GRE阅读高频机经原文及答案：云和气候变化预测

　　15. 云和气候变化预测 1996年04月北美 D9604

　　As of the late 1980s, neither theorists nor large-scale computer climate models could accurately predict whether cloud systems would help or hurt a warming globe. Some studies suggested that a four percent increase in stratocumulus clouds over the ocean could compensate for a doubling in atmospheric carbon dioxide, preventing a potentially disastrous planetwide temperature increase. On the other hand, an increase in cirrus clouds could increase global warming.

　　That clouds represented the weakest element in climate models was illustrated by a study of fourteen such models. Comparing climate forecasts for a world with double the current amount of carbon dioxide, researchers found that the models agreed quite well if clouds were not included. But when clouds were incorporated, a wide range of forecasts was produced. With such discrepancies plaguing the models, scientists could not easily predict how quickly the worlds climate would change, nor could they tell which regions would face dustier droughts or deadlier monsoons.

　　15.1. The author of the passage is primarily concerned with

　　confirming a theory

　　supporting a statement

　　presenting new information

　　predicting future discoveries

　　reconciling discrepant findings

　　15.2. It can be inferred that one reason the fourteen models described in the passage failed to agree was that

　　they failed to incorporate the most up-to-date information about the effect of clouds on climate

　　they were based on faulty information about factors other than clouds that affect climate

　　they were based on different assumptions about the overall effects of clouds on climate

　　their originators disagreed about the kinds of forecasts the models should provide

　　their originators disagreed about the factors other than clouds that should be included in the models

　　15.3. It can be inferred that the primary purpose of the models included in the study discussed in the second paragraph of the passage was to

　　predict future changes in the worlds climate

　　predict the effects of cloud systems on the worlds climate

　　find a way to prevent a disastrous planetwide temperature increase

　　assess the percentage of the Earths surface covered by cloud systems

　　estimate by how much the amount of carbon dioxide in the Earths atmosphere will increase

　　15.4. The information in the passage suggests that scientists would have to answer which of the following questions in order to predict the effect of clouds on the warming of the globe?

　　What kinds of cloud systems will form over the Earth?

　　How can cloud systems be encouraged to form over the ocean?

　　What are the causes of the projected planetwide temperature increase?

　　What proportion of cloud systems are currently composed of cirrus of clouds?

　　What proportion of the clouds in the atmosphere form over land masses?