单选题 Farmers in the United States and around the world are likely to face serious challenges in the coming decades as new kinds of weather test their ability to bring us the food we all depend on. The weather, of course, has never been exactly dependable—farmers have always been at the mercy of the vagaries of sun and rain. But general weather patterns have at least been broadly predictable, allowing farmers to know when to sow their seed, when to transplant, when to harvest. As weather patterns become less reliable, growers will be tested to develop new rhythms and systems for growing crops.
Climate change is likely to impact different parts of the world in vastly different ways, climatologists and agronomists say. Scientists at a recent international conference in London reported that warming temperatures could lead to substantial harvest reductions in major food crops such as wheat, soy and rice. And for years the World Bank and others have been warning that climate change will be especially burdensome on poor countries in the tropics, where soil quality is generally inferior. According to a study conducted in the Philippines, for every one degree C increase in temperature, there will be a 10-percent reduction in yields for rice, a staple crop for billions of people.
But here in the U.S., most observers agree, it's doubtful that climate change could cause a food security crisis. The U.S. food system—though highly concentrated in terms of ownership and control—is geographically very diverse, which means that crops could be shifted to other areas if necessary. Also, the U.S. produces so much surplus grains for animal feed and food processing that it would take enormous crop failures to create real food scarcities. At least for residents of the U.S., a climate-change induced famine is unlikely.
Farmers are a famously adaptive lot, well accustomed to reacting to forces beyond their control. The worry among scientists is that if the agriculture establishment does not take climate change seriously enough, it will become much more difficult to respond effectively when weather disruptions hit. Easterling says the window for farmers to successfully adapt to new weather conditions is about six to ten years—the time it takes for researchers to breed new seed varieties suited for specific conditions. "What would worry anyone is if climate change starts to exceed the system's built-in adaptive response," easterling says.
Among farmers and researchers, there is disagreement about which types of growers climate change will impact most—large agribusiness growing operations, or smaller, family-run farms. Some agriculture industry observers say that the bigger farmers will have an advantage in coping with weather changes, as they will have more resources to switch to new crops. Others say that since family farms usually grow a wider range of crops, their biological diversity will make it easier to cope with whatever changes occur.

单选题 The most serious problem confronting the farmers is that
A. they lack the knowledge about weather forecasts.
B. once-dependable weather patterns are shifting.
C. the farming pattern is changing in strange ways.
D. the farmland is not as productive as it used to be.

单选题 It can be inferred that tropical developing countries are more vulnerable to
A. global warming.
B. dry weather.
C. soil erosion.
D. too much rain at the wrong time.

单选题 The United States is unlikely to suffer from food crisis because of its
A. geographical complexity.
B. mechanization in agriculture.
C. diversity of crops.
D. abundance of food.

单选题 According to the text, the scientists seem to worry about
A. farmer's ability to produce food.
B. the environment's capacity to absorb pollution.
C. agricultural system's capacity of innovation.
D. human's ability to respond to emergency.

单选题 What advice might agricultural experts give about crop growing?
A. Don't put all your eggs in one basket.
B. The first step is the only difficulty.
C. Caution is the parent of safety.
D. Early start makes easy stages.