Some climatologists argue that the burning of fossil fuels has raised the level of CO2 in the atmosphere and has caused a global temperature increase of at least 1℃. But a supposed global temperature rise of 1℃ may in reality be only several regional temperature increases, restricted to areas where there are many meteorological stations and caused simply by shifts in the pattern of atmospheric circulation. Other areas, for example, the Southern Hemisphere oceanic zone, may be experiencing an equivalent temperature decrease that is unrecognized because of the shortage of meteorological recording stations.
21. The passage supplies information for answering which of the following questions?
(A) Why are projections of the effects of changes in water vapor levels on the climate so inaccurate?
(B) What are the steps in the process that takes place as CO2 absorbs long- wavelength radiation?
(C) How might out understanding of the green- house effect be improved if the burning of fossil fuels were decreased?
(D) What might cause a series of regular increases and decreases in the amount of CO2 in the atmosphere?
(E) Why are there fewer meteorological recording stations in the Southern Hemisphere oceanic zone than elsewhere?
22. The author's primarily concerned with
(A) explaining the effects that the burning of fossil fuels might have on climate.
(B) illustrating the effects of CO2 on atmospheric radiation
(C) discussing effects that changes in the CO2 level in the atmosphere might have on climate
(D) challenging hypotheses about the effects of water vapor and CO2 on climate
(E) refuting hypotheses by climatologists about the causes of global temperature fluctuations
23. The passage suggests that a large decrease in the amount of CO2 in the atmosphere would result in
(A) at least a slight decrease in global temperatures
(B) at the most a slight increase in short- wavelength radiation reaching the Earth
(C) a slight long-term increase in global temperatures
(D) a large long-term increase in the amount of volcanic activity
(E) a slight short-term increase in atmospheric water vapor content
24. The author refers to Venus primarily in order to
(A) show the inherent weakness of the green- house effect theory
(B) show that the greenhouse effect works on other planets but not on Earth
(C) show the extent to which Earth's atmosphere differs from that of Venus
(D) support the contention that as water vapor increases, the amount of CO2 increases
(E) support the argument that the CO2 level in the atmosphere has a significant effect on climate
25. The passage suggests that if there were a slight global warming at the present time, it would be
(A) easy to measure the exact increase in temperature because of the abundance of temperature recording stations throughout the world
(B) difficult to measure the increase of CO2 in the atmosphere because of local variations in amounts
(C) easy to demonstrate the effects of the warming on the water vapor in the atmosphere
(D) difficult to prove that the warming was caused by the burning of fossil fuels
(E) easy to prove that the warming was caused by an increase of cloud cover
26. The discussion of climate in the passage suggests which of the following conclusions?
Ⅰ Climate is not perfectly stable, and slight regional temperature variations can be considered a normal feature of the environment.
Ⅱ We are unable at present to measure global temperature changes precisely
Ⅲ The most important cause of regional climatic fluctuations is the change in CO2 levels in the atmosphere.
(A)Ⅰonly
(B) Ⅲ only
(C)ⅠandⅡonly
(D)Ⅱand Ⅲ only
(E)Ⅰ,Ⅱ, and Ⅲ
27. All of the following can be found in the author's discussion of climate EXCEPT.
(A) a statement about the effects of increased volcanic activity on the Earth's temperatures
(B) an indication of the effect of an increase