MS. DIANE REHMThanks for joining us. I'm Diane Rehm. Floods in Pakistan and China, record heat in Russia and parts of the U.S., millions of people displaced, thousands dead as a result of extreme weather. For this month's Environmental Outlook series, how and whether extreme weather relates to climate change and adaptation planning. With me in the studio, Captain Tim Gallaudet. He's deputy director of the Navy's Task Force on Climate Change. And Heidi Cullen, senior research scientist with Climate Central, she is the author of a brand new book titled, "The Weather of the Future."

MS. DIANE REHMJoining us by phone is Gavin Smith. He is executive director of the Center for the Study of Natural Hazards and Disasters. He is an associate research professor of city and regional planning at the University of North Carolina at Chapel Hill. And of course, this is a subject that affects all of us. If you would like to join us, 800-433-8850. Send us your email to drshow@wamu.org. Feel free to send us a tweet or join us on Facebook. Good morning to all of you.

MS. HEIDI CULLENGood morning.

CAPTAIN TIM GALLAUDETGood morning.

MR. GAVIN SMITHGood morning.

REHMAnd Heidi, if I could start with you, you identify yourself as a climatologist. Tell us the difference between a climatologist and a meteorologist.

CULLENOh, great question. Well, I think time scale would be the easiest way to start. If you think of a meteorologist just focused on forecasting, you know, the next five to seven days and a climate scientist, I kind of think of them like an auto mechanic, under the hood trying to figure out how the whole system works and actually trying to forecast the system on much longer timescales.

REHMAnd how long have you studied as a climatologist?

CULLENI'm actually an engineer by training. And after I finished up engineering school, I decided I wanted to get a Ph.D. in ocean atmosphere dynamics and so I went to graduate school and have been essentially working in the field. I got my Ph.D. in 2000 so a little over ten years.

REHMSo I would like for you to give us the definition of extreme weather.

CULLENYou know, one way that I like to look at it -- because it's almost like trying to get a sense of intuition about the difference between climate and weather. And one of the ways that I like to describe it is, climate is what you expect. It's a statistical average. Climate is what you expect. Weather is what you get. And now, with climate change, I think one way to look at it is that climate is what we affect and the weather is what gets us.

REHMSay that again.

CULLENSo we used to say climate is what you expect, weather is what you get. Because climate is the statistical average and weather -- today, as we increasingly emit carbon dioxide into the atmosphere, heat up the planet, we say climate is what we affect and weather is what gets us.

REHMSo you believe that the climate is changing?

CULLENI believe that there is a human fingerprint on climate. Climate has always changed. There's tremendous natural variability within the system, but I think since the 1800s when we first started studying the impact of fossil fuel burning on our climate, we have shown steadily over time that additional carbon dioxide is actually forcing the atmosphere.

CULLENIt's heating up our planet about 1.4 degrees Fahrenheit over the past century. And we can very nicely attribute that long-term trend that is sort of set on top of all of these other variations that happen on different timescales, but that long-term trend is us.

REHMHeidi Cullen, she's senior research scientist at Climate Central and author of "The Weather of the Future." Turning to you, Captain Tim Gallaudet, tell us about the work of the Navy's Task Force on Climate Change.

GALLAUDETCertainly, Diane. The navy established this Task Force for Climate Change in 2009. Initially, the chief of naval operations, Admiral Gary Ruffhead was concerned about the rapid decline of Arctic sea ice steadily decreasing and 2007 saw a record low in sea ice in the Arctic. And because of that, there was increasing access in the region and we've seen the northern sea route in the Northwest Passage open to commercial traffic, an event unprecedented in history. And as the Arctic is an ocean and the navy has global responsibilities in all the oceans, he wanted to take a look at it.

GALLAUDETAnd so what he did is he called to the table, his green table with all his executives, his three stars, to talk about this Arctic change. He asked my admiral, Admiral David Titley, the oceanographer for the navy, to brief him about Arctic change and the environment, but also the consequences. And with the activity in the region, for example, the increase in resource exploration and in eco-tourism and some of the security aspects, too, what the other Arctic nations were doing in response to this because they have all acknowledged the rapid loss of sea ice and they incorporated that into their strategic guidance.

GALLAUDETSo we answered some questions for him and he saw the need to look at the Arctic initially, but also in global change more broadly. And he established this task force consisting of principally navy officers, but also a large component of the coast guard and the National Oceanic and Atmospheric Administration so we have that as a core element. But we also have a broad outreach program where we involve all of the Department of Defense, the federal agencies and also a number of different partners, for example NGOs and the nations and some international scientific institutions to help ensure that we're well informed.

GALLAUDETBecause Admiral Ruffhead asked us to base our recommendations to him about the Arctic's ice loss and climate, base those decisions on facts and not folklore so a scientific basis for this is really important for our approach.

REHMAnd that is the voice of Captain Tim Gallaudet. He's deputy director of the Navy's Task Force Climate Change. Turning to you, Gavin Smith, do you see all of this -- do you see a scientific basis for drawing a connection between what we've seen this summer and over the past few years of extreme weather as indicating or the result of climate change?

SMITHI think one of the issues we need to talk about and to think about is this issue of climate and meteorology. And there is a growing evidence to suggest that our changing climate is affecting extreme weather patterns, but one of the things that we also ought to recognize is that given that our weather is changing, our communities, our cities, our human settlements have been built up over centuries in a way that reflects the climate in which they lived. As that climate is changing, we're having increased droughts and increased heat waves.

SMITHJust look at Chicago. The idea of increased heat in Chicago, in a city that was not, is not adequately prepared for this change, is just one example. If you were to look at coastal -- the eastern U.S., for example, looking at intensive development in areas known -- that are subject to the impacts of coastal storms, surge in coastal flooding and hurricanes, as rapid development increases, whether we have increasing extreme events or not, we're still continuing to grow in areas that are highly vulnerable to natural hazards.

SMITHAnd in fact, one way to think about it as natural hazards are just that they're part of the natural environment. And we're always going to have natural hazards, be they floods, wildfires, extreme heat and so on. It's the way that we adapt to them that can minimize or reduce the likelihood of them actually becoming disasters.

REHMSo what you're saying is that the growth in population has an effect on how the climate affects the people who are experiencing it?

SMITHWell, that's right. The choices that we make, both today and -- even, for example, if we're looking at the development of an urban area and looking at where we place infrastructure, which in turn often guides development, we continue to place large amounts of our public infrastructure in areas that we know are prone to flood, that are prone to wildfire, that are prone to coastal storm surge and so on. And if, in fact, these events become more extreme, they will -- we will be placing more people in harm's way.

SMITHAnd one way to think about this is that if, in fact, we can almost take what some people have called a no regret strategy, whereby we look at where and how we build in relation to natural hazards. And by doing that, that will help us adapt to the impacts of climate change.

REHMGavin Smith, he is executive director of the Center for the Study of Natural Hazards and Disasters. He is at the University of North Carolina at Chapel Hill. Do join us 800-433-8850. Send us your email to drshow@wamu.org and you can join us through Facebook or Twitter. Heidi, what can we expect from what we've seen, this kind of extreme weather? We've seen lots of floods. We've seen fires. We've seen hurricanes. Are we going to get more of the same as the population decides to gather in places that maybe it shouldn't be gathering?

CULLENRight. You know, building upon what Gavin just said, I think it's one of these situations where as population grows and demands for electricity increases, our vulnerability to coastal hazards increases. Water resources -- if you look at population growth just over the past 30 years, we can see lots of migration to the U.S. Southwest, an area that we expect to see increased droughts. So I think it's one of these situations where we have always had extreme weather, but our understanding of climate science now is such that we expect to see these extremes happen more and more frequently.

REHMHeidi Cullen, senior research scientist with Climate Central, author of "The Weather of the Future."

REHMAnd here's our first e-mail as we talk about extreme weather, what's been happening around the world, not only in 2010, but certainly in the years leading up to the current one. It's from Jeff in Catonsville, Md. He says, "I'd like it if someone could address the National Academy of Science statement that 97 percent of climatologists believe that human activities are causing warming. This seems to crystallize the issue as analogous to the tobacco situation in the '60s." What would you say to that, Gavin Smith?

SMITHWell, the fact is that the vast majority of scientists around the world do realize or do believe that climate change is occurring and that it is being caused by our behavior, our actions. So I certainly don't dispute that. The question that you raised earlier, the direct nexus between climate change and increasing number of extreme events, those are issues that, again, it goes back to the weather versus climate. I think if we're -- as we look into the future, if we were to try to predict whether there is that direct nexus, I would argue that, in fact, that there is becoming greater evidence that suggests that climate change -- being the (sounds like) likemer of extreme hurricanes. Couple that with rapid and continued development in known high-hazard areas on our coastal -- in our coastal communities, that certainly spells disaster.

REHMHeidi.

CULLENYou know, in this issue of just climate scientists and, you know, to the extent that they're incredibly concerned about the issue of climate change, it's been really interesting. When you look at polling studies, concern within the general public about global warming, it depends on a few different factors. One is belief that climate change is caused by human activity. That is the single largest predictor for someone's overall level of concern about global warming. But there's a couple of additional factors that, I think, play in it that are very interesting. One is the general public's trust in science and in scientists. The second is the extent to which the public believes that scientists agree on this issue. And that's why that 97 percent number from the national academy is to say, look, there is consensus around this. And then, finally, the last issue is the level to which climate change is discussed in the media. And I'd say that when you look over the past year or two, we've seen a significant drop in science journalism and in science coverage overall. And as an effect, folks tend to become less concerned about this issue.

REHMCaptain Gallaudet.

GALLAUDETSure. I'd like to echo on what Heidi said. We, as I said, are basing all our decisions and recommendations on the best science. And many people will come back to us and say, wait a minute, there's no consensus. There are those few scientists out there who are skeptics. But when we've done our surveys, we've seen that almost every university in the country with an environmental science program acknowledge this link between greenhouse gas emissions, you know, anthropogenic forcing and the changing climate. And that just can't be discounted, along with many of the federal and national research institutions like the National Academy of Science and the National Oceanic and Atmospheric Administration. So we have to listen to that.

REHMHere's an e-mail from Peter in Tarrytown, N.Y. who says, "We had a record-breaking winter last year. I heard many people say no such thing as global warming. Can your guests explain why we had such a cold snowy winter in the context of global warming?" Heidi.

CULLENYou know, I think that's such a great question and it's such an important question because this happens all the time. When we have a severe winter like we did in the northeast, it's natural to try to understand our weather within the larger context (technical) ...and what epic snow, what is cold temperatures, just cold enough for it to snow. And then, the second is moisture. And so what I would say is that, you know, you've got natural climate variability. But then, where climate change or global warming could come in, is it juices up the system essentially. So as the world warms, we have more water vapor in the atmosphere, more fuel for these storms. And that could actually help explain the extent to which we set some records with respect to snowfall.

REHMDoes that also indicate a basis for flooding?

CULLENWell, essentially, that is the connection. So we've got warmer temperatures. That explains the shift towards more extreme heat and draughts. But the water vapor connection essentially is that if you warm up the planet, you evaporate more water from the oceans as the oceans warm and that is there to fuel these stronger storms. And so actually, when you look back over the observational record, just looking back from 1958 onward, an excellent report done by NOAA, the National Oceanic and Atmospheric Administration, showed that there's been a 67 percent increase in very heavy rainfall in the northeast. And that trend exists throughout the country. But just in our observational records, we're already seeing this shift towards very heavy downpours.

REHMCaptain Gallaudet.

GALLAUDETYeah, I'd just like to kind of answer this in two ways, this e-mail here. First off, in terms of why did it snow so much, I had my snow shovel out on these three weekends and how can there be global warming? Here's a sailor's analogy. When you stand on the shoreline, you don't really notice the tide coming in. You notice the waves rushing in and rushing out. That's the weather. But as the tide arises, that's climate. And so that's kind of how we understand you can have an extreme winter, but gradually global temperatures are increasing. And the trend is very clear around the world and so are the trends in some other weather parameters and events.

GALLAUDETIn fact, however, I would say, though, that there is a great uncertainty about what will happen in the future. Our climate models, I think, lack precision, firstly at a regional to sub regional scale, and certainly in a decadal to sub decadal scale. I think out to a hundred years, we're pretty sure the planet's going to warm a few degrees. But when you really want to look at the likelihood or the certainty of more tropical storms or hurricane activity in the north Atlantic and how intense will they be and where will they strike, well, that's challenging. And so what we're doing to respond to that is we've corroborated with a number of federal agencies, including NOAA, the Department of Energy, the National Center for Atmospheric Research, where Heidi used to work. And we formed this consortium to develop a national strategy and implement more improved climate prediction capability that can go from the operational requirements we have, for example, safety forces and bases and hours, like, on weather forecast, out to the strategic decisions we need to make, you know, with decades of where should I put my bases based upon extreme weather events, flooding and whatnot and how do I retrofit them if required?

REHMOkay. So if you say you're working on these calculations, the weather is going to warm a few degrees in say 100 years, Gavin, what difference does it make? Aren't we going to adapt and create new models for living, new models for existing? What difference does it make?

SMITHWell, I think we will adapt. I know we will adapt. It's a matter of how we adapt. For example, just looking at the issue of climate change, kind of a -- somewhat of a slow onset disaster, if you will, in the making, versus one of these episodic events, be it flooding, hurricanes, wild fire and so on. You know, we have a unique opportunity after -- both before and after a disaster. For example, after a major hurricane, if you were to look at the Mississippi Gulf Coast or New Orleans to look at how we rebuild during that large scale reconstruction process, how do we incorporate what we in the hazards management field refer to as hazard mitigation, in essence taking steps to reduce the vulnerability of these communities to future events? How do we incorporate that into the massive sums of federal assistance and corporate assistance and nonprofit assistance into these communities when they rebuild? So that's one issue, kind of the post-disaster reconstruction piece.

SMITHBut the other thing that we need to do a better job of, and there are federal laws that require states and local governments to do this, is to adopt what are called hazard mitigation plans. And again, this is an important distinction. Because when you talk about the hazards management community, we refer to hazard mitigation in a way as a means to reduce future losses with -- associate with disasters. The climate change adaptation community refers to that as adaptation. So we even have an issue of semantics. And one of the challenges we face, too, is the hazards management community and the climate change adaptation community, we're not doing a good enough job of coming together and talking about synergies, if you will. If, in fact, we take the steps to reduce the impact of flooding or heat waves or wildfires or a coastal storm surge, we're also looking at reconstruction, rebuilding in a way that reduces the likelihood -- or assist us in adapting to climate change.

REHMBut you're also, it seems to me, talking about aspects of national security as you talk about hazard mitigation or hazard management. So how do you think about national security in that same breath, if you will, Captain Gallaudet?

GALLAUDETWell, certainly, just as Gavin mentioned, one piece of it is our infrastructure, our installations. And so we are -- right now, an important piece of what we're doing, as I mentioned, is to improve the national predictive capability, numerical prediction. In fact, relatively, my boss is at a meeting with Dr. Jane Lubchenco, the Director of NOAA in Boulder, Colorado today. It's a kickoff meeting of the executives to build this national predictive capability to improve it. So I can understand, for example, in Hampton Rhodes, what the impact of sea -- I can better understand how much sea level rise will occur in that region and how that will contribute to any storm surge in the area to potential damage and how do I adapt to that or mitigate the impacts of that damage.

GALLAUDETBut we also have security risks abroad due to climate change that we have to look at and inject into our planning and our strategy. You look at Diego Garcia, for example, with an average elevation of four feet, I believe. And if we don't have that huge strategic asset, in terms of basing and prepositioning for forces, where are we going to put it? We have to answer that question. And when there's such extreme weather events, for example, Africa and the southwest Asia region are certainly going to be at increasing risks, especially with other factors like political instability and economic decline. And those all might contribute to increasing tensions and vulnerability of those nations. And that has to be incorporated in our strategy.

GALLAUDETIn fact, we're doing this today with two missions, the African Partnership Mission and the -- or Station and the Pacific Partnership Mission where we send out our forces and we help communities build resiliency on a number of different levels, like economic and education. And one of the things we always do is we start -- we build wells for them. And so those are some of the aspects that we're looking at.

REHMCaptain Tim Gallaudet. He's Deputy Director of the Navy's Task Force on Climate Change. And you're listening to "The Diane Rehm Show." As we look at this entire picture then, if you talk about population and you talk about climate change, we, here in this country, are not doing much about either population growth or where populations locate themselves. We've seen the devastation that both those issues can cause. But it would seem until we address those -- I mean, you're talking about hazard mitigation plans, hazard management, but you're not talking about population, Heidi.

CULLENWell, I think that it's one of these issues where, as Gavin was saying, we can look across the U.S. and pinpoint regions of extreme vulnerability. And in many respects, it's looking at vulnerability across many different timescales. The longer out we look -- as scientists, that is fully the goal is to be able to look out on long timescales and prepare and reduce vulnerability. And that's where weather and climate essentially come together. And as anyone who works in infrastructure will tell you, anything that we do today will help us today. And anything that we do today will help us as we move forward into the future.

CULLENSo by addressing infrastructure issues, it really shows to be a win-win. And I think that a lot of the work that Gavin has done has really shown that when you do this stuff upfront -- it's tough to do. It's expensive. We're in the midst of a recession. It's very hard to make infrastructure upgrades. But when you do it up front, it's so much cheaper.

REHMBut, Gavin, looking at it the other way, how has weather affected the way human society has developed?

SMITHWell, that's true. I mean, if you think about -- even looking at New Orleans or looking at many of our port cities, I mean, we grew up around water-based transportation systems and then we have the interstate transportation network. In many ways, you could argue that increased suburban sprawl. So we play -- we have adapted over time. I guess one thing I would like to come back to is what Heidi mentioned about the value of investing upfront and again, what we would call pre-disaster hazard mitigation.

SMITHThere has been a congressional study that has shown that for every investment we make in hazard mitigation dollars, if you will -- and that could be moving homes to higher ground, elevating structures and so on, there's a four-to-one return. And that was done by the Multihazard Mitigation Council, which is pretty significant. If we're talking about not only protecting lives and property, but also our national security, hazard mitigation can work and it has been done on fairly large scales.

SMITHIf you were to look at, for example, the '92 Midwest floods, large relocation efforts relocating properties off and out of the floodplain. There was a fairly large relocation program in eastern North Carolina following hurricanes Fran and Floyd where approximately 4,000 homes were relocated to higher ground. So it can be done. The challenge, of course, is encouraging people, if, in fact, they have chosen to build in a known hazard area and then after disaster, one option is to relocate entire communities. It's very difficult to do. It makes a lot more sense to try to guide development in a smart and sustainable way before a disaster ever occurs.

REHMOkay.

SMITHBoth options are hard.

REHMBut, Captain Gallaudet, give me an idea of your projection of how a temperature increase of just one degree Fahrenheit over the next 50 years could alter the planet.

GALLAUDETI'm probably not the best qualified to make a climate-change projection. As I mentioned, we rely on the scientific institutions that are doing climate research. And some of those projections right now for the increase in extreme weather, flooding, extreme climate events, like Arctic ice decline and sea level rise, we've seen and we've looked at those and raised concern for...

REHMIn the past.

GALLAUDETNo. I'm talking about the projections.

REHMProjections.

GALLAUDETBut we're not making projections. We're evaluating those by the various institutions that are doing those. And I think we need to improve the resolution and space and time to make the big investments in terms of relocation that Gavin talked about or the adaptation.

REHMAll right. And Heidi Cullen, I'm going to come back to you on that question after we take just a short break. We'll be right back.

REHMAnd welcome back as I talk with Heidi Cullen. She's senior research scientist with Climate Central and author of "The Weather of the Future." Gavin Smith, he's at the University of North Carolina at Chapel Hill. And Captain Tim Gallaudet, he's deputy director of the Navy's Task Force Climate Change. Heidi, tell us first what Climate Central is.

CULLENOh, Climate Central is a young nonprofit organization that was essentially formed to fill this growing void -- this sadly growing void in science journalism and actually brings together PhD scientists and engineers who work on whether it's clean energy solutions or the impacts of extreme events. It brings those scientists together with journalists and we essentially aim to cover the issue of climate science.

REHMAll right. Let's open the phones first to Lexington, Ky. Good morning, Laurie.

LAURIEGood morning. First of all, as a Navy veteran, I am so ecstatic to hear the captain talking about that the Navy's on board with this. But my question for the panel is, is we hear a lot of contention about the role that environmentalist -- environmental issues here on the planet are playing in the changing patterns of our weather. So I'd really like for them to kind of answer the question is -- my question is what role does, like, issues like deforestation and mountain top removal, strip mining play in how our weather changes? And are these areas that are having these environmental consequences, are they going to be more susceptible to extreme weather?

REHMLaurie, thanks for your call.

GALLAUDETThanks Laurie. I appreciate your kudos and am glad to talk to a fellow veteran as well. But how the changing climate will exacerbate existing environmental degradation, I see that is still certainly a risk. And from what I can speak to, is that all Naval installations are required by the Endangered Species Act to maintain certain habitats on our training ranges, for example, of those types of species. And we already have observational evidence that the changing weather patterns and precipitation patterns are impacting those areas. And so we are building programs now to respond to those changes and incorporate them in the planning so that we can adhere to the -- to our obligations to preserve these habitats. So that's one aspect that is occurring. And we observed it and we're working to mitigate those impacts.

REHMThanks for your call, Laurie. And before the break, Heidi, I was asking about a 1 degree increase in temperature over, say, the -- or a few degrees over the next 100 years. How might that affect us?

CULLENYeah, I think that's actually a great thought experiment to help us connect climate and weather, right. So if you have a large scale warming of a few degrees, how does that make its way into our weather? So, for example, we did a study this summer where we looked at the very hot temperatures that we saw in New York, in Philly, in Washington D.C., yes, you know, very, very hot summer. And if you -- actually, if you run a climate model and you just assume that we continue to omit greenhouse gases, business as usual, very interesting thought experiment.

CULLENThis summer in D.C. or New York, when you fast-forward 40 years out into the future to the middle of the century, this actually becomes a cool or, you know, average summer. So that's, I think, the way to think about climate and weather together. When you move forward through time, the things that we think of right now as extremes, they actually become the average. And so when we talk about our infrastructure, which is old to being with, it was built for a very different weather and climate. And so the envelope of that variability will increase and that just makes us so much more vulnerable.

REHMCaptain?

GALLAUDETYeah, Diane, I'd like to use an analogy we've talked about every so often. And that's when someone comes to us and says, what's so big about a few degrees? And well, where are you at right now, Diane? You're at 98.6 degrees like all of us. We're pretty healthy. And what happens when you add a few degrees Celsius, like 2 degrees Celsius is 4 degrees Fahrenheit and so you're having a fever. And for prolonged fever, you're seeing systems shut down in your -- within your nervous system, et cetera. The earth is a finely tuned system. And we have subsystems within that -- in the environment. And so that little bit of warming can cause a disruption in the system. And that's what you have to appreciate, is that it does have a significant effect.

REHMGavin, do you want to add to that?

SMITHSure. I'll tell you, if I could, just briefly to the caller's question, which I thought was a very good one, is this nexus between the natural environment and hazards, if you will. When she had mentioned issues of deforestation and so on, if you think about, for example, the connection between sea level rise and the potential degradation of our wetlands. And we can see that how New Orleans faired after Katrina, the realization that there was significant wetland loss, dramatically increased their vulnerability to storm surge.

SMITHSimilarly, if you look at healthy forest ecosystems, particularly in mountainous terrain, if, in fact, they're denuded, that can -- and, in fact, if that's coupled with increased rainfall, you could end up with increased landslides like we're seeing in South America. Finally, if you look at kind of the preservation and protection of healthy wetlands, those, in turn, are able to better absorb floods. So all of these connections are critical to think about. And when we change our climate, not only are humans going to have to adapt, but our natural systems will as well. And sometimes that can make us more vulnerable.

REHMLet's go now to Pikesville, Md. Good morning, Janie.

JANIEHi. My question for your panel is relative to the accuracy of their predictive climate models. I'm wondering whether or not they are familiar with an astronomical phenomenon that is known as the Barry Center, that's "b," like "boy," A-R-R-Y center. It occurs during a very predictable segment of Jupiter's orbit around the sun. And because of the massiveness of Jupiter, it's bigger than all our planets, moons, asteroids and debris in our own solar system. During the finite periods of time when that elliptical orbit passes the sun, on both sides of the sun, the sun's activity changes dramatically. And we have documented over history that extreme weather patterns affect the earth during those Barry Center phenomenon times.

REHMHeidi?

CULLENYou know, I think the best way to look at it is there's been a number of attribution studies that have done -- that have been done to try to understand the root cause of this long term warming trend. Because that's fundamentally what scientists have been working on is to attribute that long term trend in warming to human activity. So you can look at natural factors, whether it's astronomical or, say, solar variability or volcanoes, natural phenomenon that could help explain the trend, versus something like human activity. And through the variety -- there's several different fingerprinting techniques that have been used. And it's been shown repeatedly all of these lines of evidence match up, that there's nothing that can explain the long term warming trend aside from carbon dioxide emissions because of the fingerprinting techniques that we use.

REHMGavin, I'd be interested in the work that I know you're doing in assisting North Carolina to develop a sea level rise adaptation strategy.

SMITHSure. One of the things that North Carolina's been fortunate to do is to embark on a fairly complex and comprehensive study of the effects -- potential effects of sea level rise on eastern North Carolina. In particular, given its extreme vulnerability, if you look at the Outer Banks and you look at a lot of low lying areas in eastern North Carolina, it is one of the most vulnerable states to the potential impact of sea level rise. So one of -- what we're doing is looking at several scenarios of sea level rise. The area that I'm focusing on is working with the larger team to come up with a series of what we would call adaptations strategies.

SMITHFor example, everything from relocation, abandonment of infrastructure, elevation of structures, better protection of natural systems, all of these things combined trying to understand what may be feasible because all of these issues are going to entail some degree of cost. They are highly politically sensitive. It's going to involve changing human settlement patterns or it could. And all of those issues are complex and they're a real challenge. But I'm glad to see that North Carolina is certainly one of the states taking a lead on this issue.

REHMAnd I gather you're leaving for the Philippines and Hong Kong later this month with the State Department. What's the purpose of that trip?

SMITHWe're leaving this Saturday and going to the Philippines and Hong Kong to talk with people from the Philippines, both government officials, nonprofit foundations in the private sector, about this connection between hazards management and climate change adaptation. Doing the same in Hong Kong. In Hong Kong, speaking fairly extensively with not only university officials, but also the business community.

SMITHAnd they're very interested in -- both the universities and the business communities are very interested in trying to figure out what they can do to adapt to issues like sea level rise. And, of course, in the case of Hong Kong, one of their greatest challenges is its highly -- a highly urbanized area that is very densely built. Whereas the Philippines, there's great variation in Manila and elsewhere. There's also, in the Philippines, very small communities that are highly vulnerable to the impacts of typhoons, sea level rise and so on.

REHMHere's a message from Facebook. Jason writes, "While not denying that global warming is happening, can the panel explain why CO2 is such a huge focus when it's a lagging indicator behind temperature? Doesn't this show we've not had as a significant impact on climate change? And also, how did they factor out the urban heat island effect when they're talking about temperature increase?"

CULLENGreat technical questions. And I think, you know, point one is just to make it clear that these are good questions that scientists have been working on. With respect to the urban heat island effect, several papers have come out over the past several years. I'm thinking of one by folks at the National Climatic Data Center in Asheville that looked at our temperature records in our stations and found that the urban heat island effect was not responsible for this long term trend that we've been seeing. Another way to look at that is the fact that our oceans are warming. There are no cities in our oceans. And so there's further verification there.

CULLENSimilarly with, you know, Arctic sea ice, we have multiple lines of evidence that establish the fact that there is a warming trend. And then, with respect to the other point, I think it's just really important that -- not to get too focused on the ice core records. I believe that he's thinking about the leads and lags in temperature and CO2 in those. In our record of carbon dioxide emissions taken by Keeling in Hawaii, there's a really nice way to fingerprint the source of CO2 to fossil fuels. And it's because of what we call isotopic fractionation. And there's different kinds of carbon and -- there's C12, there's C13 and C14. And so we can very nicely look at the carbon dioxide in our atmosphere and see that 25 percent of it -- 20 to 25 percent of it is being put there by fossil fuel burning and other issues because of the way the chemical fingerprint of CO2 can be measured.

REHMHeidi Cullen, she's the author of "The Weather of the Future: Heat Waves, Extreme Storms and Other Scenes from a Climate-Changed Planet." And you're listening to "The Diane Rehm Show." One person writes, "We have only 130 years of climate recordkeeping. How do we know this isn't just cyclical?" Gavin?

SMITHWell, you know, I would actually defer to Heidi on that probably. But the issue, again, of climate and weather is important. You know, I would say 130 year time span, if you're looking at long term trends and if you're able to go back and look at dramatic changes in CO2 emissions with the advent of the Industrial Revolution and how that affects our temperature, again, that is not my area of expertise, but it's my understanding that there is a clear demarcation and there is a dramatic -- or a consistent trend over that period of time.

REHMHeidi?

CULLENWell, it's called attribution science. And there's a large community that has essentially focused on attributing the source of that trend. And you can use computer models to do it, where you basically run a computer model for 1,000 years, see what the natural climate does all by itself and then see what it would take to recreate the trend that we've seen over the past 130 years. And it's -- I mean, it's really, really interesting work. And what it shows us is that nothing that Mother Nature puts out there can explain the trend that we've witnessed over the past century or so, that the only way that a climate model can reproduce that trend is by adding carbon dioxide to the model. So that's one way to attribute it.

CULLENSecond way -- and that's how you get around the fact that there's only 130 years of data. 'Cause you can run these models for thousands of years and it's very much a statistical exercise. The other component is what I was describing before, where you actually chemically fingerprint the carbon dioxide in our atmosphere. And, like I said, we can use isotopic fractionation and the fact that carbon dioxide comes in these, you know, slightly different forms to say that, you know what, one out of every five of those CO2 molecules that are in the atmosphere were put there by us because they're depleted in C13 and C14.

REHMTim?

GALLAUDETYeah, this argument is sometimes -- it's interesting. I think we have to acknowledge there are natural sources to climate change. That's something no one -- none of the three members here in the discussion will deny. So -- but there are also human contributions, which are very obvious. I mean, you have to think about -- here's another analogy, probably not scientifically rigorous, but just think about it. All that carbon used to be underground. It was fossil fuels, charcoal and oil, petroleum. That was all underground. It was not in the atmosphere. It is in the atmosphere now. And it's -- we're talking gigatons of carbon in the atmosphere. And the radiative transfer properties of that element are scientifically proven. It absorbs heat, incoming solar radiation at high frequencies (unintelligible).

REHMAll right. And one last question for you, Tim, because you've talked about the water and ice melting. There are those who would deny that that water melting has any deleterious effects, that it's simply going to make the planet more habitable, warmer, more comfortable and growing more agriculture.

GALLAUDETSure. Well, there's no -- well, there are different impacts to the Arctic sea ice decline. It's changing habitats in that region. It doesn't contribute to sea level rise. It's the Greenland and Arctic ice sheets that are contributing to sea level rise. So in terms of overall Arctic change, we're very concerned about those ice sheets melting. And -- but -- and so there might be arguments in certain regions for positive outcomes, like Russia, extended growing season's good for them. But the open sea lanes mean there will be more activity and we want to insure it remains a safe and stable and secure zone and not a zone for competition.

REHMCaptain Tim Gallaudet, deputy director of the Navy's Task Force Climate Change. Heidi Cullen, senior research scientist with Climate Central, author of "The Weather of the Future." Gavin Smith, executive director at the Center for Study of Natural Hazards and Disasters. He's at the University of North Carolina at Chapel Hill. Fascinating discussion, folks. Thank you so much. And thanks for listening, all. I'm Diane Rehm.