Take a very commonplace, often discussed and critical topic: Are we de

Question

Take a very commonplace, often discussed and critical topic: Are we detecting a greenhouse effect, and related to this, is it exacerbated by "homogenic factors," i.e., human actions? Most would be inclined to give a positive answer to both of these questions. But, if pushed, what would be the evidence, and how well grounded would it be for such affirmations?

Within scientific communities and associated scientifically informed circles, the answers have to be somewhat more ambiguous, particularly when rigorous questions concerning evidence are raised. Were scientific truth to be a matter of consensus, and some argue that scientific truth often turns out to be just that, then it is clear that there is beginning to be a kind of majority consensus among many earth science practitioners that the temperature of the Earth, particularly of the oceans, is indeed rising and that this is a crucial indicator for a possible greenhouse effect.

Most of these scientists admit that the mean oceanic temperature has risen globally in the last several decades. But this generalization depends upon how accurate measurements may be, not just for samples, but also for the whole Earth. Hot spots, for example the now four year old hot spot near New Guinea which is part of the El Niño cycle, does not count by itself because it might be balanced by cold spots elsewhere. And the fact of the matter is that "whole earth measurements" are still rare and primitive in the simple sense that we simply do not have enough thermometers out. Secondly, even if we had enough thermometers, a simply synchronic whole earth measurement over three decades is but a blip in the diachronic history of ice age cycles over the last tens of thousands of years. Thirdly, even if we know that the earth is now heating up, has an ever increasing ozone hole, and from this strange weather effects can be predicted, how much of this is due to homogenic factors, such as CFCs, CO2 increases, hydrocarbon burning, and the like? Is it really the case, as Science magazine claimed in l990, "24% of greenhouse encouraging gases are of homogenic origin"?   1 
 B 
 1. In this passage the author is primarily interested in

(A) Whether scientific truths are simply a matter of consensus
(B) Determining how well established the greenhouse effect is and to what degree it is worsened by human actions
(C) Whether the hot spot El Niño is balanced elsewhere by cold spots
(D) Determining if most scientists would be inclined to give a positive answer to the question of whether there is a greenhouse effect and if it is worsened by human actions
(E) Making a simple synchronic whole earth measurement more than a blip in the diachronic history of Ice Age cycles over the last tens of thousands of years.

2 
 D 
 2. The author of the passage would be most likely to agree with which of the following statements about the greenhouse effect?

(A) 24% of greenhouse encouraging gases are of homogenic origin.
(B) There is a greenhouse effect that is exacerbated by homogenic factors.
(C) The ozone hole is increasing due to homogenic factors, such as CFCs, CO2 increases, hydrocarbon burning, and the like.
(D) One can determine if mean oceanic temperatures have risen globally in the last several decades only if measurements of ocean temperatures are precise.
(E) Hot spots, such as the El Niño cycle, should not be counted as a factor in the greenhouse effect.

3 
 A 
 3. It can be inferred from the passage that

(A) We cannot be certain that strange weather effects are a result of the earth heating up and an ever-increasing ozone hole.
(B) The greenhouse effect is the most widely discussed topic in the scientifically informed circles.
(C) If the temperature of the oceans has ceased to rise at an ever-increasing rate, then the rate of global warming has increased.
(D) Strange weather effects have been shown to be due to the diachronic effects of hydrocarbon burning and not to increases in CFC.
(E) Strange weather effects are caused by the increase use of CFCs, CO2, and similar gasses.

4 
 D 
 4. The author’s claim that, a simply synchronic whole earth measurement over three decades is but a blip in the diachronic history of ice age cycles over the last tens of thousands of years would be strengthened if the author

(A) Indicated the minimum number of thermometers necessary for a whole earth measurement.
(B) Described the factors that precipitated the start of a new ice age.
(C) Compare synchronic whole earth measurements with diachronic whole earth measurements.
(D) Proved that the mean number of years required to detect significant changes in weather patterns is greater than thirty.
(E) Specified the exact location and quantity of thermometers placed by scientists around the globe.

GMATNinja · Accepted Answer

Question 3 
 
As you point out, "the earth" is the subject for the two phrases "is now heating up" and "has an ever increasing ozone hole." In the next phrase, the word "this" refers back to the two facts just stated about the earth -- that it's heating up and that it has an ozone hole. So basically, the phrase tells us that "strange weather effects" can be predicted from the ozone hole and the earth's heating up.

As you suggest, this isn't the most gracefully written sentence, and some of your corrections make grammatical sense. But on RC passages, I wouldn't worry too much about grammar rules. Your top priority is to make sense of the sentence as best you can. Identifying grammar errors or revising the sentence, on the other hand, will probably just distract you. Ultimately, your goal should be to find a logical interpretation that fits with the overall meaning of the passage.

Let's now take a look at question 3:

The passage tells us that "strange weather effects" can be predicted from from the earth's heating up and the increasing ozone hole. However, it also questions whether these strange effects are really due to "homogenic factors," such as CFCs, and CO2 increases. In other words, the author is questioning whether the homogenic factors, the heating earth, and the ozone hole are actually causing the "strange weather effects."

By asking this question, the author is making clear that we "cannot be certain" that the heating up and the ozone hole are  causing  the "strange weather effects." So (A) is correct.

Let's now consider the sentences you mentioned as confusing:

The first sentence tell us that "most" (i.e. most people) would say we are seeing a greenhouse effect exacerbated by homogenic factors. The second sentence is asking what evidence "most" people would give if we pushed them to defend their beliefs.

By saying "were scientific truth to be a matter of consensus," the author isn't suggesting this scenario is  unlikely . Rather, the author is acknowledging that the definition of scientific truth isn't a settled question. Nonetheless, the author is asking us to consider what would be the case if scientific truth "were a matter of consensus."

Reading further, we see there is a consensus that "the temperature of the earth... is indeed rising." So if "scientific truth were a matter of consensus," then the belief that "the temperature of the earth is rising" should probably be considered a "scientific truth."

Overall, you're heading in the right direction by analyzing these sentences closely to determine their meaning. But on RC, hunting for grammar errors is just a distraction. Instead, try coming up with the most logical interpretation you can, taking into account the context of the passage as a whole.

I hope that helps!

GMATNinja · Answer

Question 1 
 
To answer broad questions like question 1, start by breaking down the passage as a whole. Why did the author write each paragraph?

Paragraph 1 : the author  poses a question.

What and how strong is the evidence for the greenhouse effect, and for human involvement in the greenhouse effect?

Paragraph 2 : the author  introduces the opinion of the scientific community

The community's opinion is "somewhat ambiguous," but consensus is building that there is a greenhouse effect.

Paragraph 3 : The author  evaluates the evidence for the greenhouse effect.

From the above, we can see that the author is primarily interested in discussing the strength of the evidence for the greenhouse effect/human involvement in the greenhouse effect.

With that in mind, here's (A):
 
Consensus is mentioned in the second paragraph, but only to explain the scientific community's opinion on the greenhouse effect. So (A) really doesn't capture the author's primary interest -- instead, it is just a small point that the author considers before moving onto the stuff that he/she finds more interesting.

(A) is out.

This aligns nicely with our passage breakdown. The author evaluates the evidence pertaining to the greenhouse effect/human involvement in the greenhouse effect.

(B) is the correct answer to question 1.

Question 4 
Question 4 asks us to strengthen the claim that "a simply synchronic whole earth measurement over three decades is but a blip in the diachronic history of ice age cycles over the last tens of thousands of years."

Here's (C):
 
The main issue with (C) is that the author has  already  made the most relevant comparison between synchronic and diachronic measurements -- diachronic measurements would be much, much longer than synchronic ones. So, we can't really say that making this comparison would add much to the existing argument.

Compare that to (D):
 
How do we know that a 30 year measurement doesn't give us clear evidence about the green house effect? The author doesn't explicitly give us that info in the passage. (D) fills in that gap -- if the author proved that you need more than 30 years to detect significant changes in weather patterns, then the point that these measurements are a mere "blip" in the big picture would be stronger.

(D) is the correct answer to question 4.

I hope that helps!

purvikhandelwal1 · Answer

Hi,

Can anyone explain Q2. I was stuck between D and E.

Thank you:-)

Sajjad1994 · Answer

Why E is incorrect

According to paragraph 3 "Hot spots, for example the now four year old hot spot near New Guinea which is part of the El Niño cycle,  does not count by itself  because it might be balanced by cold spots elsewhere". So  the author does not say that Hot spots should not be counted, rather it should not be counted by itself , we should also consider other cold spots. For this reason, we can cancel E.

Why D is correct

According to paragraph 3 "Most of these scientists admit that the mean oceanic temperature has risen globally in the last several decades.  But this generalization depends upon how accurate measurements may be , not just for samples, but also for the whole Earth.". So this supports D.

Answer: D

krittapat · Answer

Could you please explain question 1 and 4 in details?
For question 1, I was hesitating between choice A and B.
For question 4, I was hanging around choice C and D, but I ended up choosing C as it seems to connect a synchronic whole earth measurement over three decades with the diachronic history of ice age cycles. Whereas, choice D only talks about a synchronic whole earth measurement over three decades.

Thanks in advance for your help.
 GMATNinja   KarishmaB   egmat   mikemcgarry

GraceSCKao · Answer

Hi avigutman GMATNinja IanStewart I have some questions about three sentences in this passage and about the third question that no previous posts addressed. So I decided to write my own post and hope that you could share some thoughts when you have time.

1. How should we read this sentence? Thirdly, even if we know that the earth is now heating up, has an ever increasing ozone hole, and from this strange weather effects can be predicted, how much of this is due to homogenic factors, such as CFCs, CO2 increases, hydrocarbon burning, and the like? I know that this is in the RC section and we do not need to examine the sentences by the same standards in the SC section, but I am really confused about this sentence and thus have trouble with the 3rd question. even if we know that the earth is now heating up, has an ever increasing ozone hole, and from this strange weather effects can be predicted, It is clear that the that clause's subject is "the earth," with the first verb "is heating" and the second verb "has," but I am unsure about "from this strange weather effects can be predicted." Does it have its own subject? Does it mean " effects could be predicted from the strange weather (heating up and increasing ozone hole) " ? If yes, why doesn't it just say "the strange weather's effects can be predicted?" After practicing so many SC questions that require that parallel verbs be connected by "and," I think it is weird if the subject "the earth" has two verbs without proper connection--the sentence should be revised into "the earth is now heating up and has an ever increasing ozone hole," should not it? It is not my intention to criticize the writing in PC passages, but this sentence's structure does make me wonder whether the subject "the earth" is related to the following parts. Or, does the verb "can be predicted" go with the subject "the earth" as the third verb? But, "the earth can be predicted from this strange weather effects" does not really make sense, not to mention that the singular "this" does not agree with the plural "effects". 2. How is the option (A) correct? I can see why the other options are incorrect, but I cannot articulate why (A) is correct, because I cannot really understand what "the strange weather effects" refer to. I feel that the "strange weather" refers to the heating up and increasing hole, so I think that there will be no such effects without the two phenomena. Maybe the use of the word "result" is not ideal, but it does not seem very wrong to me. On the other hand, I would definitely pick (A) if it said "we cannot be certain that the strange weather effects are a result of human behavior." 3. How much can we tolerate grammatical issues? Though I am not fully certain, I feel that the following two sentences both contain some errors that would not be ignored if the sentences appeared in the SC section. I am aware that this is in the RC section, but these errors (or not errors, if I have mistaken them) have made me unable to grasp the author's real meaning. I do think that is an important ability for shorter, tighter and more difficult passages. a. In the end of the first paragraph: But, if pushed, what would be the evidence, and how well grounded would it be for such affirmations? ->What is being pushed here? the evidence? or the most people in the preceding sentence? b. In the end of the second paragraph: Were scientific truth to be a matter of consensus, and some argue that scientific truth often turns out to be just that, then it is clear that there is beginning to be a kind of majority consensus among many earth science practitioners that the temperature of the Earth, particularly of the oceans, is indeed rising and that this is a crucial indicator for a possible greenhouse effect. ->This sentence is in the conditional tone. "Were" should go with "would" to indicate that the author thinks it is an unlikely case. But, "would" is missed in this sentence. Does the author still think that this is an unlikely case? Sorry experts that my questions are a bit long. Usually RC passages do not confuse me so much and I avoid asking grammar-related questions in the RC section. But since I have difficulty understanding the option (A) in the 3rd question, I hope to enhance my reading ability. Thank you for helping me learn.

bhanutomar111 · Answer

how is the answer of the 4th question is option D

GMATNinja · Answer

The author argues that three decades is just a blip, and not long enough to detect significant changes in weather patterns.

But how long IS long enough to detect significant changes? 50 years? 100 years?

What if you actually only need 20 years? If that's the case, then the author's argument has a hole: three decades of data actually WOULD be enough. So proving that the mean number of years required to detect significant changes in weather patterns is GREATER than thirty would strengthen the author's position.

For more on question 4, check out the second half of this post:  https://gmatclub.com/forum/take-a-very-commonplace-often-discussed-and-critical-topic-are-we-de-108340.html#p3011941 .

Dbrunik · Answer

What is going on with question two, A answer., there appears to be a grammatical mistake here and it should not say encouraging

Posted from my mobile device

GMATNinja · Answer

Question 2, choice (A) is actually taken directly from the final sentence of the passage. It's a bit confusing, but it's grammatically okay.

In the phrase "24% of  greenhouse encouraging  gases are of homogenic origin", "greenhouse encouraging" modifies the gases. (It probably would have been clearer to write "greenhouse-encouraging" with a dash, but the dash is not strictly required.) And "homogenic" modifies "origin" -- so there's no issue with that either.

Here's how the structure of (A) compares to the structure of a similar sentence:

"Nearly half / of Guatemala's 15 million inhabitants / are of Mayan descent."
 
 "24% / of greenhouse encouraging gases / are of homogenic origin."

Both are completely fine.

SiddharthSachdeva · Answer

GMATNinja   IanStewart

For question - 1

Since it is written " Take a very commonplace, often discussed and critical topic " - I thought that the entire purpose of greenhouse effect is just to act as an example and the main point which author wants to convey is something related to scientific community only , hence marked option A

agrasan · Answer

Hi  GMATNinja

For question-1, could you please explain why option D is wrong?

My reasoning is that para-2 talks about scientists and then the author challenges scientists' opinion/view in para-3 through the line  "Most of these scientists admit that the mean oceanic temperature has risen globally in the last several decades.  But this generalisation depends  upon how accurate measurements may be, not just for samples, but also for the whole Earth....".  He then evaluates three conditions by finally casting a doubt on green house effect happening due to humans. Overall, he seems like he is asking scientists to give him a solid evidence to show that human actions cause green house effect.

Please help me with the reason to eliminate option D.

agrasan · Answer

Hi experts  KarishmaB   GMATNinja

In question-2, could you pls explain why option D is correct?

According to paragraph 3  "Most of these scientists admit that the mean oceanic temperature has risen globally in the last several decades. But  this generalisation depends upon how accurate measurements may be, not just for samples, but also for the whole Earth ."

I understand that above lines say that "accurate measurements" are important but they also need to do it for  "whole earth" and not samples .

In the question, option D doesn't mention whether oceanic temperatures are for whole earth or not. How can we infer that "accurate measurements" is the ONLY condition required?

Please let me know where I am going wrong here.

KarishmaB · Answer

Question 2

2. The author of the passage would be most likely to agree with which of the following statements about the greenhouse effect?

(A) 24% of greenhouse encouraging gases are of homogenic origin. 
 (B) There is a greenhouse effect that is exacerbated by homogenic factors. 
 (C) The ozone hole is increasing due to homogenic factors, such as CFCs, CO2 increases, hydrocarbon burning, and the like. 
 (D) One can determine if mean oceanic temperatures have risen globally in the last several decades only if measurements of ocean temperatures are precise. 
 (E) Hot spots, such as the El Niño cycle, should not be counted as a factor in the greenhouse effect.

(A) 24% of greenhouse encouraging gases are of homogenic origin.

Given:   Is it really the case, as Science magazine claimed in l990, "24% of greenhouse encouraging gases are of homogenic origin"? 
 The author is questioning this. He is not sure whether this is correct.

(B) There is a greenhouse effect that is exacerbated by homogenic factors.

Look at the first paragraph:
 Are we detecting a greenhouse effect, and related to this, is it exacerbated by "homogenic factors," i.e., human actions? Most would be inclined to give a positive answer to both of these questions. But, if pushed, what would be the evidence, and how well grounded would it be for such affirmations?

He questions whether we have evidence that homogenize factors are exacerbating greenhouse effect. So again he doesn't hold this opinion.

(C) The ozone hole is increasing due to homogenic factors, such as CFCs, CO2 increases, hydrocarbon burning, and the like.

Look at the last paragraph:  Thirdly, even if we know that the earth is now heating up, has an ever increasing ozone hole, and from this strange weather effects can be predicted, how much of this is due to homogenic factors, such as CFCs, CO2 increases, hydrocarbon burning, and the like?

Again he is questioning this.

(D) One can determine if mean oceanic temperatures have risen globally in the last several decades only if measurements of ocean temperatures are precise.

This statement can be restated as: Precise measurements of ocean temperatures are required to determine whether mean oceanic temperatures have risen globally in the last several decades

Third paragraph: Most of these scientists admit that the mean oceanic temperature has risen globally in the last several decades. But this generalization depends upon how accurate measurements may be, not just for samples, but also for the whole Earth.

He says that whether mean oceanic temperatures have risen depends on how accurate measurements are. Hence if measurements are not accurate then this claim cannot be made. 
Hence (D) works. 
 
  (E) Hot spots, such as the El Niño cycle, should not be counted as a factor in the greenhouse effect.

Third paragraph: Hot spots, for example the now four year old hot spot near New Guinea which is part of the El Niño cycle, does not count by itself because it might be balanced by cold spots elsewhere.

He says El Niño BY ITSELF does not indicate global warming because it may be balanced off somewhere. So we need to know whether it is balanced off. If it is not balanced off by a cold spot, then it could indicate global warming. Hence this option is not correct.

Answer (D)

agrasan · Answer

Thanks  KarishmaB  for your detailed answer.

(D) One can determine if mean oceanic temperatures have risen globally in the last several decades only if measurements of ocean temperatures are precise.

I think I read the option D as X  (measurements of ocean temperatures are precise)  is the  only  condition required for Y  (mean oceanic temperatures have risen globally in the last several decades)  to happen whereas the real meaning of this option is that  X is just necessary for Y.

GMATNinja · Answer

Question 1 Check out the first sentence of the second paragraph: "Within scientific communities and associated scientifically informed circles, the answers have to be somewhat more ambiguous ." In other words, most scientists would likely NOT be inclined to give a positive answer to the question of whether there is a greenhouse effect and if it is worsened by human actions. Most scientists would likely respond, "Maybe?" instead of "Yes!". The author isn't really interested in WHETHER most scientists would give a positive answer. Instead, the author takes it as a matter of fact that they would likely NOT give a positive answer. The author is not interested in exploring that point, so (D) is out. Here's more on Question 1 for anyone else who missed it: https://gmatclub.com/forum/take-a-very- ... l#p3011941.

Take a very commonplace, often discussed and critical topic: Are we de

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