Practising Reading Comprehension and Writing

For the following passage, identify the main idea, structure, and author's primary purpose in writing it. Briefly paraphrase each paragraph after you read it.

Global Warming
Since 1979, there has been a consensus that a doubling of carbon dioxide would raise global temperatures 1.5 to 4.5 degrees Celsius. Emissions of methane, nitrous gases, and other gases that absorb infrared radiation could speed this process further. Although attention has been given to strategies intended to limit global warming, most climatologists feel an average temperature increase of one to two degrees Celsius is inevitable.

A potentially hazardous consequence of even a slight increase in worldwide temperature was identified in the early 1970s. Scientists predicted a nearly 20-foot rise in global sea levels as a result of the Antarctic ice sheet melting. Although this prediction has since been discredited by new research that shows such an occurrence would take place over a span of roughly 500 years, more recent studies have identified several sites, including smaller glaciers and large parts of the ice sheet in Greenland, that are more susceptible to rapid thawing. Based on data compiled from researchers, a seven-foot rise in sea level is possible by the year 2100.

Even a small rise in sea level, an average of two feet worldwide, would result in inundation, erosion, flooding, and saltwater intrusion. Coastal areas of the United States would lose a significant amount of land: Scientists predict a 50- to 100-foot loss in New Jersey, and up to 1,000 feet of shore areas flooded in Florida. According to some studies, the rise in water levels could contribute to a loss of 50 to 90 percent of U.S. wetlands.

Currently, two major policy approaches are being considered by coastal communities. The first, known as the no-protection approach, is based on a philosophy of nonintervention. Communities in coastal regions simply zone areas they anticipate losing land to erosion within the next 30 to 60 years. No new buildings are permitted to be built in zones likely to be lost to flooding or erosion, and the current structures are left to their fates. Communities that take a no-protection approach acknowledge the coming danger, but they are often unwilling or unable to incur the financial losses associated with condemning and removing beachfront property. However, it should be noted that communities that elect a no-protection approach place the financial burden on the federal government, which compensates home owners for homes lost to floods or storms.

The second option, and certainly the more appealing one, involves raising the land level along the shore. This approach, although a far costlier one, offers several advantages. First, it does not require the removal or demolition of buildings. Instead, the entire land mass is raised to protect it from the ocean. Second, the federal government does not have to intervene in the form of land buys or flood insurance. Despite these benefits, many communities choose not to raise the land due to the great cost and large amount of labor involved. To raise the land, sand must be pumped onto the beach (including the underwater part of the beach) until the land level gradually rises. In addition, roads, houses, and other structures must be gradually raised again. The size of this undertaking prevents many communities from considering it.

One of the major hurdles facing policy makers is the lack of urgency surrounding the onset of global warming and rising sea levels. Many communities do not see the need to take action in response to effects that will not materialize for 100 years. However, considering the possible consequences of inaction, community leaders would be wise to begin serious discussions about their preferred strategy.
628 words


Source:
Cracking the iBT TOEFL, 2013, p. 85


Overall Purpose?