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LUKE BURBANK, host:

Well, yesterday's opening ceremonies are done, and today, it's time for getting down to business on the island of Bali where, all this week, the representatives of the world's governments are talking emission limits and caps and trade and carbon credits. Thrilling, right?

What if I told you about some fantastical scientific ideas that could make it all go away tomorrow? Well, that would be a dirty, dirty lie, because nothing like that really exists.

However, there are a number of pretty cool areas of research that might at least help in ways that we haven't even thought of yet. And this week, we're taking a look at some of those ideas in a series we are calling…

(Soundbite of song, "Theme from The A-Team")

BURBANK: …It's So Crazy, It Just Might Work. Yesterday, we talked about building huge mechanical trees that grab CO2 out of the air. Later this week, we're going to investigate the idea of erecting a sort of particle umbrella over the atmosphere.

But today, could dumping a bunch of iron shavings into the ocean do the trick? A while ago, I talked about the idea with Bob Anderson of the Earth Institute at Columbia University. The idea behind this bit of geo-engineering is that the iron dust would cause phytoplankton to bloom…

STEWART: Of course, it would.

BURBANK: …and suck CO2 out of the atmosphere.

STEWART: It makes perfect sense.

BURBANK: It's an idea, Alison, so crazy - actually, just let me have him explain.

Dr. BOB ANDERSON (Earth Institute, Columbia University): If I can start with a simple analogy about a garden: If you're growing plants in a garden, you add fertilizer. You add nitrogen and phosphorus typically, and the plants grow faster. When the plants grow, they take up carbon dioxide from the atmosphere to build their tissue. In the ocean, plants are microscopic, but they still need nutrients like nitrogen and phosphorus. But what they don't have is soil to get their iron from.

Because of iron's unique chemistry, it's rapidly removed from the ocean, so that oceans in many places are iron-limited. So you can add iron in a location where there's sufficient nitrogen and phosphorus. The plants will grow much faster, take up more carbon dioxide from the water, and then, eventually, from the atmosphere. And that's the basic principle of how it works.

BURBANK: So somehow, that interaction between the surface of the ocean and the air, there's a process by which the stuff gets sort of drawn down and then recycled through the plant life that's in the ocean?

Dr. ANDERSON: Right. There's already some carbon dioxide present dissolved in seawater. But if you stimulate their growth enough, they will use more than is available, and that will cause carbon dioxide in the atmosphere to diffuse into the ocean.

BURBANK: I guess a question that comes to my mind is doesn't the ocean have a certain homeostasis already?

Dr. ANDERSON: There are at least three or four answers to that question. Most of my own work is looking at the paleorecord of whether the ocean changed in the past. We know it changed in the past quite substantially, yes, the ocean has a homeostasis, but in terms of natural variability, they're actually quite large-ranged as the fluctuations.

BURBANK: Okay. So we could add in, potentially, something like this iron filings, and it wouldn't necessarily mess up the sort of balance of everything.

Dr. ANDERSON: Well, that's a tricky question - a very controversial one. There are some pragmatic consequences of adding iron. For example, if you increase the biological productivity of the ocean, one of the consequences that could occur is that many of the low oxygen zones - maybe you've heard of some of the hypoxia events off of the mouth of the Mississippi River…

BURBANK: Sure.

Dr. ANDERSON: …or off of Oregon. It's where respiration by bacteria and zooplankton and fish exceeds the supply of oxygen by a mixing of water from the surface down. So the oxygen concentrations go to zero - close to zero, and pretty much everything, except bacteria, will die. We all need oxygen - so do the fish, so do the shellfish.

The other practical consequence is that a process called denitrification occurs there. That produces nitrous oxide. Nitrous oxide is a more powerful greenhouse gas than carbon dioxide. So…

BURBANK: Oh, that's not good.

Dr. ANDERSON: No. So even though you're taking carbon dioxide out of the atmosphere, adding iron could increase the nitrous oxide going back into the atmosphere and offset part of the greenhouse benefits of removing the carbon dioxide.

BURBANK: Let - so let's say that this process was going work, and it wasn't going to damage the ocean so badly that it couldn't recover. How much carbon dioxide could this really draw out of the atmosphere?

Dr. ANDERSON: Sort of a back-of-the-envelope calculation - which I would say has a huge uncertainty - we're looking at something the order of 10 percent of the carbon dioxide released by fossil fuel burning, and that's if we did it perfectly. That's pretty unrealistic.

BURBANK: This idea, which sounds kind of a little bit fantastic and then maybe like it's a magic bullet, what do you like about this idea?

Dr. ANDERSON: One of the most appealing features is that it's relatively inexpensive, and mechanisms of people are talking about require new inventions, new technology. The technology exists to do this. What I do not like about it is there are possible unexpected negative consequences affecting fisheries, affecting nitrous oxide.

But I think the biggest single difficulty is coming up with a mechanism to verify how much carbon a corporation should be credited with when they add iron to the ocean. A company may say we deserve one million tons of credit. And an adversary may say, no, it's only a hundred thousand tons of credit. And the technology right now doesn't exist to discriminate between those two, and that makes a big difference in terms of whether or not this could be profitable.

BURBANK: And providing businesses with some incentives to combat climate change, that has to be part of any proposal to deal with CO2, Bob Anderson went on to tell me. That was Bob Anderson of the Columbia University Earth Institute - part of our series It's So Crazy, It Just Might Work.

STEWART: So as you're discussing these topics with all these very smart people, are - isn't this what they spend their lives work doing? You know, like, solely focused on these issues?

BURBANK: Well, I think what's happened with a couple of these guys is that they sort of were doing a bunch of different things, and then they got on to something like this, like the guy on yesterday with the mechanical trees. He'd - his daughter actually did a science project…

STEWART: Oh, that's funny.

BURBANK: …when she was in eighth grade kind of loosely based on this idea. He had sort of told her, why don't you trying to do something with these mechanical trees? And she built this little mockup, which he helped her with. And he got so into it that now it's become this huge area of kind of emphasis for him.

This guy, Bob Anderson, we just heard from today, he actually is kind of a guy who's an oceanographer. And so he was more here just to tell me about - he is actually not even a big proponent for this iron filing thing. But it does seem that in talking to these guys that one of these ideas is going to have to sort of catch.

STEWART: Right.

BURBANK: It may not be either the ones we've heard about already, or even the one we'll hear about later this week, but something's going to jump and kind of make a big difference. It's just a question of which one of these things it's going to be.

STEWART: We'll talk about the big umbrella later in the week.

BURBANK: Yes. Space umbrella.

STEWART: Also in THE BRYANT PARK PROJECT today, you're talking into a machine, it comes out in another language. That's not nearly as fun as saying, the Phraselator. That's what it's called, and we'll find out more about it.

BURBANK: And planning your funeral online. We're going to talk to a guy who developed a site that's being billed as TripAdvisor of the afterlife. That's coming up.

Plus, new music on this Tuesday on THE BRYANT PARK PROJECT from NPR News.

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