IRA FLATOW, host:

This is TALK OF THE NATION: SCIENCE FRIDAY from NPR News. I'm Ira Flatow.

A bit later in the hour, we'll be talking about the rise of mammals and new recommendations for breast cancer screening. But up first, vanishing climates.

When scientists talk about the consequences of global warming, we hear a lot of them talking about melting glaciers, rising sea levels, but not so much about changing and even disappearing climates. Well, a study out this week tells that story. It forecasts a planet in which some of our climates disappear entirely at the poles and in the high tropics, while other climates never seen before suddenly pop up on Earth to take their place.

Such changes would radically affect the flora and fauna all over the planet. The research is published in the Proceedings of the National Academy of Sciences. Joining us now to talk about that paper is one of the authors, Stephen Jackson, professor of botany and director of the program in ecology at the University of Wyoming in Laramie. He joins us today from Wyoming Public Radio in Laramie. Welcome to the program, Dr. Jackson.

Dr. STEPHEN JACKSON (Botany, University of Wyoming Laramie): Yeah, thank you, Ira.

FLATOW: Give us an idea of what would change. Where would things disappear? What is most threatened here?

Dr. JACKSON: Well, let me start with just a quick ecological definition of climate. Different locations on the Earth have characteristic climates. Laramie, Wyoming, Washington, D.C., Bogotá, Colombia, all have characteristic climates that include the different seasonal temperatures and seasonal precipitations. And those climate combinations, those combinations of summer and winter temperatures, summer and winter precipitation, make up the regional climates that basically determine who lives there, what kinds of plants and animals, how many they are, how fast they grow, what they do.

So our study was really interested in exploring what the ecological consequences of future climate change projected from increasing greenhouse gases would be.

FLATOW: And what did you conclude?

Dr. JACKSON: Well, we found that under the - we used two different scenarios from the most recent IPCC simulations. The worst-case scenario is a tripling of atmospheric carbon dioxide levels by the year 2100, tripling relative to pre-industrial levels. The other scenario was a less-bad but still fairly bad scenario where carbon dioxide levels would double by 2100 A.D. and I might add that we're well on the way to that. At current rates, we'll probably double by mid-century, well before the 2100 A.D. date.

And what we found was that under - particularly under the tripling scenario, climate changes sufficient to cause widespread ecological disruption, wholesale transformations of forest to grassland, tundra to forest, (unintelligible) to desert, rainforest to savannah, are indicated virtually throughout the globe. No place escapes. No place on Earth escapes under that scenario.

Under the other scenario, there's still very widespread, large-scale ecological change. It's more concentrated in the tropics, but in many regions, including parts of North America, it spreads up into the high latitudes as well.

FLATOW: So, do we see things like where the climate in Washington, D.C. becomes something like Florida, Florida's climate moves northward and Florida gets hotter and drier, things like that? What exactly do you see in some of these places.

Dr. JACKSON: Well, climate change is not quite so simple. It won't be like we're taking Miami and moving it to Atlanta or Atlanta to Cincinnati because all of these different variables, all of these different climate factors are going to change in complex ways. And one of the consequences of that is that everywhere we're going to see large-scale change, in many cases we are going to see the climate of Atlanta reappear somewhere else on the planet.

But one of the most worrisome and most interesting findings from our study was that in many parts of the world, the climates that exist today are going to simply disappear. Those particular suites of summer and winter temperature and summer and winter precipitation are going to vanish, and in many other parts of the world, novel climates, climates that are unlike any that exist on the planet today, are going to arise.

FLATOW: What are some of the most vulnerable or changing areas?

Dr. JACKSON: Well, the disappearing climates are really concentrated in the tropical mountains, places like the Andes, the Guyana Highlands, the mountains of Mexico, the African mountains, and also at the high latitudes, places like Siberia, the Canadian Archipelago, and particularly worrisome, the southern parts of Africa.

And those are areas where the climates will - those particular climate ensembles will simply disappear, which has very large ecological consequences because the ecosystems in those areas and the species that comprise those ecosystems are simply going to have nowhere to go. Those climates are not going to reappear anywhere on the planet. So we have risk of widespread extinction of the species that lives in those regions.

FLATOW: When you say there's no way to predict what the new climate will look like and it's going to be something totally different, are you really saying that we can't find a place on Earth we might compare this new climate to?

Dr. JACKSON: Well, it becomes difficult. Again, the disappearing climates are simply going to go away, so - and it's - we can't predict what every species is going to do. Some of them will undoubtedly be able to survive, but many of them probably won't.

The other problem is that in many parts of the world, particularly the tropical and sub-tropical lowlands, novel climates are going to develop, climates that are unlike any that exist on the planet today. Again, just…

FLATOW: Can you give me - what would that be - can you describe one for me?

Dr. JACKSON: Okay, an example would be taking the Amazon basin, which is one of the warmest and wettest places on Earth, and we're going to increase the temperature and increase the rainfall there so it will become even warmer and wetter than it is today. And that really takes us off the map in terms of our current experience of climates and of ecosystems in particular climates.

In other words there's no place we can go today and look at ecosystems that are under the same kind of environment that the Amazon will be under by the end of this century under these scenarios.

FLATOW: Now, today we're seeing visibly the greatest changes happening at the poles, let's say the North Pole. We talk about - you know, we're watching the glaciers melting, we're watching the waters being free of ice in the summertime. Is that the kind of thing that's going to happen in these other places, not with the ice, but - to these dramatic changes? And are they more vulnerable to the quick changes we're seeing in the poles?

Dr. JACKSON: Well, they won't be quite so dramatic in terms of the melting ice and so forth, but they will - and the climate changes we're talking about are more subtle. It's going to be increases of a few degrees in temperature, increases or decreases of a few millimeters of precipitation on a daily or weekly basis.

But ecologically speaking, the consequences are huge. Again, we're looking at the potential for major transformations of the biomes, and those transformations aren't necessarily going to be pleasant. In order to change one ecosystem into another, the organisms, the plants and animals that comprise the existing ecosystem have to undergo mortality. And then once that mortality has happened, it takes a good deal of time to be able to convert into another ecosystem.

There are examples already where this sort of dynamic is playing out.

FLATOW: Such as?

Dr. JACKSON: Well, if you want to get a look at the future, go to the Southwestern U.S. right now. And you can start in the four-corners region, up in the Grand Canyon area. And in the Pinion-Juniper Woodlands and the Ponderosa pine forests they've been experiencing eight years of severe drought. And in those years, those forests and woodlands have gone from green to brown to gray - over tens of thousands of square miles. And this is an interaction of the severe drought with insect pathogens and diseases.

And we don't know whether that drought is related to global warming or if that's just part of natural variability, but it is a good example of the kind of dynamic that's likely to play out, interactions between the kinds of physiological stress that's imposed by the climate, as well as invasive species pathogens, human land use, pollution and so forth.

FLATOW: Should we be expecting to see a shifting of the growing areas for our crops? You know, California, Florida, things like that. Are we going to be -breadbaskets in Iowa, Nebraska, things like that?

Dr. JACKSON: Those could certainly be affected. I think the agricultural implications have not really been explored for our analysis. But certainly it's - climate change is going to be - it's not going to be simply a matter of taking growing zones and shifting them northward or upward along mountain slopes, because climates consist - ecologically, climate consists of several different factors that all interact to influence the growth and reproduction of organisms, whether they're natural organisms or crops and livestock.

And because of the complexity of those changes, it becomes difficult to predict exactly how those zones are going to shift. In some cases it will be relatively simple. When we're lucky we'll be able to predict that. But in other cases it is going to be complex and much more difficult to anticipate.

FLATOW: Is there anything we can do to prepare for all these changes that are coming?

Dr. JACKSON: Well, my feeling is that the best strategy is prevention. This three-times CO2 world is one we don't want to live in, we don't want our grandchildren and great-grandchildren to live in. We simply don't want to go there. So I think that even the two-times CO2 world, the one that we're heading for now by mid-Century, is one that ecologically is not going to be a very good world. So what we really need to be doing now is to try to prevent these trends and try to alter the greenhouse gas trajectory. I don't think we have a whole lot of time to lose, according to what the people in the climate science community are telling us.

FLATOW: Should we expect other studies after this one?

Mr. JACKSON: Yes, I think there will be follow-up studies. My coauthors, Jack Williams and John Kutzbach of the University of Wisconsin, and I will be doing some follow-up studies to really explore this issue in more depth and explore the ecological consequences. And I'm sure that ecologists, conservation biologists, water resources people, forest resources people are all going to be looking very closely at these kinds of trends and try and anticipate what we might have in store for us in the future.

FLATOW: Stephen Jackson, thank you very much for taking time to be with us today.

Dr. JACKSON: Okay. Thank you. It was my pleasure.

FLATOW: Dr. Jackson is professor of botany and director of the program in ecology at the University of Wyoming in Laramie. Take a short break, we're going to talk about mammals. And, you know, that old relationship about the asteroid killing the dinosaurs and the mammals emerge and whatever? Uh-uh-uh, they're rewriting all of that now. So stay with us. We'll talk about it when we get back.

(Soundbite of music)

FLATOW: I'm Ira Flatow. This is TALK OF THE NATION: SCIENCE FRIDAY from NPR News.

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