MS. DIANE REHMThanks for joining us. I'm Diane Rehm. Two new studies show ocean levels are rising on both coasts of the United States. For this month's environmental outlook, rising sea levels and what it means for coastal cities. Joining me in the studio, Dr. Ben Strauss from Climate Central, Jessica Grannis from Georgetown University's Climate Center and from a studio in Tampa, Fla., Asbury Sallenger, an oceanographer with the U.S. Geological Survey. Please join us, 800-433-8850. Send us your email to drshow@wamu.org. Join us on Facebook or Twitter. Good morning to all of you.

DR. BEN STRAUSSGood morning.

MS. JESSICA GRANNISGood morning.

DR. ASBURY SALLENGERGood morning.

REHMAnd Ashbury Sallenger, if I could start with you. I know you led the U.S. geological study on rising sea levels on the east coast. Tell us what you found.

SALLENGERWe focused on the acceleration of sea level. Not so much the rate at which it's coming up, but how rapidly that rate is changing with time. This has been a controversial subject for some time, both in the United States and around the world, particularly in places like Australia. You know, as sea level rises, is the rate of sea level rise increasing? And that's what we focused on. And we were surprised to some extent to find a localized increase in sea level, increase in rate at sea level that occurred from about the middle of North Carolina, around Cape Hatteras, up above Boston, along the coast, over a 1000 kilometers, to above Boston. And some of our rise is well into Canada. And again, this is what we call a hot spot of accelerated sea level rise.

REHMExplain just how you measure that rise.

SALLENGERYeah, historically within our country and many countries around the world, tide gauges have been set up, you know, attached to piers and docks. And they measure the rise and fall of sea level every day and that kind of information that's gathered at our country by NOA, you know, is used for a wide variety of purposes. When you get a relatively long record you can start looking at long term averages and trends and it tells you how sea level is coming up relative to the land.

SALLENGERYou know, we had in our particular study, we needed to separate out as best we could the effects of land, land falling or rising versus the sea actually falling or rising. And we were able to come up with a methodology to do that. So what we believe we're seeing is a response in the currents that run along the Eastern seaboard in the United States that actually causes this sea level rise.

REHMAshbury Sallenger, he's an oceanographer with the U.S. Geological Survey. Ben Strauss, first, tell us what Climate General is and then tell us your assessment of where we are now in regard to climate change and whether that's affecting these rises in sea level.

STRAUSSThank you. Climate Central is an independent, non-profit research and journalism organization focused on climate change and the science of climate change. And it's been a pretty eventful couple of weeks in the weather and climate world, I must say. Coming to D.C., I got wet just walking from the Metro station. But we are seeing very clear signals around the globe now of a warming climate. One of the, you know, we don't have to wait for it to happen in the future. We've already seen eight inches of sea level rise, largely from warming over the last century. That's been happening very slowly, close to an inch a decade now. It seems to be accelerating globally.

STRAUSSBut it also appears to be accelerating most rapidly in this hot spot that Dr. Sallenger addressed in his study. One thing that I find very interesting about that is that the leading global climate models, which project temperatures into the future, to the middle of the century, the end of the century, have been the subject of controversy by many because they're models. Well, for about a decade, they have been making a very specific prediction that the Gulf Stream would slow down, this current in the Atlantic Ocean transporting heat to the North. And that a consequence of that slowdown would be extra sea level rise from around North Carolina to Boston.

STRAUSSSo here we have, ten years after the fact, a very distinct fingerprint that matches the prediction. So that's I guess, gives us potentially a more measure of confidence in the climate models and also some cause for alarm because those same models project an extra six to ten inches of sea level rise in that zone over the course of the century, much of it by the middle of the century.

REHMBut it's fascinating to me to think about whether it's land moving down or sea moving up. I read just the other day about the loss of sand, for example, in beaches all the way up the East Coast. So is the sand moving down or is the water moving up, Ben?

STRAUSSWell, in the Northeast, I'm afraid, if this projection is true, and what Dr. Sallenger is finding is true, then we have a triple whammy. We have land that's moving down at a pace of six inches to a foot per century. We have water that's rising from changing currents at perhaps a pace of half a foot to a foot for the century. And we have water that's rising from melting ice sheets, what we normally think of and warming expanding ocean water. And that's projected to be around three feet for the century.

REHMBen Strauss, he's chief operating officer and director of the Program on Sea Level Rise at Climate Central. Jessica Grannis, as these observations and predictions continue to play themselves out, what are cities and towns along the coast doing to adapt or prepare. What are they doing, how are they reacting?

GRANNISYes, Diane, lots of cities and towns across the U.S. are starting to do adaptation planning. The states on the West Coast and Northeast states all have developed an adaptation plan specifically considering their vulnerabilities to sea level rise and what to do about it. You also have a lot of local jurisdictions who are starting to plan. New York City, San Francisco are a couple examples. Unfortunately, some of our more vulnerable states are absent from the planning process in the Gulf Coast and the Southeast. The one example there is in Fla. where they do have an adaptation plan that was developed under Governor Crist, but with the change of administration, that climate commission that developed the plan was disbanded.

REHMSo what kinds of plans for adaptation are they making?

GRANNISSo essentially most of the plans look at what the vulnerabilities of the state will be. Looking at projected sea level rise, estimates over 30, 50, 100-year time frames. And then thinking about are the adaptation responses that are available to that state. Looking at things like protection, building sea walls and levees to hold flood waters out, accommodation which includes building buildings higher to be more resilient to flooding and things like moving development out of harm's way, moving development inland.

REHMBut aren't some communities still allowing people to build on those very shores that are vulnerable.

GRANNISYes, I mean, the big message is that there's a lot of planning happening and much less action happening on the ground. Some communities are starting to grapple with it while other communities are having huge political push back and they're seeing development pressures increase in these very vulnerable parts of our community. North Carolina is struggling with this issue right now. Their coastal commission came out with a projection of 39 inches of sea level rise for the state and that...

REHMIn what period of time?

GRANNISI think it was over the next 100 years, over the next century.

REHMI see, I see. And you see when we get those predictions of over a century, people perhaps right now are going to say, I don't need to worry about that.

GRANNISI think that is definitely one of the political challenges of sea level rise in estimating over these long time scales.

REHMRight.

GRANNISBut I think that information is necessary because a lot of this information is being used by a lot of different people on the ground. From emergency planners who are trying to deal with big, big catastrophic weather events like Hurricane Katrina to transportation planners that are trying to build a bridge that's supposed to last for a hundred years. They want to know what the future looks like and how to design that bridge so that it can, you know, survive over a hundred years with sea level rise to urban planners that are looking at a more short time frame, over a 30-year period. So a lot of the studies are designed with that in mind.

REHMJessica Grannis, she's staff attorney, adjunct professor at the Georgetown Climate Center and Georgetown University Law Center. Short break here, we'll take your calls when we come back. Do join us.

REHMAnd we're talking in this hour for this month's environmental outlook about projections in the rise of sea level from 3' on the east coast to 3 to 6' on the west coast. And joining us now is Philip Mote from Corvallis, Ore. He's professor at Oregon State University. Good morning to you, sir.

MR. PHILIP MOTEGood morning, Diane.

REHMI know you worked on a study focusing on west coast sea levels. What did you set out to do and what did you find?

MOTEThis study was called for in 2008 by then Governor Arnold Schwarzenegger of California who had directed state agencies to plan for climate change and ask the National Research Council, which is the operational arm of the National Academy of Sciences to write a report on sea level rise. And California teamed up with Oregon, Washington and several federal agencies to fund this study.

MOTEIt was a group of 13 of us led by Robert Dalrymple from Johns Hopkins University and the study director Ann Lynn. We had people from all sorts of backgrounds. We had oceanographers, geologists, atmospheric scientists and wetlands ecologists to try to understand the current state of science of both global climate change and how that -- how various processes would influence local climate change along the west coast. So the way these NRC studies work there is a very clearly negotiated what's called the committee charge and that's what we were operating under and delivered this report to congress two weeks ago.

REHMAnd exactly what did the report find?

MOTEWe assessed the current state of science for global climate change and came up with some projections of global change that were a little higher than from the last report of the intergovernmental panel on climate change. Another difference globally with the IPCC was that we included some terms that had fairly controversially been left out. And also that we gave both a central projection -- we're trying not to call it a best estimate or anything like that but it's our main projection and then also a range.

MOTEOur main projection for global sea level rise for 2100 is 83 centimeters. And for those of us who aren't savvy in the metric system...

REHM...in centimeters, yeah.

MOTE...that's 33", so just less than 3'. Another thing we were charged to do was to provide projections for 2030 and 2050. And as you noted in your last segment it's a little hard to think of things that were -- are going to happen in the year 2100 and be worried about them. So we actually provided projections for the year 2030 relative to 2000. And as your previous guests were noting, we have observed sea level rise both globally and around the coast of the U.S. It's not something that's going to sneak up on us in the year 2098 and suddenly we'll have to deal with it.

REHMRight, right. Tell me why the predictions are substantially higher in California than in either Oregon or Washington?

MOTEThere are two factors and by far the biggest is vertical land movements and your previous guests were talking about that. We have a very interesting tectonic environment out here on the west coast. California has the San Andrea Fault. About the southern two-thirds of California has a slice running through it. And the part to the left of that slice is sliding northwards and slightly downwards.

MOTENorth of Mendocino those of us in the northwest live in the Cascadia Subduction Zone where the Pacific plate of earth's crust is sliding underneath the North American plate. And as it slides under that that juncture is under tension and it's bulging upwards. And we know from very good historical records in Japan that there was a probably magnitude nine earthquake here in this subduction zone region in January of 1700. It released an enormous tsunami. And scientists have determined that when that happened there was about 3 to 5' of landfall.

MOTESo the big difference right now between the northwest and the southern two-thirds of California is that we are slowly rising relative to center of the earth, which gives us a little lower sea level rise. So that's the good news. The bad news is when we get another one of these subduction zone earthquakes not only will have an earthquake and very likely a tsunami but we will also suddenly have land that is a meter -- you know, 3 to 5' lower than it used to be.

REHMAnd does the rise in sea level give any indication whatsoever of how rapidly those tectonic plates are moving?

MOTEGeologists use GPS measurements now to track the movements of these plates and they found all sorts of interesting things. That was not something we covered in this report other than the vertical component of the movement.

REHMAll right. I want to open the phones. We've got lots of callers. Let's work some of these in as we continue our conversation. First to Oswego, N.Y. Good morning, Eddie. You're on the air.

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

REHMSurely.

EDDIEThe way I see it the poles are melting and they're getting lighter. The oceans are getting deeper and they're getting heavier. And this is happening at such a great length that our tsunamis are going to be more, our earthquakes are going to be more severe. And regarding global warming, all we have to do is check the center of our country. Now we're debating all this stuff after we pay to have scientific studies and then try to prove them wrong. Now we're fiddling while the Rome burns.

REHMAll right, sir. Thanks for your call. Ben, what is your assessment as to how much of this climate change, how much of this warming is, in fact, natural variability, how much may be caused by human behavior?

STRAUSSClimate has varied naturally for all of earth's history and it's undergone very great swings. But that doesn't mean that we don't have the power to make a big change ourselves. Unfortunately, we do have that power and we are making one. A very interesting fact is that the climate of the last six to 10,000 years has been really abnormally stable. In the history of the earth, it looks like a billiard table. I mean, the history of the earth's climate is like a roller coaster. The last 10,000 years is like a billiard table.

STRAUSSAnd that's exactly when agriculture and civilization developed. I find it hard to believe that that's a coincidence. So right now what we're doing is we're trying to bend that billiard table into a roller coaster again. Unfortunately all the evidence I've seen points to, you know, this time, it's humans pushing the climate change.

REHMI'd be interested in your reaction, Philip Mote.

MOTEYeah, there are a couple of ways to look at extreme events. One is that, you know, the last -- the amount of warming that humans may have added to a given event by adding to the head-trapping blanket of the atmosphere, that additional warming may only be a couple of degrees. But if you look at the incidents of heat wave event above a certain threshold, when you get out to the very rare events the likelihood of those rare events might, you know, triple or even more just from adding that extra couple of degrees.

REHMAnd you mentioned what could happen if a major earthquake occurred. What do you see going on there?

MOTEYour caller made some elusions to apparently thoughts about influencing tectonic activity through the changing weight of the oceans. You know, we're talking about adding 8" to the depth of the oceans from ocean thermal expansion and another couple of feet from melting ice. So the additional weight of, you know, the melting ice -- that first part expanding ocean, that doesn't change the actual mass of the ocean. It just makes it bigger so part of sea level rise is not actually not the ocean getting heavier. But this is such a tiny, tiny additional load that I have a hard time seeing how it would affect tectonic activity.

MOTEOn the other hand, part of what we have to take account of in computing sea level rise is the way that earth's crust responds to the removal of ice. So when there was a mile of ice sitting on Canada the earth's crust was quite a bit lower. And there's still very residual rebound from that.

REHMAsbury Sallenger, I'd be interested in how your own study of the ocean and its rise has similarities or is different from that of Philip Mote.

SALLENGERYeah, I've looked a bit at the inner sea study that came out a week or so ago. And our study was different in the focus. We really were looking at the acceleration of sea level rise. As Phil was talking about, they were doing a projection into the future of how sea level rise will vary along the west coast. Again, ours is a focus effort on the acceleration. That is how much quicker our rate's rising as we go forward.

MOTEAnd that was from observations, right?

SALLENGERIt is completely from observations, yes. The...

REHMSo...go ahead, Asbury.

SALLENGERYeah, the -- you know, the models that were mentioned earlier by Dr. Strauss, you know, they predicted the location of this hot spot that we're talking about quite well I think. And that our focus here was to take data to see whether it was happening now. Their projections in these models were to go into 2100. I'm not talking about Phil's study now. I'm talking about a series of climate models that have been published over the last five years. And our focus was to take real data to see whether it was happening now. And we find a very similar signal to what they're projecting.

REHMAll right. Let's go to Grand Rapids, Mich. Good morning, Brian.

BRIANGood morning, Diane. Great show. I'm reading a book on climate crash and some of the core samples they pulled out of Greenland, the Poles and some of the light sediments all kind of point to a possibility of an abrupt change, something in the matter of 15, 20 years. And I'm wondering if the scientists feel that that's something that may be happening now.

REHMBen Strauss.

STRAUSSMy understanding is the models are not predicting right now an abrupt change in the Gulf Stream, which I think the caller is referring to. But there is indeed evidence that that current which carries warm water from the Caribbean up toward Europe and Greenland, and keeps Europe warm by the way -- Europe is up in the latitudes of Canada -- that in the past that current has switched on and off across a ten or twenty-year period, that's currently rated as very unlikely for this century by climate models. But it would certainly be a terrible event.

REHMAnd...

MOTEIf I could interrupt, even the models that show and we have to be clear, the Gulf Stream is a wind-driven ocean circulation. You're referring to the thermahaline or density-driven circulation that's most variable over history. And even the models that have a nearly complete shutdown of the thermahaline circulation in a world with more greenhouse gases still produces warming over Europe. So the events of the last -- coming out of the last ice age and the Younger Dryas period 11,600 years ago are not likely to be repeated without that massive instability of the ice sheet and the fresh water runoff.

REHMPhilip Mote of Oregon State University and you're listening to "The Diane Rehm Show." Asbury Sallenger, I understand North Carolina legislators drafted a bill that would require sea level estimates to be based only on historical data. Tell us what this means and what drove the legislature to do that.

SALLENGERYou know, I'm not sure what politically was going on with the State of North Carolina. You know, I could address the implications of what we have found technically...

REHMSure.

SALLENGER...on North Carolina. And North Carolina actually turns out to be a very interesting case from a technical point of view in that it forms the southern boundary of what we are calling this hot spot. It actually -- the northern half of the state is having -- undergoing significantly higher sea level rise than the southern half. As a matter of fact from Cape Hatteras, which is about the center of the state, again like I mentioned earlier, all the way up to Boston you have accelerated sea level rise.

SALLENGERWell, to the south of that, both in the southern half of North Carolina and all the way down to Florida, there's no indication in the data today, and over the past 60 years for instance, of acceleration. And so, you know, I see our results as policy relevant but we don't get into making policy here. And so we make the information available.

REHMAll right, Jessica, this has to do with business and planning and...

GRANNISYeah, so what drove the North Carolina process was concern by the development community that there was going to be a potential move to use these sea level rise estimates to restrict development along these vulnerable coastal areas. The bill that was proposed initially to lock in only considering historic rate of rise actually failed.

GRANNISBut there has been a new bill that's been passed by both houses in North Carolina to basically require more study of what sea level rise means for the state and have a moratorium on the state using any sea level rise projections to restrict development of coastal areas. So there's basically kicking the can down the road to require more study.

REHMSo in the meantime, what happens to -- does development continue?

GRANNISWell, yeah, I mean, if, under North Carolina's existing coastal laws, development can continue.

REHMJessica Grannis. She's Staff Attorney and Adjunct Professor at the Georgetown University Climate Center. Short break here and when we come back, more of your phone calls and email. Stay with us.

REHMAnd welcome back. We'll proceed right to the phones to Sterling, Va. Good morning, Gary.

GARYThank you. In 1957, on the southeastern arboreal forest, it's visible from Interstate 95, just after you go past the first exit in Georgia, the moss was two feet high on the forest. In 1968, it was five feet high and then I didn't see it for 40 years. And in 2007, when I saw it, the moss had grown 105 feet and it was branching out into the crowns. And one of the possible solutions to these erratic and extreme weather is if everybody was to cut their grass longer we would have weaker thermal updrafts and thereby we'd have less wind shear and we'd be consuming more CO2, producing more oxygen and you'd have more lightening bugs.

REHMAll right, sir. Thanks for calling. But you know that takes me right to this email from Bob in St. Louis who says he's very concerned about global climate change, but as one person feels quite helpless he wants us to talk about things that an individual can do to help curb climate change. Ben?

STRAUSSWell, it's a very important concern for this issue because it is so huge and feels unempowering.

REHMRight.

STRAUSSAnd you can change a light bulb, you can make your home more energy efficient, you can buy a more energy efficient car or use mass transit, all of those things do contribute. You can eat less meat; that does, too. On some level you may feel that that's not credible. What difference is that really going to make? It's a little bit like voting. And that's another way that people can contribute. They can ask what their public officials, their elected representatives, their companies are doing.

REHMJessica?

GRANNISYeah, I mean I think the first caller raised an interesting point about using the natural systems to buffer against climate impacts. One example here locally is in Maryland they have what's called the Living Shorelines Protection Act where, you know, a local waterfront owner installs a natural shoreline that not only mitigates carbon emissions, but also protects the property from storm surge and buffers flood impacts.

REHMAsbury, do you have something to add to that?

SALLENGERSure. I think one thing is just really trying to understand the problem better. And let's assume, you know, over the next decades that there's a 30 centimeter or one foot rise in sea level. And that may not sound like a lot to people, but if you think of it as occurring and then storms occur on top of that extra foot, it makes the storm surge that much higher. It makes the reach of the waves onto the beach towards buildings that much more higher and more effective in causing damage. And I think that, you know, there'll be scientists looking at this problem, but I think, you know, people can recognize it, too. And it won't always be obvious what the cause is.

REHMJessica, do you believe that some of these coastal cities which are most vulnerable are moving quickly enough?

GRANNISI think that, you know, there's a lot of things that communities can do now in the short term. I think when people think about the coast they think about beach communities. They don't think about large-scale cities like New York that are vulnerable to impacts. And Boston and even D.C. is vulnerable to sea level rise. And most communities aren't even effectively addressing their existing flood risk. We talk about extreme events and sea level rise on top of extreme events, but there's also inland flooding that's caused by increased precipitation in some of these areas.

GRANNISSo there are things that communities can do to increase their resilience to existing flood impacts. There's a program within the National Flood Insurance Program called The Community Rating System that actually gives people discounts on their flood insurance if the community itself implements some of these more robust flood plain policies.

REHMAnd go ahead, Ben.

STRAUSSWell, I think it's very interesting to think about current flood risks. In fact an analysis that we conducted suggested that the sea level rise we have already seen from global warming has in fact more than doubled the odds of extreme coastal flooding at most locations around the U.S. today. And if you consider that we've already seen up to eight inches of sea rise from warming, that means that every single coastal flood is bigger than it would have been without the warming we've already seen.

STRAUSSWe don't always label it that way, but we're already experiencing increased damage from climate change and coastal floods.

REHMBut here's a tweet from Randy who says, "If we in America do all we can to reduce global warming would it offset what China and India are doing to the environment?" Ben?

STRAUSSWell, we're already committed to a lot of sea level rise and a lot of damage if we all stop emitting tomorrow. But if we reduce our emissions as one nation or collectively, we can reduce the damage that we'll see in the future, give ourselves more time to adapt. So each step is a contribution.

REHMAll right. To Syracuse, N.Y. Good morning, David.

DAVIDGood morning, Diane. Wonderful program and a wonderful episode, great panelists. I'm not popular in some global-warming-climate-change discussion circles because I keep suggesting -- and I'm very interested in your panelists opinions -- that it's wonderful to talk about compact fluorescent bulbs and energy star appliances and so on, but that if we really want to reduce the American carbon footprint in a meaningful way, we have to start looking at things that would actually require significant sacrifices.

DAVIDSuch as reducing our mobility, not driving all over the place all the time, a virtual elimination of pleasure and recreational flying, those kind of things, reducing our living spaces so that we're not air-conditioning or heating as many cubic feet in our homes. And my great fear is that people in general, from scientists to activists, right down to common citizens are simply unwilling to give up these sort of luxuries that we've adopted as rights, I guess a lot of people looked at them. And I'll take the answer off the air.

REHMAll right, sir. Thanks for calling. Philip Mote?

MOTEWell, it's a tough question. I think he's right that if you look at these sort of very modest lifestyle changes, absent massive technology changes, we can certainly bend the curve. And California has an extremely energy efficient economy, much more so than the rest of the country or than any other state in the country. And they, you know, enjoy a very fine quality of life. They started 30, 40 years ago investing in energy efficiency and renewables and that got them to where they are.

MOTEBut to stabilize the climate we need to cut greenhouse gas emissions by on the order of 80 percent. And we can imagine getting to maybe a 10 or 20 percent cut with energy efficiency and another, you know, 10 or 20 percent with renewables, but to think about decarbonizing our economy to the scale required to stabilize the climate that is eventually going to require very, very large changes in how we use energy.

REHMIndeed.

MOTEOn the other hand, very high gas prices and gradual depletion of oil reserves may do it for us.

REHMI want to really return to this issue of rising sea levels. And the fact that flood insurance, Jessica, has been federally insured, backed up. So how does that figure into whether people feel they're safe by continuing to build on these precarious lands?

GRANNISYeah, I mean I think there are several, what you would call perverse incentives that exist right now. One of them is the Flood Insurance Program that subsidizes flood insurance for, you know, flood-prone properties. It's …

REHMAnd that was created back in '68.

GRANNIS'68, correct.

REHMYeah.

GRANNISYou also have, you know, federal disaster assistance. So any time a community is flooded by a hurricane or natural disaster the federal government steps in and provides, you know, taxpayer money to help rebuild those communities. You also have a lot of funding for hard protection structures, flood control projects through the Army Corps that builds seawalls and levies that we saw fail in New Orleans. And all of these things are being born by the general tax base and not necessarily by the people at risk. So the market is not reflecting the true costs of living in those highly vulnerable areas.

REHMWhat do you think about that, Ben?

STRAUSSWell, there is a huge amount of population and assets at risk. We estimate that there are five million Americans who live on land less than four feet above their local high tide line. About half of those are in Florida. And our body of laws, it's my understanding, tend to be designed for disasters which happen with the same probability year in, year out, a tiny chance all the time. But what sea level rise does is it increases the chances over time.

STRAUSSWe really don't have instruments designed for that world where the chance just doubles and triples over the decades. And a once-in-a-century storm turns into a once-in-ten-year storm or an annual event. So I think if we want to reduce the potential for great damage we need to figure out how to accommodate those kinds of changing risks.

REHMAll right. Let's go to Okanogan County in Washington State. Yanaka, you're on the air.

YANAKAYes. I'm getting tired of climate change scientists only talking about predictions and not making clear to the public the connections between current events and climate change. Like the catastrophic fires that we're having. I heard that this is the worst fire season in recorded history. The other half of the country has a huge flood and we're all hearing about that. But I don't hear any climate change scientists pointing out to the public the connection between these events. Now 20 or 30 years ago you guys were predicting them, but now that these things are actually happening, nobody opens their mouth and says anything about how these things are happening.

REHMWell, let's see what Philip Mote has to say. And let me remind you're listening to "The Diane Rehm Show." Philip?

MOTEWell, maybe we're not saying it in the right places, but there's quite a lively field of study called Detection and Attribution. And that's precisely what you're talking about. It's looking at current events and determining what role human modification of the climate played. And that's been done for extreme precipitation for changing snow hydrology in the West, for changing wildfires so quite a lot of these things actually get papers written about them. Maybe the scientists aren't appearing on NPR often enough to talk about them, but it is a field of active study. And we're very interested to know how these changes are unfolding on our planet.

REHMSo, but be specific. Look at those extraordinary fires barely under control in Colorado, Philip, is there any way to connect them to the issue of global warming now?

MOTEI work with some scientists back about 10 years ago and wrote a paper on looking at the area burned state by state and connecting that with climate of that year and did statistical analysis and so on. And, you know, we wrote this paper. And I came home and told my wife, hey, we, you know, we discovered that in hot dry summers it burns more. And she looked at me and said...

REHMDuh.

MOTE...you needed this study to figure that out?

REHMYeah, right, right.

MOTEBut, in fact, you know, it's different in different eco regions, but primarily if the snowpack is lower and/or the summer is hotter and dryer, then in most forests, you get a much more extensive fire year.

REHMAnd here's an email from John who says, "Is it even possible to stop or reverse the global warming trend? What exactly would be needed to actually stop it?" Ben?

STRAUSSWe can slow it down and we can eventually reverse it with technologies that remove carbon dioxide from the atmosphere, but that's a long-term process and a very heavy lift.

REHMYou talk about 100 years in terms of forecasting the rise of sea level. How many years would it take to reverse a trend that's been in place now for so long?

STRAUSSI think that if we implemented very strenuous policy, we could see declining carbon and temperatures in the 22nd century.

REHMTwenty-second.

STRAUSSBut not this century.

REHMJessica?

GRANNISI mean I think the important thing to note is that greenhouse gasses are persistent in the environment. So what we emitted 50 years ago is impacting us today. And what we emit today is gonna impact us 50 years from now. So that's why adaptation is so key because there's a certain amount of impacts that we have to adapt to 'cause we're going to see them. We can't change that.

REHMAt this point, we can't change that.

GRANNISRight.

REHMWe can only change what happens 100 or 200 years from now.

STRAUSSI think we can make a difference in sea level rise, for example, in the second half of this century. It's still going to be going up, but if we continue business as usual it will be going up rapidly. If we cut down on emissions very sharply it will go up much more slowly. The speed of change makes a really big difference for the danger, just like a bullet's speed is what makes it dangerous. So we can affect things this century, but in terms of actually reversing trends, the reading I've done suggests that we might only see that in the next century.

REHMAnd on that note we'll have to leave it. Dr. Ben Strauss, he's chief operating officer, director of the program on sea level rise at Climate Central; Jessica Grannis is at the Georgetown University Law Center; Dr. Asbury Sallenger of the U.S. Geological Survey; and Philip Mote, professor at Oregon State University. Thank you all so much.

GRANNISThank you.

STRAUSSThank you.

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

ANNOUNCER"The Diane Rehm Show" is produced by Sandra Pinkard, Nancy Robertson, Denise Couture, Monique Nazareth, Nikki Jecks, Susan Nabors and Lisa Dunn. And the engineer is Tobey Schreiner. Natalie Yuravlivker answers the phones. Visit drshow.org for audio archives, transcripts, podcasts and CD sales. Call 202-885-1200 for more information.