You can find a table below showing the population change from 2010 to 2015, projected by the Population Council in New York, and

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问题    You can find a table below showing the population change from 2010 to 2015, projected by the Population Council in New York, and a short material explaining some conditions of population prediction. Read them carefully and write an essay of no less than 300 words, in which you should:
   1. summarize the ideas in both materials;
   2. comment on the situation.
   Table
   
   Excerpt
               ASSUMPTIONS UNDERLYING THE PROJECTIONS
      (http://info.worldbank.org/etools/docs/library/48424/mls3bongaarts.pdf)
   The population of the world now increases every year because the global birth rate exceeds the death rate. The annual birth and death rates of populations are in turn primarily determined by levels of fertility and mortality experienced by individuals. The most widely used fertility indicator is the total fertility rate (TFR). Mortality is usually measured by the life expectancy at birth (LE), which equals the average number of years a newborn would live if subjected to a given set of age-specific mortality rates. In order to make longrange population projections, assumptions have to be made about the future trajectories of fertility and mortality.

   Future trends in fertility in the South are based on the assumption that the total fertility rate will eventually reach and then remain at the so-called "replacement" level in all regions. Replacement fertility is just above 2 bpw and it represents the level at which each generation just replaces the previous one, thus leading to zero population growth. Below-replacement fertility produces, in the long run, population decline.

   Mortality levels have also changed rapidly over the past few decades. By the early 1990s, Latin America had reached mortality levels similar to those prevailing in the North in the 1950s, and Asia was not far behind. Africa has had the highest mortality levels and the slowest rate of improvement. By 2025, mortality conditions in Asia and Latin America are expected to be similar to those that prevailed in the North in the 1970s. Africa will continue to lag, in part because the continent is most heavily affected by the AIDS epidemic.
   It should be noted that the assumptions made by the UN about future trends in fertility and mortality are not based on a firm theoretical basis. Instead, the UN relies on empirical regularities in past trends in the now-developed countries, mostly in the North, where fertility declined to around the replacement level, and increases in life expectancy became smaller over time. This is a plausible approach that unfortunately leaves room for potential inaccuracies in projection results.

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答案 The two materials project population change and basic assumptions for population prediction. According to the table by Population Council, from 2010 to 2030, world population will rise by 20.7%. Among the top ten populous nations, Nigeria and Pakistan will experience the most dramatic increase. Except for China and Russia, the other six countries will witness a sharp increase. On the whole, the most populous countries will be found in Asia and Latin America. The projection results are roughly in agreement with the assumptions made by the UN. That is, population prediction is chiefly based on total fertility and mortality rates; the fertility rate will reach stable in all regions; and that mortality conditions in Asia and Latin America will improve. Both excerpts indicate that Asia and Latin America will face a drastic increase in population. Population growth, as a double sword, could bring about greater pressure on land and food as well as more labor force. Therefore, any nation which strives for improvement in living standard must remain alert so as to keep a balance between population and environment. As most of the Asian and Latin American countries are developing ones, population multiplication has the potential to incur higher unemployment rate, more social violence and poorer health care service etc. As a result, the general level of living in such countries will deteriorate with huge population growth. China is the only Asian country which has adopted population control over the past decades and the figure in the table implies that the measure is fruitful. It may be advisable for other Asian and Latin American countries to learn from China. After all, land on earth is not unlimited. Before science and technology are advanced enough for human beings to find another planet for existence, it may be a more sensible option for us to keep earth population under a manageable scale.

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