We can begin our discussion of "population as global issue" with what most persons mean when they discuss "the population problem": too many people on earth and a too rapid increase in the number added each year. The facts are not in dispute; it was quite right to employ the analogy that likened demographic growth to "a long, thin powder fuse that bums steadily and haltingly until it finally reaches the charge and explodes".
To understand the current situation, which is characterized by rapid increases in population, it is necessary to understand the history of population trends. Rapid growth is a comparatively recent phenomenon. Looking back at the 8,000 years of demographic history, we find that populations have been virtually stable or growing very slightly for most of human history. For most of our ancestors, life was hard, often nasty, and very short. There was high fertility in most places, but this was usually balanced by high mortality. For most of human history, it was seldom the case that one in ten persons would live past forty, while infancy and childhood were especially risky periods. Often, societies were in clear danger of extinction because death rates could exceed their birthrates. Thus, the population problem throughout most of history was how to prevent extinction of the human race.
This pattern is important to notice. Not only does it put the current problems of demographic growth into a historical perspective, but it suggests that the cause of rapid increase in population in recent years is not a sudden enthusiasm for more children, but an improvement in the conditions that traditionally have caused high mortality.
Demographic history can be divided into two major periods: a time of long, slow growth which extended from about 8000 B.C. till approximately 1650

• A.D. In the first period of some 9,600 years, the population increased from some 8 million to 500 million in 1650. Between 1650 and 1975, the population has increased from 500 million to more than 4 billion. And the population reached 6.2 billion throughout the world by the year 2000. One way to appreciate this dramatic difference in such abstract numbers is to reduce the time frame to something that is more manageable. Between 8000
• B.
• C. and 1650, an average of only 50,000 persons was being added annually to the world’s population. At present, this number is added every six hours. The increase is about 80,000,000 persons annually.

Which statement is TRUE about population increase

Air: the World Health Organization (WHO) says three million people are killed worldwide by outdoor air pollution annually from vehicles and industrial emissions, and 1.6 million indoors through using solid fuel. Most are in poor countries.
Water: diseases carried in water are responsible for 80% of illnesses and deaths in developing countries, killing a child every eight seconds. Each year 2.1 million people die from diarrhoeal(痢疾的) diseases associated with poor water.
Soil: contaminated land is a problem in industrialized countries, where former factories and power stations can leave waste like heavy metals in the soil. It can also occur in developing countries, sometimes used for dumping pesticides. Agriculture can pollute land with pesticides, nitrate-rich fertilizers and slurry from livestock. And when the contamination reaches rivers it damages life there, and can even create dead zones off the coast, as in the Gulf of Mexico.
Chronic Problem
Chemicals are a frequent pollutant. When we think of chemical contamination it is often images of events like Bhopal that come to mind. But the problem is widespread. One study says 7-20% of cancers are attributable to poor air and pollution in homes and workplaces. The WHO, concerned about chemicals that persist and build up in the body, especially in the young, says we may "be conducting a large-scale experiment with children’s health".
Some man-made chemicals, endocrine(内分泌) disruptors like phthalates(酞酸盐) and nonylphenol-a breakdown product of spermicides (杀精子剂), cosmetics and detergents-are blamed for causing changes in the genitals, of some animals. Affected species include polar bears-so not even the Arctic is immune. And the chemicals climb the food chain, from fish to mammals, and to us.About 70,000 chemicals are on the market, with around 1,500 new ones appearing annually. At least 30,000 are thought never to have been comprehensively tested for their possible risks to people.At first glance, the plastic buckets stacked in the comer of the environmental NGO office look like any others. But the containers are an unlikely weapon in one poor community’s fight against oil companies which they say are responsible for widespread ill-health caused by years of pollution. The vessels are used by a network of local volunteers, known as the Bucket Brigade, to gather air samples in neighborhoods bordering oil refineries, as part of a campaign to monitor and document air pollution which they believe is coming from the plants.
In South Africa, as m many developing and newly industrialized countries, legislation on air pollution has failed to keep pace with mushrooming industries. So local residents, like many in poor communities around the globe, have faced the problem of investigating their claim that industries on their doorsteps are making them sick.
Trade-off
But the snag is that modern society demands many of them, and some are essential for survival. So while we invoke the precautionary principle, which always recommends erring on the side of caution, we have to recognize there will be trade-offs to be made.
The pesticide DDT does great damage to wildlife and can affect the human nervous system, but can also be effective against malaria(疟疾). Where does the priority lie
The industrialized world has not yet cleaned up the mess it created, but it is reaping the benefits of the pollution it has caused. It can hardly tell the developing countries that they have no right to follow suit.Another complication in tackling pollution is that it does not respect political frontiers. There is a U.N. convention on trans-boundary air pollution, but that cannot cover every problem that can arise between neighbors, or between states which do not share a border. Perhaps the best example is climate change-the countries of the world share one atmosphere, and what one does can affect everyone.
For One and All
One of the principles that are supposed to apply here is simple-the polluter pays. Sometimes it is obvious who is to blame and who must pay the price, but it is not always straightforward to work out just who is the polluter, or whether the rest of us would be happy to pay the price of stopping the pollution.
One way of cleaning up after ourselves would be to throw less away, designing products to be recycled or even just to last longer.
Previous generations worked on the assumption that discarding our waste was a proper way to get rid of it, so we used to dump nuclear materials and other potential hazards at sea, confident they would be dispersed in the depths.
We now think that is too risky because, as one author wrote, "there’s no such place as ’away’, and there’s no such person as the ’other’ ."
Irritating Air
Despite recent improvements, however, the health problems are still there. A 2002 medical study, carried out by Durban’s Nelson Mandela School of Medicine and a U.S. university, found that an abnormally high 52% of students and teachers at a primary school bordering the Engen plant suffered from asthma (哮喘). It found that increases in air pollution tended to aggravate asthma symptoms in children.
The petrol producers do not dispute the findings but argue that researchers were unable to establish a causal link between air pollution and the high prevalence of asthma among the school population.
For the community, the next step is to take legal action. But, according to internationally recognized environmentalist Bobby Peek, targeting the companies would be difficult as it would be near-impossible to prove that illnesses suffered were caused by pollution coming from a particular plant.
Mr. Peek, who grew up beneath Engen’s stacks, says the activists are now considering taking action against the authorities. "We are now looking at suing the government on constitutional grounds, for failing to ensure our right to protection from a harmful environment as stipulated in the constitution," he said.
Legislative ChangeA new batch (批) of environmental laws, the National Air Quality Management Act, has just been passed by the South African parliament to replace outdated 1965 legislation with tighter controls and tougher sanctions.
Martinus van Schalkwyk, the minister of environmental affairs and tourism, visited the south Durban basin earlier this year and said there were measures in place to improve the situation. "I share the anger and frustration of this community. It is long overdue," he told the South African Broadcasting Corporation.
The local authorities have also established a "Multi-Point Plan" for the area. They say it is a powerful model for tackling pollution and points to a 40% reduction in sulphur dioxide emissions in recent years.