MS. DIANE REHMThanks for joining us. I'm Diane Rehm. A new report shows worldwide carbon emissions from energy use have risen to record highs. Yesterday, New York City Mayor Michael Bloomberg issued fresh warnings about that city's vulnerability to climate change. Joining me to look at the growing pressure on political leaders to take action against global warming: David Kreutzer with the Heritage Foundation, Steven Mufson of The Washington Post, and Nathaniel Keohane of the Environmental Defense Fund.

MS. DIANE REHMI know many of you feel strongly about this issue. I hope you will join in our conversation. Give us a call, 800-433-8850. Send us an email to drshow@wamu.org. Follow us on Facebook or Twitter. Good morning to all of you.

MR. STEVEN MUFSONGood morning, Diane.

MR. DAVID KREUTZERGood morning, Diane.

MR. NATHANIEL KEOHANEGood morning.

REHMBut first, joining us by phone from Marion, Mass., Jennifer Francis, she is a research professor at the Institute of Marine and Coastal Sciences at Rutgers University. Prof. Francis, I wonder if you'd give us a brief overview of the International Energy Agency's report on climate change.

PROF. JENNIFER FRANCISSure. Good morning, everyone. The impetus of this report, as Diane already mentioned, is that we have recently broken two very important records, and the we there is all of humanity on this planet. And neither of these records is something for us to be proud of. As Diane mentioned, the first one is that we have reached the highest ever emissions of carbon dioxide and greenhouse gases in 2012, and we recently broke through the 400 parts per million concentration of carbon dioxide in the atmosphere.

PROF. JENNIFER FRANCISThis is the highest amount of carbon dioxide that's been in the atmosphere in at least 800,000 years. And we know that the last time there was this much carbon dioxide in the atmosphere, the earth was a very different place. It was several degrees warmer, sea levels were tens of feet higher, and there were forests in the Arctic. So both of these records are very significant, and that's why this report came out. And...

REHMAnd who set the goal, Prof. Francis?

FRANCISThe goal of two degrees?

REHMYes.

FRANCISWell, it's been a generally recognized goal. It's not very exact, I would say. It's an estimate of how much warmer the earth can be compared to, say, before 1950 without having very damaging changes to the climate system. But we're -- I should note that we're already almost halfway there. We've already warmed about almost one degree. So the report points out that we're -- right now, if we keep going the way we're going, we're on track to warm more like 3 1/2 to 5 1/2 degrees centigrade, which is about eight degrees Fahrenheit.

REHMWhat about China? I gather China experienced the largest growth, but its increase was one of the lowest in a decade.

FRANCISRight. So China is being -- is taking very seriously this problem of increase in greenhouse gases in the atmosphere, and even though they are using a lot of coal to generate the energy that they need to grow, they're also investing heavily in renewable power. So it's starting to show up as an improvement in their emissions, as it is also in the United States.

REHMSo what about the IEA's suggestions on how to reduce these emissions? What are they?

FRANCISRight. So they have come up with basically four specific steps that are considered doable based on existing technology, and they pretty much target the energy sector of our society. And that's because two-thirds of the global emissions of greenhouse gases come from the generation of power, and 80 percent of that comes from fossil fuel. So fossil fuels play a huge role in generating the electricity that we all use. These four specifics steps, very briefly, include basic conservation and increased efficiency.

FRANCISThat accounts about half of the emission savings that they're recommending. The second is to replace more of the coal that's being used to generate electricity with either natural gas and particularly with renewable sources. The third is to reduce the amount of methane that is sort of waster by the development of fossil fuel extraction and also the processing and also to accelerate the phasing out of subsidies for fossil fuels.

REHMAnd you talk about the fact that we've got to figure out where impacts from climate change are greatest. What did you think about Mayor Bloomberg's comments?

FRANCISRight. Well, I think, you know, Mayor Bloomberg got -- his city was smacked right between the eyes by Hurricane Sandy, and it really woke up the world to the fact that climate change is playing a role in not only changing the weather patterns that we're seeing in all seasons now, really, but also probably contributing to real vulnerability for most of our cities along the coast.

FRANCISNot only are sea levels rising, but we have moisture in the atmosphere now. And the atmosphere is warmer. And both of those factors mean that storms that form these days have more energy to work with. They have more moisture to work with. And so we're seeing the impacts of these changes coming before our very eyes now.

REHMJennifer Francis, research professor at the Institute of Marine and Coastal Sciences at Rutgers University, thanks so much for joining us.

FRANCISYou're welcome.

REHMAnd, David Kreutzer, turning to you, your take on Jennifer's comments and the IEA's suggestions?

KREUTZERWell, the IEA seems to be proposing that things are getting worse when the scientists who are -- that study the impact of CO2 on temperature are shaving down the high-end estimates. They don't expect to see the 4 1/2-degree-plus warming. And Andy Revkin and the Dot Earth Blog has really been covering this very well. His with, you know, The New York Times blog. But the study that just came out highlights one of the big problems with doing a policy in the U.S. or even in Europe.

KREUTZERWe've seen that our CO2 emissions have gone down in the past year, primarily from lackluster rebound from the recession and also switching from coal to natural gas. Europe's CO2 emissions have been lower. The big growth is going to be coming from the poor countries that are energy poor already, and it's going to be tough to get them to hold back. I would like to make some comments on people who point to things like Hurricane Sandy or floods or tornadoes and say, see, this is from climate change.

KREUTZERIf you look at the trends of hurricanes over the past century when we have had this degree of warming, there's -- it's flat. The hurricanes in the U.S. -- there's no upward rising trend in hurricanes. There's no upward rising trend in powerful tornadoes, the F3, 4, 5. People look at flooding worldwide in the U.S. There's not an upward trend in flooding.

KREUTZERSo it's really disingenuous to say, we believe in science and then point to these events that we've had all the time. We've had hurricanes hit New York and the Mid-Atlantic. We've had a lull lately, but now they're coming back. We had that in the '50s. So I think we need to be careful if we're talking about science not to abuse individual events, link them to warming when the trends simply aren't there.

REHMDavid Kreutzer of the Heritage Foundation. Nat Keohane, you have a different view.

KEOHANEYes. Thanks, Diane. Let me address the science really quickly although David and I are both economists, so it's too bad Jennifer's not here to address the science as well. First, David mentioned some of the new thinking he referred to about how sensitive the climate is -- the atmosphere is to greenhouse gases. And that's -- I think the jury is still very much far from out. And the scientist I have talked to say, we still see the same kind of concern, the same kind of urgency and sensitivity of the atmosphere.

KEOHANEThere's a couple of new models, but there are other models that say something very different. And I think, overall, we clearly see the direction and the concern about warming. Second, just briefly on the trends, again, I think you see a number of scientists coming out and saying, what you can say about attributing the effects of climate change in terms of extreme weather is things like the storm surge associated with Hurricane Sandy was greater than it would have been because the oceans are higher.

KEOHANEWe know that sea level has risen. And so at the very least, we can say, Superstorm Sandy in New York, where I'm from, had a greater effect than it would otherwise have. We can also say that the models -- the best available science we have tells us this is the type of thing, the type of event we're likely to see more and more and more of. So I think in terms of the impacts, we're already starting to see what the world looks like with a warmer climate.

REHMNathaniel Keohane, he's at the Environmental Defense Fund. Steven Mufson, what about these recommendations? Are they economically practical for countries and even companies?

MUFSONYes. I think in a lot of ways, they are. And I think that was what the IEA was trying to do, is to come up with things that we could do that wouldn't necessarily hurt our economies. And energy efficiency measures, for the most part, are things that pay off in very short periods of time. The capture of methane emissions from upstream oil and gas operations are something that would benefit the companies that did it because they'd be able to sell that natural gas, although in some places it would require building substantial amount of infrastructure.

MUFSONBut it's still something that would have at least some sort of payoff at the end. Probably the hardest thing, in some ways, would be to limit the emissions from coal-fired power plants. But a lot of those are older plants, and I think we're going to see a lot of those plants going offline anyway. So I think that, again, it's something that could be doable.

MUFSONI'd say one thing about some of the things David said, that while the U.S. has made some steps toward reducing CO2 emissions in the past year, it's important to remember that some of those trends might not last that long such as the switching from natural -- from coal to natural gas. That could be a limited phenomenon.

REHMSteven Mufson, he's energy correspondent at The Washington Post. Short break here. And when we come back, we'll talk further and take your calls.

REHMAnd we're talking about a new report from the International Energy Agency regarding climate change, the rise in CO2 levels beyond what are healthy and good for human beings, good for the country, good for the world. We talked with a scientist who laid out what that energy report says. But, David of the Heritage Foundation, you argue that the cure is really worse than the disease.

KREUTZERRight. You know, actually, I did a report recently where I took some estimates that economists did from MIT on how much warming impacts growth, primarily of the poor countries. And I looked at the estimates that the EPA made of how much doing something like the Waxman-Markey cap-and-trade bill or an equivalent carbon tax cut would do to our growth. And if we had that, the damage to our growth is worse than the benefit to the poor country so that worldwide GDP drops.

KREUTZERAnd if you bring in Europe, it actually gets worse. So that's exactly right. The cure can be worse than the disease. And the reason is none of these policies are going to end CO2 emissions. They're going to stop global warming if it is caused by the CO2 emissions or to the extent that it's caused by the CO2 emissions.

REHMAnd, Nat, you totally disagree.

KEOHANEYes. Well, I mean, I've read David's report, and it's, you know, I think it's best to call it, David, a back-of-the-envelope calculation. And I think there's a lot missing from it. Frankly, these tricks have been -- well, I think we've seen this kind of report again and again, and it feels like we need to move beyond this false debate. Look, what we're seeing in terms of Hurricane Sandy, what we're seeing in terms of droughts and floods, again, I think -- and a lot of scientists think you can attribute that to climate change.

KEOHANEWe know that that's -- what the future looks like. And those costs, the cost of inaction, the cost of the consequences of climate change, those are the costs we should be focused on. I also want to pick up something about the report -- the IEA report. You know, climate -- taking action on climate change to reduce emissions, it's not going to be free. But the IEA report gives us a path forward for things that will make money back and that overall, as a package, will have no net economic cost.

KEOHANEThings like removing inefficient fossil fuel subsidies or things like making greater investments in energy efficiency that pays back over time, as a package, the IEA says -- and this is the world's most respected energy authority -- says these things don't have a net economic cost on any country or region, and they can get us on a path to safer trajectory.

REHMSteven Mufson.

MUFSONWell, I must say just something about the costs of climate change going forward. And I think any projection that's out to 2050 is going to have a huge margin of error. And in evaluating these predictions for the newspaper, I'm always a little cautious. But directionally, I think they tend to be similar. And even if you assume half of what some climate scientist predict will actually come true, that would still be quite serious.

MUFSONIf you look at some of the things big insurance companies are saying, like Munich Re is probably the best known for this, but they're increasing their estimates of what potential damages could be and how they would grow from climate change in the future. And that's pretty persuasive. Those are the people who are in the business of calculating risk.

REHMSteven, where are with the number of scientists who argue that climate change not only is happening but that it is indeed man-made? You know as well as I that there are still a great many people out there who argue that climate change may be happening, but it has nothing to do with human activity.

MUFSONI think, at this point, the vast majority of climate scientists would agree that climate change is happening and that humans are contributing to it in some significant way. And if you look at opinion polls of the public, the public, even among Republican Party members, tend to believe this as well. I think it's one reason why Gov. Romney's statement at the Republican National Convention was probably not a good political move to poke fun at President Obama for caring more about oceans than jobs.

MUFSONYou know, the climate issue seems very real to people, especially in some swing states like Colorado and Florida. So I think that both at the expert level and the public opinion level, there's a fair amount of consensus about this.

REHMAnd just to be clear about positions here, David Kreutzer, would you agree with what Steven just said?

KREUTZERRight. Because he didn't talk about any sort of hysterical climate catastrophe coming. You know, I run in these circles of people who are called climate skeptics or deniers. It's not clear what they think we're denying. Universally, all of the scientists that I talk with say, yes, there is an impact from CO2. It's a greenhouse gas. Nobody can deny that. And there's some warming from it. Now, the question is, how much warming are we going to get?

KREUTZERAnd as an economist, I say, OK, if you have that, how much benefit are we going to get from the costly programs to cut it because we cannot eliminate this impact. And so that's where, I think, we will have the biggest disagreement, not that there are some fingerprint of man-made global warming. But how significant is it, and what would the policies do to mitigate it?

REHMSo has this become a political argument? Nat.

KEOHANEWell, I think one thing you do see is signs of renewed interest and concern about this in government and in high levels of politicians. I think you see the president -- Obama looks in his second term. He's talking -- he started off the term, started talking much more about climate change. I think we'll see more action from the administration on climate change, which is welcome.

KEOHANEAnd you also see -- you see folks like the World Bank President Jim Yong Kim and you see -- like the head of the IMF, Christine Lagarde, starting to talk about this, putting it in the mainstream discussion from people saying, look, the biggest threat to our economy long term, from people like the World Bank and the IMF president, is climate change. So I think you're starting to see more people of that caliber and that stature talking about this. And I hope that that focuses and translates into action, and groups like ours will certainly be pushing them.

REHMDo you believe it will, Steven?

MUFSONYes, I do. And I think that one of the things to think about when we're talking about measures to limit climate change is that some of these measures aren't necessarily bad from a -- just, let's say, take a carbon tax from a tax policy point of view. I think that almost anyone at Heritage or any place else would say that it's a bad idea to tax labor. It's a bad idea to tax capital. We do it because we need tax revenue, not because we think it's necessarily a good idea.

MUFSONAnd so we do it, you know, as little as possible, given the amount of revenue we want to have. But if you're taxing carbon, that's actually taxing something that we don't want to have happen, that could increase sufficience (sic) to the economy, that could have some positive effect on national security. And I think that at some point, if only as a matter of tax policy as well as a climate policy, that we're going to have to have a more serious discussion about whether or not we want to tax carbon.

REHMDavid, it's so interesting to me to read Mayor Bloomberg's comments yesterday that he was encouraging business and residents to better prepare against hotter weather, fiercer storms, increased rainfall. Administration officials estimate that more than 800,000 city residents will live in 100-year flood plains by 2050. That figure is now more than double the current estimate. I mean, how do you react to that?

KREUTZERWell, first of all, Mayor Bloomberg isn't -- I'm not -- is not a scientist. All right? And I'm not very impressed with his projections. He got caught, I think, with his pants down with Sandy and would like to blame it on other things. There...

REHMDo you think his statement was pure politics?

KREUTZERI don't think it's going too far out on a limb to say that a mayor of New York is primarily focused on politics.

REHMAnd I want to get your reaction to that, Nat?

KEOHANEWell, I'll just say as someone who lived in New York -- who lives in New York City and saw some of the destruction on Long Island, in Queens, certainly first hand, saw some of the destruction in New Jersey, the shore, I think if you can say even part of that, and I think scientists are comfortable saying even part of that is attributable to climate change and part of those damages, I think that's just a sign of what's coming. And I think Mayor Bloomberg is right to be focusing on this as an issue.

REHMSteve Mufson.

MUFSONI think that from -- my takeaway from looking at some of the climate scientists is that a lot of the risk is on the, I don't know what you'd call it, upside or downside, but on the more serious side, and that some studies that we've seen coming out of places like Alaska and the Arctic suggest that if there's any error in forecast, a lot of that error is toward the more serious consequences, looking forward. So I'd be very cautious about dismissing some of these concerns, and we're pretty cautious about it at the Post.

KREUTZERI'm not dismissing concerns about damage from hurricanes. We've had them in -- you know, they had hurricanes in Mid-Atlantic in the '50s. They had worse storms earlier, and they had them in the 1800s. I think it's very prudent when you have more people living in areas that are storm-prone to take more measures.

KREUTZERI think it's wishful thinking to say, we're going to cut CO2, and in 100 years the sea level will be a couple of inches lower than it would have been otherwise if we hadn't cut it because cutting it is not going to do much. It's better to take -- to look at the problem directly, take action right now, than to say, we're going to cut CO2. That will have almost no impact in the next 10 years.

REHMAnd what action would you take right now?

KREUTZEROh, I think they should look at seawalls, building up -- there's some -- there was a town in New Jersey that did a decade or so ago. You know, they built up the sand dunes around the town, and they were much less impacted than the towns that didn't take protection.

REHMBut wouldn't you say doing that would cost a great deal of money?

KREUTZERYes. It cost a great deal of money, and it had saved a lot of real estate.

REHMNo, no, around the country, in vulnerable areas.

KREUTZERYou -- I wouldn't do it for the Everglades. I would do it for Miami, I would do it for New Orleans, and it's because we're going to have hurricanes regardless. And so if the question is we want to have a costly program that's going to have a moderate impact 100 years from now, or a less costly program that's going to have a direct impact immediately, I would go for the second one.

REHMI want to ask about the trend line that David talked about. Nat, what does the Environmental Defense Fund see in terms of frequency of hurricanes, floods, tornadoes and the like? Are we simply experiencing a funny bump?

KEOHANESo I think it's an excellent question, and it's a hard question to do the attribution to any individual event. And so that's why, for example, when I talk about Hurricane Sandy, I say, OK, what I think scientists are comfortable saying is rising sea levels translate into a higher storm surge. Can we say that Sandy in particular? Well, you know, there was actually -- there was a paper that was written a couple of weeks or months before Sandy that predicted that global warming would lead to a change in the jet stream that would bring more hurricanes at the Eastern Seaboard.

KEOHANEDoes that mean that Sandy was attributable to climate change? I don't know. Is it consistent with everything that models say? Yes. And so I think the question of attributing this event versus that event is not as much important as the overall trends we are already seeing. The trends in terms of drought and temperatures and so on and 100-year floods coming every couple of years, I think those we're seeing.

KEOHANELet me make one more quick point just to follow up on something Steve said, and that is an economic argument for doing this. Look at the package of things the IEA says we should do. Here's a package of things, no net economic cost, that get us back on a trajectory toward climate safety. Do those by 2020.

KEOHANEIf David Kreutzer -- if David is right and we start learning, oh, the climate is not as bad as we think, then we've done some things that save people money, that save energy, that give us cleaner air. And if I'm right, then we are in a position to really take the actions we need to avoid catastrophe.

REHMAnd you're listening to "The Diane Rehm Show." Steve, I'd like your reaction to this trend line. Different trend lines from these two men.

MUFSONWell, I think the -- I think on the question of how you -- if you see the trend line as something growing more serious, how do you respond to it? And I think it needs to be a bit of both. I mean, we are already, in New Orleans, having to build levees higher. So it's not...

REHMOf course.

MUFSON...it's not as though we're not doing things now to defend against phenomenon that may at least, in part, be attributable to climate change. So -- and I think we're seeing some adaptation efforts in a lot of other countries that are much more aggressive because they're in much more serious trouble. You look at...

REHMSuch as?

MUFSON...Bangladesh or parts of China, Southeast Asia. These places are already inundated on a regular basis, and there are a lot of people working on efforts to try to build levees or to stop erosion in places that could help in the near term. So I don't think they're -- these things are mutually exclusive.

REHMAnd do you see those other countries making other efforts to reduce CO2?

MUFSONWell, some of the developing countries aren't, you know, admitting that much, but in the big ones -- you know, in India and in China -- this is going to be important. And in China, there's a very sharp awareness of this already partly because of the phenomenon this winter of the very severe attacks of air pollution in the major cities, which wasn't just about CO2. It was about other pollutants. But I think it sharpened people's awareness of the effect that industrialization in China is having on the environment and has built some pressure for the government to take some sort of action.

REHMAnd China is doing just that.

KEOHANEI was just going to say very briefly, there's a sort of myth that China is not doing anything, that the U.S. has to go at it alone, but, in fact -- and -- now, you know, China needs to do more. The U.S. needs to do more. The world needs to do even more. But what we're seeing in China is a response to the air pollution problems that they have and a very real awareness on the part of the government that getting to cleaner energy, getting away from coal is part of their solution to giving their citizens cleaner, healthier air.

KEOHANESo that's one of the examples of the great benefits you get in terms of cleaner air, less air pollution, from doing the same things that also cut greenhouse gas emissions and carbon.

REHMWhat about that, David?

KREUTZERYou look at China. They have a horrible traditional pollution problem. We have the technology to clean that up, and it's effective. We've been using it in the U.S. for 20, 30 years, and they're not adopting that. This is the pollution that hurts you. So they -- the fact that they won't even cut the pollution significantly that harms them directly, all right, really brings into question what makes you think they're going to have serious expensive efforts to cut energy use for the pollution that doesn't affect them directly?

REHMSteven.

MUFSONWell, as you know, Diane, I was The Washington Post correspondent in Beijing from '94 to '98, and I was just back over there for three weeks, and I think they are doing things. They're not doing nearly as much as they could be doing, but you can already see some effect. The emissions went up 3.8 percent, but that's much lower than the rate of growth of the economy. So energy efficiency has improved about 17 percent in recent years.

MUFSONAgain, that's not nearly enough from a climate point of view, but it is -- there are strides going forward. There are problems with enforcement on pollution issues. A lot of -- there are a lot of plants that may have scrubbers to deal with traditional pollutants that don't run them because they cost some -- lose some of the energy output. But I do think things are moving in generally the right direction, if not fast enough.

REHMSteven Mufson, he's with The Washington Post. Nat Keohane, he's at the Environmental Defense Fund. David Kreutzer of The Heritage Foundation. Your calls when we come back.

REHMAnd we're back. Time to open the phones, 800-433-8850, to Gainesville, Fla. Good morning, Jules.

JULESHi. I actually have two questions for you.

REHMSure.

JULESBut first, it's a pleasure to speak with you.

REHMThank you.

JULESBut, this is for the gentleman who said that the solution is sometimes bigger than the problem in regards to developing countries. I'd like to hear what he has to say about sea level rise in the island nations, such as Vanuatu and Papua New Guinea in the Maldives that are physically losing ground. And secondly, about the rise in global temperature and the species migration and the spatiotemporal distributions that we're experiencing, how it's going to affect our pollinating species and the crops that we use and any other ecosystems and dysfunctions we're going to experience.

REHMAll right. Thanks for your call. David.

KREUTZERYeah, well, the sea level rise -- the sea level has been rising since before the industrial revolution, so you can't blame all of that on CO2.

REHMBut how fast in the...

KREUTZERIt's about a foot in 150 years and they're looking at about a foot in 100 years. So it's not that much faster.

REHMNat.

KEOHANEWell, I have a broader point to make, which is reflecting back on Jennifer's opening.

REHMOK. We'll let David finish then.

KREUTZERYeah, OK. So the sea level doesn't -- it goes up in some places and down in some places. It's not even across the globe. In the island of Tuvalu, for instance, everybody is worried about that and sea level is actually going down there. Yeah, I mean, whether it's from CO2 or not, these countries have to worry about the ocean coming in. But the question is, how much can you slow that, at what cost? The species migration, we've had ice ages come and go, and we have pretty much the same species we've had for the past several ice ages. So they managed to adopt -- adapt, excuse me.

REHMAdapt. Go ahead, Nat.

KEOHANESo, first of all, I mean, there is, I think, unquestionable evidence that the seas are rising. That's something we can measure. We can measure it with our sea gauges. The models are very clear, but, I mean, that's basic physics, right? It's not only the effects of melting glaziers and so on, but it's just warmer water expands. It's like, you know, put an ice cube in a glass. And so the...

REHMBut the question is, how much and how fast?

KEOHANEWell, here's the point that I wanted to make, going back to Jennifer's opening. As she noted, we've gone above 400 parts per million of CO2 in the atmosphere. This is terra incognita. We have not been to those levels. We have not seen the levels we already have. We have not seen those in millennium, hundreds of thousands of years, in basically recorded human history.

KEOHANESo we're going into totally different territory here, and we simply -- when we talk, I think that Jules, the questioner, is absolutely right to talk about the disappearance of island nations, the species migration because we're going to see impact. If we don't do something about this problem, we and our children, our grand children are going to see impacts that are very hard to comprehend because we haven't seen this kind of world ever in our history.

REHMSteven.

MUFSONWell, I think the other unknown is that -- is the sort of baked in the cake phenomenon, that the impact of the emissions we have today, we won't see until tomorrow. So how big those are? It's hard to forecast. We haven't run this global experiment before.

KREUTZERYeah. I mean, if you think that CO2 is the only thing driving this, then the 400 parts per million is pretty scary. If you think that four-one hundredths of 1 percent of the atmosphere might not be the total impact but have other things causing it, which is pretty clear and true, then this 400 parts per million need not be scary. We were talking about population during the break.

KREUTZERBack in the '70s, people were making all sorts of horrendous projections of what's going to happen if we don't slow population growth, which we didn't. People are better fed now. They have a higher standard of living, and in most places, there's less pollution.

KEOHANEI'm sorry. I just -- I have to go back to this four-one hundredths. I mean, that -- this is basic science. And I thought we were all agreed five or 10 minutes ago, that we all agreed that on the science and the fact the world is warming and CO2 is the problem or it was one of the problems. And this notion that, oh well, it's just 400 parts per million -- that's, you know, if I get -- if I have that much arsenic in my drinking -- you know, I mean, the point is, if I have that much, I can have tiny amounts of poison in my water, and it'll kill me.

KEOHANESo the point is not 400 parts per million sounds small, the point is we know it's basic physics. We are putting more carbon dioxide into the atmosphere. That traps heat.

KREUTZERNo.

KEOHANEAnd we're seeing the impacts of that already. So there's -- I mean, that's not a...

REHMAll right.

KREUTZERWe know that, but we don't how bad it is, and we don't know absolutely that all these things you're talking about are due to climate change. You say the model show this. The evidence shows flat trend lines for all of these events. We're seeing people back off on the high end of the sensitivity. So, yes, it's basic science at one level, but it's pretty complicated science at another.

REHMSteven.

MUFSONI'm not sure what David's talking about exactly because it was my impression that some of the people who had been the most prominent skeptics about climate change in recent years have changed their views and...

REHMSuch as?

MUFSONThere was a fellow at Berkeley, I believe, and another one at MIT. I can't remember their names off hand. But -- so if anything, it seemed to me that consensus was growing on this issue.

REHMOK. And the issue of trend lines, which I was trying to get to earlier.

MUFSONRight. And the trends are toward rising seas, and it seems to me, as an economic matter as well as the scientific matter, that if the risks of catastrophic change are even moderate that you would want to do something to hedge that risk, and, you know, this is what you come down to from a policy point of view. You're dealing with the issue of uncertainty, but the consequences are so grave on the downside that it would seem to me prudent to take actions that aren't that incredibly hard to take in any case and might have some other good effects as well.

KEOHANEJust a notion on this question of trend lines, Diane. There's one trend line that matters. And that's global temperature, and it's rising. And that's just incontrovertible. We're already up almost a degree as Jennifer said in the opening, and we're headed to 3, 4 1/2, 5, 6 degrees.

REHMOK. But what about David's point that maybe it does matter if the temperature rises?

KREUTZERNo. The trend line -- nobody is talking with 5 1/2 right now, I mean, some are, but the main scientists are backing off of that. And the -- this catastrophic thing, what does the policy do to mitigate or ameliorate that? If it doesn't do much, then the cost can still be too high.

REHMSteve.

KREUTZERWe need to have something -- some other plan.

REHMSteve.

MUFSONWell, I'm not sure that the costs are too high on some of these measures, but I also want to say something else about the trend lines is that it's not just a question of what you're seeing in ocean levels, talk to people who deal with infectious diseases. A friend of mine just moved from Washington to Texas because the rate of infectious disease in the southern part of the United States is rising at a significant rate, and it's a great place to study infectious diseases.

MUFSONWe didn't need to worry about some of these things until the last 10 or 15 years. So I think we see all kinds of different effects. They have all kinds of different costs, and I think that people who are on the ground looking at some of these are seeing things that they believe are trends that were only going to become more serious.

REHMAll right. To Yorkville, Ill. Good morning, Bob.

BOBGood morning, Diane. Thank you for taking my call.

REHMSure.

BOBI have got a couple of questions. I just kind of think that we probably been in global warming since the ice age went away, and as far as putting certain things in the year, the forest fires used to burn, literally, millions of acres, which, of course, now was a kind of national news if it's a couple a hundred acres. And I just -- curious what your guests feel about that.

REHMForest fires. Nat.

KEOHANEWell, first, let me address Bob's first point about global warming. I mean, I think we've been talking a lot about the science and the trends. I think what you also see is people observing this in their own backyards. You know, you were seeing increasingly there was a polling from last fall that 70 percent of Americans see global warming already affecting their weather. And I say that not as a substitute for the science but because, in addition to what the scientists are saying and what the climate models say and what the best available science says, we can also see it with our own eyes.

KEOHANEAnd so, I think, you can start to see the impacts. Just ask yourself, does the world look like it did 10 years ago, 30 years ago, 50 years ago? And I think you'll see that's where the trend line is. In terms of the soot in the forest fires, you know, I mean, I think what we're talking about here, for the most part, is carbon dioxide, a little bit different than soot. But, hey, forest fires, there's, you know, there's another piece.

KEOHANEIf you're in Colorado, then you should be worried about the warming winter is making your forests more susceptible to pine bark beetles and, therefore, the forest fires in the summer months. And so that's another example of trend lines and of the kind of impacts we're going to seeing in a warming world.

REHMSo, Steven, talk about what's happening around the world. Has the issue of climate change, because of economic concern, slipped in priority?

MUFSONWell, it's kind of a tug of war because, on the one hand, we do want people's living standards to improve.

REHMRight.

MUFSONWe're expecting a major increase in things like the sales of air conditioners in the Southeast Asia because people there don't want to be as hot in the summer. People are -- more people are using more and better and bigger appliances in places like China. So on the one hand, you want advances. On the other hand, the costs are, you know, there are -- these are areas that are under environmental stress from a whole raft of factors.

MUFSONThere are water shortages in large parts of China. There are the pre-existing pollution problems that David mentioned before that are exacerbating the water shortages. They have energy shortages. So they have conflicting goals right now.

REHMExactly.

MUFSONAnd they're at a point of stress that a lot of us start, you know, to find out too.

REHMAll right. To Hedgesville, W.Va. Good morning, David.

DAVIDGood morning, Diane. I have a couple of comments to see what your panel thinks.

REHMSure.

DAVIDFirst, I feel that no one without a good basic science background should make any pronouncement about global change. I earned a second degree in earth science, and that just gives me a basic ability to understand the science. So -- and my second comment is with Senate 744 projected to increase our population by 10 percent over the next decade. If the world's countries ever agree on mandatory emission limits, the U.S. will have a much more hard-pressed job to try to meet our allotment if it is passed.

REHMSteve.

MUFSONWell, I think the population issue is important. The more people we have, the more we're going to want to consume. But, certainly, no one wants to say that the next billion people shouldn't share the same aspirations in standard of living as we're all enjoying. So that's going to make it definitely a more difficult task.

REHMWhat about that, Nat?

KEOHANEWell, you know, I think we've been talking about some of the impacts, the economic impacts on the developing world in particular. And one of the things that I think we've seen that's very striking in recent -- in just the last year or so is people are starting to say -- people like, again, Jim Kim of the World Bank saying he sees his mission -- the mission of the World Bank -- is to lift people out of poverty then get broad economic prosperity.

KEOHANEAnd he says, if we're going to do that, and we're serious about that, we need to address climate change 'cause if we're concerned about poverty around the world, then we need to be concerned about the impacts that climate change is going to have on those vulnerable populations.

REHMAnd you're listening to "The Diane Rehm Show." To Felipe in Fort Lauderdale, Fla. Good morning. You're on the air.

FELIPEHi there. Good morning, Diane.

REHMGood morning.

FELIPEI love your show.

REHMThank you.

FELIPEAnd I've very glad that you're doing this show today because it definitely goes with the one you had last week about the, you know, the Portuguese man-o'-war, you know, the jellyfish...

REHMAh, yes, the jellyfish.

FELIPE…that's so much all over the place. And, you know, the tie-in is it's quite simple. They are indicator species, such as insects, maybe, like, bees, or like birds, they indicate either the health or the lack thereof of an environment. And this business of denying the effects of climate change is the same as believing that the earth is flat, you know?

REHMWhat do you say to that, David?

KREUTZERWell, you can look at Harrison Smith, an astronaut, the last person to step on to the moon. He certainly knows the earth is not flat, and he is classified as a climate skeptic. You know, what we have, in some sense, is a bit of snake oil. It's every kind of problem you imagine is due to climate change. That's where you could call it a hoax if you want. Not that people on my side think that the earth isn't warming or that CO2 is not a greenhouse gas.

KREUTZERBut you say to yourself, look at people looking in their backyards. We have data. We don't have to just trust what people think. They always think the weather is unusual. You look at the temperature increase for the past 100 years has been about a degree. Look at it for the past 50 years. It's been about a degree per century. In the past 30 years, about a degree per century. And you're wrong. The temperatures have flat lined for the past 15 years. You say it's growing.

KEOHANEThat's just -- that's not correct.

KREUTZERNo, that is correct. The...

KEOHANEThat's just false.

KREUTZER...group in England says so, the people that do it. They said there's no significant warning. It goes up and down, sure. But you look at for the past decade, it's pretty level.

REHMSo from your perspective, all of this talk about global warming and what to do about it as far as reducing carbon emissions is a waste.

KREUTZERNo. There's -- clearly, we have efficiency. People don't like to pay more for energy, so they do things that economize on the use of energy. So we see that. We see new technologies being developed. But when you look at things that just restrict CO2 and you look at the benefits you get from that versus the cost, it seems like it's not worth it. There are other things we can do to mitigate the impacts from the warming.

REHMSteve, is it my incorrect understanding that some 90 percent of reliable scientists belief that the earth is warming?

MUFSONI actually thought it was closer to...

KREUTZERNinety-seven.

MUFSON...97 percent. Right. So...

KREUTZERBut that's the study. But go ahead.

REHMBut you reject that, David.

KREUTZERNo, OK. The -- well, that study has lots of problems. Yeah, most of them say it's warming.

REHMBut I want to know...

KREUTZERThe question is, how much is it warming, and how much will our policies reduce it?

REHMOK. Nat.

KEOHANESo, look, we could sit here all day and...

REHMRight.

KEOHANE...disagree. And so let me take another cut at this, which is here we have an I -- a report from the IEA, the leading energy authority in the world, backed by a huge amount of economic analysis that says, here are four policies. Things like eliminating fossil fuel subsidies, which, you know, David probably would think is a great, I mean, should think is a great idea -- I think we could all agree on -- things like that and energy efficiency, here are four policies: No net economic cost.

KEOHANEPut us in position in 2020 to turn the corner towards a safer climate trajectory. If we do those things, no net economic cost, cleaner air. If David is right in 2020, then we can say, OK. We did those things, no regrets. But they put us in a position to act when we need to.

REHMSteve.

MUFSONWell, just -- in trying to evaluate things as news stories and trying to figure out how to describe things, I mean, when you get to 97 percent consensus on an issue, we tend to, you know, to treat that as something fairly real. And, I think, as I said before, if anything, the margin -- the error seems to be -- the most likely direction of errors seems to be towards something even more serious. So we've kind of stopped agonizing about whether or not climate change is real at The Post and trying to figure out just how serious it is and what kind of policies people can pursue.

REHMAnd that's the last words.

KREUTZERWe agree with.

REHMSteven Mufson of The Washington Post, Nathaniel Keohane of the Environmental Defense Fund, David Kreutzer of The Heritage Foundation, surely, much, much more to be said on this subject. Thanks for listening, all. I'm Diane Rehm.