JUDY WOODRUFF: Finally tonight: Yesterday was Earth Day, with celebrations around the globe.

Hari Sreenivasan talked recently to a geologist who is also the host of a new film. And he's traveled the globe looking for ways human ingenuity has solved tough energy problems.

HARI SREENIVASAN: "Earth: The Operator's Manual" is a new three-hour PBS documentary that looks at different ways communities within the United States and the world are making smart energy choices based on their pocketbooks and the environment.

The host of the series is Richard Alley, a professor of geoscience at Penn State university.

In this clip, he tells us what ice core samples show us about the Earth's temperature and carbon dioxide over time and takes an extreme leap to make a point.

RICHARD ALLEY, Host, "Earth: The Operator's Manual": This is a pattern of natural variability of the climate that our planet has experienced over the past 400,000 years, as recorded in the physics and chemistry of ice cores.

The regular ups and downs in temperatures are the result of changes in Earth's orbit around the sun and their subsequent effects on the levels of carbon dioxide and other heat-trapping gases. You can think of this natural variation as the Ice Age roller coaster.

Occasionally, we cross some sort of a tipping point and the Earth evolves really rapidly to a new state which is very different. Over the last 100,000 years of the Ice Age cycling, we have had a couple dozen of these large, abrupt, widespread climate shifts, almost as if the Earth was bungee jumping off the climate roller coaster.

HARI SREENIVASAN: Richard Alley joins us now.

Thanks for being with us.

So, why jump off a bridge to make a point?

(LAUGHTER)

RICHARD ALLEY: Well, we want the show to be engaging, something that will catch people's attention, but we want to tell the real story.

Now, we humans are pushing the climate. We hope that it goes nice and smoothly and gently. But when we look at history, way back in climate history, we know that when nature pushed the climate, sometimes it was smooth and sometimes it wasn't.

HARI SREENIVASAN: So when you look at those core samples, you see this fluctuation up and down. What's to say that—a lot of that happened way before humans were around. So what is to say—what is the impact that humans are having on it?

RICHARD ALLEY: Right.

So what we see from the core samples is ultimately the climate makes sense. If the sun gets brighter, it gets warmer. If you change where the sun hits the planet with the orbits, the places getting more sun tend to get warmer. If you change the CO2, raise it, it gets warmer.

What the core samples show us is that climate makes sense and that our understanding is sort of working pretty well. And so then we ask, what is pushing it now? The orbits are real slow—10,000 years from now, they will matter. Next year, nah.

The sun, if anything, has been dimming a little bit, but not much change. It really hasn't been very stable and friendly to us. But we are turning that CO2 knob. So we take the understanding that works in history and apply it to the future, and we see that we're going to matter.

HARI SREENIVASAN: Now, you have had an opportunity to visit several different communities around the country. For example, in Baltimore, some of the poorest folks are actually making the biggest difference and saving the most money when it comes to starting to conserve the energy that they use.

But one of the questions people ask is, will changing my lightbulb really make a big difference?

RICHARD ALLEY: Changing your light bulb will make a little difference for you, but it will save you money. And if all of us change our lightbulbs, it really does make a difference.

And this is something I think is really important, is that these things work for people. They're—people are enjoying it. They think they are doing the right thing, the good thing, but they are also helping themselves in the pocketbook.

HARI SREENIVASAN: Now, let's take a look at the producer's side of the equation. You had a chance to go to China and take a look at Shidongkou—or Shidongkou energy plant there, where they have a pretty promising technology to try to clean up the CO2 that they are emitting.

Let's take a look at that clip.

RICHARD ALLEY: This plant uses a process called post-combustion capture, PCC, where coal is first burned in a more or less traditional manner, and then the CO2 is captured.

JULIO FRIEDMANN, Lawrence Livermore National Laboratories: So, Shidongkou is remarkable in every way. They are capturing 150,000 tons of carbon dioxide, and they have been doing that now for about 18 months successfully.

RICHARD ALLEY: Shidongkou sells the captured CO2 for use in soft drinks and chemicals, turning it into a resource. In the future, they will scale up and begin sequestering the CO2 deep underground.

JULIO FRIEDMANN: Already, that means that it works and that the cost and performance are pretty well understood. So, if it can be widely applied, then it creates the new benchmark that will define whether or not this works anywhere else.

HARI SREENIVASAN: I should mention the gentlemen in there is Julio Friedmann from the Lawrence Livermore National Laboratories.

Further in the documentary, it says maybe that could work for a 20 percent cost increase. Do we collectively have the will to swallow that kind of pill?

RICHARD ALLEY: I think we do. I think ultimately we love the benefits we get from energy.

And ultimately we're going to want a lot of energy and we're going to want energy in the way that our grandchildren and their grandchildren can have it. And so we will do what is needed in the brains, in the invention, in the implementation that will get us the energy in the best way. And by finding out what this will cost, what you can do, it lays it out for you.

And now you can say, look, this is doable. We can do this. We can mine coal and we can get energy from coal, put the CO2 down. Or we can do wind, or we can do sun, and we can conserve, and we can -- now you have a full menu that you can choose from for what works for you, your country, your individual community, for yourself.

HARI SREENIVASAN: How important is convincing governments of this?

RICHARD ALLEY: There are problems that each of us as an individual can solve. We do not need a federal monitor to make sure I wash my hands after I use the restroom.

There are problems that our governments have solved with barely a problem for us. The ozone hole is going to get fixed because inventors came up with new things, and the governments agreed how to implement them. This problem is—energy and environment is probably big enough that it's going to take us as individuals and us working together.

HARI SREENIVASAN: Richard Alley, thanks so much for joining us.

RICHARD ALLEY: And thank you.