In the spring of 1903, while visiting Yosemite, President Theodore Roosevelt slipped his Secret Service detail to go camping with John Muir. The first night, the President, the naturalist, and two park rangers camped out by a grove of sequoia; the second, in a hollow at Glacier Point. Roosevelt emerged from the woods to learn that an elaborate banquet had been planned for him, complete with fireworks. He stayed long enough for a glass of champagne, then announced that he was skipping the rest of the festivities. He and Muir spent a third night camping in the shadow of El Capitan.

The only record of what passed between Roosevelt and Muir during their trip comes from one of the rangers, Charles Leidig. According to Leidig, among the topics the two discussed were: lion hunting; Muir’s theory—controversial at the time—that Yosemite had been shaped by glaciers; the importance of forest conservation; and the need for more national parks. Roosevelt and Muir had some difficulty communicating, Leidig observed, “because both men wanted to do the talking.” Nevertheless, their journey has been described as the most consequential camping trip in American history. Roosevelt went on to create eighteen national monuments, five national parks, and a hundred and fifty national forests. All told, he conserved some two hundred and thirty million acres—an area larger than Texas.

This past spring, President Obama visited Yosemite. Instead of camping, he stayed at the park’s fanciest hotel, and, instead of ditching his Secret Service detail, he was accompanied on his hike by snipers posted strategically on the rocks. Still, he, too, seems to have been moved by the spirit of John Muir.

Last month, Obama designated eighty-seven thousand acres in central Maine as a new national monument. He bypassed Congress to make the designation, invoking the Antiquities Act, which was signed into law by Roosevelt in 1906. (The act allows the President to create national monuments “by public proclamation.”) And, on August 24th, he added almost three hundred million acres to the Papahānaumokuākea Marine National Monument, northwest of Hawaii; the additional acres made Papahānaumokuākea (pronounced “Papa-ha-now-moh-koo-ah-kay-ah”) the largest ecological preserve on the planet. Obama has now put more acreage under protection than any other President, though the bulk of it is underwater. The historian Douglas Brinkley recently dubbed him “a 21st-century Theodore Roosevelt.”

When Muir and Roosevelt made their escape, the main threats to America’s wild spaces were the tangible sort: logging, mining, and ranching. Today, what we still call wilderness, for lack of a better word, is subject to more insidious hazards. By 2030, Glacier National Park is likely to be stripped of its active glaciers. In Joshua Tree National Park, it’s getting too warm for Joshua trees—already they are disappearing from lower elevations. The delicate hydrology of Everglades National Park, it’s now clear, won’t last forever. In the face of climate change and sea-level rise, even creatures living in the planet’s newest, largest aqueous preserve may not be preserved; as conditions shift, they may be forced to swim and slither beyond its borders.

The fluidity—or, if you prefer, chaos—that’s approaching doesn’t make parks and national monuments irrelevant; it makes them even more essential. In a rapidly changing world, plants and animals need places to move to and they need places to move through. Obama alluded to this last week, during a visit to Lake Tahoe, whose waters are warming so fast that scientists fear it could soon become an algae-filled tub. The President had come, he said, “to keep faith with this truth: that the challenges of conservation and combatting climate change are connected. They’re linked.”

To its credit, the National Park Service is trying to grapple with these challenges. A 2012 report by the service’s scientific advisory committee recommended that the parks’ resources be managed “for continuous change that is not yet fully understood,” a task that’s probably as difficult as it sounds. The Park Service, which celebrated its hundredth anniversary on August 25th, has assembled a team to plan for climate change and to reduce the service’s own carbon emissions. Naturally, Congress tried to gut the program, at one point cutting its budget by two-thirds. In general, lawmakers have been putting the squeeze on the parks’ finances. According to the Government Accountability Office, in real dollar terms Park Service appropriations fell eight per cent between 2005 and 2014.

For many in Congress, underfunding isn’t enough. Last summer, Representative Cresent Hardy, a Nevada Republican, offered an amendment to an appropriations bill that would have sabotaged the Antiquities Act, curtailing a President’s ability to create national monuments. (National monuments are a lot like national parks; most are managed by the Park Service, and many—including the Grand Canyon, first designated by Teddy Roosevelt—have gone on to become parks themselves.) The Hardy amendment was approved by the House but then dropped in the bill’s final version.

More recently, Representative Rob Bishop, a Utah Republican, who is the chairman of the House Natural Resources Committee, tried to prevent Obama from creating the preserve in central Maine. Bishop, too, has introduced legislation to undermine the Antiquities Act, which he has called “the most evil act ever invented.” (Last year, he was recorded suggesting that anyone who supports it ought to die.) The Republican National Committee’s 2016 platform—a hair-raising document if ever there was one—seems to subscribe to this sentiment. It calls on “national and state leaders and representatives to exert their utmost power and influence” to wrest land away from federal protection.

During Obama’s first term, he used the Antiquities Act sparingly, even timidly. He created only four national monuments, in Virginia, California, and Colorado, with a total area of less than twenty thousand acres. Perhaps he was operating under the belief—valid in Roosevelt’s day but outdated by the nineteen-eighties—that parks were a bipartisan concern. Or perhaps he just had other things on his mind. In his second term, and especially in the past few months, as he enters what the Washington Post recently called the “grand-gesture stage,” Obama has emerged as a champion of conservation. As he observed a few months ago in Yosemite, quoting a speech that Roosevelt gave in Sacramento after his camping trip with Muir, “We are not building this country of ours for a day. It is to last through the ages.” ♦