This is Talk of the Nation, Science Friday from NPR News and I'm Richard Harris, sitting in for Ira Flatow. A bit later in the hour, we will be talking about a new event called the World Science Festival. Up first, a new climate of this week puts the focus on the U.S. Some climate reports, like the ones from inter-governmental panel on climate change are broad in scope. They detail the impacts of climate change and options or adaptation and mitigation, on a global scale.

Well, this new report looks at how global warming is affecting us here in the U.S. It documents changes that are already taking place in the areas of agriculture, land and water resources, and biodiversity. It also makes predictions for the near future that is 25 to 50 years out. It is a government report out from the U.S. Climate Change Science Program. It is written by authors from 13 federal agencies, universities, national labs and other organizations that are outside the government. We will start the hour today talking about our climate future with one the lead authors of the report.

If you would like to joint the discussion, give us a call. Our number is 1-800-989-8255, that is 1-800-989-TALK. If you want more information about what we will be talking about this hour, go to our website at www.sciencefriday.com, where you will find links to our topic. Now, let me introduce my guest, Peter Backlund is Director of Research Relations at the National Center for Atmospheric Research in Boulder, Colorado. He is an author on the new climate report. He joins me today by phone from his office in Boulder. Welcome to the program.

Mr. PETER BACKLUND (Director of Research Relations, NCAR): Thanks.

HARRIS: Well, we have been hearing a lot about climate change from scientists and economists, and other blue-ribbon panels for the last couple of years. What is the point of your new report?

Mr. BACKLUND: Well, it is a bit different than most of the recent reports. Particularly those from the IPCC, and that it's the first really extensive look at how climate might affect the U.S. that has been done in about eight years. And the time frame of the report is quite a bit different from other analyses. We focused very much on the recent past, and next 20 to 50 years, as supposed to the longer range, kind of, 100-year projections that are more typical in most work.

HARRIS: Why so? Why did you focus on a shorter time frame?

Mr. BACKLUND: Two main reasons, one is that the shorter time frame is more relevant to people that have to make decisions about natural resource management, and things like that. The other reason is that, our view is that the climate changes that are going to occur in the next, say two to four decades are somewhat better understood than longer-term projections, because much of the change that we are going to experience is based on emissions that have already occurred. So, the coming changes are somewhat less uncertain in the near term.

HARRIS: You are saying that the climate will change regardless of what actions we take in the next couple of decades?

Mr. BACKLUND: Yes, the IPCC and other groups, including my own lab here have done a series of projections that look at what would happen to climate if CO2 emissions were curtailed almost immediately, and we are still facing very substantial climate change, mainly because of the heat that has been stored in the oceans, and will be released over that time, and because of the long atmospheric lifetime of CO2. So we are facing a pretty substantial climate commitment, regardless of any emission mitigation actions that we take in the near term.

HARRIS: Yes, and if we could cut to the quick, what did you find, a sort of a take-away message of what you discovered in this report?

Mr. BACKLUND: Well, there are a few things that I would emphasize. One is that we have identified a very wide range of climate impacts that are already occurring across all the sectors that we examined. Also related to what we were just talking about, we believe that these impacts will continue to occur over the next, you know, two to four decades, regardless of emissions-limitations actions, so adaptation is really a necessity.

Another thing that we are quite worried about is that we see a lot of potential change in the ecosystems services, but we do not have really enough knowledge of the way the climate is affecting ecosystems to project how those changes will affect the way that the ecosystems provides services to us, and by services, I mean, things like clean water, and actually the removal of carbon from the atmosphere.

HARRIS: Trees soaking up carbon dioxide, stuff like that?

Mr. BACKLUND: Exactly, they provide substantial benefits doing that right now. They are limiting the amount of climate change we are seeing, but the question is, how that is going to change as temperatures continue to increase in the next few decades.

HARRIS: If you had to point to one finding that was most alarming or concerning to you, what would that be?

Mr. BACKLUND: I think the one that really jumped out at me did have to do with forests. And it is the very large increase in the number and severity of forest fires and insect pest outbreaks that we are experiencing right now, that are definitely related closely to climate change. We are having, you know, very large forest fires as everyone who watches the news can see. But we are also having these insect outbreaks that are very serious.

In Colorado, we are having mountain pine beetles that are just exploding in the forest, on the western slope, and starting to come over on to the eastern slope as well. The large full pine forest is experiencing mortality of 30 up to 90 percent in some areas. And this is happening because the warmer, less wet conditions have increased the vulnerability of the trees. And the warmer conditions have also removed the natural limitation on the spread of the beetles, because they were not getting enough cold weather in the winter to inhibit their spread.

HARRIS: So frost used to kill them off? Is that it?

Mr. BACKLUND: Yes, exactly. Usually you need about 10 days of really cold subzero weather to kill off the beetles, and we have had quite a few winters were we haven't had those conditions, so they're spreading much more rapidly previously.

HARRIS: One item that you spent some time on in the report has to do with water resources. We know that there has been a drought fairly, extensively in the southwestern United States. Do you attribute that to human-induced climate change?

Mr. BACKLUND: It is likely that human-induced climate change is playing a role in that. I would not specifically say that the exact southwestern drought is due to climate change, but over the last century, the southwest has become quite a bit drier, as the southeast, for instance, some areas in the east have become wetter. The projections from the models all show that the southwest is liable to become quite a bit drier, and in fact, this is one of the impacts that we are very, very concerned about.

HARRIS: Yes, anything you can do about it, once you have this knowledge, does that help you? Say, oh well, I don't suppose you can prevent a drought, but can you change the way you handle water resources, for example?

Mr. BACKLUND: Well, we think that there are a number of things that can be done. Our report does not focus on evaluating or identifying adaptation options. But we have certainly, I think, produced a lot information relevant to that. In the case of water management, what is going to have to happen is, we are going to have to change to more of an anticipatory system that relies more on projections and model-based work.

As opposed to past practices which really relied very much on looking at the past records of climate as a proxy for the future. What is happening is we are finding that the past really is not a good indicator of future conditions. And so some of the water management practices are going to have to change. The community that deals with that is very creative, but this is going to be a large challenge for them.

HARRIS: Yes, I guess once question is, are these findings - are you confident enough in these findings, to able to tell somebody, we know this is going to happen, and you should spend a lot time and effort building dams or whatever they need to do. I mean, are you sure that you are going be right about that or could they be wasting their time and effort, or maybe addressing the wrong problems?

Mr. BACKLUND: We consider it very likely that these changes are going happen in the west. And in fact, at my own lab, and other places, we're already interacting with water managers, trying to help them devise some of these modeling tools that will help them manage their way through the climate-change challenge.

HARRIS: OK. Well let's go the phones, and take some questions. Our number here is 1-800-989-TALK. Please give us a call. And let's take a call here, let's start with Joe from Ferroux(ph), California. Joe, hello?

JOE (Caller): Hi. When you are talking about - I have two points, one near-term, one long-term. One in California, I looked at the heating and cooling index, cooling days in California, and I see over the last 15 years, that there's almost no change. A few more cool - cooling days required, but on the average not much change.

And along with that, Mount Shasta's reporting a more glacier and more snow than ever before. And my long term point is between 400 and 1100. We had the medieval cooling period, where we had a - excuse me, a warming period, we're we know that the - Europe experienced extreme warm climate.

They had grapes growing in the northern part of Europe, which had never grown before. You know, what caused that? Isn't that related? And it probably more warming than today. So, how do you explain that in terms of our current global warming?

Mr. BACKLUND: Well, I would address that in two ways. First of all, with regards to your first point, there's a lot of texture to climate change. And regional and global trends don't necessarily translate into the exact same thing, happening at a particular spot.

So, it's certainly true that a particular range, or a mountain, or an area might get more snow, but the overall trend certainly in California and in the Pacific Northwest, is towards somewhat more rain and somewhat less snow, and earlier runoff in the spring. And this is one of these factors that is challenging the water managers.

And this has been quite conclusively attributed to human-induced climate change. With the - regard to the kind of medieval warm period, you're bringing up a very important point, which is that human-induced climate change is an overlay on a background of very substantial natural variability.

And there are cycles in the year system, in particular the Pacific Decadal Oscillation has a big effect on California where, you know, there are warming and cooling events that happen naturally. Superimposed on that though, we're seeing a very clear signal of human-induced warming from the increase of greenhouse gasses in the atmosphere, and this is very well-understood physics and it has been confirmed by observations in a very wide-ranging sets of analyses.

HARRIS: Right. I think your report did show, that you saw cooling in some places or - and warming in others, and obviously that on the whole dramatic warming in Alaska and places like that, but it doesn't - global warming didn't necessarily mean every place is getting hotter all the time.

Mr. BACKLUND: It's one of the things that makes it so complex and such exciting science frankly to work on, is that there are so many factors that affect the climate, and then there are so many factors in addition to climate that affect ecosystems. This is one of the things that makes it very challenging.

HARRIS: Yes. Let me ask you one last question which is about - do we have all the right data to really understand this? Or do we have all the right satellites in place? Do we really understand looking ahead well enough, everything we need to know to really make good firm projections and so on?

Mr. BACKLUND: We're actually quite concerned about the state of the observations. A lot has been learned about climate, essentially by piecing together observations from many different systems designed for other things, primarily weather forecasting. These systems aren't really optimized to produce climate information, and so our sense is that we're getting a very good sense of the big picture, but we're missing a lot of the details.

And we're very concerned, because of the complexity of the issue that the details are really what matters. So, we would like to see some improvements in observing systems all the way from satellites down to ground-based systems.

But we also feel that it's very important to have some improvements in the modeling capabilities, to take that observational data and analyze it, and ultimately begin to forecast ecological conditions in about the same way that we do weather.

HARRIS: Well, thank you very much. I'm sorry, we've ran out of time. But I'd like to thank Peter Backlund, director of research relations at the National Center for Atmospheric Research in Boulder, Colorado.

(Soundbite of music)

HARRIS: We'll be right back after this short break.

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