve been working on. I think there’s more to do.”

The president, like Teddy Roosevelt, who more than a century ago camped with Muir in a hollow near Yosemite's Glacier Point, seems to relish the grandeur of the parks. Saturday, he mentioned that he keeps a painting of Yosemite’s Vernal Fall and Half Dome in the lobby of the White House’s West Wing lobby, adding with understated humor that the real things are “slightly better.”

During his presidency, Obama has made a point of recognizing that for many, the nation’s relationship with parks is also about adventure. In June 2015, Obama tweeted congratulations to climbers Tommy Caldwell and Kevin Jorgeson for their history-making ascent of El Capitan's Dawn Wall, adding "you remind us that anything is possible." Friday, the Obama administration allowed Jorgeson and a few climbing pals, including Conrad Anker, Kai Lightner, free climber Alex Honnold, and National Geographic photographer Jimmy Chin, to take over the White House Instagram feed. They posted riveting images of big-wall climbers bouldering and scaling Half Dome and other walls.

On Saturday, it was Obama who was talking about the value of exploring and being awed by nature.

View Images National Geographic's Richard Bacon walks with U.S. President Barack Obama near Yosemite Falls. Photograph by David Guttenfelder, National Geographic

“When it comes to a natural marvel like Yosemite or Grand Canyon, that tells everybody's story,” he said, “the story of humanity exploring and seeing and being amazed.”