Last week, John Holdren appeared for a 45 minute interview on NPR Science Friday with host Ira Flatow. Below the fold, I have pasted excerpts of his comments relative to climate change policy options as well as investment in nuclear energy. In the interview, Holdren also had the chance to elaborate on his past comments on geo-engineering. Here's what he said:

FLATOW:...Let's talk a little bit about - back to energy a little bit and in global climate change. I know you've been in the press a lot, in the media a lot, talking about geo-engineering as something that is - you were quoted as, "something that was on the table." You're not the first one to talk about geo-engineering. There's been a lot of science agencies that have been talking about that for quite a while.

Dr. HOLDREN: Well, I didn't really talk about it in the way that that was reported. I was taken out of context, and I did not say it was under consideration by this administration. What I was asked about, whether I thought geo-engineering needs to be thought about in the context of the climate question, and I said, from the scientific standpoint, of course it has to be looked at. We have to understand if there's any potential there, we have to understand what its costs and its downsides are.

But there are vast, different set of possibilities for doing that. And then I said in the interview - although this part didn't get reported in most of the stories - that the approaches to geo-engineering that have been looked at so far mostly looked very expensive, of limited effectiveness and burdened by big side effects.

That doesn't mean we should keep looking at them, but they're certainly not under consideration for use in this ad-ministration. This president is committed to an approach to global climate change which includes putting a cap on car-bon pollution. It includes having a renewable electricity standard and a number of other measures. And we think those are going to do the job. If they don't do the job and people become interested in geo-engineering, it will be important to have some scientific analyses that show whether there's any potential there that is worth pursuing. There are a couple of rather simple approaches that actually fall under the heading of geo-engineering that could be valuable. One is turning black roofs into white roofs. If you just put white roofs on top of all your buildings instead of having a dark-colored roof, you reflect more of the incident sunlight back into space and you warm the area less than you otherwise would. Strictly speaking, that's geo-engineering, too, probably a lot more reasonable than some of the more far-out schemes that have been discussed.

*More general comments on global warming.

FLATOW: Let's turn a little bit to something that you brought up before, and it is really an 800-pound gorilla, and that is climate change, global warming. How big of a problem does this administration view that, and how much are the alarm bells going off up there in Washington?

Dr. HOLDREN: Well, again, the president has been very clear about this. He's been clear through the campaign, he's been clear in many, many speeches he's given since he was inaugurated. He sees climate change as a major chal-lenge, but also, as with many challenges, a major opportunity.

It's going to drive innovation. It's going to lead to the development of new technologies and new businesses that are able to deliver the energy services that people want while reducing the carbon pollution that we produce, and we're go-ing to get it done.
He is on record repeatedly as saying in this country, we need a set of climate-change targets and mechanisms for getting there that will reduce our emissions of heat-trapping gasses by something like 14 percent before the 2005 levels by 2020 and that will reduce them by more than 80 percent by 2050.

That is a big task, but the ambitiousness of those goals underlines how the president sees the importance of this problem. This is something that, for ourselves and as our contribution to the rest of the world, we need to get right, while helping everybody else to get it right too, because this is a problem that the United States cannot solve by itself.

FLATOW: Are we talking about a carbon tax here? Are we talking about cap and trade? Are we talking about - just what? And what methods are we looking at in our...

Dr. HOLDREN: Well, again, there are many different ways to go at it, but economists will tell you that the most efficient ways - that is, the ways to reduce carbon pollution most - at the lowest possible cost, are likely to be found by putting economic incentives to do it out there and letting the private sector and ingenuity determine the most economi-cal ways to proceed.
There are basically two approaches that fall in that category. One is a tax, and the other is the so-called cap-and-trade system, putting a cap on carbon pollution and having tradable permits that determine who gets to do the emissions and how much they pay for them.
In the U.S. political environment at the moment, it seems overwhelmingly likely that the approach to capping car-bon pollution, rather than taxing it, will be the one that is embraced.

That's the one that's embodied in the bill currently being debated in the House Energy and Commerce Committee in the U.S. Congress. It's the one the president advocated during his campaign. And again, he was very clear about that. He said he wanted to use the cap-and-trade approach. He wants to auction 100 percent of the permits, and there's now, of course, proceeding in the government the usual complicated process. The House will produce a bill. We trust eventually the Senate will produce a bill. There'll be an attempt to get those bills reconciled and to come out ultimately with something that the president will be willing to sign. My hope, and the president's hope, is that that happens sooner rather than later, because this really is a challenge on which we need to get going.

Just before his answer above on global warming, Holdren was asked about nuclear energy.

FLATOW: Do you also believe that we should be investing in nuclear power and building new nuclear-generating capacity?

Dr. HOLDREN: Well, I think, first of all, yes, we should be investing in nuclear energy. We should be investing in approaches to addressing the difficulties that have prevented us from expanding nuclear energy to a greater extent up until now. We should be doing research that is addressed at making nuclear energy more cost-effective. We should be doing research to address the problem of how we manage the radioactive waste. We should be doing more research to reduce the linkages between nuclear energy and the proliferation of nuclear weapons.
I do think that if we could get an expanded contribution from nuclear energy, it would be a tremendous help in ad-dressing the climate-change challenge, which is almost without question the toughest part of the energy challenges we face.

In addition, going back to the previous point, if we did have plug-in hybrid vehicles, you could finally have nuclear energy, as well as renewable forms of electricity generation, making a contribution to motor-vehicle energy consumption, and that would be terrific.

FLATOW: If we don't have - if we have not solved the waste-disposal problem, how can we move forward on building plants?

Dr. HOLDREN: The approach to waste disposal can take a number of different forms. Right now what we're doing is we're storing the radioactive wastes at the reactors in fuel-storage pools and what's called dry cask storage. We could, if we chose, build at a variety of places around the country, engineered interim nuclear-waste-storage facilities, basically steel- reinforced concrete facilities that would contain the radioactive waste safely for a century or more while we explored what the best geologic options would be for the longer term.

So we're not without options for dealing with our radioactive waste, but I think everybody will be more comfortable about expanding nuclear energy once we have chosen a particular path, and that is why the secretary of energy has announced the creation of a blue-ribbon panel to look again at the options that the country has for radioactive waste management going forward. There are, again, a variety of those options, and I trust that that blue-ribbon panel will be help-ful in steering the country toward a choice that will enable us to proceed.