MR. KOJO NNAMDIWhat is it with the weather? Last summer a string of heat waves broke records across the country. The thermometer hit 113 degrees in Los Angeles last fall. It was 25 degrees below zero in Vermont this morning and who can forget last February, right here in Washington, went back-to-back blizzards, broke the capital's 110-year-old record, dumping 54 inches of snow on Washington. Many climate scientists had predicted that we'd get more extreme weather, harsher droughts, very severe storms, more major floods, hotter summers and colder winters.

MR. KOJO NNAMDISo as you got up and put on a pair of long johns this morning, you may have been wondering is climate change here and if it has arrived, are we prepared to deal with the effects? Well, joining us in studio to discuss this is Mark Hertsgaard. He is a journalist and author. His most recent book is ''Hot: Living Through The Next 50 Years On Earth.'' Mark, good to see you.

MARK HERTSGAARDGlad to be back, Kojo.

NNAMDIAlso with us is Peter Hildebrand. He is the director of the Earth Science Division at the NASA Goddard Space Flight Center. That’s a group of over a 1,000 scientists studying Earth's climate and weather. Peter Hildebrand, thank you for joining us.

PETER HILDEBRANDIt's a pleasure to be here.

NNAMDIYou, too, can join this conversation. If stronger storms and rising water are in our future, what do you think we should be doing to prepare? 800-433-8850. Peter, last year, five cities in the northeast broke their own records for the all-time hottest year. Out of 35 cities monitored by the National Oceanic and Atmospheric Administration lowered the average temperature in 23 cities ranked among the 10 hottest years on record. We’ve had historic snowstorms as far south as Atlanta, while Greenland and the Arctic are 15 degrees above normal. What does this all mean?

MR. PETER HILDEBRANDWell, it's what's going on with the normal weather patterns added to climate change. The earth is warming up, but you also have big oscillations from season to season, year to year and month to month. So you can think of the weather as the teeth of a saw, pretty big teeth and the tilt of the saw is the climate change.

NNAMDICould the extremes we've had be within the range of normal weather variation?

HILDEBRANDWell, every year you're pretty much within the extremes of normal. But as you just said, Kojo, we set a record last winter, didn't we, with a lot of snow? And one of the things we predict with climate change is larger amounts of -- bigger storms, bigger droughts, things like that. So we expect more of these things.

NNAMDIWell, let's cut to the chase here, Mark. You've done a lot of research and you feel that climate change is going to define the next 50 years. You've dubbed the next generation, Generation Hot and your daughter and your goddaughter are parts of that generation. Why are they going to be a part of something called Generation Hot?

MR. MARK HERTSGAARDBecause for the last 20 years, our government has ignored the warnings of scientists and has listened to the people who say, no, it's not real. Let's not hurt our economy by cutting back on greenhouse gas emissions. And so we've emitted about 40 percent of all of our greenhouse gases since the industrial revolution have (sic) come, since the beginning of Generation Hot, which I date to 1988 -- June of 1988 when Peter's colleague, Jim Hansen of NASA went to the United States senate and testified that manmade global warming had begun.

MR. MARK HERTSGAARDAnd when the New York Times put that story on page one the next day, it immediately made global warming a household phrase in government ministries and living rooms and news bureaus all over the world. And it effectively put the world on notice that this is a problem we have to deal with and yet we have done very, very little since that time. And now, because of that, global warming has triggered outright climate change. And one of the most fiendish aspects of climate change is that once it's been triggered, you can't turn it off very quickly. And so my daughter and my goddaughter and basically all the children, all two billion of the children born on this planet since June of 1988, they are now locked into at least 50 more years of rising temperatures and all the extra extreme weather that Peter just mentioned.

MR. MARK HERTSGAARDAnd so I wrote this book "Hot" as an attempt -- as, at the time, a relatively new father to try to find a way for my then infant daughter and the rest of her generation to survive all that lies in store for them in terms of really the hottest and most volatile climate in our civilization's history.

NNAMDIPeter, a big part of the climate change discussion here in the U.S. is focused on whether any changes we are seeing are caused by humans. Is that debate happening as much outside the U.S.?

HILDEBRANDI think that the debate is happening around the world. It's not a debate, though, in the science community. There's no debate at all there. The scientists know that human influences are creating greenhouse gases and these are warming the earth. And other things are -- other human impacts, such as changing the earth's surface, paving over things and the like is also having an effect on the earth. So there's no debate there in the science community.

HILDEBRANDThe debate -- there is a debate amongst people who are happy with the idea of climate change and other people who are not.

HERTSGAARDI don't think there's even much of a debate among governments. It's really only here in Washington D.C. that we think there's much of a debate, but because of the Republican majority newly ascended now on Capitol Hill since the midterm elections.

NNAMDIYou say these people are not even climate skeptics. They're climate cranks.

HERTSGAARDI do say that because skeptics play a valuable role in science. You have to be skeptical. But a genuine skeptic is open to the evidence and the evidence has been accumulating now for 20 plus years. And you now have a situation where virtually every major scientific organization in the world, starting with our own National Academy of Sciences and its counterparts in all these other countries, and the American Geophysical Union and the Physicists Society and on and on, and hundreds of scientific organizations, they all say that global warming and climate change are real, happening and extremely dangerous.

HERTSGAARDAnd at this point, anyone who is still saying in the face of that kind of scientific unanimity that it's all some leftwing plot, to me that qualifies as a crank. They have decided they're not real skeptics because they're not going to be moved by a fact or evidence. They've decided what they want to believe and the facts are not going to get in the way.

NNAMDIMark Hertsgaard is a journalist and author. His most recent book is "Hot: Living Through the Next Fifty Years on Earth." Peter Hildebrand also joins us in studio. He is Director of the Earth Science Division at the NASA Goddard Space Flight Center. I can't say that today properly. That's because my wife works there.

NNAMDIAt the NASA Goddard Space Flight Center. That's a group of over a thousand scientists studying earth's climate and its weather. We are inviting your calls at 800-433-8850. Do you think the extreme weather we've been having is part of climate change? If not, why not? 800-433-8850. Mark, you argue that even if we stop all emissions of greenhouse gases tomorrow, the effect of what's already been done will last for decades.

HERTSGAARDI don't argue that. That's what I report the scientists saying that. And that was Sir David King, the Chief Science Adviser to the British government who pointed that out to me in 2005 when he said in an interview -- and this was later affirmed by the IPCC reports, that outright climate change had begun. And that -- you know, it's the -- this lag effect, I think, is one of the things that the general public still has not quite absorbed about climate change. We still think of it as a future problem that we can try and turn off. And God knows that we have to turn it off.

HERTSGAARDBut what has not sunk in yet and what I hope this book will try to make people understand, and policy makers understand, is that we now have got to begin preparing for the inevitability of decades more of sea level rise and temperature rise and storms and droughts and so forth. And it's going to take a lot of planning to do this. And there are some good success stories both here in the United States and the municipal governments in Seattle and Chicago and New York are world class on this. The government of the Netherlands is doing a lot. Even Bangladesh, which is incredibly poor, but has a very well...

NNAMDIAnd incredibly threatened.

HERTSGAARD...and incredibly threatened and they have a very well articulated plan for adapting the climate change, but they don't have the money to do it. So we know what needs to be done, but we really have to focus on that side of the problem.

NNAMDIPeter Hildebrand, what are the tipping points that will make changes irreversible?

HILDEBRANDWell, that's one of the things that the science community really worries about is a tipping point. It can be something like losing all of the arctic ice -- sea ice, in which case the Arctic Ocean would be accepting the solar radiation, almost all of it. When it's covered with sea ice, it reflects it so that if we have a ice-free ocean, it will be warming up even faster than it is now. And if you look at the trend in the sea ice, what you see is that it's continuing to decrease the amount of sea ice in the Arctic Ocean. And it's not even clear that it's a straight line. It looks as if it's curving towards faster decrease every year.

HILDEBRANDOf course, there's years when there's more and less, but the concern is if this continues for very long, and only a few decades, you could end up with a situation where there is no sea ice in the Arctic Ocean. It's warming a lot faster than it would otherwise be.

NNAMDIRising sea levels are also one of the biggest threats. Is there a solid prediction as to how high the sea level could rise in the course of the next 50 years, and what would that mean?

HILDEBRANDWell, the prediction is something we're still learning about because we're learning about how fast the ice sheets on Greenland and Antarctica are melting. But we know that the ocean is rising and we can actually measure how fast those ice sheets are melting. And just like the sea ice, the ice sheets are melting at an increasing rate each year. And we have several completely independent measurements of that so this is an unequivocal result. That adds up to rising sea levels. And as Mark's book, which is really quite good, points out very clearly, major cities around the world, not just to mention Bangladesh, which would be a tragedy of its own -- but major cities around the world in all countries are going to be threatened by this, the seacoast cities, New York City, Miami...

HERTSGAARD...Washington, D.C….

HILDEBRANDYes.

HERTSGAARD...is going to be severely threatened by this. We know -- let me give a journalist's slant on that from what the scientists say, what I read in the literature and in my interviews. We're looking at a minimum of 3' of sea level rise. Lloyds of London, the famed insurance company based in London, of course, their expert says to prepare for up to 7' of sea level rise by the year 2100. But Peter's colleague, James Hansen, at NASA just came out with a paper last week suggesting that we could see even more than that.

HERTSGAARDThe point is that by, for example here in Washington, D.C., the kids of Generation Hot, by the time they're adults in, say, 2040, the simulations that I've seen suggest that we are going to have, you know, every other or every third summer, the western half of the national mall's going to be underwater. The Lincoln Memorial and the Jefferson Memorial will be ringed by motes when there's a combination of sea level rise and strong storm surge coming up the Potomac.

HERTSGAARDSo, you know, this is going to be something that our kids are going to experience in a very profound way in their lifetimes.

NNAMDIWhen you say Bangladesh and New York City in the same breath, there are some people who are saying, wait a minute here. We have much more sophisticated technology then Bangladesh has. We have more sophisticated equipment. Does it make a difference when the water's rising, Peter?

HILDEBRANDWell, it does make a difference, but we also have this huge investment in New York City. I mean, if you start imagining trying to protect that huge investment, the cost of reacting is going to be huge also. One of the things that's very interesting that comes out in Mark's book is the effectiveness of taking individual actions, which is in many ways a lot easier in a more rural environment with lower investment is individuals can have the resources to take those actions. Whereas if we're dealing with all of Miami, for example, there's a huge investment there in trying to raise all those buildings another 3' or 6' or something like that.

HILDEBRANDSo we're looking at a huge problem here and we're also looking at a problem that we really need to address in the immediacy of now rather than waiting for our children to act because it's happening.

NNAMDIAgain, the number's 800-433-8850. But before we get to the telephones -- if you have already called stay on the line, we will get to your calls -- allow me to complicate it just a little more. Because, Mark, it isn't just that we'll have to deal with any effects of climate change at home. Military experts apparently say climate change is also what they call a threat multiplier. What does that mean?

HERTSGAARDA threat multiplier is something that worsens already existing instabilities or conflict areas, tensions. So one of the expectations, for example, if we see an acceleration of sea level rise in Bangladesh -- and this is -- I write in the book about a war game that some of Obama's advisers did on climate change right after he got the Democratic presidential nomination in 2008. And that scenario, which was bedded by government scientists was in the year 2015. So pretty close. And they envisioned a series of weather events that included a terrible category four and five cyclones hitting Bangladesh at the same time sea level rise and so forth. And the projection on the part of the military experts was that that would unleash vast migrations of people understandably fleeing that weather. And in Bangladesh, the one place they would flee to is -- or try to flee to would be over the border into India.

HERTSGAARDIn the real world, India has already built a wall along that border and the fear on the part of military and security planners is that those kinds of migrations -- and not just in Asia, but also in Africa with Africans trying to get into Europe -- that this will trigger threats to security, which is a diplomat's way of saying it could cause war. And so we're going to see a lot of that kind of scenario playing out. And I think that's actually one of the silver linings here in terms of preparing for all this, is that there are going to be, are and will continue to be a number of people in the military and security fields who are going to be forcing this issue onto the agenda of policy makers. This began under George W. Bush. It was his Pentagon who did the first important studies of this.

NNAMDIHere's this e-mail we got from Don in Rockville, Peter Hildebrand. "Snowplows run on internal combustion, as do evacuation boats and helicopters. Populations displaced by rising sea levels will need relocation and new homes. We can try to reduce emissions, but the mandatory responses to the very problem at hand will result in ever greater expenditure of resources and creation of pollution. Are we doomed?" Don asks.

HILDEBRANDOh, no, we're not doomed. We're also pretty clever animals, we humans. And I'm very confident that there are a lot of very positive things we can do. And also, it's important to realize that the cost of reacting, adapting and mitigating is a lot lower than the cost of not. If we just wait for climate change to come land on us, we'll have unmitigated disasters that will be much more costly than it will be to address a climate change both through mitigation and through adaption. And we're going to have to do both of those things.

NNAMDIWell, we're more aware now. But, Mark, you say you feel awareness is high, but understanding is low. Can you explain that?

HERTSGAARDSure. I think that, as I said earlier, when you talk to the average person on the street, and even most politicians and business leaders, they still think of climate change or global warming in the old way, which is as a future problem and if we're gonna address it, we've gotta go solar and wind and all of that. And don't get me wrong, that's all to the good. We certainly have to do all of that. But what has changed and what accounts for the new realities of climate change is that we are now locked into 50 years. And that part has still not sunk into people. There's no dialing this back. We cannot say, oh, we're gonna prevent those temperature rises. So we've got to figure out how to deal with it.

HERTSGAARDIt's two things we have to do now. We have to -- on the front end of the problem, we have got to get the emissions down and the concentrations of greenhouse gases in the atmosphere down as soon as possible. Because, as Peter said earlier, we are in grave danger of passing tipping points that will make this an irreversible problem. At the same time that we try to avoid that kind of unmanageable climate change, we also have to do the second half of the problem, which is manage what is now unavoidable. And that means manage the fact that here in Washington by the year 2040 that terrible summer that you suffered through in 2010, that's gonna be normal. That's gonna be an average summer, it's not gonna be record anymore.

HERTSGAARDAnd so we have to begin putting in place now the kinds of protections, increased public health systems, increased public awareness, cooling centers, all these sorts of things. And what I try and do in this book is to look around the world at the best practices that are already underway. And there's a lot that we can learn, including from places like Bangladesh, from farmers -- illiterate farmers in West Africa, from above all, the Netherlands and Great Britain who have been real leaders on preparing for climate change. There is a lot we can do. But the main thing is we've got to start thinking differently about this problem.

NNAMDIOnto the telephones. We start with Fran in Laurel, Maryland. Fran, you are on the air. Go ahead, please.

FRANHi, Kojo. Thanks for taking my call. I think this is a very interesting conversation you're having today and a very needed one. I just wanted to give a comment and a question to you and it's -- the comment is this. When I was in junior high school back in the '70s, I remember reading in a book in school where scientists had predicted the next ice age and would begin in our time in the 1980s. And then we have all these global changes coming about. And I'm sure you're wise enough to know that ice age just doesn't happen overnight. I think that that's what actually is happening here and I think you're exactly correct that we need to be preparing for that. Because our earth is changing, there's really nothing we can do to stop it. But we have to adjust for that.

FRANDo you feel that the leaders -- that they understand that well enough to where we can adapt to that?

NNAMDIIs that, in fact, what is happening, Peter Hildebrand?

HILDEBRANDWell, we're not heading into an ice age right now. But if you look at the historical record, the whole question of when the forcing due to earth's orbit might force us in that direction is something that obviously people have thought about. The whole point here, though, is that the combined effects of human activities with the greenhouse gases and land use change and the like, also have a big effect on the earth's radiation balance. And that's put us into a warming trend. And so that's the issue we really need to deal with right now. And that -- the concern over that is why really all the agencies in government who are concerned with national security take this very seriously, as does the insurance industry.

HILDEBRANDThese are basically all the very large parts of our society that are concerned with possible adverse effects. All of those groups are very concerned about this process and the climate change process and how we can make changes to adapt and mitigate.

NNAMDIThank you for your call, Fran. We move on to Linda in Washington, D.C. Linda, your turn.

LINDAThank you very much. I'm calling to ask -- I understand that the amount of carbon in the atmosphere can be measured by, I think, fermilimeter and that this measurement is rising. And I was wondering if your guests could address the meaning of that and the measurement of that.

NNAMDIAgain, Peter Hildebrand.

HILDEBRANDWell, you measure the amount of any of the gas constituents in the atmosphere -- and carbon dioxide and methane are just two of those -- in the fraction of the air that is made up of that particular gas. And so it's just a proportion of how much there is. And the element of concern is that the amount of carbon dioxide and methane are now more than twice what the background value was before the industrial revolution. So it's that type of forcing that we're concerned about.

HERTSGAARDAnd it's parts per million, it's not millimeters. It's part per million, and the carbon has gone up from about 280 parts per million before the industrial revolution to about 390 parts per million today.

NNAMDILinda, thank you very much for your call. Does that answer your question?

LINDAWell, I just wanted to know what -- how that also affects this climate change.

NNAMDIAgain, Peter?

HILDEBRANDWell, it's the amount of these greenhouse gases, and that's the carbon dioxide and methane, and water vapor actually also. And they act as a blanket, and they reflect heat back down to the earth that would otherwise go out into space from the surface of the earth. And so if you have more of it, you just reflect more heat back down, and it's just like having one too many blankets on your bed at night. You end waking up in the middle of the night sweating and have to throw the blanket off. Unfortunately, it's not that easy with the atmosphere.

NNAMDIThank you very much for your call, Linda. We got this e-mail from LCC in College Park, Md., Mark. "The current logic among Republicans is, okay, climate change may be occurring, but it's not manmade." How would you respond to that argument?

HERTSGAARDI would respond to that argument by saying that that is not a new argument for the climate cranks. They have been saying variations on that since the early 1990s when the fossil fuel industry first began to sponsor multimillion dollar disinformation campaigns on this. It's interesting to me, because of course I hear from people who dispute climate change all the time when I write my articles, and it's only somewhat -- it'd be hilarious if the consequences weren't so dire.

HERTSGAARDBecause they throw in my face things like that it's not manmade or all these new objections that they somehow think the scientists have -- it just never occurred to scientists that that could be the case. So I -- in terms of responding to that, I go back to the -- I think the central point. And those of you who need a response to the climate cranks, here's what you should say, I think.

HERTSGAARDWhen virtually every major scientific organization in the world has been saying forever, including the National Academy of Sciences and its counterparts overseas, they have been saying this forever. They have checked out all of these supposed objections, and they don't pass the smell test. When they have been saying that this is real and it's dangerous, why -- why would you think they're all lying? Are they all in on the conspiracy? How is that possible?

NNAMDIWell, there are consequences. Let's go to Jen in Washington, DC. Jen, you're on the air. Go ahead, please.

JENOkay, Kojo. Thank you. As I sit here putting together my apparatus to start my seeds early for my garden to grow my own vegetables, I find this conversation very compelling. And what I would say is that especially for the climate cranks, and even for people who are out there kind of who have an abstract idea, they need to see the ten-year animations that NOAA has put together on their website. They are vivid detail, they don't require commentary.

JENAll -- you don't have to look at the data, all you have to do is look at the pictures at the changes in sea level. It's the temperature, the vegetation, the desertification, the population. The pictures of -- we all know that Congress can only -- like they're so dumb they don't need to listen to cartoons -- to watch cartoons in order to get this data straight. We need to have a public viewing of that information, with Congress present, and then tell those guys and say, okay, now what?

NNAMDIJen feels that the people who need proof are the ones who are currently controlling the Congress, at least the House of Representatives in the United States, if they need proof, what does this mean in your view for our future policies, Mark Hertsgaard.

HERTSGAARDI don't think it's a question of proof. If it were a question of fact, this would have been settled long ago. These people have either ideological or economic reasons for deciding that they simply do not want to accept that climate change is real. Because they fear, I think, the consequences of that, which in their view would be too much government regulation of the economy, taxes, etc., or reductions in fossil fuel consumption. And because of those political or economic or ideological objections, they have essentially made up their minds.

HERTSGAARDThey are not going to believe this. And it doesn't matter how many times you tell them, they are not going to believe it. The point then, I think, in terms of changing policy, is that you have got to essentially, I think the media has a great job to do here. The media has been giving these antiscientific views a pass. They are acting as if oh, this is just one different opinion about a public policy issue. It is not, you cannot say that at this point when all of the scientific opinion repeatedly has been on one side.

HERTSGAARDThe doubters and the deniers and the cranks and Congress, they have about as much scientific credibility as the flat-earth society. They should no longer be influencing and holding hostage our nation's response to climate change.

NNAMDIJen, thank you very much for your call. We're going to take a short break right now. When we come back we will continue this conversation on climate change and what needs to be done about it and when, as in yesterday. I'm Kojo Nnamdi.

NNAMDIIt's a discussion both on climate change and the weather we’ve been seeing lately that may be an indication of climate change. We're talking with Peter Hildebrand. He is director of the Earth Science Division at the NASA Goddard Space Flight Center. That's a group of over 1,000 scientists studying earth's climate and weather. He joins us in studio with Mark Hertsgaard, journalist and author. His most recent book is called, "Hot: Living Through The Next 50 Years On Earth."

NNAMDIPeter, it might help to better understand the science, can data on the weather tell us cause and effect? It's my understanding that you can do that with data and a model.

HILDEBRANDWell, yes. We make all sorts of measurements of how the earth is working, the health of the biosphere, of the temperature of the ocean, of precipitation and things like that with our satellites at NASA, and we can get a really good view of what's going on. We can use those data to help with famine forecasts and understanding of changes in precipitation patterns and things like that. That's looking at all at the short term issues relative to weather mostly.

HILDEBRANDA famine is a longer term thing, so that would typically be related. We're getting to short term climate effects. But we also do modeling, because if we can't -- if we can't analyze our data in a model that predicts the future and then have that prediction be correct, we don't understand things very well. So that's why we're involved in modeling and we actually help the National Weather Service and actually the Air Force forecasting service with some of their land surface modeling.

HILDEBRANDWe're involved in helping that, and we need to do the modeling in order to verify that we really understand the processes that form weather and climate change.

NNAMDIThe models are getting better in representing reality, more sophisticated, but they aren't perfect. Is that the reason there is uncertainty about any prediction about climate?

HILDEBRANDWell, there are really two dimensions there. The biggest dimension is we're still learning things about climate change. So although we know that in the long term that is measured in multiples of years or decades, the climate is going to be warming, right now we don't know how to predict something like an El Nino, whether that will happen next year, or other year to year variations, whether it's going to be a cold summer or a warm summer, things like that.

HILDEBRANDAnd that falls into a short-term climate, or a long-term weather are where we're -- we're just learning about that type of variability. But that's a lot different than understanding the longer term climate over a decade. That we understand really quite well.

NNAMDIHere is Alex in Woodbridge, Va. Alex, you're on the air. Go ahead, please.

ALEXI just wanted to talk, you know, one of the issues I feel is that when people hear global warming, in place of climate change, they assume everything should be getting warmer. So when we had this snow last year, you know, people used that and said, well, look, see, it's not real because it's colder. But I knew it was coming, and I know people, plenty of people who knew it was coming because we had that hot summer, and more precipitation means it -- or more evaporation means there has to be more precipitation. That just happened to come in snow.

ALEXAnd the reason that the east coast got so cold was the shifting of the gulf stream current over to Greenland. For about two weeks, the capital of Greenland was actually warmer than London. I just think that the public should, you know, pay attention to these things, and they can take action. They can go onto NOAA's website, they can look at the currents, and they can see the evidence right there, rather than trying to draw simple black-and-white conclusions about heat and cold.

NNAMDII'd like you to answer this e-mail, Alex, that we got from -- actually, it's a post on our website from William. I won't ask our guests to answer it, because it seems like they've answered it so many times already, but William says, "How do I answer my brother who says that 80 to 95 percent of the greenhouse gases are made up of water vapor, and therefore man didn't do it and can't impact it." What would you say to William's brother, Alex?

ALEXWell, with the, you know, the condensation being put up, this evaporation, that is caused by an excess of heat. I mean, the more heat, the more evaporation obviously. And so greenhouse gases can get that ball rolling -- manmade greenhouse gases can get that ball rolling and make it a little warmer, but then as the water vapor piles into that warming effect, it just sort of snowballs into a greater effect.

NNAMDIYou would -- would you also advise him to go to the NOAA website?

ALEXOh, yeah. No. Definitely go to the NOAA website. You know, there's plenty of sites out there that track the currents, you can look at them for yourself.

NNAMDIThank you very much for that. I wanted to get back to the telephones. Here is Aaron in Arlington, Va. Aaron, you're on the air. Go ahead, please.

AARONHello?

NNAMDIYou're on the air, Aaron. Go right ahead.

AARONAll right. Very good. Thanks for taking my call. I listen to your show all the time, Kojo.

NNAMDIThank you.

AARONI was calling because I was curious, I know that we set aside a certain amount of money for relief and aid every year for countries and displaced people. And I was just wondering if there's any study on like the -- like human interaction in regards to what kind of impact are we going to have to have before people set aside money for this. You know, like how many people -- has somebody thrown a number out there like, you know, a $50 billion disaster will actually get all of these, you know, climate cranks to change their mind? Or, you know, or...

HERTSGAARDDon't -- don't expect anything to change the climate cranks' mind, I don't think. There have been plenty of disasters. The 2003 heat wave in Europe that was, according to the British government, the first real measurable impact of climate change, that killed 71,000 people -- 71,000 people. Hurricane Katrina, certainly not totally caused by climate change, but it's the kind of thing we expect, killed 1800 people. There's plenty of disasters.

HERTSGAARDJust last year, the Pakistan floods, 14 million people left homeless. But to your specific question about numbers, one of the very few positive hopeful things that has happened on international diplomatic scale of this issue recently, was at the Cancun Climate Negotiations last December, were governments, rich and poor nations, finally agreed that the rich nations will begin to put aside money to help poor nations pay for this adaptation.

HERTSGAARDThe argument there is that it's the poor nations who are going to suffer first and worst from climate change, even though they did virtually nothing to produce it because they have simply not industrialized yet. And so, we're going to begin to see, at least on -- there's a commitment for the rich nations to begin providing $30 billion a year over the next three years, and a $100 billion a year by the year 2020. No word yet on exactly where that will come from, but it is a welcomed first step.

NNAMDIThank you for your call, Aaron. Here is Bobby in Washington, DC. Bobby, you're on the air. Go ahead, please.

BOBBYHello, Kojo. This is Bobby Coward. I just want to ask a question. And I agree with Peter when he mentioned about awareness to global warming, but lack of understanding.

NNAMDIThat was Mark, but go ahead.

BOBBYAnd my question is the understanding part. And understanding the extreme hot temperatures and the extreme cold temperatures, what affect it could have on we as humans. But my concern is understanding was health outcomes may result from the climate change.

HERTSGAARDVery severe health outcomes. The British medical journal, Lancet, has declared that climate change will be the number one threat to human health in the 21st century, largely because of increased temperature. And that's not just because humans cannot get too hot, but what that's going to mean to storms, floods and above all water quality around the world. We're gonna have a lot more dysentery and diarrhea, unless -- unless we take the steps that we know how to take.

HERTSGAARDAnd I -- always this conversation tends to go in very dark places. And I want to just emphasize that the point of my book is to try and say no, we do know what we can do. There are a lot of very practical things, cutting edge governments and leaders in the communities all around the world are grasping this problem and dealing with it. It's only in this city in Washington, DC, really alone in the world where there is any more debate about this. And so look at what is going on. Roll up your sleeves, get started.

NNAMDIAnd in the book, "Hot: Living Through The Next 50 Years On Earth," Mark Hertsgaard talks about the options, sharp immediate cuts in emissions or reducing the carbon in the atmosphere. But we're running out of time very quickly, Peter Hildebrand, and I wanted to get to geo-engineering, because that's a hot topic. What not only are some of the bigger ideas out there, but tell us why scientists seem to be worried about geo-engineering and what they don't know.

HILDEBRANDWell, I think that the easiest response there is to say that it's not nice to mess with Mother Nature. And that's -- it's an amusing comment, but it's really true. We wouldn't really know what we're doing. There are all sorts of ideas about things.

NNAMDIGiant mirrors to reflect the sun's rays…

HILDEBRANDOh, yeah.

NNAMDI...back from the earth.

HILDEBRANDBut there is -- there is a simple geo-engineering solution -- step that we can take, and that has to do with taking the steps of reducing emission of greenhouse gases. That's geo-engineering also. It's really what we need to do, and it's straightforward. It's going to have economic impact, but much smaller economic impact than if we don't act.

NNAMDIIndeed, there are a lot of very bleak scenarios out there, Mark, when we talk about climate change, but how do you give young people hope when you talk to them?

HERTSGAARDI have a five-year-old daughter, and I insist on hope. That's the only way. If you don't hope, you are guaranteed of defeat. If you do hope, there's no guarantee of victory, but you have a good shot at it. And when I see the kind of energy that young people bring to this, and there are very few climate skeptics among young people. And as Peter just said, look, we've got the tools. We know how to change our energy system. We know how to change our agricultural system. Get out and do it.

HERTSGAARDAnd I think it's really the young people of generation hot who are going to make the difference here. But let's us in the older generations stop getting out of their way.

NNAMDIAnd you tell your daughter hers is the generation that is going to have to solve this problem. Your daughter, Kiara, born in 2005.

HERTSGAARDYes, sir.

NNAMDIAnd Mark Hertsgaard is a journalist and author. His most recent book is "Hot: Living Through The Next 50 Years On Earth." Thank you very much for joining us. Mark will be at Politics and Prose at 7:00 tonight. That's at 5015 Connecticut Avenue Northwest -- 5015 Connecticut Avenue Northwest. Peter Hildebrand is director of the Earth Science Division at the NASA Goddard Space Flight Center. Peter, thank you for joining us.

HILDEBRANDIt was my pleasure.

NNAMDIThank you all for listening. I'm Kojo Nnamdi.