MS. DIANE REHMThanks for joining us. I'm Diane Rehm. Are we heading to a world without snow? It's a provocative question posed in a recent article by journalist and skier Porter Fox. The answer is probably no. But climate models suggest there could be a lot less of it. Joining me in the studio to talk about some of the many implications of a warmer world, Coral Davenport of The New York Times.

MS. DIANE REHMJoining us from studios in New York, Gavin Schmidt -- he's a climatologist and a climate modeler with NASA's Goddard Institute for Space Studies -- and Porter Fox, a features editor for Powder Magazine and author of "Deep: The Story of Skiing and the Future of Snow." I hope you'll join us, 800-433-8850. Send us an email to drshow@wamu.org. Follow us on Facebook or Twitter. And welcome to all of you.

MS. CORAL DAVENPORTGood morning, Diane. It's great to be here.

REHMGood to have you all with us. Porter Fox, if I could start with you, in a piece published in Sunday's New York Times, you wrote that pretty soon there will be only a few places in the world where the Winter Olympic Games can be held. What are the projections?

MR. PORTER FOXThat was a study done by Daniel Scott who -- he works at the University of Waterloo. They've been studying the specific effects of climate change on the ski industry since the early 1980s. And they predicted that that number under a high emissions scenario is very soon going to drop from 19 cities that have had the winter games in the past down to 10. And by the end of the century, that number will drop to six.

REHMAnd tell me about the snow we're seeing at Sochi.

FOXSochi is an interesting case. It's a fairly warm region of the world to start with. But, you know, I've worked for Powder Magazine for a long time, and we've actually sent journalists to that region several times. I believe the first time was -- it was over 10 years ago. And we kept running stories on it because of the great powder that was there, the terrific winter conditions.

FOXAnd, as you can see, they had to cancel two test events last year for the Olympics. They stored -- I think it was 16 million cubic feet of snow for this year from last year, just to make sure there was enough snow on the course to do the skiing events and outdoor winter events. And they have over 400 snowmaking guns that also have been making all that snow that you see on the television.

REHMAnd, Gavin Schmidt, you've said that Porter -- the title for Porter's article, "The End of Snow," is not quite right. Tell us why.

MR. GAVIN SCHMIDTSo I thought the article was great. And I think it was a -- it's a very interesting perspective on what climate changes are anticipated and how that's actually going to effect not just winter sports but also water resources and snowpack and the consequences of that. The funny thing about this particular article was that it was entitled "An End to Snow?" And every time there is such an article that is -- you know, it gets quoted for decades hence as a prediction that it will never snow anywhere ever again. And...

REHMOf course, I'll bet Porter himself did not write that headline.

SCHMIDTOf course. Of course. I totally understand that.

FOXUnfortunately not.

SCHMIDTBut he will unfortunately pay the price for that. You know, the turns in snow are very, very interesting. We've seen already very large changes in springtime snowpack in the Northern Hemisphere, particularly in April, May, June. Our winter levels are more erratic, and there's no clear trend yet. But if we end up with a business as usual scenario for the rest of this century, we're going to see very large changes in snow cover indeed. And I don't think it's just going to be the Winter Olympics that are going to suffer because of that.

REHMBut are you saying there's going to be less snow or that it's going to be melting faster, Gavin?

SCHMIDTSo the melting faster in the spring, I think that's a very clear sign that we've already got in the record and that will continue. The actual total amount of snow, that's going to be very -- there are issues there with, you know, how wavy the jet stream is. You know, we've seen some very high snowfalls this winter on the East coast of the U.S. particularly. And that's due to these big fronts coming through that are related to meanders in the jet stream.

SCHMIDTNow, what's going to happen to that and how those -- that cold air intersects with very warm humid air from the south to create snow during the winter, that's a slightly more nuanced issue. And so we might end up with situations where we're getting just as many snowfalls, but it's not lasting as longer and it's not going to last into the spring. And, obviously, if you're a skier, having snowpack and depth is important, rather than just when it snows.

REHMSure. And what about Western states that really depend on snowpack? We're seeing something going on there that's even more critical.

SCHMIDTSo, with all due respect to Porter and the skiers, I think the water resource issue associated with the mountain snowpack is actually a bigger issue for society. And you put your finger right on it. The changes that we've seen in the Sierra snowpack, in California, in the headwaters of the Colorado, those are extremely worrying for areas in the American Southwest, including California, that are already water-stressed. And the issue with snow is that it provides a reservoir that allows water to come down from the mountains past the spring, even into the summer.

SCHMIDTAnd as that snowpack recedes, as it becomes smaller every winter, what you're going to see is that the water is going to come down faster. And then during the summertime, you know, peak wildfire season, peak drought season, those are the kinds of times when you're going to be seeing large shortages of water more than we have already.

REHMHmm.

SCHMIDTAnd that's very concerning.

REHMCoral Davenport, I know you want to jump in here.

DAVENPORTDiane, Gavin is right. It's interesting. It's often skiers and snowboarders and, you know, these winter sportsmen who are the first to sort of see and recognize this reduction in snow. And that is an issue for the winter sports industry.

REHMOf course.

DAVENPORTThis is, you know, an issue globally, though. Around the world, snowpack and glaciers, for centuries, have been the foundation for how humans get their water. This is a primary system that humans have used for centuries for getting water, for irrigation, for drinking. So as the snowpack diminishes, and also as glaciers diminish, there's less water to melt down each spring and supply drinking water, supply water for irrigation. This is what we're seeing in India and Pakistan as well.

DAVENPORTAs the glacier levels diminish, there's increased water shortages. We're seeing this in Montana, in Glacier National Park. Reports show that Glacier National Park might be glacier-free within the next 20 years. And, again, this is an issue not just for, you know, the end of the natural beauty of those glaciers but the fact that the water runoff from those glaciers is an essential source of water for states around the West.

DAVENPORTSo this is a, you know, a system for storing and preserving water and then using water in the spring that's been in place, again, for thousands of years. And it's changing. And, you know, right now, our governments aren't quite equipped to handle it. We don't know where that water is going -- new water is going to come from or what different kinds of water systems we're going to have to use.

REHMBut this has become a huge political issue as well.

DAVENPORTThis is one of those issues that, you know, that the -- the issue specifically of climate change is, you know, an intractable issue, I would say, in Washington. It's really difficult. I wouldn't say that, you know, we're likely to see any action from Congress on climate change in the near future. But these are the kinds of things that help move the needle.

DAVENPORTWhen you see these tremendous changes, when you see changes that are manifested with droughts that have huge economic impacts that cost taxpayer dollars, that sent -- that lead to lower crop yield, higher food prices, these are the kinds of things that get lawmakers' attention.

REHMWhat are the polls telling us now as to what people are thinking?

DAVENPORTSo a poll conducted last month by Pew found that 67 percent of adults say that there is solid evidence that the earth has been getting warmer. You know, that's a significant majority, but only 44 percent believe that it's getting warmer because of human activity. So, you know, they're still, you know, where public opinion is still pretty far behind the science unfortunately.

REHMAnd, Gavin, what difference does it make that people are not quite caught up yet with the science?

SCHMIDTSo if you ask people in depth what they understand about many science issues that make it into the public sphere, what you find is that people don't know very much. You know, it's a kind of shallow -- no, I mean, there's obviously some people who know a lot. But in general, if you ask people about bird flu, if you ask people about climate change or the ozone hole or, you know, some kind of health issue, you know, people know that there's an issue.

SCHMIDTAnd they work on trying to understand it. But the depth of knowledge is not very high. And one of the things that we can do as scientists, I think, is try and help people, point them to resources where they can get more information, and then look into -- in-depth into these situations.

REHMGavin Schmidt, climatologist and climate modeler. Short break here. We'll be right back.

REHMAnd welcome back. We're talking about what's happening to snow and of course snow and water and of course snow temperatures and the question of climate change. Here's an email: "Never mind subzero temperatures across the U.S. from the polar vortex or winter storms slamming the southeast. If The New York Times says we'll have no more snow, well, it must be true." Porter, do you want to comment?

FOXPeople believe what they see, and the polar vortex could very well be linked to what's happening on this warming planet. At the same time it was freezing cold here, it was 62 degrees in Alaska on Jan. 27. That's unheard of. There were rains to fairly high elevations. The Richardson Highway was closed for one of the biggest avalanches they've ever seen up there.

FOXYou know, it's all interrelated. What we know is the planet is warming. What scientists are still figuring out is exactly how that plays out regionally around the world. So if you see it snowing outside one day, it doesn't mean that climate change has stopped. It just means that it's snowing outside.

REHMGavin, in a warmer world, in fact, there could actually be more snow? Is that correct?

SCHMIDTSo this goes to the subtleties that I mentioned earlier on. So snow that we get on the East coast particularly is related to warm humid air that's coming up from the Gulf, and that intersects with cold air that's coming down from the (word?). And that happens most when you get these big meanders in the jet stream.

SCHMIDTNow, so we're getting more water vapor in the atmosphere because the whole planet is warming. And so when there's a collision between those warm air masses and that cold air mass, you tend to get a lot of snow being formed. And it may possibly be that you get more snow in very short amount of time into the future. But I think you have to be very cautious about making attribution statements related to weather events. Those are very, very difficult things to attribute.

SCHMIDTAnd I know that there's a lot of people who are talking and say, oh, well, this is exactly what -- this isn't exactly what we expected. And, you know, it may be that there is a connection. But I think you have to be very, very cautious until the science has been done, which takes a long time. And you need to get good statistics. You need to really work at this. I think, you know, we should try and kind of hold off saying that everything is climate change. You know, some things are just weather events.

REHMAnd...

FOXWell, if I could just jump in on that.

REHMSure.

FOXAlso, you have to look at historical evidence. It's not all modeling. It's not all speculation into the future. You know, what history tells us is the rate of winter warming in the U.S. has tripled since 1970. Nine of the 10 warmest years on record have occurred since 2000. Alaskan winters have warmed nearly 6 degrees Fahrenheit. You know, these are things that we have witnessed in the past.

REHMBut is it true -- here's an email: "Is it true that even three decades of temperature measurements are insignificant in terms of the age of the earth?" What do you think, Porter or Gavin?

FOXI think it's significant, absolutely. I don't think you can define global warming by that by any means. There's a difference between weather and climate. And typically, from the researchers that I spoke with, you're talking about 50-year segments, 100-year segments and even more. That's when you can establish a trend.

REHMGavin.

SCHMIDTSo obviously the planet's climate has changed enormously over the last 4 billion years. And, you know, we're just starting to piece that together. But when we're looking at a specific change like the trends over the last 30 or 40 years, we are looking for fingerprints of change that are, you know, associated with the ocean, associated with the sun or volcanoes or greenhouse gases or aerosols.

SCHMIDTAnd when we look at that and we see what those fingerprints are and we match it up to the real world evidence, it's quite clear that the trends over the last 30 years really have been driven almost entirely by human activity.

REHMAll right. And now we're joined from Lincoln, Neb. by Mark Svoboda. He's a climatologist at the National Drought Mitigation Center. Welcome, Mark. I'm glad you could be with us. I gather you monitor drought in the U.S. Explain the pattern affecting the Northwest at this point.

MR. MARK SVOBODAYeah, well, thanks, Diane. We've heard this alluded to a little bit earlier by Gavin and Porter with regards to both mention of the polar vortex but also the mention of the abnormally warm temperatures we've seen in Alaska. And that's due to displacement of the jet stream well north due to high pressure over the Gulf of Alaska. And that's really shunted the storms from coming into California and the Pacific Northwest to date and displacing that warmth and moisture up to the north.

MR. MARK SVOBODAAnd on the other side of that high pressure ridge has been just like opening the backdoor to this cold Canadian air that's coming sweeping down into the Midwest and even down to the Gulf of Mexico and the southeast resulting in snow, even in Florida. So, you know, it's a whole relationship globally, not just what's happening right in your backyard.

REHMSo how long has the pattern been in place?

SVOBODAWell, it's been pretty firmly in place this entire winter pattern. And we even saw remnants of that last winter. So the question is, these longer-term decadal oceanic oscillations that you hear about and how do they interplay between what's going on in the north Atlantic and the Pacific and the Indian Ocean and the Equatorial Pacific, they all play off of each other to drive longer-term climate based on what we see on week-to-week weather. So these sort of patterns have an influence eventually on where you have the haves and the have-nots.

REHMSo how has the snowpack in the upper northwest been affected?

SVOBODAWell, for the Pacific Northwest, they're a little better shape because they had the snow last winter. California's coming off of consecutive -- this would be the second consecutive very low snowpack year. So they've drawn down the reserves a little bit in those reservoirs. And they're much more vulnerable to the drought that's occurring this year. We've had consecutive low snowpack years in the central Rockies as well, which feed the Colorado, which is a vital lifeline to the desert southwest and southern California.

SVOBODASo we're seeing it on both fronts with regards to where the snow is not falling, well below 50 percent of normal for most reservoirs in that region. And the amount of water in the snow is of concern too because it's well below -- in many cases below 25 percent of normal in California.

REHMSo, Gavin, what do you make of those two opposing situations?

SCHMIDTWell, this is the kind of thing that you see every winter in that we tend to see places that are very warm or very cold at the same time. And when you're looking at the climate trends, you're generally averaging over those weather events so that you have something that's a little bit more robust. And when you look at the global trends, the hemispheric trends, the signal is very clear.

SCHMIDTWhen you're looking at how variable that pattern is, that's very noisy, and there's a lot of kind of chaotic dynamics in the atmosphere that makes it very difficult to just look at one particular pattern and say, oh, it's because of this or that that's going on in the Pacific or that's going on in the Atlantic. And so those are really interesting research questions, but there is a lot of chaos -- real chaos in the system. And we need to be aware of that as well.

REHMPorter, turning to you and your article, you mention that ski resorts in Colorado, in Keystone and Breckenridge, for example, are now seeding the clouds. What exactly are they doing?

FOXThat's a process that people have been doing for many years actually, water districts, ski areas. You can introduce silver iodide into a cloud and essentially promote the formation of snow crystals. And Vail says that it's increased snowfall at their resort over the last 30 years. Several other resorts are giving that a try. You know, again, it really depends on where the clouds go in the future, where the jet stream goes. That kind of points the hose at various ranges.

FOXBut what a lot of researchers like Noah Diffenbaugh's studies have come up with is they find that temperatures the predominant parameter in the future. So by the end of the century, what falls in a lot of mountain ranges will fall as rain in the winter instead of snow.

REHMMark, what do you make of cloud seeding?

SVOBODAWell, I think most people view that as a long-term activity, as he mentioned, like over a 10-, 20-, 30-year period because you can't make clouds during a drought. I mean, dominant high pressure leads to fair weather, subsiding air, not a lot of cloud formations. So you're not looking to get you out of a drought. What that sort of activity -- initially, in the Midwestern Great Plains, it's even considered more for the effect of a lessening hail risk than it is generating precipitation. So you view that as more of a long-term proactive activity for water supply.

REHMGavin, what do you make of it?

SCHMIDTSo cloud seeding has been something that people have tried since the '60s. And, as Porter mentioned, in Colorado, they've been doing it since the 1980s mainly as a privately-funded venture. But the scientific evidence that this actually works to increase snow is actually pretty slim. There's a big study that's been going on in Wyoming that's been going on since 2007. And that preliminary report in 2012, after five years of trying to do this in a controlled, well-studied manner, said, well, OK, well, we don't have enough information yet.

SCHMIDTLet's just do it for another couple years, and maybe we'll have something that's statistically significant. But the -- our ability to tell whether, you know, what you did with the silver iodide actually made a difference downstream is really quite poor. So most of this cloud seeding activity is kind of like a Pascal's wager. Well, it probably won't do any harm, rather than it being a demonstrable useful activity.

REHMCoral, let's talk about the cost of all of this, both the drought and the flooding and these snowstorms that we're seeing. They're all costing taxpayers lots of money.

DAVENPORTIt's really interesting to see the rising cost to taxpayers as we see these changes in weather. In 2012, taxpayers paid $60 billion for restoration after Super Storm Sandy. Currently, the National Flood Insurance Program is $25 billion in debt. This is, again, money that taxpayers are going to have to pay. That program has a $30 billion limit. It's nearing the brink of insolvency. Congress will probably have to vote to borrow more money from Treasury for that flood insurance program.

DAVENPORTIn 2012, after we saw record droughts in the Midwest, the flood -- sorry, the crop insurance that taxpayers had to pay was a record $11 billion. Usually that program pays out at about four to 5 billion. So these costs keep adding up. We keep seeing year over year an increase in number of what the government calls $1 billion disasters. So, you know, as these costs keep rising, as we see an increase to what taxpayers are paying, that really does influence the discussion in Washington.

REHMAnd you're listening to "The Diane Rehm Show." This whole question of cost affects food as well. The cost of food is on the rise. How much of that is due to the economics of weather?

DAVENPORTSo, in 2012, when we saw these record droughts across the Midwest, the National Bureau of Economic Research did a really interesting report where they found that a lot of -- because there were so much crop die-off, a lot of crops, particularly corn, went up. The price of corn went up about 20 percent. That is a cost that ripples through the economy. Corn is the main source of feed for beef, for cattle, for pork, for chicken. It's used in many other products. It's used in corn syrup.

DAVENPORTSo we see these commodity prices rippling through the economy. And a group of economists found, you know, this is a cost that can be -- this is a price tag that can be attributed to climate change. The economists were careful to say, this particular drought might not specifically be attributable to climate change, but this is the kind of cost we're going to see because climate models show us we're going to see more droughts like this. And this is what's going to happen.

REHMMark, what do you make of that?

SVOBODAWell, I think the very -- well, a couple things. The very fact that drought has such a large spatial footprint is one of those, compared to other hazards that are usually quick hitting, confined to a storm track both spatially and temporally, that makes a big difference on the sort of ripple impacts because of the duration of this hazard of drought.

SVOBODAThe second thing, it's a vulnerability issue of putting more and more pressure on the need to produce more with less water. They become very efficient in the way that -- much, much more efficient in using less water to grow the same amount of crop and even more. But, you know, in California alone, we've seen a doubling of population since the '70s. So the drought of the '70s -- it doesn't take a drought of the '70s to have impacts that we saw in the '70s. It takes a lot less.

REHMGavin, do you want to comment?

SCHMIDTI'm just going to agree with both of the previous speakers. The impacts of climate change that we're going to see are going to be multi-variant. They're going to be based on lots of different intersections of climate and our expectations of climate and the systems that produce our food, that control, you know, how our cities function, where we build things, how we build things, and how we transport things. All of those things are going to be affected by climate change. And costing that into the future is a really, really difficult job. And I don't envy the economists, their task there.

REHMAnd, Mark, what do you make of Porter's theory that we may, in the future, be limited as to the number of cities where Winter Olympic Games can be held?

SVOBODAWell, maybe more so from the non-recreational viewpoint, that maybe Porter's coming from, is the concern of the water supply and resource issue, of dwindling water resources and supplies amongst increasing population and demand for that same amount of water, which is a relatively finite resource. So I think from that standpoint is a concern we see is, is the water staying in the system longer into summer?

SVOBODAAnd if we're seeing rains at higher elevations later into the fall and then melting out earlier in the spring, or bringing rains to upper elevations and melting off that snow earlier in the spring, that's a doubled-edged sword on both sides of the water supply equation.

REHMAll right. We're going to take a short break here. Mark, I hope you can stay with us as we come back to open the phones, take calls from listeners. Mark Svoboda, Porter Fox, Gavin Schmidt, Coral Davenport, they're all here for you.

REHMAnd welcome back. We'll go right to the phones, first to Michael, in St. Louis, Mo. You're on the air.

MICHAELHello, Diane. Thank you very much for taking my call.

REHMSurely.

MICHAELI have been reading some articles lately about scientists who are studying the sun. And they are saying right now that the sun is going to sleep. There's no sun spot activity, and this is very typical of something that happens right before a mini ice age. And I'd like to hear the comments of your panelists on this idea.

REHMAll right.

MICHAELIt sounded very convincing to me.

REHMGavin Schmidt?

MICHAELI'll listen offline.

REHMAll right. Thanks for calling, sir. Gavin?

SCHMIDTSo there's been some very interesting activity on the sun, actually. So we are currently in a solar maximum, which is a maximum amount of activity, a maximum amount of solar sun spots. And that generally gives you a slightly brighter sun, but this solar maximum is quite a bit smaller than the last solar maximum, which happened 11 years ago. And if you look at the trend over, say, the last 30 years, we seem to be moving into a situation where the solar maximums are becoming a little bit smaller each time.

SCHMIDTNow, there is historical precedent for that. Back in the 17th century, there was a period with almost no solar cycle activity for 30 or 40 years. And that did, at that point, coincide with a relatively cool period in the climate. But there were other things going on at that time as well. There were a lot volcanic activity, which is also a cooling effect. And this time around, we don't have any particularly increased volcanic activity, but we also have the changes because of greenhouse gasses.

SCHMIDTSo the impact of the sun this time around is very unlikely to produce anything like a mini ice age. And if you actually look at what the solar scientists are saying, that's not what they're predicting. They're talking about changes in the sun. The impacts of that on the climate are going to be completely dwarfed by the increases in greenhouse gasses.

REHMAll right. To Chuck in New Bedford, Mass. Go right ahead, sir.

CHUCKDiane, thank you for returning again and again to this important topic. I worked in the energy efficiency world and what we call global warming 20 years ago. And it's very discouraging that we have to keep answering these same questions over and over again. My question is why the scientists and associated engineers find it so difficult to move away from the question of, is it happening or did we cause it to what can we do about it?

CHUCKAfter Sandy, there was some considerable discussion of mitigation in terms of whether even the reduction in production of CO2 could have an effect -- that's the more interesting question. It will never be about certainty. It is always about possibility and likelihood.

REHMAll right. Coral, what can be done?

DAVENPORTWell, just to be clear, it's not actually the scientists' jobs to enact policy, to enact climate policy. Scientists do research. They make the research available to the best of their efforts. They communicate that research to the public and to policymakers. Then it's the job of policymakers to take action. So in Washington, after Hurricane Sandy, after the droughts, you know, there was a little bit of discussion of what can be done for mitigation.

DAVENPORTAnd the answer is that economists and most policymakers will tell you there's one very clear policy that can slow the rate of carbon emissions and that can slow the rate of climate change, and that is taxing or pricing carbon dioxide pollution. That would mean raising the price of coal, which coal emissions are the number one source of greenhouse gas emissions around the world.

DAVENPORTIt would mean raising the price of oil, also a major cause of greenhouse gas emissions around the world. It would mean using these market solutions to fundamentally change the fossil fuel economy that the world has enjoyed for the past 100 years. And there's tremendous well-funded political resistance to that. And, to date, that is what has kept anything from happening -- certainly in Washington.

REHMAnd following up on that, here's an email from David in Baltimore. He says, "Long before an absolute lack of snow kills the ski industry, the dramatic impacts of climate change across the globe will likely demand such enormous responses across the energy and transportation sectors to render absolutely untenable the idea of loading kids into a big, gas-guzzling SUV, driving up to a big heated chalet to go skiing on snow made from pumping vast quantities of water uphill. Much of the commercial ski industry is already an anachronism." Porter?

FOXIt absolutely is. And those are all very good points. In the big picture, the ski industry is not producing as many greenhouse gasses as, say, coal-fired power plants, things like that. But what the point of "Deep," this book was, was to try to activate the 65 million skiers around the world who, indeed, are very influential people.

FOXThey're living in places in the mountains where they can see this visible evidence of climate change. And we're trying to get them together, strength in numbers, let them become a vanguard of this movement. And there are politicians that go to Aspen to ski, business leaders, whatnot. That's the real point of this, not necessarily to keep snow on the slopes, more to get skiers to do something about it.

REHMAll right. To Mike in Athens, Ohio. You're on the air.

MIKEThank you, Diane. Thank you for taking my call.

REHMSure.

MIKEBack in the '70s, Saudi Arabia wanted to a tow an iceberg. And a lot of people said, no, you don't want to do that. But now that seems like the right thing to do. According to an encyclopedia of the earth and oceans and islands, there's enough fresh water ice coming off of these ice shelves equivalent to all the drinking water in the world, and we're just letting it melt.

MIKEIt sounds like to me that this would be a great job for the United States to get into, just as an experiment, like they did with NASA, as we have how many people who are unemployed, how many ships have we got in mothballs that we could probably just try to experiment. Can you actually tow one of these things to a place? We'll bust it up, and it's fresh water.

REHMAll right. Mike, let's see what Mark Svoboda's comments are on this.

SVOBODAWell, that discussion certainly has been around for a long time, I mean, close to home here with Canada, for example. I'm not as well-versed in the feasibility of such an effort to speak on it as an expert by any means, but the idea of moving water around -- even within the United States -- is a contentious issue, the ownership of that -- and it takes two to be trading partners. So I think there's a lot involved with such a scenario, but I can't speak explicitly to the feasibility of that.

REHMAnd here's an email from Bethlehem, N.H., from Ken, who says, "We are certainly warming. But, at some point, won't the warming cause a salinity change in the oceans and then create a cooling effect as warm air from the equator will not circulate in the manner to which it does now?" Gavin?

SCHMIDTSo that's actually eluding to a scenario that was the topic of a Hollywood movie back in 2004, "The Day After Tomorrow." The idea there is that increased rainfall and melting in the northern latitudes would change the ocean's circulation so that heat wouldn't go as much towards the poles. The situation in that movie was completely ridiculous. But the actual kernel of scientific truth in there, that does exist.

SCHMIDTAnd so we are concerned about that. We're monitoring those circulations. We are monitoring changes in the salinity and we're trying to work out what's going on. The changes so far have been small, but there does seem to be a very small trend. And we're projecting that that trend is going to continue. But it isn't going to be such a large change that it's going to suddenly turn all of the areas that are warming into cooling.

REHMSo do you see anything happening in Congress, Coral?

DAVENPORTThis year, absolutely not. I will say that President Obama has recognized that Congress is probably not going to take action. He has called on Congress repeatedly and he's also told Congress at this point, if you don't take action, I will. And he is moving forward using his own executive authority to create new regulations on coal-fired power plants. We'll see those come out later this year. I think they'll be very controversial.

REHMCoral Davenport of The New York Times. And you're listening to "The Diane Rehm Show." Let's go now to Mary Dee in Chevy Chase, Md. You're on the air.

MARY DEEHi, Diane. Thank you for taking my call.

REHMSure.

DEEWhat I've read -- a lot of what I've read -- is that Greenland is the key. The glaciers that are melting, the prediction is that the water will rise globally 24 feet if those glaciers melt. And they're melting at a rapid rate, much more rapid than was predicted by scientists. My question is, how long could this actually take? And the second is that there's another theory that every 25,000 years, we have an ice age. And it's time. And I don't know if we're right in it or it's around the corner, but many people believe that we have had little to do with this picture.

REHMAll right, Mary Dee.

DEEAnd this is the earth, just time to have an ice age again.

REHMOK. Let's see what Gavin thinks.

SCHMIDTOK. Two questions there. That sea level rise from the melting of Greenland is if the whole of Greenland melted. That's not's very likely to happen any time in the next few thousand years. So there is melting from Greenland. It is putting water into the ocean. It's about 15 percent of the current rate of sea level rise just from Greenland. And that is projected to increase. So we do need to worry about that, but it isn't as large as the numbers that you just gave.

SCHMIDTAs for the cycles of ice ages, those are totally real. We've been looking at those very carefully for the last 20 or 30 years in the records of the ice cores and the ocean sediments. But your timing is slightly off. They're not every 22,500 years. They're more like every 20,000 years, 30,000 years. These are related to wobbles in the earth's orbit.

SCHMIDTAnd where we are right now -- we're not actually anticipating another one of those natural ice ages for perhaps another 30,000 years. So, again, that's not something that's really relevant to the time scales that we're talking about or the impact of human activity on these relatively short decade-to-century time scales.

REHMAnd to Grand Rapids, Mich. Akosh, you're on the air.

AKOSHHi, Diane. Thank you for taking my call.

REHMSure.

AKOSHI'm calling regarding the confusion that people often get in climate change with respect to the winters becoming more and more cold but ignore the fact that for the last few years we are having very extreme summers, to the extent that we have emergency and drought situations coming out across the U.S. And it's not really addressed in your discussion so far. And the other concern is that winter is extreme in the U.S. for reason of polar vortex, but it's not really that extreme in other parts of the world.

REHMAll right. And I think, as a matter of fact, Mark Svoboda did talk about the drought, but you might just go on there a bit, Mark.

SVOBODAI'm not sure I quite caught what the question was. I understood the comment.

REHMWell, he was saying that we shouldn't just be concentrating on the lack of snow or the cold, but rather paying close attention to the drought, as well.

SVOBODAOh, absolutely. And one of the key pieces of legislation that's gone to the president for his signature is reauthorization of the National Integrated Drought Information System or NIDIS for short. That is really a way to stay on top of early warning. Drought is a hazard, as I mentioned, is a very long-lived hazard. You can't see it coming on a satellite or radar image.

SVOBODAAnd so you do have to have due diligence in monitoring that. And preserving our monitory networks -- recording impacts, which are sorely lacking across the U.S., these are the things that hit home for constituents within congressional districts. How was your constituency impacted? NIDIS is going to give us that ability to keep doing that for the next five years.

REHMAnd, Coral, you mentioned that the president could act on executive order. What could he do?

DAVENPORTWell, it's not executive order. The president actually has much greater authority under the Clean Air Act. And I fully expect that we will see this action later this year. The president has given the Environmental Protection Agency a deadline of June 1 -- so this is coming right up -- to put out a draft regulation that would cut carbon pollution from existing coal-fired power plants. This is a huge regulation.

DAVENPORTIt will be tremendously controversial because it would probably lead to the shutdown of hundreds of existing coal-fired power plants. A big pushback on that from coal country, big pushback on that from the coal industry. But the president and the Environmental Protection Agency do have the authority to put out this regulation. Although it will be legally challenged, they'll contend that they do have the legal authority to do that.

DAVENPORTSo we'll see a draft regulation of that probably by June, a final regulation, final proposal by June of 2015, and states will be told to implement their plans for that, implement that proposal by June of 2016. All of that is the president trying to use his executive authority to push as much as he possibly can through on climate change before he leaves office at the beginning of 2017. That said, this is going to be very politically controversial. It's going to come under huge legal fire -- would not be at all surprised if these regulations end up in front of the Supreme Court.

REHMCoral Davenport of The New York Times, Gavin Schmidt, climatologist, climate modeler for NASA's Goddard Institute for Space Studies, Porter Fox, features editor for Powder Magazine -- he's the author of "Deep: The Story of Skiing and the Future of Snow" -- and Mark Svoboda, climatologist at the National Drought Mitigation Center -- lots to think about -- thank you all so much.

SCHMIDTThank you.

REHMAnd thanks for listening, all. I'm Diane Rehm.

ANNOUNCER"The Diane Rehm Show" is produced by Sandra Pinkard, Denise Couture, Susan Casey Nabors, Rebecca Kaufman, Lisa Dunn, Danielle Knight, and Alison Brody. The engineer is Erin Stamper. Natalie Yuravlivker answers the phones. Visit drshow.org for audio archives, transcripts and podcasts. Call 202-885-1200 for more information. Our email address is drshow@wamu.org, and we're on Facebook and Twitter. This program comes to you from American University in Washington, D.C. This is NPR.