When the railroad tycoon Edward H. Harriman fell ill from stress and too much work, his doctors recommended that he take a sea cruise. Unable to do anything in a small way, Harriman filled a ship with America’s foremost scientists, artists, and writers, and sailed the coast of Alaska for two months in the summer of 1899.

The expedition, which also included the renowned preservationists John Muir and George Bird Grinnell, found two Alaskas wherever they went, one for the taking, one for the saving. Each at odds with the other. Foremost among the places for saving was the great coastal rainforest of the Southeast Alaska panhandle, a wondrous world of mountains, ice fields, tidewater glaciers, rock-ribbed fjords, coastal brown bears, bald eagles, and 11,000 miles of shoreline.

Eight years later, in 1907, President Theodore Roosevelt took a bold step in that direction by creating the 17-million-acre Tongass National Forest, the largest national forest in the United States. Today, the Tongass contains two national monuments and 19 designated wilderness areas. It also has countless undammed rivers and streams, and some of the world’s last great runs of wild Pacific salmon.

Dominated by Sitka spruce and Western hemlock — mighty conifers up to 10 feet in diameter and 800 years old — the Tongass represents the world’s largest remaining temperate rainforest. Many of the great trees wear long beards of lichen and moss, and drip with rain, and echo the calls of ravens and the liquid songs of hermit and Swainson’s thrushes.

Ecologists today call the Tongass the Amazon of America.

And for good reason. It’s under serious threat.

The Trump administration has announced its intention to open more than half of the Tongass — 9.5 million forested acres — to development. First roads, and then most anything after that: clear-cuts, dams, lodges, etc. To do this, the U.S. Forest Service must exempt the Tongass from a key conservation initiative, known as the Roadless Rule, which in 2001 banned new roads on nearly 60 million acres of untouched national forest lands in 39 states.

The Forest Service recently held hearings in communities through Southeast Alaska, and took testimony. Most attendees saw it for what it was: a dog and pony show. Six alternatives ranged from number one, keeping the Roadless Rule in place, to number six, which would once again open the Tongass for business.

Trump’s proposed assault on the Tongass is just one of several administration initiatives to open large parts of Alaska’s wilderness to development. The administration wrapped oil drilling in the biological heart of the Arctic National Wildlife Refuge into a disastrous budget bill. The Pebble Mine project, a massive proposed open-pit gold and copper mine in Southwest Alaska, was considered dead after the Obama administration ruled that it posed too grave a threat to the world’s largest run of sockeye salmon — an astonishing 62 million fish last year — in nearby Bristol Bay. Now, however, the project is rising again as the U.S. Environmental Protection Agency ruled it will not oppose Pebble Mine, leaving the decision up to the U.S. Army Corps of Engineers — an agency with a dismal environmental record.

Alaska and the Tongass have long faced such threats.

Soon after Teddy Roosevelt established the Tongass National Forest, Puget Sound timbermen in Washington State set their sights on the big trees, just a boat ride away to the north. As he watched federally protected lands across the U.S. come under threat, John Muir noted: “Nothing dollarable is safe.”

At first, timbering in the Tongass was small scale. But as the decades rolled by, and more roads appeared as tall trees disappeared, the battle intensified. Twenty years ago, during the Clinton presidency, 1.6 million people responded to the U.S. Forest Service’s proposed “Roadless Rule.” In 600 public hearings and in written comments, more than 95 percent said they favored the rule for no more new roads in undisturbed national forests. Our national forests — already fragmented by hundreds of thousands of miles of roads that opened the way for everything from clear-cut logging to dams to recreation to mining and grazing — needed a break. The people had spoken. Trees had more value standing than felled.

In 2001, the Forest Service enacted the Roadless Rule. The Tongass, already the victim of extensive logging that in some places had cleared entire islands, valleys, and mountainsides of trees, finally achieved the protection it deserved.

My little town of Gustavus, Alaska — reachable only by boat or plane — sits across Icy Strait from Chichagof Island, one of the largest islands in the Tongass. When I first came here 40 years ago, I learned to sea kayak, catch salmon, and make room for bears. I can’t imagine living anywhere else. This land nurtures my neighbors and me, and we defend it. At the Gustavus hearing, 100 percent of the attendees opposed opening the Tongass to logging and other development.

I remember the passage of the Roadless Rule as if it were a renaissance, a time of light and hope. I remember fisherfolk (commercial, sport, and subsistence), deer hunters, berry pickers, Native elders and their clans, kayak guides, poets, politicians, artists, parents, children, and many others celebrating. We could once again walk into our favorite forest — one that’s pristine, its salmon streams clean — without worrying about one day losing it. Much of the Tongass remained intact. Our forest would be here to stay.

I was fortunate to join a retracing of the Harriman Expedition in 2001, the same year the Roadless Rule passed. I remember talking animatedly with my shipmates as we walked into the Tongass, step by step, following a bear trail, until we went quiet and stopped, suspended in wonder.

Paul Alaback, a professor of forestry from the University of Montana, spoke about how the Tongass contained more living plant life per area, and stored and sequestered more carbon, than nearly anywhere else on earth.

Later, we discussed how large-scale clear-cut logging in the Tongass made sense only if you had no ecological conscience, and saw trees only as timber. As many people did. Beginning in the 1950s, entire mountainsides and valleys were shorn to feed two pulp mills on 50-year contracts. Some trees went into lumber for construction. Some into musical instruments. Most became paper, rayon, cellophane, and later, “fluff-puff” to help make disposable diapers. Countless others were shipped “in the round” to Asia.

Throughout the 1970s, 80s, and 90s, as market demand for Tongass timber declined, Alaska’s congressional delegation fought to keep the industry going — subsidizing it at a heavy cost to U.S. taxpayers: $600 million over the last 20 years. One deficit U.S. Forest Service sale offered every 1,000 board feet of timber for less money than the cost of a Big Mac. Another generated only 2.5 cents on every dollar the Forest Service spent to build roads and prepare paperwork.

Today, building new roads in the Tongass would cost an estimated $200,000 to $500,000 per mile. It’s madness. Especially considering that the bottom has fallen out of the timber industry in such a huge way that one recent proposed Forest Service sale, in a portion of the forest still open to logging, didn’t receive a single bid.

No matter, the assault continues, driven by Trump and Alaska’s all-Republican congressional delegation. Their aim, they say, is to eliminate the “suffocating” Roadless Rule.

In February, President Trump told Alaska’s Republican Governor, Mike Dunleavy, “Mike, anytime you have a problem, you call me.” Dunleavy did, and later sent a letter asking the president to help him “save what’s left” of the timber industry. Alaska Senator Lisa Murkowski added that she expected Trump to push for a full repeal of the Roadless Rule.

And let us not forget Secretary of Agriculture Sonny Perdue, who once said that a healthy forest can be healthy in many ways, including providing jobs. Jobs, he explained, that would cut down significant areas of the forest.

This is precisely what we do not need in a world with 7.7 billion humans who burn so much fossil fuel that we send 2.4 million pounds of carbon dioxide into the atmosphere every second of every day. Cutting down the Tongass, one of the best carbon sequestration forests in America, would be a crime, not a job. In the past 20 years, more than 800 million acres of forests around the world — an area 47 times larger than the Tongass — have been removed by logging. All of this contributes to the destruction of a stable, livable planet. If it cannot be stopped here, in Alaska, where can it be?

Together with phytoplankton in the oceans, old-growth forests are the best thing we have going. They are the lungs of the Earth. In an advocacy film he made with Swedish teenage climate change activist Greta Thunberg, The Guardian columnist George Monbiot says, “There is a magic machine that sucks carbon out of the air, costs very little, and builds itself. It’s called ‘a tree.’”

If politicians want to protect the economy of Southeast Alaska, they should focus on fishing and tourism, which bring in $2 billion annually to the region, while timber accounts for only 1 percent of regional employment and jeopardizes fishing and tourism. People don’t travel here to see destruction. They come to find beauty and hope. And, if like me, they’re lucky enough to live here and eat garden carrots and wild salmon, they share Alaska with others.

“Stay together,” I tell a group of summertime visitors as we walk into the Tongass. “Oh, yeah,” I add with a grin, “and watch for bears.”

We arrive at a river where coho salmon flash silver in the rich light, fighting their way upstream. Bald eagles perch in nearby Sitka spruce. We see no brown bears, but find their tracks everywhere.

I point to a dead salmon that’s been dragged out of the water and into the forest, and partially eaten by a bear or an eagle. After it emerged as a little fry in this river and spent years in the ocean, the salmon returned here to spawn and die, as others have done for millennia. As the salmon decomposes, its nutrients will be absorbed by tree roots and riverside willows and alders, which in turn will nourish insects and birds. “There are marine isotopes from these fish in the tops of the trees,” I tell my companions. “That’s why this is called a ‘salmon nation.’ It’s why Alaskans say, ‘It takes a fish to feed a forest.’”

Everything is interconnected.

For hundreds of years too many Americans have bought into the “myth of super-abundance,” the notion that the party will never end, that our fish and forests are so inexhaustible we’ll never run out of them. It’s a dangerous deception, one many members of the Harriman Expedition recognized and cautioned us about. Alaska doesn’t go on forever.

If we cut down vast numbers of Tongass old-growth trees, especially now at this critical time of climate change, when such big trees are most needed, we will help to condemn ourselves — and generations to come — to a destabilized, hothouse Earth.

Will we let that happen?