For more than a century, the National Park Service’s core mission has been to preserve the natural heritage of the United States. But now, as the planet is warming and ecosystems are changing, the agency admits that in many cases its traditional goal of absolute conservation is no longer feasible.

Late last month, the service released an 80-page document containing new guidelines for park managers in the age of climate change. The document, along with two peer-reviewed articles, is essentially a toolkit for the new world. It is designed to help park ecologists and managers face the fact that they must increasingly actively decide what to save, what to guard through radical environmental changes, and what will go away forever.

“The concept of things that go back to a historical solid state really is no longer tenable,” said Patty Glick, a senior climate adaptation scientist at the National Wildlife Federation and a lead author on the document.

The new research and guidelines, which focus on how to plan worst-case scenarios, which species and landscapes to prioritize, and how to assess the risk of relocation of species that otherwise cannot survive, represent a kind of ” Billing ”is the Park Service, said Ms. Glick.

The change is brutal for a profession that has long been tied to upholding historical precedents, said Gregor W. Schuurman, a scientist with the Park Service’s climate protection program who helped create the new guidelines.

“It is negotiated. Nobody wants to do that. We all took part in this game, as the Park Service mission says, to “stay unaffected,” “said Dr. Schuurman. “But if you can’t do it the way you thought, you have to see what you can. There is often more flexibility there than you might imagine. “

The team behind the report went low-profile during the Trump administration when the Park Service was at the center of frequent political battles. For example, in 2018, managers tried to remove humanity’s role in climate change from a report on sea level rise. The day before President Biden’s inauguration, they began publishing their papers, which were years in the making.

The first title, entitled “Resist, Accept, Direct”, is intended to help park employees search through species and landscapes. In some cases, this means giving up long efforts to rescue. The second section explains how the risks involved in species relocation are assessed. This can be crucial in saving plants and animals that can no longer survive in their natural habitat.

These two papers formed the basis for the guidelines published last month. On the very first page of this document, overlaid over a photo of the charred Santa Monica Mountains after the Woolsey fire in 2018, it says, “It will not be possible to keep all park resources, processes, resources and values ​​in their current Form to protect form or context in the long run. “

Decisions about what to protect are especially imminent for forests, where changes lead some researchers to wonder if the age of North American forests is coming to an end.

In the southwestern United States, for example, research suggests that in the event of forest fires, up to 30 percent of forest land may never regrow because global warming encourages shrubs or grasslands in their areas of distribution. Joshua trees seem likely to lose all of their habitat in their national park of the same name by the end of the century.

The new guidelines essentially ask park managers to think beyond resisting change and see transformation as the dominant theme to be welcomed and managed. In some individual cases, it can take a while for ecological change to resist. In other cases losses must be accepted. But just as often there can be room to guard against change in a less disastrous direction.

For example, some native tree species in Acadia National Park, Maine, struggle to survive when temperatures are warm. Invasive Brambian shrubs brought to the U.S. as ornamental plants are much better able to adapt to warmer temperatures than native species and are quickly moving in to take their place. The invasives produce leaves earlier in the spring than native species and shade any young tree that emerges. And as the mild weather arrives earlier and earlier (the growing season on the coast of Maine has already lengthened by two months over the past century and a half due to global warming), the blackberries only become more successful and abundant.

“They are dense thickets that you cannot walk through,” said Abraham Miller-Rushing, ecologist and science coordinator at Acadia National Park. They’re also a perfect habitat for ticks that can transmit Lyme disease.

For the past 30 years, the park has sent teams of people to cut down and pull out the bushes. But that won’t last long. “The models show that of the 10 most common tree species in the park, nine will lose their habitat over the next 80 years, either decline sharply or disappear entirely,” said Dr. Miller-Rushing. This includes red spruce, which makes up 40 percent of the trees in the park. When these disappear, a large part of the forest floor suddenly opens up to the invasive shrubs, which would fill the open space faster than manual efforts could stop them.

At the moment, park managers are still finding new red spruce seedlings in the park, which is a good sign. But things could change very quickly – much sooner than in 80 years. “This decline could be rapid,” said Dr. Miller-Rushing. Red spruce is very sensitive to drought. “You can imagine a scenario where we get a drought combined with an insect pest or pathogen. That could set the spruce back very quickly. “

It’s already happened to the red pine. Almost every species in the park has been wiped out by a single invasive insect, the red pine scale, in the past 6 years. “That’s probably how many of these transitions will happen,” said Dr. Miller-Rushing. “Not slowly, but quickly.”

Acadia park managers already use the Resist, Accept, Direct framework to decide what to do. At the moment, they are considering choosing certain southern tree species to be hand-planted in the park in the hopes of avoiding a forest full of blackberries.

Regardless of what action they take, the park won’t look like the Acadia of the past for decades to come. “When our forests turn to hardwoods or, God forbid, invasive shrubbery, the postcards will look different,” said Dr. Miller-Rushing.

“There is definitely a sense of loss,” he added, but also “a sense of urgency”.

Dr. Miller-Rushing received his PhD in Conservation Biology in 2007. At that time, protected areas like the national parks were still considered static places that could be preserved forever with the right techniques. “We weren’t trained to deal with change,” he said. “We were trained to keep things as they were in the past.”

This means that almost everyone in their industry has been caught unprepared for the current reality. “You have a whole job of people who need to change the way we think,” said Dr. Miller-Rushing.

The changes come at a time when other aspects of the traditional American approach to protection, such as the forced removal of indigenous peoples from the lands that had farmed them for thousands of years, are also being reviewed. Far from being pristine expanses, it is now understood that these lands were indeed shaped by Native American administration. For example, researchers have found evidence that indigenous cremation practices helped keep the lush oak and pine forests European colonists encountered along the east coast healthy and free of undesirable species.

In the midst of these major changes, the new framework also appears to be gaining ground outside of the parking service. In April, the US Fish and Wildlife Service launched a new website on Resist, Accept, Direct, recognizing that climate change is profoundly changing the ecology of several of its wildlife sanctuaries. In 2017, Canadian officials reached out and looked for new approaches to protecting against climate change. Parks Canada has since considered the concept. And in March, Dr. Schuurman was invited to present the frame to officials of the South African Park Service.

“I think what the Park Service is proposing here is a well-designed, sensible answer,” said Susan G. Clark, an associate professor of wildlife ecology and political science at the Yale School of the Environment who was not involved in making the new Documents. “It signals the Park Service to rethink its responsibilities and what it can and cannot do in the face of all these changes.”

“We have to learn how to walk and we have to learn very quickly,” added Dr. Clark added. “There is clearly much more to come.”

Dr. Schuurman hoped the framework would help managers make smart decisions in an uncertain world.

Right now, he said, climate change is teaching them to abandon the concept of “forever”. This does not apply to the parks they manage today. “Climate change is ruining that.”

According to Dr. Miller-Rushing, the earlier approach may have been flawed from the start. After all, the rule of nature is change. Now the climate crisis is making that clear.

“We have probably always been wrong about considering protected places as static,” he said.