VOA标准英语2010年-Colombian Scientists Predict Climate C（在线收听）

For generations, rich Colombian mountains have produced a variety of food crops, beans, cassava and notably coffee. But local coffee farmers say the weather is changing, and so are crop yields. Carmen Eneida Trujillo is worried. "Look, there are not too many coffee flowers around here; this is a sign that the weather is already damaging the crop," she said.

Eneida says until a few years ago, this plantation would be loaded with white flowers in September, announcing a good harvest. Her husband, Elias Claros, says they are already considering other crops. "I believe we won't be able to plant coffee here for much longer," he said.

More than a million people in Colombia grow and produce coffee, a crop sensitive to climate change. And what they are experiencing now is what scientists at the International Center for Tropical Agriculture, or CIAT, in Cali, have forecast for some time -- climate change is changing agriculture. Many traditional crops will have to move to other regions.

"Essentially, the geography of agriculture is likely to change significantly, so where you grow maize today may not be the same areas in the future. In temperate regions, crops are moving north. Here in Colombia is more across the elevation, so it moves upwards, in the mountains to greater altitude," said Andy Jarvis, who is in charge of the climate change and policy program at CIAT.

CIAT is conducting a study about the impact of climate change on 50 of the world's major crops, including rice, maize and wheat. Jarvis says every region of the world is experiencing different climate change, from extreme heat or drought to cold and flooding.

"In the past, the bamboo would have troubles at 2,000 meters, but now is growing and adapting well to higher altitude," said Carlos Arturo Trujillo, who has been a farmer all his life.

Some scientists are increasingly concerned about food security, especially for the poor.

"We are finding large scale producers are just as susceptible to unexpected, uncertain highly variable weather patterns as the small holders. Small holders are much more vulnerable because they have less access to knowledge and information in the right time and the right place," said Erick Fernandes, an adviser on climate change and natural resource management at the World Bank in Washington.

However, he says large farmers have more access to information and insurance that help them mitigate the impact. "Work done recently by Stanford University researchers have projected that for southern Africa where maize supplies a huge amount of the calories for the poor, by 2030, relative to 1990 production, there may be as much as 30% negative impact on maize productivity," he said.

Researchers expect crops in Africa, Asia and Latin America to suffer greatly over the next few decades and they also expect extreme temperatures to contribute to land degradation and an increase in agricultural pests. Meanwhile experts predict that in order to feed the world's growing population, agriculture will need to nearly double its production by the year 2050.