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

Hello Vorskl,

This is my take on 18.

As per the passage para 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 18 E.

As per the passage para 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 18 D.

I don't understand the logic in the 17th OA. The author states that there is no firm evidence to prove that there is a greenhouse effect, doesn't he?
I picked D for 17th.
So can anyone help me solve this particular question?

I think the author already mention "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?"

The author is not determining.

Could someone give an explanation for Question 4 -
Primarily the answer choice difference between C and D.

Thanks

6 mins all correct, SajjadAhmad please share difficulty levels.

The difficulty levels of the questions are as follow:

Question 1: 700
Question 2: 700
Question 3: 650
Question 4: 700

Overall: 700

Thank you

I would appreciate some help with question 1! I was stuck between B&D. If I were to exclude the second paragraph it would be straightforward to me that the answer is B. However, since the author focuses so much on the views of scientist in paragraph 2 and finally in paragraph 3 again mentions science magazine, which is a peer-reviewed academic journal in which scientist publish their work, I was led to believe that the focus on scientists and their work would make D correct. GMATNinja would you mind helping out?

Hi GMATE1,



I would say D is incorrect because the passage is not about whether scientists are inclined or not to prove whether there is a greenhouse effect and if it is worsened by human actions. It more about about whether there is a greenhouse effect and if its worsened by human actions, which is exactly what option B points out.


Hope This Helps.
Thanks.

please explain Q4 stuck between C AND D

Hi,

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

Thank you:-)

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

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

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!

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.

GMATNinja In question 4, could you please explain how we cannot eliminate D? based on the question we are supposed to show that since synchronic measurements are just a ''Blip" in the diachronic measurements that spread through thousands of years, a wider range is needed to be taken into account to have the bigger picture.
Answer choice D only states that it should be bigger than 30, meaning 31 is okay, so how does 31 years i.e shows the wider range that we need to not have the ''blip''.