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Our World — 2 February 2008

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Straight ahead on "Our World" ... Climate change and the threat to world food supplies ... a genetic approach to battling a nasty parasite ... and a new animal discovered in Tanzania ...

RATHBUN: "It's pretty rare that anyone walks into a forest and sees an animal and says, oh my goodness — that is obviously a new species! And that's pretty much what we did."

Discovering the grey-faced sengi, a space age anniversary, and more. I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."

In news stories about global warming you've probably heard about polar ice melting and sea levels rising. But one of the most dramatic impacts of climate change may be seen in the food we eat. This week a team of Stanford University researchers published a study in the journal Science reporting on what is likely to happen to global agriculture over the next couple of decades. David Lobell is the lead author of the paper, and he says the future may be here sooner than we expect.

LOBELL: "Our conclusions are that there are some regions and some crops in the world that look particularly urgent in terms of needing efforts to adapt them to a new climate, and those regions being southern Africa and southern Asia."

Q: What makes them particularly vulnerable, those regions?

LOBELL: "It's a combination of factors. One is that they have a large population of hungry people. Another is that the climate in those regions [is] particularly likely to become drier and hotter. And the other is that the crops that they rely on are particularly sensitive to drying and warming."

Q: What kind of crops are we talking about?

LOBELL: "In southern Africa we're talking about maize or corn. Wheat, also. A little bit of sorghum. In South Asia, like India, Pakistan, we're talking rice and wheat, crops like rapeseed, crops like peanuts, which are very important locally there for the hungry populations. And then in other parts of the world, cassava in central Africa or sorghum in the Sahel."

Q: There are, among climate scientists, quite a few models predicting where our climate is going to go over the next decades. And how did you choose which one, or did you have to choose one?

LOBELL: "The approach we took was to use all of the models that have participated in the IPCC, Intergovernmental Panel on Climate Change report, and so we're using output from 20 different climate models from throughout the world. And the philosophy there is that, if most of those models are agreeing on what's going to happen, then we have more confidence in that projection. And so we use the whole range of models to look at uncertainty in what's going to happen to climate. Each model projects temperature and rainfall for each individual point on the land's surface. And so we averaged the model over the regions we were interested in and found that in some regions the models agreed quite well, and in others they did not."

Q: What's the time scale here? How much of this is a near-term threat, versus something that's many decades away?

LOBELL: "The study we did really focused on the near-term, or a single generation. So, what are the impacts out to 2030? And this is quite different from a lot of studies previously that have looked at the end of the 21st century. The reason we did that was to focus this question of adaptation, which really involves investments that are going to pay off in 20, 25 years, and not necessarily the 70, 80 years that are involved with the end of century projections."

Q: What sort of investments are we talking about?

LOBELL: "The type of investments that are most needed for adaptation are in breeding varieties of crops that are especially tolerant of heat or drought, and improving infrastructure of rural areas, for example improving irrigation systems or installing them where they didn't exist. And also trying to diversify, perhaps, the crops that the farmers are growing from the ones that are most vulnerable to climate change to those that are least."

Q: In some areas it seems that, because there'll be a change in climate there'll be a change in what crops might be suitable. Not that an area won't be suitable for growing any crops at all, the mix might have to be different. Is that right?

LOBELL: "That's correct. And it's not only a matter of climate, of course. It's a matter of markets and soils and all the factors that really determine what is profitable to grow in that area."

Q: Some of the impacts of climate change seem to be showing up already. We've seen historically low levels of arctic ice, for example. Is there any indication that agriculture has yet actually been affected, on the ground?

LOBELL: "We did do a study last year looking at the global scale, and we found that on the order of one-to-two percent of production is lost every year because of the warming that's already occurred. And so these are effects that we're seeing now and we will see really in our lifetime, or certainly in the next generation, not simply projections of what will happen in 100 years. There is still time to do something. There's just not a lot of time. And so our hope is that this study will really help people answer that question and give them guidance on specific crops and specific regions to really focus on."

In years to come, David Lobell says, some countries may actually benefit from global warming. For example, parts of Canada, Russia and China will be warm enough to grow crops that today would not thrive there. But he says that by mid-century, just 40 years or so from now, when global average temperatures will have gone up by about two degrees, the world's overall food-growing capacity will have declined.

One more item related to global warming: U.N. Secretary General Ban Ki-Moon, in a report made public on Thursday, said as much as $20 trillion dollars may need to be invested over the next 20 to 30 years to put the world on track to develop energy sources that don't emit greenhouse gases. The U.N. report was prepared ahead of a special General Assembly session on climate change starting in two weeks.

Scientists working in southern Africa this week report discovery of a new mammal species in the mountains of Tanzania.

RATHBUN: "It's pretty rare that anyone in this day and age walks into a forest or a desert and sees an animal and says, oh my goodness — that is obviously a new species! And that's pretty much what we did."

Galen Rathbun of the California Academy of Sciences writes about the discovery in the new issue of the Journal of Zoology. Rathbun has been studying a family of animals known as elephant shrews — small, furry animals that mostly eat insects. Fifteen species had been known, and now it's sixteen, all of them found in southern Africa.

There's an interesting story behind the naming of elephant shrews. They originally got the name because they resemble rodent-like animals called shrews and have a long nose, sort of like an elephant's. Taxonomy — the study of how species are related to each other — now is more sophisticated, and includes DNA analysis, and so now this small group of animals is classified differently, and the preferred name — sengis — eflects this better understanding.

RATHBUN: "It turns out they're not shrews at all, and that's kind of the genesis of why we're trying to use the different name for them, based on an African name, called sengis because they're not related to shrews at all other than that they're both mammals."

Q: And it was named originally elephant shrew because of its long proboscis, but it turns out actually that it is, in fact, relatively closely related to elephants?

RATHBUN: "Yes, exactly. The long, flexible nose reminded early biologists of an elephant's nose, and as chance might be, it turns out that they are reasonably closely related to elephants."

Most of the new species of mammals discovered these days are newly re-classified or have very subtle variations from existing species. Not so in this case, where the new species, the grey-faced sengi, was instantly identified from a blurry picture that was taken by an automatic camera triggered by a passing animal in the forest. Since this kind of discovery is so unusual, I asked Galen Rathbun about it. He said it started five years ago with a vague email.

RATHBUN: "Back in 2002 a colleague sent me an email describing what he thought was a fairly odd giant sengi in the forest in Tanzania. But it was only a fleeting description, and so we couldn't do much with it. Then the next step was another colleague, Francesco Rovero, an Italian colleague, set out some camera traps in a forest and got some images of an elephant shrew and sent them to me. And he realized that it was quite odd-looking and wasn't sure what it was as far as what species [of elephant shrew]. And based on the photographs I immediately knew something new was at hand, but we weren't sure exactly what because we need specimens. So in..."

Q: Let me interrupt. What was distinctive about the photographs?

RATHBUN: "All the giant elephant shrews — and they're large, they're the size of a small rabbit or a small cat — are distinguished by their coloration. They're very flashy animals. One species has a bright golden rump on an amber background. Another one has a very glossy dark black rump. And the new one didn't match any of the known species, based on the fuzzy camera-trap photos. And so that's what kind of got us really interested.

RATHBUN: "And so Francesco Rovero, the fellow who took these camera-trap images, pulled together an expedition and included me. And so we went off into the Edzungwa Mountains in March 2006, and during two weeks of soggy weather in deep jungle habitat, we managed to get four specimens. "

Q: When you say 'get,' what do you mean?

RATHBUN: "We had to trap them. Which was fairly interesting in that we'd taken traps which normally work for these giant sengis, but after almost a full week we hadn't caught any. And we were getting very depressed and frustrated. And one of our African colleagues, Ruben [Mwakisoma], said let me try some traditional African snares, and he set out a whole bunch of snares and lo-and-behold, he caught the four animals that we ended up catching."

It turns out that the newly-discovered grey-faced sengi was 20 percent bigger than the largest previously-known elephant shrew, and at 700 grams, was simply too big for the traps that Rathbun and his colleagues had brought along.

In the paper announcing the discovery, Galen Rathbun and his co-authors note that although the grey-faced sengi was found in a protected area with no signs of human presence, the human population in the area continues to expand and could threaten this animal, which appears to live exclusively within a small area of Tanzania. Rathbun says he hopes his group's discovery of the new species will help with conservation efforts in what he calls a "spectacular ecosystem."

Time again for our Website of the Week, when we showcase interesting and innovative online destinations.

This week's site opens a window on U.S. government research reports that the government doesn't routinely make public.

MEEKS: " is a clearinghouse to access Congressional research reports that are typically unavailable to the American public.

Brock Meeks is a spokesman for, where you can search through some 13,000 reports prepared by the widely-respected Congressional Research Service, or CRS, which is part of the U.S. Library of Congress.

MEEKS: "And it's kind of a think tank. The reports, which are requested by members of Congress can cover anything from the economy to the environment to the likely outcome of electronic voting in the year 2030."

CRS reports also cover a range of international issues. In the past few weeks, for example, has added studies on nuclear proliferation, elections in Georgia and Pakistan, Hong Kong democracy, and Iraq.

The CRS works for Congress and releases its research reports directly to the legislature, not to the public, so OpenCRS has to get copies indirectly.

MEEKS: "There's nothing secret or classified about the reports, and if you ask a member of Congress if they can get you that report, they will do that for your as a courtesy. The folks then will send us the report so that the next time, somebody can just come to our site and search for it there without having to go through this process of requesting it through their member of Congress."

You can locate research studies of interest through the keyword search on, which also indexes Congressional Research Service reports archived at other institutions and libraries.

There are commercial services that collect and sell these research studies, but why pay for what you can get for free at, or get the link from our site,

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Free to all, it's VOA's science and technology magazine, Our World. I'm Art Chimes in Washington.

New research, now, describing a new approach to fighting a common, water-borne parasite that thrives in areas where poor-quality drinking water is a concern.

In a report issued two years ago, the World Health Organization called cryptosporidium "one of the critical pathogens for the water industry" — because it occurs in water supplies around the world and because the parasite is so hard to kill.

It has a tough, outer shell that makes ordinary drug treatments ineffective. So now researchers are taking a genetic approach and, as we hear from health reporter Rose Hoban, they're starting to see the first signs of possible success.

HOBAN: Cryptosporidium is a water-borne parasite that's responsible for many of the cases of diarrhea that affect children in the developing world. In more developed countries, cryptosporidium is often a problem for people who have compromised immune systems, such as those with AIDS or cancer.

Researcher Liz Hedstrom from Brandeis University in Massachusetts says the drugs currently available for treating cryptosporidium are not very effective. And there are no vaccines against the microbe. She says there's a reason for that.

HEDSTROM: "It's what's known as a eukaryotic parasite, which means it's very closely related to humans, and that actually makes it hard to develop a drug."

HOBAN: Some proteins in the parasite are quite similar to those in humans. So Hedstrom says there are few chemical compounds that work well against cryptosporidium without making their human hosts sick. In addition, she says, the parasite is difficult, if not impossible, to grow in a lab. But researchers recently sequenced cryptosporidium's DNA. Hedstrom and her colleagues made use of that information.

HEDSTROM: "So from that, we could make a good guess about how cryptosporidium grows, what sort of food it needs to eat, how it metabolizes its food into DNA, RNA, the things it needs to proliferate. And so from that, we could make a guess about which proteins were crucial for the growth and the reproduction of the parasite."

HOBAN: Hedstrom and her team isolated a particular enzyme the cryptosporidium needs to make in order to survive. Then they screened about 40,000 different chemical compounds to see if anything worked to inhibit its production.

HEDSTROM: "And we found 10 compounds that did selectively bind to the parasite enzyme and not the human version, and it turns out that those 10 compounds do actually inhibit parasite growth."

HOBAN: The next step, Hedstrom says, is to test these ten compounds to see which works best and can be tolerated by animals and then by humans. She hopes that in several years, they'll be testing prototype drugs in animals.

Her research is published in the journal Chemistry and Biology. I'm Rose Hoban.

Back in the '90s, when I was a VOA correspondent in the Middle East, I learned about drip irrigation — a very efficient way to farm where water is scarce or expensive. It's not the dominant form of irrigation here in the United States, where big farms and typically abundant water supplies make it impractical. But as we hear from reporter Kyle Norris in Michigan, some farmers here are taking a second look at how they use water which, as we heard earlier, may be in shorter supply as we enter an era of climate change.

NORRIS: Anne Elder and Paul Bantle are farmers, and they're pretty hard-core about water. These folks consider water to be a valuable resource. The farm is a biodynamic farm. Which means it's organic, but it kind of goes a few steps further. Anne Elder says biodynamic farming emphasizes healthy soil, and how to make soil benefit the most from water:

ELDER: "Healthy soil means it's alive, it's active, it's not compressed but fluffy. It will have a lot organic matter which will make it more sponge-like rather than compacted hard tight soil. So when it does rain or when moisture does come, fluffy soil can take that in and it can just drain through and the roots can absorb it."

They till an organic compost into the soil. It's made of manure, vegetable matter, hay, and straw. And as biodynamic farmers, they spread herbal teas on their fields. They do this to feed the plants, and to fight off problems like fungus. Their farm is in southeastern Michigan and they get plenty of rain storms. Paul Bantle says they try to take as much advantage from the rain as possible:

BANTLE: "Rainwater is way better than any kind of water you're going to pull from earth. Irrigation water is cold, whereas rainwater is warm, in the summer, obviously. And in the late spring and early fall."

The thing about cold water is that it shocks plants that have been sitting in the warm sun all day. And that's no good. When they need to water the fields, they pump water from a 65-foot [20-meter deep] well.

Bantle says he thinks long and hard before using this water for irrigation. He doesn't want to dig down further to tap deeper aquifers, even if that means that the crops will go through a hard time:

BANTLE: "It's an issue. I mean it's a huge problem. So definitely I try to be very conservative about pulling water for irrigation."

Basically, there are two main irrigation techniques typically used in farming. The first is drip or trickle irrigation, and this is what Bantle and Elder use. It's a slow, easy method that takes time for the water to soak deep into the soil. It's kind of like a light, slow rain.

The other technique is overhead irrigation. Picture your garden hose on spray, with overhead irrigation the water sprays all over. The downside is that it wastes water because it evaporates and runs-off from the fields.

Lyndon Kelley is an irrigation educator with Michigan State University and Purdue Extensions. He says drip irrigation is like a mini-van and overhead irrigation is like a school bus:

KELLEY: "It's sort of like are you going to take three or four kids to the baseball game after school each day, well then you're going to take the mini-van. But if you're going to take fifty kids to the baseball game after school every day then you're going to want a school bus."

So, drip is typically used on smaller operations and overhead is usually used on the larger ones. But Kelley says drip irrigation can be used on larger farms. It depends on how the roots of the plant take-in water.

Farmers are going to have to reevaluate the ways in which they use water. Some scientists believe climate change will make some places much drier, and a growing population is already putting heavier demands on the existing water sources.

Support for the Environment Report comes from the U.S. Department of Agriculture, the George Gund Foundation, and the Americana Foundation. More information about Environment Report stories is at

And before we go today, we just have time to remember the launch of an historic satellite.

[Explorer launch countdown]

Those count-downs all sort-of sound the same, don't they?

They haven't changed much since this one, 50 years ago, on January 31, 1958, when the United States put its first satellite into earth orbit.

It came four months after the Soviet Union stunned the world with the first Sputnik launch and then followed up with a much larger satellite that carried a dog into space.

The first U.S. satellite attempt, in December '57, was an embarrassing Cold War failure, when the rocket got only one meter off the launch pad before collapsing and exploding on live television.

A month later, Explorer 1 finally made it into space. The United States may have been the second country to put a satellite in orbit, but Americans claimed an important first 50 years ago, the first scientific discovery made from space: the Van Allen radiation belts, rings of charged particles that surround the earth.

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That's our show for this week. If you'd like to comment on our program, or if you have a science question that we might answer on the air, email us at Or use the postal address —

Our World
Voice of America
Washington, DC 20237 USA

Rob Sivak edited the program. Bob Doughty is the technical director this week. And this is Art Chimes, inviting you to join us online at or on your radio next Saturday and Sunday as we check out the latest in science and technology ... in Our World.