It’s hard to believe in 2018—when every day brings news of a fresh attempt by the Trump administration to roll back environmental protections—that the Republican Party has a deep tradition of environmental stewardship. Ulysses S. Grant created Yellowstone National Park. Benjamin Harrison created the first national forest reserves, the precursor to our national forests. In the 20th century, Richard Nixon created the Environmental Protection Agency by executive order and signed into law a dozen big environmental laws, including the Endangered Species Act. President George H.W. Bush moved aggressively, and despite howls by industry, to stem acid rain.

That legacy now seems very long ago. Why, and how, did the Grand Old Party turn its back on the environment over the past 40 years? Those questions form the subject of an upcoming book, The Republican Reversal: Conservatives and the Environment from Nixon to Trump, out October 15 and available for preorder now. Outside spoke to the book’s authors: James Morton Turner, an associate professor of environmental studies at Wellesley College, and Andrew C. Isenberg, the Hall Distinguished Professor of American History at the University of Kansas.

OUTSIDE: What made the Republican reversal worth studying?

ANDREW ISENBERG: Two things drove our interest. We were looking at a Republican Party in the 21st century that was really opposed to most of the environmental laws that were on the books, and those were laws that Republicans had helped to create in the 1970s. And so we started with a very basic question: How did that happen?

The other thing that really interested us is that a lot of stories about how environmental laws and the environmental movement came to be have come from environmentalists. We’ve heard again and again about Rachel Carson and Earth Day. What Jay and I both recognized is that the passage of big environmental laws was not the end of the story. For the past couple of decades, there’s been the back-and-forth between people who wanted to roll back those laws and people who have been defending them.

What surprised you most while researching this book?

JAMES TURNER: One moment was just how important the Reagan administration’s leadership was on addressing the stratospheric ozone hole and regulations on chlorofluorocarbon emissions. In the 1980s, you had the Reagan administration pushing for an international agreement based on the work of atmospheric scientists, which led to an international treaty and substantive regulations to tackle an urgent environmental issue. It was one of the most important international environmental treaties that’s ever been put together, and one of the most successful.

ISENBERG: What surprised me was the extent to which Democrats signed on to the effort, beginning with James Watt and the first Reagan administration, to ramp up fossil-fuel production within the United States. We’ve now reached the point where we’re producing a whole lot more fossil-fuel energy in the United States than 40, 50 years ago. And that philosophy—that energy should be cheap and we should produce a lot of it—in a lot of ways, that was a bipartisan initiative. That shows how powerful the conservative revolution was in the Republican Party in the 1980s. It didn’t just remake the party—it also influenced the way a lot of Democrats thought about policy as well.

I mean, if you think about Barack Obama in his first administration, his energy policy was, as he stated, “all of the above,” which was exactly the same thing Sarah Palin was saying.

People under 50 years old might be surprised to learn that Republicans once had a strong legacy of protecting the environment that lasted into the 1970s and beyond.

ISENBERG: To understand what happened, you have to understand the rise of conservatism and how the Republican Party has really been transformed in the past 40 years or so. When Ronald Reagan came along, there were a lot of moderates within the Republican Party. That was the faction that had helped pass those environmental laws.

The rise of conservatism has been so all-consuming that, for a lot of younger people, it’s hard to even think of the Republican Party as having once supported those laws. In this book, we tried to put together what historians know about the environmental movement and what historians know about the rise of conservatism. Those are two ways of looking at the past 50 years that very few people have tried to put in conversation with each other.

One of the surprises for me was the interest in environmental issues by politicians such as Barry Goldwater, whose name is now shorthand for an ultraconservative who loathes big government. As a U.S. senator, he co-sponsored the Senate bill that became the Clean Air Act of 1970.

TURNER: For people today, it’s hard to imagine just how urgent the issues around clean air and clean water were in the 1960s and 1970s, to the point where someone like Goldwater would consider that we needed government involvement and regulation. I think one part of this story for us was understanding why it was that Republicans saw this urgent need for laws like the Clean Air Act and the Clean Water Act. A big part of that was just how unrestrained pollution was—just how extensive the smog was, how dirty the rivers were.

And, you know, that contributed to the moment of crisis that brought this bipartisan support together for these environmental laws.

You write, though, that this sense of urgency and unity of purpose began to fray. What happened?

ISENBERG: I think that fraying began during the energy crises of the 1970s. A lot of that enthusiasm about doing something for the environment began to wane when people had to actually, in a very sudden way, pay much higher prices for energy, in addition to lots of other economic problems at the same time.

Conservative Republicans seized on the crises, and on the economy of the 1970s, to leverage themselves to power starting in the 1980s. One of the things they did was ramp up the cheap production of fossil fuels. There was bipartisan consensus around that for a lot of years. Politicians were in support of clean air and clean water, but they were also in support of cheap energy.

The reason climate change has become such a divisive issue, I think, is that it puts those two things in conflict with each other. You can’t have both cheap energy, if you’ll be getting that from fossil fuels like oil and coal, and address climate change. Republicans want to have it both ways. They want to position themselves as environmentalists who are supporting clean air and clean water, in a kind of old-timey, 1970s way, but they also want to push for cheap fossil-fuel energy. That’s one of the reasons they don’t want to concede that climate change is a real problem.

You write that the Trump administration represents both a continuation of a pattern and a break with the tradition of environmental protection. What’s different?

ISENBERG: The challenge of addressing climate change requires international cooperation. And what makes the Trump administration different is that he came into office with this “America first” populism and is not at all amenable to that kind of international cooperation.

TURNER: Three things stand out. One is this disproportionate attention the Trump administration is giving to climate change and energy policy.

Second would be the success with which the Trump administration has really avoided discussing science and has focused much more on values like American exceptionalism, the importance of work, and the importance of local communities.

The third big change is just how important administrative action has become to environmental policy. It’s not Congress that’s driving the agenda, as it was in earlier decades. We’re at a point where an administration can come in and roll back regulations or break treaties and profoundly affect the direction of our environmental policy. We’ve seen this with Trump pulling out of the Paris Climate Accord or reversing the Clean Power Plan. So we see much more dramatic swings as we go from administration to administration than we did in previous decades.

In the book, you mention another historian’s idea of “green drift”—the notion that despite different administrations with different philosophies, over time the nation has tended toward generally better environmental protection. Is that still true today?

TURNER: That notion of green drift is in jeopardy now in a way that it never has been before, and for two reasons. One is that the executive branch has become so much more powerful, and our environmental policies are so much more dependent upon presidential action.

The other key piece is the judicial branch, which has been the backstop that has protected laws like the Clean Air Act and the Clean Water Act. With the Trump administration changing the composition of the Supreme Court, and of appeals courts across the country, we’re going to be in a very different judicial environment for decades to come. That really should make us question whether what we have seen historically, with these laws being upheld, is going to be the case going forward.

Surveys show that Americans of all political stripes care about the environment. Do you see a path back to a more environmentally friendly platform for the GOP? What would that look like?

ISENBERG: I think a good historian only predicts the past. But I would say that if the Republican Party is going to have a different position on the environment, Republicans who are running in primaries need to be concerned about a challenge from the Republican center. Right now, very few of them are.

TURNER: There are Republicans who are concerned about, say, climate change. Just this past July 2018, Representative Carlos Curbelo from Florida introduced a carbon tax. Nobody expects that to go anywhere, because the House of Representatives overwhelmingly passed a resolution against a carbon tax in July as well.

But Curbelo is not the only Republican who’s talking about needing to move forward on environmental issues. There are other Republicans who realize that there’s a younger generation coming of age that is concerned about climate change. This anti-environmental strategy may be working for the Republicans now, but if they want to have relevancy with younger voters, the environment and climate are issues that the rising generation care about.

This interview has been edited for length and clarity.