This story is an expanded version of the 3 Questions page that appears in the July 2017 issue of National Geographic magazine.

With his 2006 documentary, An Inconvenient Truth, former U.S. vice president Al Gore drew public attention to the threat of climate change. This July, An Inconvenient Sequel opens in theaters. Gore, 69, says the stakes are higher now but the solutions are clearer.

What do you think the public misunderstands about climate change?

I think the overwhelming majority of the public understands very well that climate change is an extremely important challenge, that human beings are responsible for it, and that we need to act quickly and decisively to solve it. The most persuasive arguments have come from Mother Nature. Climate-related extreme weather events are now so numerous and severe that it’s hard to dismiss what’s happening. But even those who don’t want to use the words “global warming” or “climate crisis” are finding other ways to say, “Yes, we’ve got to move on solar, wind, batteries, electric cars, and so on.” We have so much at risk.

Why have such sharp political divisions emerged over climate change?

There’s an old saying in Tennessee: If you see a turtle on the top of a fence post, you can be pretty sure it didn’t get there on its own. A determined minority—with active financial support from a few large carbon polluters—has held up progress for quite a while. They have used lobbying power and the threat of financing primary opponents, using the same techniques we saw in the past with Big Tobacco to falsely create doubt. All of us are vulnerable to what psychologists call denial: If something is uncomfortable, it’s easier to push it away, to not engage. But the solution is to listen and approach people on the basis of where they are.

You’ve publically called the Trump administration’s withdrawal from the Paris Agreement on climate change “a reckless and indefensible action.” Where do we go from here?

Even if Trump succeeds in eliminating measures that will help the U.S. reduce emissions, developments in the marketplace—with the cost of renewable electricity continuing to plummet—mean that the U.S. could meet our Paris goals in spite of what Trump does. California and New York are moving much faster than the Clean Power Plan requires. A growing number of cities are moving even faster. And the business community is way ahead of the political community, with many consumer-facing companies pledging to go 100 percent renewable energy.

What about China’s role?

China is moving in a very impressive way. We are into the fourth year of carbon dioxide emission reductions by that country, and the third year of declining coal use. They are implementing a cap and trade plan later this year. They have led the world in manufacturing solar panels and wind turbines, and fast trains and smart grids. So they have shown a lot of leadership on this issue.

An Inconvenient Truth really struck a chord in 2006, and helped bring about a tipping point of awareness around climate change. Why do you think that was?

I give most of the credit to David Guggenheim, the film’s director. I’m embarrassed to say I didn’t think it was a good idea to make the movie. I didn’t think you could turn a slideshow into a movie. But he convinced me and he did a terrific job.

The first movie dovetailed with the continuing scientific study that made the case for action to stop manmade global warming, and so it was a happy confluence of events. But after, the large carbon polluters regrouped and started pouring a lot more money into climate denial and phony pseudo-scientific arguments, backed up by campaign contributions and lobbying money, and they succeeded in slowing down progress. More recently, we have regained the initiative.

What is your goal with the new film, An Inconvenient Sequel?

My main goal is to add to the momentum. One hundred percent of the profits I would otherwise get from the movie, and book we’re doing, will go into training more climate activists. That was true with the first movie as well.

In the new film, a powerful scene shows you visiting conservative Georgetown, Texas, where the Republican mayor, Dale Ross, has led an effort to move his city to 100 percent renewable energy. You seem to really hit it off with Ross; how did that take place?

We connected on a human level, despite our opposite partisan affiliations. He is a CPA, so he could see very clearly how much money the citizens of his city could save if he took a bold step in moving to 100 percent renewable electricity. That opportunity to save people money, while simultaneously reducing pollution, is becoming available all over the world.

What is the secret to working with people who may not agree with you on many issues?

Well, you need to listen and approach people on the basis of where they are in the moment in their thinking. I guess as I’ve gotten older I’ve learned a little bit more about how to do that. Just as Mother Nature is a big ally in convincing people how serious this is, the marketplace is a big ally.

In the new film you say you consider recent setbacks around climate a personal failure. Could you explain why?

There have been times when I thought I could have done more. If you devote yourself to something and you don’t see that goal realized you become vulnerable to thinking maybe you failed. In some dark moments over the last decade I had allowed myself to worry that we were losing this battle. That’s not where I am now. I do believe that we will win this struggle.

Some environmentalists say you're the wrong messenger for climate because of your political affiliation and background, the way Hillary Clinton may have been the wrong messenger last November—that you just turn too many people off. What do you say to that?

Social science refutes that. What caused the spike in denial was the great recession in 2008 and accelerated spending by climate deniers. We have seen recently a return to levels of public support for action on the climate crisis, just as much as after the release of An Inconvenient Truth.

What scares you most about the future?

While we are winning, we are not yet winning fast enough. The continued accumulation of manmade global warming pollution in the atmosphere adds to the damage that we will pass on to the future. Some of the changes are not recoverable. We can’t just turn a switch and reverse the melting of big ice sheets.

What gives you hope for the future?

There are so many people working around the world on this that I am extremely optimistic. It would certainly be helpful to have policies and laws that speed up our response. But market forces are working in our favor. Solar, wind, and other technologies are getting cheaper and better. More cities and companies are pledging to go 100 percent renewable. I believe the sustainability revolution is unstoppable.