Scientist: A greenhouse gas, for example, carbon dioxide, forms a tran

Question

Scientist: A greenhouse gas, for example, carbon dioxide, forms a transparent layer that traps solar heat beneath it in the earth's atmosphere. Atmospheric levels of carbon dioxide are currently increasing, causing the climate to warm—an effect that is predicted by at least one computer model of the greenhouse effect. But the warming that has occurred is a great deal less than what would be expected based on the model. Therefore, _______.

Which of the following most logically completes the scientist's argument?

A. better measurements of atmospheric levels of carbon dioxide are needed
B. the definition of “greenhouse gas” should probably be reconsidered
C. there are factors besides the increase in greenhouse-gas emissions contributing to the warming of the climate
D. the computer model of the greenhouse effect must be incorrect in some respect
E. the likely consequences of any warming of the climate are unlikely to be much less damaging than predicted

CR51080.01

ArtVandaley · Accepted Answer

I was very tempted to choose but invested 1 more minute to arrive at D.

C says that other factors may still exist. But nowhere in the stem it is mentioned that the model has not considered other factors. D, on the other hand, is a clear winner.

GMATIntensive · Answer

The Story

Scientist: A greenhouse gas, for example, carbon dioxide, forms a transparent layer that traps solar heat beneath it in the earth’s atmosphere.  - In this statement a scientist tells us a bit about GH gasses. A GH gas forms a transparent layer in the earth’s atmosphere. The layer traps solar heat below it. Carbon dioxide is an example of a GH gas.

Atmospheric levels of carbon dioxide are currently increasing, causing the climate to warm—an effect that is predicted by at least one computer model of the greenhouse effect.  - Carbon dioxide is increasing. This increase is causing temperatures to rise. This rise in temperature is predicted by at least one computer model.

But the warming that has occurred is a great deal less than what would be expected based on the model. Therefore, _______.   - The model predicted a much higher temperature rise than what actually happened. We have a blank in the end. ‘Therefore’ indicates we need to fill the blank with something that can be inferred on the basis of the passage.

Gist:   GH gasses warm the climate. Increasing levels of carbon dioxide (a GH gas) are causing temperatures to rise. A computer model had predicted the climate to be much warmer than the climate currently is.

(Since the given passage is not an argument, we are not going to try to find any gaps here.)

The Goal     
We have to think of something that can be concluded (inferred) on the basis of the passage. One thing that comes to mind is: the model is flawed to some extent.

The Evaluation

A. better measurements of atmospheric levels of carbon dioxide are needed 
  Incorrect  . There is nothing in the passage to suggest that current measurements of carbon dioxide are flawed. So why would better measurements be needed?

Do not make the mistake of thinking that the current measurements are not accurate must  be  why the model did not predict temperatures accurately. There is no such indication. There could be tonnes of reasons for why the model predicted inaccurately.

On top of that, even if assume that the model faltered because of poor measurements of atmospheric levels of CO2, can we infer that better measurements are  needed ? How about “better models are  needed ”? Basically, can we infer that there is a need? Is something not working perfectly enough to infer that it needs to be improved?

John has a light in his room that has not been working for six months. Does that mean he  needs  to get the light fixed? Not necessarily. Maybe he has other light sources that are sufficient for his  brightness needs  (?). Maybe he has adjusted to the dark. The passage does not indicate any problem for which an accurate model of GH effect is needed.

B. the definition of “greenhouse gas” should probably be reconsidered 
  Incorrect  . What is the definition of “greenhouse gas”? We’re told one thing that the gas is responsible for. Is that the definition of GH gas? Anyway, there is no indication at all in the passage towards changing the definition of GH gas. Baseless!

C. there are factors besides the increase in greenhouse-gas emissions contributing to the warming of the climate 
  Incorrect  . Again, we need to be very precise with our understanding here. “There are other factors that contribute to the warming” is not the same as “the computer model failed to take into account all relevant factors”. This option does not even say that the model fails to consider all factors. It simply tells us that there are multiple factors that contribute to warming. That may be the case; that may not be the case. Probably, the model has considered all the factors there are. A model can be inaccurate even after considering all the factors.

Let’s have some fun. Can we infer any or all of the following?

The model does not take all factors that impact temperature into consideration 
 There are factors besides the increase in greenhouse-gas emissions contributing to  the warming  COOLING of the climate

D. the computer model of the greenhouse effect must be incorrect in some respect 
  Correct  . We can infer this. The computer model gives an incorrect prediction. So, the model must be incorrect in some way. If the model functioned correctly in  every  aspect, could it make an incorrect prediction? Nope. The only reason the model would make an incorrect prediction is that it did something incorrectly. (could be an incorrect formula, could be not taking all factors into account, could be a units error. We cannot infer what the error may be. However, there must certainly have been some error.)

E. the likely consequences of any warming of the climate are unlikely to be much less damaging than predicted 
  Incorrect  . Need to be careful here too. Let’s first try to clearly understand what this option is saying.

‘The likely consequences of any warming of the climate’: probable consequences of warming.

‘Unlikely to be much less damaging’: not likely to be much less damaging. Is X much less damaging than Y? Unlikely. I.e., X is probably barely less, equal or more damaging than Y.
‘than predicted’: A is much more time-consuming than predicted. A was predicted to be time-consuming. It turned out to be much more time-consuming than was predicted.

This option is incorrect since the prediction was simply of the warming. Not of damage from consequences. Consequences of warming, and their damage are way beyond what’s being discussed in the passage. This cannot be inferred.

Additional Notes     
Given the way the question is framed, it is an inference question. Remember the direction in an inference question. While going through each option, we do not ask: does this option help us justify the above passage? No! We instead ask: can we infer this based on the passage above?

SC Notes:  
Comprehend the meaning of option E very clearly. Note how the comparison is presented. Understand what the word “predicted” refers to.

If you have any doubts regarding any part of this solution, please feel free to ask.

Skywalker18 · Answer

Scientist: A greenhouse gas, for example, carbon dioxide, forms a transparent layer that traps solar heat beneath it in the earth's atmosphere. Atmospheric levels of carbon dioxide are currently increasing, causing the climate to warm—an effect that is predicted by at least one computer model of the greenhouse effect. But the warming that has occurred is a great deal less than what would be expected based on the model. Therefore, _______.

Which of the following most logically completes the scientist's argument?

A. better measurements of atmospheric levels of carbon dioxide are needed- incorrect, we can not conclusively say this. The reason for discrepancy might be somewhere else in the model
B. the definition of “greenhouse gas” should probably be reconsidered- irrelevant
C. there are factors besides the increase in greenhouse-gas emissions contributing to the warming of the climate- Incorrect, even if there are other factors, it does not explain why the actual warming is a great deal less than our expectations based on the model. But if the option said, there are factors that cause global cooling and these factors have not been considered by the computer model, then it would be correct.
D. the computer model of the greenhouse effect must be incorrect in some respect- Correct, This has to be true because otherwise we should not have a significant difference in ACTUAL vs Model simulation value
E. the likely consequences of any warming of the climate are unlikely to be much less damaging than predicted- incorrect

Answer D

gmatt1476 · Answer

Official Explanation

Argument Construction

This question requires us to choose the option that most logically completes the scientist's argument.

The scientist's argument points out that at least one computer model has predicted that the amount of warming the atmosphere would by now have experienced as a result of the greenhouse effect would be significantly greater than what has actually occurred.

Because what precedes the blank is the word therefore, we must choose the statement that is most strongly supported by the information given.

A. It is reasonable to infer from the given information that some aspect of the computer model is incorrect in some way. One way that it might be incorrect is that the measurements of atmospheric levels of carbon dioxide used are inaccurate. Nevertheless, there is not sufficient information to infer that this is the specific flaw in the model.

B. The given information provides no reason for us to reconsider the definition of “greenhouse gas.” Perhaps there would be a reason to do so if no warming had occurred whatsoever. However, the information tells us that warming has in fact happened, just not as much as predicted.

C. If there are factors in addition to greenhouse-gas emissions that lead to atmospheric warming, then presumably temperatures would have risen more than predicted, not less.

D. Correct. If the model were correct, its predictions would be confirmed by the data regarding warming. However, this has not occurred. It is therefore reasonable to infer that, in some way, the computer model is incorrect.

E. This does not follow from the argument: given the findings, it seems more reasonable to think that the likely consequences of any atmospheric warming would in fact be less damaging than predicted.

The correct answer is D.

sayan640 · Answer

VeritasKarishma   GMATNinja   GMATGuruNY 
Can you please explain this question , specially why option C is incorrect and option D is correct ?

GMATNinjaTwo · Answer

Anything in particular that is giving you trouble here? The more specific you can make your question, the easier it is for us to help!

chetan2u · Answer

The paragraph reasoning is..
Green house gas, such as carbon dioxide, makes a layer around atmosphere, a layer that does not allow the heat to move out, and, therefore, results in heating. Carbon dioxide levels have increased in recent past, resulting in further global warming. The warming has also been predicted by at least one computer model of the greenhouse effect. However, the warming expected as per the model has been relative less in actuals. Therefore...

We have to find the conclusion.
The conclusion should be able to bridge the gap between the observed warming and expected warming as per the model.

Since most are confused between C and D, let me touch on WHY not C and why D.

C. there are factors besides the increase in greenhouse-gas emissions contributing to the warming of the climate
 If this were true, what would be the effect on this GAP. We would expect the GAP to be lesser as in actuals there are various factors contributing to the warming while the model is talking of warming based on just green house gas emissions.  
If this choice does anything, it actually works opposite and complicates the situation further. Now the warming due to green house gas emissions would be even lesser as the observed warming is a result of various factors.  Thus the GAP has become even more, while we were looking for a reason for this GAP.

D. the computer model of the greenhouse effect must be incorrect in some respect
 Now this choice tells you that there has been some flaw in computer model and may be the reading are erroneously on higher side in the computer model.
Perfectly bridges the GAP. So, there is no GAP actually, it is just an error on part of the computer model

D

zoezhuyan · Answer

dear  chetan2u , thanks for your help, but I genuinely want your help further

my reasoning here , 
#1 the observation is less than what expectation. in addition, not only one model gets these result. so if many model get the similar result, then the observation is not occasion. we have no reason to guess there are error on many model at the same period. 
#2 I would like plug some numbers to express what I thought 
expectation : 80,
observation : 50, 
here is a gap: 30, 
what caused the gap is other factors.

see, C matchs .

chetan2u · Answer

First point on various models..
The observation being spoken about is from just one model. Nowhere it speaks of models, it speaks of at least ONE model, so it could be one or more, and thereafter the argument talks of that MODEL. 
Secondly 
Expectations from green house emissions = 80
Actual observed =50
Argument says there are other factors that are increasing the warming ( Actual warming ), day 30
This means 50 includes this 30, so observed warming from green house emissions =50-30=20
GAP has further increased to 80-20=60

mykrasovski · Answer

Let's try to simplify the argument.

There are greenhouse gasses (GG) such as CD that keep sun energy, leading to warmer climate. Lately, the amount of GG has increased meaning that the climate got warmer. There is a {computer} model that predicted the increase. However, the actual temperature increase is not as large as predicted by the model. Hm... what is going on? We have a mismatch between the real situation and the model. Let's keep the learned information in mind and look for a good answer.

Maybe the measurements were very good? We know nothing about measurements. The argument does not even address them. Out.
 
Why would we reconsider the definition? The argument does not provide any information about how people came up with existing definition. 
 
Let's say there is one or 100 factors. Let's say they do contribute to the warming of the climate. That means that the model is not optimal, we do not care whether there are factors and how many are out there.
 
While thinking about the argument, we concluded that there is a mismatch between the actual situation and the model. This option matches what we pre-thought.
 
Do we care about consequences? We need to conclude something based on the information that was given to us. We were not given any data about the effects of the climate warming.

KarishmaB · Answer

CO2 traps heat in atmosphere.
Currently, increasing CO2 is leading to warming - one model predicted this
But the amount of warming is much less than what the model predicted

Conclusion: ??

So a model takes CO2 levels into account and predicts the amount of warming - say if CO2 levels increase by 10%, the avg temp will rise by 2%.
But what we observe is that an increase of 10% in CO2 levels made the temp rise by .5% only.

Hence, there is some error in the model. Perhaps it doesn't take some other cooling factors into account. Perhaps it incorrectly calculated the amount of hear trapped by each CO2 molecule. Perhaps it doesn't take into account how the molecules space out when they increase in number (just some random thoughts). We don't know. What we do know is that the model does not predict temp increase accurately.

Hence (D) is correct.

C. there are factors besides the increase in greenhouse-gas emissions contributing to the warming of the climate
Problem. There may be factors contributing to the cooling of the climate (not warming) but we are not sure about that either. 
All we know is this - the model predicted a certain rise.
The rise was much less.
So the model has inaccuracies.

jabhatta2 · Answer

Hi  avigutman  - according to you : does option D account for the possibility that perhaps the inputs put into the computer model are wrong ?

For example - perhaps CO2 actually went up by 10 % but you put in 7 % into the model (because of an incorrect measuring device)

avigutman · Answer

In my opinion, D does not clearly account for the possibility of an incorrect input. I think you’re absolutely right to call that out. 
But the question’s exact wording doesn’t require the correct answer choice to be a full and complete inference:
“most logically completes“
D is imperfect, but it’s significantly better than the other four options.

Posted from my mobile device

Bambi2021 · Answer

My only question to D is, why the heck would someone start writing about greenhouse gases just to arrive at the conclusion that some more or less irrelevant (yes, this model is not the theme of the text) model is incorrect?

For D to be a good followup here, the main interest of the article should be the model, which should be mentioned earlier on.

Posted from my mobile device

MartyTargetTestPrep · Answer

The information in the first two sentences is background information that helps the reader to understand what the model does. Without it, the passage would say something about a model, but there would be no context.

Once that background is presented, then the information and conclusion about the model are presented.

The passage could start off saying something about the model, but it doesn't have to in order for (D) to follow logically from what the passage says.

ashutosh_73 · Answer

Hi   GMATNinjaTwo  I found (C) a bit troubling, but below is the reason i didn't find this option interesting enough. I am not sure, how logical my reasoning is:

Stimulus says:   ''Atmospheric levels of carbon dioxide are currently increasing,  causing the climate to warm — an effect that is predicted  by at least one    computer model of the greenhouse effect.''  
So, stimulus is actually suggesting that this computer model predicts the  warming effected by the greenhouse gases.  So doesn't matter if there are 1000s factors behind the warming.

Premise to conclusion:  But the warming( caused by greenhouse gases ) that has occurred is a great deal less than what would be expected based on the model. Therefore...

So i am expecting something aboout the  computer model  OR something which says  ''Greenhouse gases may not create as much problem as expected ''

One may find (C) interesting if they read the above yellow text as: Okay, so this computer model predicts the warming effect in general, hence it didn't take other factors into account.

Mantrix · Answer

P1: A greenhouse gas, for example, carbon dioxide, forms a transparent layer that traps solar heat beneath it in the earth's atmosphere. P2: Atmospheric levels of carbon dioxide are currently increasing, causing the climate to warm
P3: this is already predicted by at least one computer model of the greenhouse effect.
P4: But the warming that has occurred less than what would be expected based on the model. 
Therefore, _______.

Which of the following most logically completes the scientist's argument?

A. better measurements of atmospheric levels of carbon dioxide are needed  (not Relevant) 
B. the definition of “greenhouse gas” should probably be reconsidered (  (not Relevant) 
C. there are factors besides the increase in greenhouse-gas emissions contributing to the warming of the climate  (if that's the case, then the warming must have been greater than what has predicted) so 180 degree choice  
D. the computer model of the greenhouse effect must be incorrect in some respect  (yes very correct there must be incorrect prediction by teh model) (true) 
E. the likely consequences of any warming of the climate are unlikely to be much less damaging than predicted  (we are not concerned about the damage)

Scientist: A greenhouse gas, for example, carbon dioxide, forms a tran

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Scientist: A greenhouse gas, for example, carbon dioxide, forms a tran

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615 to 715 in 15 Days (Ria's Strategies)

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