Hearing of the Committee on Oversight and Government Reform - Black Carbon and Global Warming

Interview

Hearing of the Committee on Oversight and Government Reform - Black Carbon and Global Warming

BREAK IN TRANSCRIPT

REP. DANNY K. DAVIS (D-IL): Well, thank you very much, Mr. Chairman. And thank -- I want to thank the panel.

Now, Europeans really moved to diesel, haven't they? That -- which is worse for black carbon, am I correct? And so, you know, that's -- they may be ahead of us in some ways and kind of behind. Is there any thought there to scrubbing this and go moving to something else?

MR. JACOBSON: So the question is whether -- what the European -- so the European is about 40 to 50 percent of all the vehicles sold are diesel -- passenger vehicles that are sold are diesel, and they emit a lot more NOx. So a diesel vehicle emits a lot more oxides of nitrogen, maybe 10 times more than a gasoline vehicle. And also without a control device huge amount more, a factor of five to ten more particulate matter in particular --

REP. DAVIS: You can see it. I mean when a diesel vehicle --

MR. JACOBSON: Yeah, and -- so a lot of the new cars they will put -- they put particle traps on a lot of the new cars, okay, but the -- even with the particle trap, this particle trap decreases the mileage of the diesel by about 3 to 8 percent. So that means more CO2 emissions. So there is a tradeoff. By reducing the particles you increase the CO2 emissions from the vehicles. But also -- you also change this ratio in the exhaust of the NO2 to NO.

And in the U.S. what that does is -- basic NO2 is precursor to ozone and smog, and in the U.S. that really produces smog right out of the tailpipe. In Europe when it's still higher latitude it's not so much. But in the U.S. there is a study looking at what the effect would be increase on average ozone over the U.S. by adding a trap to diesel -- new diesel vehicles.

REP. DAVIS: Let me ask -- who -- I don't know who is best able to answer this. But what happens to black carbon once it's reached its lifespan? Does it disappear, does it settle on ice and continue to trap heat? Does it settle but stop conducting heat, what happens? What's the end of the -- what's the lifespan and how does it --

MR. JACOBSON: I can answer. I'll -- okay, I'll answer a little bit. So most of it is removed by precipitation, and most of it will go over the ocean. Now, the stuff that settles onto the snow that's -- that will have a longer -- there is a longer impact if it settles on to snow or sea ice because it sits there for a while until it gets buried or it sinks, and -- or covered up by more snow, but even that more snow will have some black carbon.

So most of it is removed to the oceans, eventually. A lot of it will deposit to the surface too, in rain or in just some driver -- deposition to the surface. And that's because the surface soil or black top or whatever it is, it is not going to have much of an impact there, except maybe if it goes over sand in the desert.

REP. DAVIS: Dr. Ramanathan, let me ask you, what percentage of the melting ice sheets in the Artic can you contribute to black carbon? Is it hard to put a percentage on it?

MR. RAMANATHAN: I have not myself estimated the Arctic part. I think that's what Dr. Zender was talking about. But the key thing is, in the Arctic -- is one -- I think as was pointed the transport comes from all directions. Some come from East Asia, we have tracked these. Some come from North America and then Eastern Europe, so all these sources contributing to that.

The one issue I want to point out, which has not come up is that, with the sea ice retreating -- there are no talks about new ships traveling through the open water, and ship is a major source for black carbon. I am concerned that now there is going to be an additional source of black carbon directly depositing and, sort of, facilitating more ship traffic. So that's an issue which has not come up yet. And we need to worry about that too.

REP. DAVIS: Are there -- let me ask Dr. Bond. What respective roles should the developing and the underdeveloped nations play in mitigating the emissions of black carbon? And what I'm trying to say is, was it a mistake not to intrude -- to include that in the Kyoto Protocol?

MS. BOND: Was it a mistake? No, I -- but that's -- the Kyoto Protocol was the first step. It was never meant to be the ultimate solution.

REP. DAVIS: (Cross talk.) -- yeah.

MS. BOND: So, I'm not going to comment on what we should have done in the Kyoto Protocol. What matters is what we can do now and next. I don't believe that we can reduce black carbon impacts on the global atmosphere without the cooperation of developing countries.

But I think that all of this is consistent with the Framework Convention on Climate Change which refers to differentiated responsibilities between developed and developing countries.

REP. DAVIS: Sure.

MR. RAMANATHAN: I think we have to remember that about close to 80 percent of the black carbon emission comes from developing nations, Asia, Africa, and Latin America. And because of the impact of the black carbon on the local regional climate and the glacier retreat my own experience with India and China there is tremendous interest in focusing on the air pollution issues.

REP. DAVIS: Yeah. I've been to Shiyan in China where people have to wear masks over their faces just to -- that's the health issues that you addressed earlier in addition to the global warming. But at the polar caps how much of this stuff finds its way up there?

Obviously, you tell about the steamships and planes. But is there that much other stuff up there that's generating the black carbon at the polar caps?

MR. RAMANATHAN: I would defer to Charles Zender.

MR. ZENDER: The concentrations of black carbon in the Arctic are relatively low relative to the developing world where the sources are -- it is -- the problem in the Arctic is that this black carbon has essentially a double or even triple lifetime.

Because the Arctic is so very bright, as you know, the sunlight that it can absorb has two chances to be absorbed by it on its way down and on its way back up being reflected from the ice sheets. But then that third lifetime that I mentioned is, once it lands on the surface, a very, very small concentration of black carbon, we're talking parts per billion.

REP. DAVIS: It's just more potent there. Basically that's what -- (Off mike.)

MR. ZENDER: It is more potent. It's the most potent warming agent we know of in the Arctic.

REP. DAVIS: Okay. So it may not be significant in terms of its volume compared to other places, but it just has a more potent effect there.

MR. ZENDER: That's right. The exposure to inhale black carbon is very low in the Arctic. It's the atmospheric and surface effects and their consequences on climate that are of the most immediate concern, I think.

REP. DAVIS: Now, the sources for black carbon for the developed world are basically different from the developing world. For example, in Africa you have wood burning stoves, you're cutting down and burning trees, and it may be diesel in Europe, is that fair to say?

MS. BOND: It's fair. It's a different mix. We still have fireplaces here.

REP. DAVIS: All right.

MS. BOND: So it's not completely different. But, for the most part this country and Europe has the benefit of access to clean household energy. And -- but we have a lot of transport -- we have a lot more transport because we have more goods. So there is a different mix and --

REP. DAVIS: So if you fly a private plane somewhere you're creating more black carbon basically.

MS. BOND: That's true.

REP. DAVIS: (Cross talk.) -- flying coach or first class or something somewhere else. I mean, just to get into it, yeah.

If we make these technologies available to the developing world, are they available now? They're just not economic. I mean, what's the issue? Because I know in China, I talked about in Shiyan in Beijing, we were there and, you know, didn't see the sky for three days. The smog was so bad. I mean, you think over there if you make these technologies available, somebody do something about it, what's the problem?

MR. RAMANATHAN: I can comment on rural regions of India which is --

REP. DAVIS: Okay. India is fine.

MR. RAMANATHAN: -- a major source of biofuel. The government has provided connections to gas, natural gas for cooking, but they can't afford it. So it's in part, some parts technology, other is just sheer affordability of it.

REP. DAVIS: Yeah. Excuse me. When you said that, you meant natural gas or propane, propane is in the third world would be the preferable -- is the preferable choice -- (Cross talk) -- available.

MR. RAMANATHAN: This one was -- its methane not propane -- (Cross talk.).

REP. DAVIS: Okay.

Thank you, Mr. Chairman.

BREAK IN TRANSCRIPT

Source