Aided by the recent ability to analyze samples of air trapped in

Question

1991 10 SECTION A 17-23

Aided by the recent ability to analyze samples of air trapped in glaciers, scientists now have a clearer idea of the relationship between atmospheric composition and global temperature change over the past 160,000 years. In particular, determination of atmospheric composition during periods of glacial expansion and retreat (cooling and warming) is possible using data from the 2,000 meter Vostok ice core drilled in Antarctica. The technique involved is similar to that used in analyzing cores of marine sediments, where the ratio of the two common isotopes of oxygen, 18O and 16O, accurately reflects past temperature changes. Isotopic analysis of oxygen in the Vostok core suggests mean global temperature fluctuations of up to 10 degrees centigrade over the past 160,000 years.

Data from the Vostok core also indicate that the amount of carbon dioxide has fluctuated with temperature over the same period: the higher the temperature, the higher the concentration of carbon dioxide and the lower the temperature, the lower the concentration. Although change in carbon dioxide content closely follows change in temperature during periods of deglaciation, it apparently lags behind temperature during periods of cooling. The correlation of carbon dioxide with temperature, of course, does not establish whether changes in atmospheric composition caused the warming and cooling trends or were caused by their.

The correlation between carbon dioxide and temperature throughout the Vostok record is consistent and predictable. The absolute temperature changes, however, are from 5 to 14 times greater than would be expected on the basis of carbon dioxide’s own ability to absorb infrared radiation, or radiant heat. This reaction suggests that, quite aside from changes in heat-trapping gases, commonly known as greenhouse gases,  certain positive feedbacks  are also amplifying the temperature change. Such feedbacks might involve ice on land and sea, clouds, or water vapor, which also absorb radiant heat.

Other data from the Vostok core show that methane gas also correlates closely with temperature and carbon dioxide. The methane concentration nearly doubled, for example, between the peak of the penultimate glacial period and the following interglacial period. Within the present interglacial period it has more than doubled in just the past 300 years and is rising rapidly. Although the concentration of atmospheric methane is more than two orders of magnitude lower than that of carbon dioxide, it cannot be ignored: the radiative properties of methane make it 20 times more effective, molecule for molecule, than carbon dioxide in absorbing radiant heat. On the basis of a simulation model that climatological researchers have developed, methane appears to have been about 25 percent as important as carbon dioxide in the warming that took place during the most recent glacial retreat 8,000 to 10,000 years ago.   
 1 
 1. ​​​The primary purpose of the passage is to

(A) interpret data
(B) explain research methodology
(C) evaluate a conclusion
(D) suggest a new technique
(E) attack a theory

2 
 2. ​​​According to the passage, which of the following statements about methane is true?

(A) Methane is found in marine sediments.
(B) Methane is more effective than carbon dioxide in absorbing radiant heat.
(C) The Earth’s atmosphere now contains more than twice as much methane as it does carbon dioxide.
(D) The higher the concentration of carbon dioxide in the Earth’s atmosphere, the lower the concentration of methane.
(E) Most of the global warming that has occurred during the past 10 years has been associated with increased methane concentration.

3 
 3. ​​​According to the passage, which of the following statements best describes the relationship between carbon dioxide and global temperature?

(A) Carbon dioxide levels change immediately in response to changes in temperature.
(B) Carbon dioxide levels correlate with global temperature during cooling periods only.
(C) Once carbon dioxide levels increase, they remain high regardless of changes in global temperature.
(D) Carbon dioxide levels increase more quickly than global temperature does.
(E) During cooling periods, carbon dioxide levels initially remain high and then decline.

4 
 4. ​​​​​​The author mentions “certain positive feedbacks” ( Highlighted ) in order to indicate that

(A) increased concentration of carbon dioxide in the Earth’s atmosphere is responsible for global temperature increase
(B) some climate simulation models have produced useful information
(C) greenhouse gases alone do not account for global temperature increase
(D) variables that benefit life are causing global temperature to increase
(E) beneficial substances that are not heat-trapping gases and that contribute to global temperature increase have been found in the Vostok ice core

5 
 5. ​​It can be inferred from the passage that a long-term decrease in the concentration of carbon dioxide in the Earth’s atmosphere would

(A) increase methane concentration in the Earth’s atmosphere
(B) accompany a period of glaciation
(C) encourage the formation of more oxygen isotopes in the Earth’s atmosphere
(D) promote the formation of more water in the Earth’s global environment
(E) increase the amount of infrared radiation absorbed by the Earth’s atmosphere

6 
 6. ​​​​​The passage suggests that when the methane concentration in the Earth’s atmosphere decreases, which of the following also happens?

(A) Glaciers melt faster.
(B) The concentration of carbon dioxide increases.
(C) The mean global temperature decreases.
(D) Carbon dioxide absorbs more radiant beat.
(E) More clouds form in the Earth’s atmosphere.

7 
 7. ​​​​​In the fourth paragraph, the author is primarily concerned with

(A) restating the main idea of the passage
(B) using research findings to develop a simulation model
(C) outlining the direction of future reserves
(D) providing an additional example of a phenomenon
(E) introducing a conflicting hypothesis

RC Butler 2021  -  Practice Two RC Questions Everyday.   
Passage # 140 Date: 08-Apr-2021
 This question is a part of RC Butler 2021 .  Click here for Details

auradediligodo · Accepted Answer

Hi everyone,
Took almost 13 minutes including 6 minutes to read and got 6/7 correct.

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P1

In this paragraph the author explains how scientists are now more able to understand the correlation between air composition and global temperature change. As a matter of fact they can now analyze the air resent in glacier and they study glaciers during the periods of warming and cooling. A similar technique to the one used in marine environment is used. Such technique uses isotopic concentration and showed that in the last 160000 years the temperature changed of 10 degrees.

Purpose:  To claim that now scientists are more able to understand the correlation of temperature change and air composition.

P2

Here the author tells us that carbon dioxide levels were in one with the changes in temperature. However we still don't know whether the temperature changes were caused by the change in the composition of air or vice versa.

Purpose:  To present a correlation between carbon dioxide levels and temperature change

P3

In this paragraph the author explains that we would expect a change in temperature much lower if we looked only at the levels of carbon dioxide. As a matter of fact the author claims that there are other events that affect as well the change in temperature. The author refers to such events as positive feedbacks.

Purpose:   to consider other elements that account for the temperature change.

P4

In this paragraph the author introduces another elements that correlates with the 2 previously mentioned: methane. We are given that methane increases as the temperature increases and vice versa. Plus we know that the concentration of methane is lower than that of carbon dioxide but methane has a stronger impact per unite than carbon dioxide.

Purpose  : To introduce methane and detail its impact on temperature change

Main point

To present and analyze 2 elements that are correlated with temperature change.

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1. ​​​The primary purpose of the passage is to

Pre-thinking

Main point question

To present and analyze 2 elements that are correlated with temperature change.

(A)   interpret data
 Correct and broad enough

(B) explain research methodology
 the methodology is not explained

(C) evaluate a conclusion
 there is no evaluation whatsoever

(D) suggest a new technique
 no new technique is suggested

(E) attack a theory
 No theory is attacked

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2. ​​​According to the passage, which of the following statements about methane is true?

Pre-thinking

Detail question

We need to look into the last paragraph

Other data from the Vostok core show that methane gas also correlates closely with temperature and carbon dioxide. The methane concentration nearly doubled, for example, between the peak of the penultimate glacial period and the following interglacial period. Within the present interglacial period it has more than doubled in just the past 300 years and is rising rapidly. Although the concentration of atmospheric methane is more than two orders of magnitude lower than that of carbon dioxide, it cannot be ignored:   the radiative properties of methane make it 20 times more effective, molecule for molecule, than carbon dioxide in absorbing radiant heat.   On the basis of a simulation model that climatological researchers have developed, methane appears to have been about 25 percent as important as carbon dioxide in the warming that took place during the most recent glacial retreat 8,000 to 10,000 years ago.

(A) Methane is found in marine sediments.
  (B)   Methane is more effective than carbon dioxide in absorbing radiant heat.
(C) The Earth’s atmosphere now contains more than twice as much methane as it does carbon dioxide.
(D) The higher the concentration of carbon dioxide in the Earth’s atmosphere, the lower the concentration of methane.
(E) Most of the global warming that has occurred during the past 10 years has been associated with increased methane concentration.

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3. ​​​According to the passage, which of the following statements best describes the relationship between carbon dioxide and global temperature?

Pre-thinking

Detail question

From P2:   Although change in carbon dioxide content closely follows change in temperature during periods of deglaciation, it apparently lags behind temperature during periods of cooling.

(A) Carbon dioxide levels change  immediately  in response to changes in temperature.
(B) Carbon dioxide levels correlate with global temperature during cooling periods  only .
(C) Once carbon dioxide levels increase,  they remain high regardless of changes in global temperature. 
(D) Carbon dioxide levels increase more quickly than global temperature does.( Opposite) 
  (E)   During cooling periods, carbon dioxide levels initially remain high and then decline.

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4. ​​​​​​The author mentions “certain positive feedbacks” (Highlighted) in order to indicate that

Pre-thinking

Function question

From P3:   This reaction suggests that,  quite aside  from changes in heat-trapping gases, commonly known as greenhouse gases, certain positive feedbacks are  also  amplifying the temperature change.

The wording used suggests that the author wants to provide a further phenomenon contributing to temperature changes, phenomenon that is different from the greenhouse gases.

(A) increased concentration of carbon dioxide in the Earth’s atmosphere is responsible for global temperature increase
 Out of scope

(B) some climate simulation models have produced useful information
 out of scope

(C)   greenhouse gases alone do not account for global temperature increase
 in line with pre-thinking

(D) variables that benefit life are causing global temperature to increase
 We cannot infer the fact that such variables benefit lifespan's. Out

(E) beneficial substances that are not heat-trapping gases and that contribute to global temperature increase have been found in the Vostok ice core
 we cannot infer that such substances are beneficial

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5. ​​It can be inferred from the passage that a long-term decrease in the concentration of carbon dioxide in the Earth’s atmosphere would

Pre-thinking

Inference question

We can infer 2 things: -temperatures would go down - methane levels would go down

(A) increase methane concentration in the Earth’s atmosphere
  (B)   accompany a period of glaciation
(C) encourage the formation of more oxygen isotopes in the Earth’s atmosphere
(D) promote the formation of more water in the Earth’s global environment
(E) increase the amount of infrared radiation absorbed by the Earth’s atmosphere

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6. ​​​​​The passage suggests that when the methane concentration in the Earth’s atmosphere decreases, which of the following also happens?

Pre-thinking

Inference question

We can infer that also temperatures and carbon dioxide decrease.

(A) Glaciers melt faster.
(B) The concentration of carbon dioxide increases.
  (C)   The mean global temperature decreases.
(D) Carbon dioxide absorbs more radiant beat.
(E) More clouds form in the Earth’s atmosphere.

--------------------------------------------------------------------------------------------

7. ​​​​​In the fourth paragraph, the author is primarily concerned with

Pre-thinking

Paragraph's purpose question

the author wants to detail the correlation between methane and temperature change

(A)  restating the main idea of the passage 
(B)  using research findings to develop a simulation model 
(C) outlining the direction of  future reserves 
  (D)   providing an additional example of a phenomenon
(E) introducing a  conflicting  hypothesis

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It's a good day to be alive!

PhantomAY · Answer

13 mins, all correct.

Notes:

Paragraph 1: Scientists can now tell the relationship between atmospheric composition and global temp change, given data of air trapped in glaciers. 
Paragraph 2: data from Vostock core suggests CD and global temp has positive correlation. But the relationship doesn't warrant "changes in atmospheric composition caused the global temp change"
Paragraph 3: Other factors in play, given changes > what CD is able to change
Paragraph 4: methane gas introduced. Its impact compared with that of CD (lower volume, higher impact). also an important factor.

Author didn't provide much opinion in this passage, rather to present how the data can be interpreted.

A) correct
B) no methodology has been explained, rather the data itself
C) no conclusion was drawn, other than "a clearer idea"
D) irrelvant
E) "attack" is not warranted

A) not mentioned
B) correct, refer to  "the radiative properties of methane make it 20 times more effective, molecule for molecule, than carbon dioxide in absorbing radiant heat." 
C) incorrect, refer to  "Although the concentration of atmospheric methane is more than two orders of magnitude  lower  than that of carbon dioxide" 
D) the correlation between CD and methane was not specifically mentioned. Other than both have positive correlation with temp change. The likely answer should be the opposite
E) the passage didn't reach to this conclusion

A) incorrect,  "it apparently lags behind temperature during periods of cooling" 
B) incorrect, not just cooling periods
C) nope, they change in coincidence with global temp change
D) not mentioned
E) correct, given the temperature initially dropped from high values and CD change lag behind it.

To indicate there are other factors impacting the global temperature change, so C is the correct answer. refer to  "This reaction suggests that,  quite aside from changes in heat-trapping gases, commonly known as greenhouse gases , certain positive feedbacks are also amplifying the temperature change. Such feedbacks might involve ice on land and sea, clouds, or water vapor, which also absorb radiant heat."

long term decrease of CD --> long term decrease of global temperature --> glaciation

A) tempting one, but the correlation between CD and methane was not mentioned. If existing they should be positively correlated
B) correct
C) not mentioned
D) should be the opposite based on common sense
E) not mentioned

Since methane concentration has a negative correlation with global temperature change, its decrease --> global temp decrease

A) glaciers, if any, should melt slower
B) again, we don't know
C) correct
D) not sure
E) not sure

in the last paragraph, the author primarily introduced methane gas as another important factor. so D is the correct answer.

A) "restate the main idea" is wrong, given 4th paragraph develops further
B) "simulation model" is not the main idea of 4th
C) direction of future reserves is not mentioned
D) correct
E) "conflicting hypothesis" is unwarranted, given two factors don't contradict with each other

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