英语翻译
The average (平均) temperature around the world is rising.However,people living in the US Midwest might find this fact hard to believe.A new study shows that in that area,summers are now cooler and wetter than they were in years past.The scientists suggest that the climate change may have happened because of farming.
　　The study was led by David Changnon,a climatologist at Northern Illinois University.Changnon and his team find that since 1970,the average temperature in the Midwest during July and August has gone down by up to one degree .Their study also shows that the average rainfall in that area during those two months has increased.Between 1970 and 2009,about 0.33 inches more rain fell than betwe en 1930 and 1969.
　　These two changes lower temperatures and more rainfall may be connected by moisture (水分),Changnon says.So where did the extra (额外的) moisture in the air come from?Changnon points to farms in the area.As plants grow,they pull moisture from the ground and release (释放) it into the air.And among plants,soybean and corn release a lot.Midwestern farms now plant more soybeans and corn than in the past,with 97 percent of farmland today planted with these two crops (庄稼).
　　These results by Changnon and his team are the first step to understand a change in the weather.