Today the earth is getting warmer and warmer. But hundreds of years a 1 , people had a different problem—a 400-year cold period! From the 1400s to the 1800s, winters in the northern half of the earth were c 2 and longer than they are now. Scientists c 3 this time the “Little Ice Age” (小冰期).
The colder weather b 4 many serious problems. Plants died of cold and illness spread among people. People had to spend a lot more time collecting wood for fires to keep their house warm. And sometimes, a h 5 piece of ice would slide down (滑落) a mountain and destroy (摧毁) some villages.
Scientists think the Little Ice Age was caused by forces (力量) that people could not control. One cause (起因), in their opinion, was the sun. The sun often has “storms” of energy called sunspots (太阳黑子). During the Little Ice Age, there were fewer sunspots than there are t 6 . With fewer sunspots, the sun was giving out less e 7 which made the earth warm. Volcanic eruption (火山爆发) was probably a 8 natural cause. During the Little Ice Age, many volcanoes erupted. Their dust (灰尘) might stop the sun’s l 9 and heat from reaching the earth.
Today we are seeing the influences of rising temperature. Scientists think people are causing this change by b 10 a lot of coal and oil. So we need to change our way of living.