第1个回答 2013-09-21
Look at your watch for just one minuite.During that time,The popuiation of the world increased by 259.Perhaps you think that is notmuch.Hoever,during the next hour,over15540 more babies will be born on the world. So it goes on,hour after hour.In oneday,people have to produce food fover 370000 more mouths.Multiply this by365.justthink how many more there will be in one year!What will happen in a hundred years? The increasing population may be the greatest challenge of the world today.The world's population is growing faster and faster.Two thousang years ago,there only 250millon people on the earth. At the beining of the20thcentury,the world'spopulation was about 1.7billion.In 1990,it reached more than five billion.Now at the beininjg of the 21stcentthe world's population has passed six billion.people say that by the yeay 2010it may be seven billion.That means in about 600 years,there will br standing room only on the earth.Each person will have one half to one square metre of space to live in.There will be hardly enough space ror angbody else.
It has been estimated that a thousand years ago there were less than 400 million people on earth. However, in the recent thousand years human population has increased nearly 20 times. Nowadays the world population has reached more than 7000 million. The population explosion has caused many problems. Generally, they come down to four major ones. First, a lot of people can't get employment, which is a universal problem in the world. Second, in developing countries there are not enough shelters for too many people and so people are not properly housed and even are exposed to the elements. Third, in underdeveloped countries a lot of people suffer from hunger because of food shortage, which in turn causes many other problems, malnutrition, disease, etc. Fourth, there are not enough schools for so many people and so a lot of people are illiterate. Therefore, to eliminate these problems, human beings should take effective measures to control population.