C: NPR reporters have had those conversations all over the world recently, with women working along a canal filled by the Niger River in West Africa.
(SOUNDBITE OF WOMAN SINGING)
: And with Denish Shandra Rai(ph) in Bangladesh.
DENISH SHANDRA RAI: (Through translator) All the (unintelligible) were submerged under water, the crops on the higher land was not sufficient to feed all the people around, and the people were suffering from hunger.
: And then there's Charlie Pedersen. He's president of the Federated Farmers of New Zealand.
CHARLIE PEDERSEN: You always hope and pray for the best weather, but you get yourself organized for the worst weather. That's what farming is about.
: This morning, NPR's Dan Charles reports on one scientist's investigation into how profound those effects will be.
DAN CHARLES: Cynthia Rosenzweig did not grow up thinking much about where her food came from.
CYNTHIA ROSENZWEIG: I am from Scarsdale, New York, which is a suburb, an archetypal suburb, of New York City.
CHARLES: She went off to college, but all the excitement of the 1960s made it hard to study. She dropped out. She and her future husband took a trip to Italy. They rented a farmhouse in the hills of Tuscany.
ROSENZWEIG: And our neighbors, who are the contadini, country people, came and taught us how to do everything. So that was my first farm. And then I decided from that, because I loved it so much, that I would come back to the States - when we eventually came back - and that then I would study agriculture.
CHARLES: It was the early 1980s. Few people had heard of the greenhouse effect. But several floors above her, other scientists were working on it fulltime. They were creating some of the first computer simulations of increasing carbon dioxide in the atmosphere. And one fateful day Rosenzweig got pulled into.
ROSENZWEIG: A question came filtering down from the top floor - what would happen to food? And I was the only person in the building who could even begin to think about that question.
CHARLES: It was a huge question. As the globe warmed up, would there be plenty of food or famine? Nobody really knew. Some scientists were optimistic because the same gas that traps heat in the atmosphere also is essential food for plants.
ROSENZWEIG: More carbon dioxide in the atmosphere, all else being equal, is good for crops.
CHARLES: Rosenzweig turned for answers to another family of computer simulations. They describe how a stalk of wheat or corn grows. These so-called crop models were created during the Cold War in part to help the U.S. predict how much grain the Soviet Union was likely to harvest.
ROSENZWEIG: What the model is actually doing is marching through crop growth day by day, seeing how much carbohydrate can be produced with the solar radiation, with the water available, and the minimum and maximum temperatures.
CHARLES: Rosenzweig and a small army of collaborators fed new information into these crop models - higher temperatures as predicted by their simulations over Earth's future climate, also new patterns of rainfall and melting snow, plus the boost crops get from that extra carbon dioxide. They were among the first to produce a credible estimate of food production in a warmer world, and they have continued to refine that estimate for almost 20 years.
ROSENZWEIG: It's not a catastrophe right away at the global scale.
CHARLES: For the next few decades, Rosenzweig says, climate change probably won't cause a huge change in the total amount of food in the world. But there will be winners and losers. Canada and some other temperate-zone countries are likely to grow more food.
ROSENZWEIG: But for the developing countries, it's a negative pressure right away.
CHARLES: There are two reasons for this: first, places like India, Pakistan and parts of Africa are expected to see more drought; second, while crops need warmth, too much warmth disrupts their development. In the tropics, if it gets much hotter, crops won't do as well.
ROSENZWEIG: Over and over again, our study, and many, many following studies, have shown that the farmers in developing countries are more vulnerable to the changing climate than those in the mid and the higher latitudes where the developed countries are.
CHARLES: And in the long-term, if the globe continues to heat up, by the time today's children become grandparents, even the most optimistic computer models show things getting a lot worse. Global food production starts to decrease. Tens of millions of additional people could go hungry.
SIWA MSANGI: In the end, you have to look at these as learning tools.
CHARLES: Siwa Msangi, an economist from Tanzania, is a researcher at the International Food Policy Research Institute, or IFPRI, in Washington, D.C. It's important to remember, Msangi says, these simulations include assumptions about human choices, about how much greenhouse gases we pump into the air, of course, but also about how much money governments spend on irrigation or on helping poor people buy food. Plug in different choices and the computer models show big changes in agricultural production and hunger.
MSANGI: And that starts to give you some insight in terms of what are the really sensitive parameters that policy can affect, what are the levers that are available for policymakers to be able to pull, to effect changes.
CHARLES: That human ability to learn and adapt is one reason why Cynthia Rosenzweig says she refuses to be pessimistic.
ROSENZWEIG: First of all, because - I think you can tell - I'm not a pessimistic person, so this is how I look at it. Global climate change is the most important challenge that we're facing as a planet, but at the same time it is providing the impetus for the planet to change to sustainability.
CHARLES: Dan Charles, NPR News, Washington.
: You can read about a new variety of waterproof rice that may help Asia's rice paddies survive floods at npr.org/climateconnections. And while you're there you can also see a video from public television's "Wild Chronicles," about how farmers in Niger are protecting themselves from climate change.
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