This is the VOA Special English Agriculture Report.
这里是美国之音慢速英语农业报道。
A new study says climate change has reduced the world's wheat and maize production. The study says rice and soybean yields have also decreased in some places -- but increased in others. In the words of the researchers: "For soybeans and rice, winners and losers largely balanced out."
一项新的研究称，气候变化导致全球小麦和玉米产量减少。该研究称，一些地区的水稻和大豆产量也有所降低——但其它地区的产量则有所提高。用研究人员的话说来说：“水稻和大豆产量的增产和减产基本持平。”
The researchers studied climate trends and global crop production from between nineteen eighty and two thousand eight. They found that climate changes "are already exerting a considerable drag on yield growth" and may have affected food prices.
研究人员研究了1980年到2008年期间气候变化趋势和全球粮食产量之间的关系。他们发现，气候变化“已经给产量增长带来了巨大的阻力”，并可能已经影响到粮食价格。
The study used computer models linking crop yields to weather. Yield is the amount produced for each hectare or acre. The researchers compared the results to what the yields might have been without climate changes. They found that corn production decreased by almost four percent and wheat production decreased by five and a half percent.
这项研究使用计算机模型把粮食产量和天气状况联系起来。模型中的产量是指每公顷或每英亩土地生产的粮食总量。研究人员将其与不受气候变化影响的产量比较后发现，玉米产量降低了近4%，小麦产量降低了5.5%。
Warming temperatures were reported in almost all of Europe, much of Asia and some of South America and Africa. During the study period most countries had greater temperature changes from year to year than they have had historically. But the study says the United States was an important exception -- at least so far.
几乎整个欧洲、亚洲大部和非洲部分地区都报告了气候变暖。在该研究包含的时间区间内，大部分国家气候变化程度都比有记录以来更为强烈。但该研究称，美国是一个特例，至少目前为止是如此。
Corn and wheat yields in most of North America remained about the same. Russia's wheat yields decreased the most. The largest loss in corn yields were in China and Brazil.
北美大部分地区的玉米和小麦产量基本保持不变。俄罗斯的小麦产量降幅最大。玉米产量降幅最大的国家是中国和巴西。
The report is in the journal Science.
这份研究报告发表在《科学》杂志上。
One of the researchers was economist Wolfram Schlenker at Columbia University in New York and the National Bureau of Economic Research. He says the report can serve as a planning tool for policy makers.
Wolfram Schlenker是其中一位研究人员，就职于纽约哥伦比亚大学和美国国家经济研究局。他表示，这份报告可以作为决策者的规划工具。
WOLFRAM SCHLENKER: "If you are worried about rising food prices, it might be good to funnel some research into breeding for heat tolerance and maybe even drought tolerance."
Wolfram Schlenker：“如果你对粮食价格上涨担忧，那么最好是进行一些耐热甚至是耐旱作物的育种研究。”
Jeffrey Stark is with a public policy organization called the Foundation for Environmental Security and Stability. This group is supported by the United States Agency for International Development. Mr. Stark recently described the effects of climate change on pastoralists in Uganda. They travel with their cattle to find grasslands and water.
Jeffrey Stark就职于一家名为《环境安全与稳定基金会》的公共政策机构。该机构得到了美国国际开发署的支持。Stark先生最近讲述了气候变化对乌干达牧民的影响，牧民们赶着牛群到处寻找草地和水源。
JEFFREY STARK: "We did hear repeatedly that there have been increasing temperatures, drying wetlands, less frequent but more intense rain, hail storms and, most significantly, unpredictable shifts in seasonal patterns. The pastoralists in the cattle corridor have to travel farther in search of pasture and water."
Jeffrey Stark：“我们不断听到说气温上升、湿地干涸、降雨和雹暴（指强冰雹降水天气）次数减少但强度增加。更重要的是，季节性规律变得不可捉摸。牧民为了寻找牧草和水源要跋涉更远。”
And that search, he says, can bring them into contact and conflict with farmers who have problems of their own.
而且，他表示，牧民寻找牧草和水源还会与那些自己还有着麻烦的农民产生冲突。