MS. DIANE REHMThanks for joining us. I'm Diane Rehm. Last year, worldwide sales for air conditioners rose 13 percent than the prior year. Growth is expected to accelerate in coming decades. For this month's Environmental Outlook, Growing Demand for Air Conditioning. Joining me in the studio, Durwood Zaelke. He's president of the Institute for Governance and Sustainable Development.

MS. DIANE REHMSteve Yurek, president of the Air Conditioning, Heating and Refrigeration Institute. Joining us from New York City, Elisabeth Rosenthal, international environment reporter for the New York Times. And from Wichita, KS, Stan Cox, senior scientist at the Land Institute in Salina, KS. Please, feel free to call us, 800-433-8850. Send us your email to drshow@wamu.org. Join us on Facebook or send us a tweet. Good morning to all of you.

GROUPGood morning.

MS. ELISABETH ROSENTHALGood morning.

REHMGood to have you all with us. Steve Yurek, let me start with you. A hundred years ago, you had this young engineer named Willis Carrier. I certainly remember the all Carrier air conditioners. He invented the very first one. How did it work? How big of a deal was it?

MR. STEVE YUREKIt was a very big deal. Prior to that time, there were other cooling technologies that were being used in different areas. Some people call them smart coolers and other things with evaporated cooling in different areas. But he was approached by a friend at that time that was having a real difficulty that was a printer where in the summertime did not have the ability to get the ink dry and was getting jammed up in the printing process.

MR. STEVE YUREKAnd so he came up with this idea, developed an air conditioner or cooling so that the process could run year round and not jam up and the ink would dry. From that, the air conditioning moved into a dying industry at the time, especially in the summertime. And that was the movie industry. Nobody wanted to go to the theaters because it was too hot. And they started putting air conditioning in there.

MR. STEVE YUREKAnd all of a sudden, you have the summer blockbusters and other things that occurred because of air conditioning. Around that time as well, they started putting air conditioning in other office buildings. It was still very, very rare in residential. They were much larger pieces of equipment. You had the capital air conditioned in some states. That was the downfall of democracy when Congress can meet year-round rather than disappearing for five months.

MR. STEVE YUREKBut from there, it continued to grow and you had the ability then of, as things developed. And at that time, air conditioning was based upon refrigerants that were hydrocarbons or ammonia and that type because we didn't have the fluorinated gases at that time. Those were developed a little bit later. When that occurred, they switched to that because of the safety. The issue of using ammonia and hydrocarbons, there were some concerns at that time.

MR. STEVE YUREKAnd that's what we've been using since that time. Initially, CFCs, which were, we found out in the '60s, '70s that ozone depleting, the industry, working with environmentalists and through the Montreal Protocol moved from those ozone-depleting refrigerants to non-ozone-depleting refrigerants. Now with the discussion of climate and looking at it, some of those refrigerants have a high global warming potential if they're emitted into the atmosphere.

MR. STEVE YUREKAnd so, as an industry, continuing to looking at possibly going full cycle once we developed appropriate safety and other things to back to the non-fluorinated gases.

REHMInteresting.

YUREKSo, it's been an interesting cycle.

REHMI should say. And really world changing. Steve Yurek is president of the Air conditioning, Heating and Refrigeration Institute. Stan Cox, you say the more we try to cool off with air conditioning, the hotter the summers are going to be in the future. Explain what you mean.

MR. STAN COXThat's right, Diane. It's kind of a vicious circle because the hotter it gets, the more we run air conditioning. And the more we do that, the harder power plants have to run to power the air conditioning and the more refrigerants that will be leaked into the atmosphere. Right now between the impact of refrigerants and the fossil fuels being used to generate electricity, the impact of air conditioning of vehicles and buildings in this country is almost half a billion metric tons of CO2 equivalent, which is a lot.

MR. STAN COXAnd it's more -- or it has been traditionally more than the rest of the world put together. That's changing very fast. And predictions are that by 2050 there will be a ten-fold increase in the amount of electricity used to run air conditioning around the world. And that will truly be a huge impact on the atmosphere.

REHMStan Cox is senior scientist at the Land Institute in Salina, KS. He's author of "Losing Our Cool: Uncomfortable Truths About Our Air Conditioned World." And to you, Durwood Zaelke, the use of air conditioning is just growing exponentially around the world, certainly now including China and India.

MR. DURWOOD ZAELKEThat's correct. The refrigerant that we use right now in air conditioning, HCFCs and moving to one called HFCs, which happens to be the fastest growing greenhouse gas in the United States and many other countries. If we don't constrain it, we can end up contributing about 20 percent of global warming to the entire world. And if you go back to what Steve was saying earlier when we were using the CFCs back in the '60s and '70s, we formulated a treaty called the Montreal Protocol, which is constrain the growth of those chemicals.

MR. DURWOOD ZAELKEIn fact, it's phased them out in about 98 other damaging chemicals that were both destroying the stratosphere and ozone layer and warming the climate. The combined efforts, both voluntary efforts, national efforts and then the international treaty have solved an amount of the climate problem that otherwise would equal the CO2 part today. That's the single biggest part, responsible for about half of global warming.

MR. DURWOOD ZAELKESo while the air conditioning demand is growing, while it's very important problem, the history of how we've controlled these fluorinated gases teaches us something incredibly important about how we should be addressing the overall climate problem.

REHMDurwood Zaelke, he's president of the Institute for Governance and Sustainable Development. And turning to you, Libby Rosenthal, you've been covering these environmental issues for the New York Times. Do you see the use of these chemicals, as Steve Yurek outlined at the start, as almost coming full circle in order to protect the environment?

ROSENTHALWell, I think there is a way they could come full circle. I don't think we're there yet. I think the problem is that all the gases we're using right now are either ozone-depleting and climate warming or seriously climate warming. And there aren't a lot of good commercial alternatives on the horizon. There are tons in development. And I know every air conditioning company is working on developing more environmentally friendly options. But if I want to go out and buy an air conditioner tomorrow, you can't buy them.

REHMYou can't buy one that's environmentally friendly?

ROSENTHALYou can buy one that will be called environmentally friendly because it's better than the one that you used 10 years ago. But if you're talking about something that's not warming and it not ozone depleting, no, you can't now buy it.

REHMSo, Stan Cox, you say we really built ourselves into an air conditioned society. So have we gone to a point of no return?

YUREKIt would almost seem that way. But we can retro fit and we can begin building for non-refrigerated cooling of buildings. And one thing that has not worked is increasing the efficiency of air conditioning equipment. Since the mid-1990s we have seen a 30 percent increase in the efficiency of residential air conditioning equipment, which is quite an achievement. Over that same time we doubled the amount of electricity we're using for residential air conditioning for home and also overall.

YUREKWell, it's doubled overall and there's a big increase in the use per home as well. Hotter summers, bigger houses and when something is more efficient, people want to use it more.

REHMSo, if I live in a condo with more than 200 units in it, I don't have very much choice in the matter. But for those buildings who had the wherewithal to convert to something like solar cooling would make a huge difference. We're going to take a short break here. And when we come back, we'll talk further about alternatives and take your calls. I look forward to hearing from you.

REHMAnd welcome back. Air conditioning. It is 100 years old this month, first discovered, invented by a man whose name was Carrier. And of course I know many of you recognize that name. Here in the studio with me, Steve Yurek. He's president of Air Conditioning, Heating and Refrigeration Institute. Durwood Zaelke is president of the Institute for Governance and Sustainable Development. Libby Rosenthal is international environment reporter at the New York Times. And Stan Cox is senior scientist at the Land Institute in Salina, Kansas. He's author of a book titled "Losing our Cool: Uncomfortable Truths About our Air Conditioned World."

REHMLibby Rosenthal, you recently went to India. Tell me what you found there.

ROSENTHALWell, I found a couple of different things. First of all, air conditioning use is exploding, which is understandable because India, on the whole, is a really, really hot and humid place. I was there in April and boy, I visited some offices where there wasn't air conditioning that were fan cooled and it's really hot. And there are studies to show that if you're really, really hot your productivity and your health goes down.

ROSENTHALSo it's understandable in a way why, as people are getting richer and entering the middle class in places like India that one of the first things they do is go out and buy an air conditioner.

REHMWell, and of course you've got the question of whether India can actually power that demand with the largest power outage ever occurred there last week.

ROSENTHALSure and there are people who say -- you know there were a lot of different theories about that power outage, about how it was a switching problem, how some parts of India were overdrawing from the grid. But one thing that everyone I've spoken to said certainly contributed is that a lot more air conditioning in India is now going to -- I mean, a lot more energy in India is now going to air conditioning so you need more energy. And most energy in India comes from coal.

REHMStan Cox, just how much is air conditioning contributing to global warming?

COXIt's -- well, as I said, right now it's about a billion metric tons CO2 equivalent and that's combining the fossil fuels used in power plants, the gas and diesel used in -- by cars to run the air conditioning and the impact of refrigerants to run both of those. And that is -- the electricity being used is predicted, as I said, to increase tenfold in coming decades. And then the -- with business as usual, the impact of refrigerants from -- this would be both air conditioning and refrigeration, is expected to triple over that time.

COXSo if that were to happen then air conditioning alone would be producing as much global warming as -- well, about half of the total global warming that we're doing today.

REHMWell, what about trying to create some new standard of efficiency and to what extent would that reduce or slow the amount of greenhouse gases?

COXWell, as I said, for the electricity consumption part efficiency hasn't worked yet. You can say, well, we would -- the impact would be even worse if we hadn't had it but still doubling in the amount of electricity used and the climate impact from residential air conditioning in just 12 years or just between 2005 and 2010 at 20 percent increase means that the improvements and efficiency haven't worked there. People are saying, well what about renewable energy? But right now air conditioning in the United States consumes five times as much electricity as produced by all renewable sources put together.

COXThe same thing is happening globally. Air conditioning is using more power than all renewable sources put together. And it's going to frustrate attempts to supply the bulk of our power with renewable electricity because the growth in air conditioning will completely swamp it out.

REHMSteve Yurek.

YUREKYes, first of all, Stan's been throwing out a lot of numbers, which the facts aren't basically true, that air conditioning has improved in efficiency by over 60 percent. The growth in air...

REHMYou mean in the last 100 years.

YUREKNo, in the last -- since the 1990s it reduced by over 20 -- 30 percent just from 2006. And prior to 1990 there was another increase of about 60 percent as well. So what was out there before has increased efficiency greatly. The amount of growth in air conditioning and the use of air conditioning in the United States in the last 10, 15 years has not been that great since most of the air conditioning has already been in the stock that we have in the United States. And that's an issue that we have.

YUREKThe biggest issue is replacing what's out there in the install base with higher efficient equipment it's looking at systems that can then be used to make sure that it's used efficiently. But again, that's a personal choice and individuals need to decide, you know, if they want -- how to do that. I think our greatest opportunity in influencing that increase -- you know, and I think what he's trying to talk about is globally -- is what we're doing as an industry in educating those people in India, China and other places so they don't take the same steps.

YUREKThey don't have the infrastructure that's already in existence. They're building new building and so they have the ability to design them better, to look at them and figure out how they can reduce the load of that system so you reduce the energy and the need for cooling and then also using new technologies. You were talking about your condo here in Washington. It's very expensive for an existing building to make significant changes. The architecture's already done. The structure's there.

YUREKAnd so you have to work within that. And the best way to do that is what we've been doing here in the United States and that's increasing efficiency of the units that are installed because that's the biggest input. Other places around the world we can do more in the design.

REHMAll right. Let me read to you an email from Bill in Dallas, Texas who said, "Air conditioning units need to be bolstered in their efficiency by building codes that mandate how they are installed so they do their work with maximum efficiency. Here in Texas AC units are usually installed inside the attic, which is the hottest place in the house. Imagine trying to generate cold air while surrounded by 160 degree heat. If there were building codes to mandate the units be installed below the attic and to have the ducts and a dropped ceiling, much electricity would be saved. What about that, Stan Cox?

COXWell, first of all, the increases in efficiency that I was talking about were in efficiency of equipment in use in the residential sector, not the efficiency of new equipment being produced. And so despite that increase in efficiency on the ground, there still was a huge increase doubling in -- according to the Energy Information Administration in electricity use. Well, I -- nobody's against efficiency of course and we need to use the energy that we do consume as well as possible, but we're going to be required to make some very deep cuts in our total energy consumption in coming decades. And it can't all be done just by doing away with air conditioning.

COXBut logically the deepest cuts ought to be in optional consumption, not in necessities. And so we've always required energy for cooking, for winter heating in cold climates, for lighting, growing and preserving food and etcetera. And we need to do that more efficiently but simply doing that is not going to make -- do the climate as much good as we need to do by reducing energy further. And there we're going to have to look hard at nonessential consumption.

REHM...like air conditioning. Is that you're saying?

COXWell, and I would include air -- yes, and I would include air conditioning in that latter category. Now, of course nobody's going to be for cutting off the cooling in an intense heat wave for people who are vulnerable to heat because of age or ill health.

REHMSure, sure.

COXBut the very lavish routine use of air conditioning and the fact that the number one complaint among office employees is that they're freezing in July.

REHM...too cold, yeah.

COXWe're wasting a huge amount of electricity, even in very efficient buildings because of that.

REHMAll right. Durwood Zaelke, I must say I have to agree with Stan Cox on that. I'm sitting here in this studio freezing. I think we waste a fair amount. We go into restaurants, we always, we as women, quite frequently have to take sweaters or shawls. We need to think about how to use what we have more wisely.

ZAELKEWell, we're moving into an era where there's very sophisticated management technologies that will sense when you're in a room. It will sense when you leave a room. It will sense how cool you like it historically. We can do much, much better in how we use it. I'd like to go back just for a moment to the way we drive the improvements in our efficiency and the way we drive the availability of alternatives to the damaging refrigerants that we're using. And this is primarily the international treaty called the Montreal Protocol.

ZAELKEIn its 25-year history, it has phased out -- completely phased out almost 100 damaging chemicals that destroy the ozone layer and that warm the climate. It's the world's most successful environmental treaty. It sets a schedule for phasing out a damaging chemical. Industry responds brilliantly with new alternatives, not always chemical. Sometimes they're not in kind. There are better ways to cool, for example, sometimes than just using a refrigerant. The Montreal Protocol by doing its phase outs has also driven great improvements in energy efficiency, as we've been hearing.

ZAELKESo to go back to the metrics that have been mentioned, just removing the HFCs, which are becoming the dominant refrigerant, would solve an amount of the climate problem about 10 percent of what the world needs to stay below the 2 degree threshold for disaster.

REHMDurwood Zaelke. He's president of the Institute for Governance and Sustainable Development. And you're listening to "The Diane Rehm Show." Going to open the phones now, 800-433-8850. First to Key West, Fla. Good morning, Harvey, you're on the air.

HARVEYWhatever happened to, I'm too hot to eat? Because we can walk into a refrigerated restaurant or home, all of a sudden when you're cool wow it stimulates your appetite. It's responsible for obesity. And when you count -- I watched the cars going down the road yesterday. Every window zipped completely up. They're in a self-contained bubble nodule. It used to be you'd open the windows to get that breeze. And if it was just too hot you wouldn't drive that day.

HARVEYThis 24/7 conquering of the environment is to our own destruction. There has to be days it's too hot to move, too hot to eat. And if you use fans and evaporation and you are forced to be less active in the hot weather than you are, it helps the entire society.

REHMAll right. Thanks for calling. Libby Rosenthal, what's your reaction?

ROSENTHALWell, I agree to a large extent. There's a lot we can do individually. And I think this is one of those problems that it's tempting to say, ah this problem is bigger than me so what can I do? But in fact, if you're like me, right now I'm sitting in an office where I can't open a window, so hopefully newer buildings will be designed so that natural ventilation can come into play more.

ROSENTHALLikewise, I'm sitting in an officer where a lot of people are wearing jackets and ties in the middle of summer. Different countries like Japan and some companies in Italy have experimented with saying, okay during summer you wear light clothes. So there are a lot of things that we can do to improve energy efficiency, improve our use of air conditioning. The U.S. has a kind of assumed set point for air conditioning, which is somewhere 70 to 72 degrees. In my experience a lot of places are cooled even more than that.

ROSENTHALIn Europe and in -- certainly in Japan at the moment that set point is set quite a bit higher, maybe 24, 25. In Japan, post Fukushima, it was set 28 because they were really short of electricity. So I think there's a lot we could do, but we do need better technology too and better air conditioning gases to help us.

REHMAll right. Let's take a caller in Black Bend, N.C. Good morning, Calvin.

CALVINGood morning, Diane. It's Black Mountain.

REHMAh.

CALVINWe are -- my wife and I built a house here recently that we both cool and heat with a geothermal heat pump. It was more expensive to install but it's quite inexpensive to operate, draws less power and has a much more positive impact on the environment. I'd just like to hear your panel comment on the potential for that technology.

REHMWhat about that, Steve?

YUREKYes. There's all sorts of technology being developed. Geothermal is there and can be used. There's thermal storage. There's the establishment of zoning so that you have the ability to shut off rooms at different times in using electronics. And you're also seeing in the industry has been developing new technologies that can be used working with engineers, working with homeowners, working with building code officials to develop new building codes. But again, in the United States we have a significant problem. We have a build environment that's already out there...

REHMExactly.

YUREK...which makes it very difficult. I think way back to the...

REHMLet me just ask Calvin very quickly. I gather, Calvin, you built your home and installed that as you were building, or was that an add-on?

CALVINNo, it's a new home. We built it seven years ago and then put it in at that time.

REHMExactly. And we've got to take a short break here. Calvin, I thank you for your call. We'll continue to discuss air conditioning and its alternatives after a short break.

REHMAnd apparently a lot of you feel as I do. Here's a straight forward email, "Why can't we immediately create a campaign to explain why buildings should be cooled no colder than 78 degrees? I have to take a jacket to the mall, to airports, to restaurants. This seems crazy." How much good, Durwood Zaelke, would that do if 78 degrees were the minimum?

ZAELKEIt would do a lot of good because it would save us a tremendous amount of energy. It would save us some on refrigerants. And it would educate people about what the consequences are for the way we're living. It's one thing to change culture. And I think this is critical for bringing the world towards sustainability in a safe climate. But it would also educate us all about what government needs to do, as well. Because the government has got to set the standards at some point and say you simply can't leave the doors to the mall shops open onto the street so all the cold air goes out and you're raising the environmental impacts for all of us.

ZAELKEI mean these are now nuisances at the grandest scale. So we need to think of what we can do to change the culture and to change the way governments regulate. They need to be stricter.

REHMOkay. And you just the two words that are going to set people off. Those especially who are looking for less government regulation. Here's an email from Brendon, "Is any work being done in the U.S. on passive house construction?" What is passive house construction?

ZAELKEWell, you know, before we had cheap electricity and before we had air conditioning as we know it today, we used to know how to design houses to take advantage of natural features. I grew up in Palm Springs. Every house in Palm Springs had a white roof, which cooled the building tremendously. The whiteness of a roof is the measure of albedo or reflectivity. You send heat back into space. You can cool the house by a tremendous amount just from that.

ZAELKEWe used to know how to plant trees around our house. So in the summer we would plant trees that would leaf and provide a shade. And then in the winter when we needed the sun…

REHMAnd create a breeze, as well.

ZAELKEAnd create a breeze. So we used to know how to circulate air better, you know. And there are other things. If you go back to Ancient Rome and then a practice still in use in some river valleys in Germany, after the harvest in the summer they would build these big wooden frames along the river. They'd take the cuttings from the grape harvest, weave them through a net and sluice water from the river. So it would function like a swamp cooler, the breeze would blow through it and cool the entire river valley.

REHMInteresting. All right. To Spencer, W.Va. Good morning, Mike.

MIKEGood morning, Diane. I think that we have to change the way we build housing. We have to get out of the box of stick-built housing and get to more energy efficient housing. There's numerous ways and methods that can be done to greatly increase the energy efficiency of a house. We have built an earth-sheltered house. This is only our first summer experience in it, but only recently has the temperature risen to 72 degrees without air conditioning.

REHMTell me what an earth-sheltered house is.

MIKEWell, some people call it underground, but that's a stigma. It's nothing like that at all. The entire front of the house is exposed to the weather with many windows and a couple of doors. And the rest of the house is actually underground. We have between and four and eight feet of earth on the roof because the roof is domed and it depends on where in the dome it is, how deep it is. And then the other three sides of the house are into the ground. Only the front of the house faces out.

REHMMike, who designed that house?

MIKEWell, there's a company that works coast-to-coast that they pour domed concrete modules for this purpose, but earth-sheltered housing has been around for a very long time. I know people right here in my county that built their own. But the contracting out of the module or the frame is easily done. And they come in and they pour that. And then usually the homeowner does the rest.

REHMInteresting. Libby Rosenthal, have you seen this happening in other parts of the world?

ROSENTHALWell, I haven't seen earth-sheltered houses, although there are similar experiments going on. In Germany, Switzerland, Scandinavia you see a lot of passive houses, which stay pretty warm in the winter and pretty cool in the summer because they're designed with the environment in mind. I mean even the U.S. Army in Afghanistan has experimented with thermal cooling from underground for tents. So the Earth is cool. You know there are lots of things that can be done.

ROSENTHALThat doesn't help most of us in cities and the increasing number of people in the developing world in these fast-growing cities in Asia who live in cities. So part of this technology change is going to have to be in big office building design and also in more environmentally friendly coolants, which we really haven't talked about. But I want to be able to go into a store when my air conditioner dies and buy something that uses a coolant that doesn't harm the ozone layer and that doesn't cause a significant amount of warming. And I can't do that right now.

REHMSteve Yurek?

YUREKWell, that's not true. There are plenty of choices out there. And it's not just, I guess, two parts. You know we're talking about air conditioning. Air conditioning isn't just about cooling. It's also removing the moisture, the humidity from the air. And there's a lot of things that can be done with technology now. If you remove the humidity people can be much more comfortable at higher temperatures. And as for products that are out there, there are a wide range of products.

YUREKThe question is the willingness and the cost of those products in what you want to purchase. As an industry we are promoting and have developed products that meet the federal minimum efficiency here, but go considerably beyond that, that use different types of refrigerant, different types of technologies. And if you want to see what's available, as an industry for over 100 years, we have been certifying that performance. And that performance is available online in a directory for residential products, for commercial products and other things, showing you how they perform and what's out there.

YUREKAnd so you can go and check. Are you going to find something that has a hydrocarbon refrigerant in it at a significant charge today? No. And the reason is because of the safety concerns and building codes. As soon as we get comfortable with the ability to produce those products in a safe manner, have them maintained and used safely, you'll be seeing more of them.

REHMAll right. And here's an email from Joseph, who says, "I work in information technology. Part of the A/C issues is the fact that we have so many computers in stores and offices. They generate a lot of heat and also need to be cooled to reduce failure rate." What do you think of that, Stan Cox?

COXWell, that's very true. And the huge server farms that help run the internet use as much energy for air conditioning and cooling as they do for actually running the machines because every bit of energy that goes into those machines comes out as heat. And then, you know, all of the heat-generating appliances we have in a house add to the burden on the air conditioning system or heat up the house if there isn't air conditioning. But there's a much bigger load, though, on the house from the sun and from 100-degree air outdoors.

REHMOf course, yeah. Now 100 years of air conditioning, have we reached a point here where we recognize something new and different has to come in to replace it because of what's happening to the ozone, Durwood Zaelke?

ZAELKEWell, I think we're on the verge of that recognition. And your show is certainly helping with that and Elisabeth Rosenthal's story in The New York Times, as well. People are now becoming sensitive to the fact that air conditioning, while it was sort of a way on the side, is now central to our life. And if we don't learn to produce the super efficient and low global warming potential coolant machine we're going to be too hot. So I think this is the moment here. And I think it could also spark a further revolution in other technologies that we need to develop for climate protection.

REHMLibby Rosenthal, what are you seeing out there in terms of what manufacturers, what inventors, what developers are thinking about as replacement for or moving away from the air conditioning as we've known it?

ROSENTHALWell, I think the hopeful thing is there are in fact a lot of alternatives. Air conditioning companies have been developing them. We know what they look like. I think one of the problems is the whole model of the industry, at some level, will have to change to make these things commercially available and cheap enough.

REHMHow?

ROSENTHALHow will that change?

REHMYeah.

ROSENTHALWell, I suppose one way is that we'll have to make what's out there now more expensive relative to what we want to be commercially available. The other thing is some of this, as was mentioned, has to do with governments developing new safety standards, new guidelines for servicing. Some of the new coolants are mildly flammable. And immediately people will go, oh, no. We don't want anything flammable in our homes. But we have lots of flammable things in our homes. And that can be managed, but it requires a whole different way of doing things.

ROSENTHALSo governments really have to get behind that because otherwise people will go with the cheapest thing and manufacturers will continue to make what they've been making. Yes. With a lot of efficiency improvements, but you won't get that kind of seminal change that maybe we need to get more environmentally friendly coolant.

REHMOf course, Durwood Zaelke was talking about the Montreal Protocol, but when that treaty was put into place global warming was rather poorly understood. So where does that leave us today, Libby?

ROSENTHALOh, well, the Montreal Protocol has been a wonderful treaty that focused on protecting the ozone layer. And it's done that pretty magnificently. The problem is the last gas that people are switching to, that countries are switching to, that the U.S. has already switched to, is really great for the ozone, but it's a pretty powerful agent of global warming still. And the Montreal Protocol has no way to control that at the moment because it doesn't regulate global warming gasses.

ROSENTHALAnd that's a big problem. So as we're solving that one environmental problem, the depletion of the ozone layer, we've actually not paid attention to this other one that continuing to grow, which is the warming affect of the air-conditioning gasses.

REHMAnd you're listening to "The Diane Rehm Show." You wanted to add to that, Durwood?

ZAELKEYes. There is a proposal that was originally made by the Federated States of Micronesia, a low line confederation of islands that fear climate-driven sea level rise. They said we need to change the Montreal Protocol to address what Libby just mentioned, the fact that they don't explicitly manage climate protection. We now have more than 108 countries who are parties to the Montreal Protocol, yes, Micronesia, you are right. We need to phase down the HFCs because of their high global warming potential.

ZAELKEWe're being blocked -- and this was a meeting just a couple weeks ago in Bangkok by the reticence of India, China, Brazil and South Africa, the bricks. We are working very hard, as is Secretary of State Hillary Clinton, who has made the so-called packaged of short-lived climate pollutants, HFCs, black carbon and methane, a priority of her final phase as a global leader. So we're hoping that she will carry this message to China and India in the next few months and say we need you to help us bring home what will be solving 10 percent of the entire climate change problem.

REHMBut what about the U.S. itself, Stan Cox? Is it willing to make the changes it's asking other countries to?

COXWell, that's the thing. Right now we're not in a very good position to lecture the rest of the world about this problem, but there are positive developments. For example, the most prominent society of air conditioning engineers a few years ago put out standards for indoor climate that apply to naturally-ventilated areas. And so this was the first time that they had done this. And it's based on what's called the adaptive model of comfort that says this 72 degrees is not necessarily the most comfortable temperature. That the range of temperatures we find comfortable varies depending on temperatures and humidities that we've been experiencing in previous days or weeks.

COXWe're a very adaptable species. We originated in the tropics. And we can certainly handle a lot more thermal variety than what we're being given.

REHMWhat do you see happening, Steve Yurek?

YUREKWell, I think, first of all, the United States has been leading in this area. The industry has been leading. We led through the Montreal Protocol. We've continued to look at this and developing alternatives. And in particular and in expanding the Montreal Protocol to also cover the fluorinated high GWP gases has been led by the United States. In a proposal by the United States, Canada and Mexico to modify that treaty to allow the Montreal Protocol to regulate those gases in a phase-down. The industry has been supportive of that, but what we need is the predictability and the ability to plan and also come up with alternatives so that they can be deployed safely out in the marketplace.

REHMAnd we shall hope for that time to come. Steve Yurek, Durwood Zaelke, Libby Rosenthal and Stan Cox, thank you all so much. And we'll see what comes next. Thanks for listening all, I'm Diane Rehm.

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