山西农业大学环境科学专业英语2.doc

环境科学专业英语-第二节Unit 2: Population Resources and EnvironmentAll too often, overpopulation is thought of simply as crowding: too many people in a given area, too high a population density. Between 1900 and now, the worlds population has roughly quadrupled from about 1.6 billion in 1900 to about 6 billion today and is currently growing at an annual rate of 1.2%, or 77 million people per year. Six countries account for half of this annual growth: India for 21%, China for 12%, Pakistan for 5%, Nigeria for 4%, Bangladesh for 4%, and Indonesia for 3%. By 2050, world population is expected to be between 7.9 billion (low variant) and 10.9 billion (high variant), with the medium variant producing 9.3 billion.There would be a rapid aging of the worlds population. In the past, the median age for the worlds population has been between 20 and 25 years. It is now about 26 years. By 2050, the median age for a depopulating globe would be about 42 years. In the more developed regions the median age of population would be over 50. That is to say: for every person under the age of 50, there would be someone over the age of 50. A complete transformation of the profile of the world would thus occur.The explosion of world population is an outgrowth of the industrial age, and three key factors are to blame: increased food production, disease control, and better sanitation. These advances greatly increase the survival rate of newborns, but this great change occurs in many countries without any decrease in the number of births.Population growth is at the root of virtually all environment problems, including pollution and resources depletion, and indirect social disruptions, such as housing shortages, malnutrition and inadequate health care. Rapid growth in population creates difficulties in meeting the basic needs of people, while crowding may cause mental illness, drug abuse and various forms of antisocial behavior. Hunger, starvation, disease, poverty, illiteracy, pollution, unemployment, and barren landscapes are, to many observers, signs that the human population is much too big for the earths resources. Among the negative trends they bet would continue are: rising global temperature, shrinking amount of cropland per person, decline in amount of wheat and rice grown per person, shrinking area of tropical moist forests, decreasing oceanic fish harvest per person, increasing number of people dying of AIDS, declining human sperm count, and growing gap between rich and poor.Population growth would have to be stopped; family planning and limited economic development are ways to bring the human population back in line. Family planning allows couples to determine the number and spacing of offspring, and the programs may be voluntary, extended voluntary, or forced. Many experts believe that family planning promotes economic development, jobs for women, health and education. To have an effective family planning program, we also have an effective economy - where jobs are available, where health facilities are adequate. Small-scale economic development, improved education, better health care, and contraception can reduce birth rates. The critical thinking skills suggest that solutions require many approaches. Family planning is a case in point.Developed nations can contribute to a solution by reducing consumption and population size. They can assist the less fortunate with population control, agriculture, health care, and appropriate technology through financial aid and, especially, information sharing. Many developing nations have population control programs, although funds are often inadequate. Increasing expenditures on such programs could have many long-rang benefits. To be effective, programs in such countries must take into account the effects of religious beliefs, psychological factors, and educational levels.New Words and Phrasesantisocial adj. 不擅社交的、非社交的；反社会的Bangladesh n. 孟加拉国（南亚国家）barren adj. 不生育的、不孕的、贫瘠的、没有结果的depletion n. 枯竭depopulate vt. 使人口减少expenditure n. 支出、花费financial adj. 财政的、金融的illiteracy n. 文盲inadequate adj. 不充分的、不适当的malnutrition n. 营养失调、营养不良newborn n. 婴儿；ad