"Titanic" and "Terminator 2" both portrayed disasters of epic proportions. Now director James Cameron is taking on climate change as executive producer of "Years of Living Dangerously," the Showtime documentary series starring Matt Damon, Harrison Ford and other A-list celebrities.

As President Barack Obama addressed the world at the U.N. Climate Summit in New York City, Cameron talked with NBC News about the making of the Showtime series (which recently became available on iTunes and DVD), the Avatar sequels, and why he does not have much faith in Washington.

Do you think movies and television have the power to change the minds of people who don’t believe in climate change?

That is a tricky one. I have always said that documentaries preach to the choir. You are talking to people who already tend to believe and just want more information to bolster their own arguments. Other people say, 'Oh, this is a climate change series, I don’t believe in climate change, so I’m not going to watch it.' We tried to get beyond that with stories that are intriguing on a human level.

How do you compare the impact of a documentary series with something like "Avatar?"

We certainly reached more people with "Avatar," but we reached them with a much softer and diffused message. It wasn’t so much of a message as it was a feeling — a feeling that you needed to connect better with nature.

It certainly does not give you any action items and it does not teach the specifics of the crisis that we are dealing with right now. So there was definitely a need for a documentary series.

With the second Avatar film, which I understand is going to have a strong focus on the planet Pandora's oceans, are you hoping to make more of a political statement?

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

First of all, you don’t want to deal with political issues in entertainment films. The Avatar films — and oceans will be an ongoing theme in all of the sequels, not just "Avatar 2"— are meant to create a sense of wonder and connection to the natural world.

I hope that when people watch them they can say, “I want to be part of that world, the world that is real," and hopefully that translates into them camping in a redwood forest or snorkeling on a coral reef. You can’t feel that you are ready to make a sacrifice in your lifestyle to protect something unless you respect and love it.

Do you think the state of the oceans is something that has been ignored in climate change coverage?

I think that people tend to think of the ocean — unless they live right on the coast — as something that doesn't affect them. I’m really involved in ocean issues. I know the impact that carbon pollution is having in our oceans with acidification and coral bleaching. If we stay on the course that we are on, or only mildly modify it, we are going to lose all of our coral, probably by the middle of the century and certainly by the end of the century.

For someone who learned to scuba dive when I was 16, and spent hundreds of hours marveling at the biodiversity of the coral reef ecosystem, to think that all of that could be gone — literally gone — in my kids' lifetime, that is shocking.

Was it difficult to find someone to back a nine-part documentary about climate change?

The thing with "Years of Living Dangerously" is that it was colossally difficult to get made. There was almost no receptivity among the mainstream media to make a series about climate change, at least on the scale that we wanted to do it. It took us two years to get it on its feet.

How much did it help to have celebrities like Arnold Schwarzenegger and Matt Damon connected to it?

It was very important. These celebrities are concerned citizens that are standing up and saying I’ll give up my time, pro bono. A lot of these people get paid an awful lot of money to make even relatively small appearances in films.

They were not being asked to sit down for a quick interview and be talking heads — because that would be pointless. They are not climate change experts and people should not get their facts from celebrities. But getting them to roll up their sleeves and get in there as investigative journalists ... I think it was exciting for them, and their own curiosity and concern over the issues is what drove them to do it.

Have you been working with any politicians to address climate change?

I don’t have much faith in the political process. I believe where I can be the most effective is at a grassroots level, which is inspiring and informing people, and using my cinematic skills to make a point. You need to move the needle at the grassroots level. Our leaders don’t lead; they follow the polls. Until they get a mandate from the grassroots up, they are not going to do anything, because the entrenched interests have too much of a lock on things through lobbying dollars and the campaign funding process. There are too many people making too much money digging up hydrocarbons and burning them.

You have made a few films that have depicted a dire future for humanity ...

Like all of them? [Laughs]

Are you hopeful that humans can change things? Or do you believe it's too late?

No, we’re not too late. I feel us waking up slowly to the problem. As the symptoms become more severe, people are going to need to face this thing. The real trigger in people’s minds should be that this is going to cost us a lot more later than it is now. Am I hopeful? I have five kids. It's my job as a father to be hopeful.