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The average temperature around the world is rising. People living in the US Midwest might find this
fact hard to believe, though. Two new studies show that in America's heartland, summers are now cooler
and wetter than they were in years past. The scientists suggest that the change in the Midwest climate
may have happened because of farming.
The first study was led by David Changnon, a climatologist at Northern Illinois University in DeKalb.
A climatologist studies the climate of an area, which includes measuring rainfall, temperature and wind.
Climatologists want to know how these factors have changed in the past, and how they will change in the
future.
Changnon and his team studied temperature records from Chicago and 13 other sites in the Midwest.
"These two changes -lower temperatures and more rainfall-may be connected by humidity," Changnon
says. Humidity is the measure of how much moisture is in the air. Humid air, which contains a lot of
moisture, takes longer to heat up than dry air.
So where did the extra moisture in the air come from? Changnon points to farms in the region. As
plants grow, they pull moisture from the ground and release it into the air. And among plants, soybean
and corn plants release a lot of moisture. Midwestern farms now plant more soybeans and corn than in
the past, with 97 percent of farmland today planted with these two crops. He also notes that the plants
are planted closer together now than they used to be, so there are more plants per acre than in the past.
The second study was led by famous scientists from the US. The researchers studied a vast area of
the United States that stretches from South Dakota to Oklahoma and the Texas panhandle. They found
that in 1930, farmers in that region irrigated only about 1.8 million acres of farmland, an amount roughly
half the size of Connecticut. In 1980, however, farmers irrigated nearly 15 million acres-more land than
Vermont and New Hampshire combined.
1. What does the underlined word "changes" mean in Paragraph 3?
A. It means that the temperature is lower and the rainfall is higher than before
B. It means that the rain is heavier than before
C. It means that the weather is cooler and there is also more rainfall than before
D. It means that our mind should be changed about farming in the future
2. From this article, we know that____.
A. the weather will be changed in the future
B. farmers irrigated nearly 15 million acres in 1930
C. we must plant more trees in order to protect our environment
D. the climatologists have told us two aspects about the reason for the climate change
3. The underlined word " moisture" in Paragraph refers to ____.
A. humidity
B. rainfall
C. water
D. steam
4. The best title for the article is ____.
A. The Weather Is Changing Better Now
B. The Analysis for the Weather
C. Why Climate in Midwest Is Changing
D. The Importance for Plants and Irrigation
