V38-10

Question

Climatologists claim: The recent pattern of prolonged droughts followed by intense rainfalls is a clear indicator of climate change. This pattern results from increased global temperatures, which enhance the rate of water evaporation and lead to more stored moisture in the atmosphere. When the moisture is released, it results in heavy rains following drought periods. The discovery that similar weather patterns occurred during the Pliocene Epoch, when the earth experienced higher global temperatures, supports the claim that our current weather patterns are due to climate change.
 
The argument in the passage relies on which of the following assumptions?

A. The conditions that caused similar weather patterns during the Pliocene Epoch must be the same as those causing current weather patterns.
B. Factors related to global temperatures, such as ocean currents or volcanic activity, did not significantly influence weather patterns during the Pliocene Epoch.
C. Without evidence of increased global temperatures, the claim that current weather patterns are due to climate change would not be credible.
D. If global temperatures continue to rise, the frequency and severity of these weather patterns will certainly increase.
E. The mechanisms that caused climate change in the past are fundamentally different from those causing current climate change.

Bunuel · Answer

Official Solution:

Climatologists claim: The recent pattern of prolonged droughts followed by intense rainfalls is a clear indicator of climate change. This pattern results from increased global temperatures, which enhance the rate of water evaporation and lead to more stored moisture in the atmosphere. When the moisture is released, it results in heavy rains following drought periods. The discovery that similar weather patterns occurred during the Pliocene Epoch, when the earth experienced higher global temperatures, supports the claim that our current weather patterns are due to climate change.
 
The argument in the passage relies on which of the following assumptions?

A. The conditions that caused similar weather patterns during the Pliocene Epoch must be the same as those causing current weather patterns.
B. Factors related to global temperatures, such as ocean currents or volcanic activity, did not significantly influence weather patterns during the Pliocene Epoch.
C. Without evidence of increased global temperatures, the claim that current weather patterns are due to climate change would not be credible.
D. If global temperatures continue to rise, the frequency and severity of these weather patterns will certainly increase.
E. The mechanisms that caused climate change in the past are fundamentally different from those causing current climate change.

Correct Answer: A. The conditions that caused similar weather patterns during the Pliocene Epoch must be the same as those causing current weather patterns. 
 
The argument is a cause and effect argument linking 2 events:
 
1. Current event: Climate change/temperature rise —(cause) —> weather patterns of intense rainfall followed by prolonged droughts.
 
2. Pliocene Epoch: high temperatures and similar weather patterns were present at the same time.
 
 Conclusion:  both events are related as they had the same cause and effect.
 
 Assumption:  both results were caused by the same cause. (this is a quick answer in your own words). The actual assumption is: high temperatures caused the weather patterns in both Pliocene Epoch and current time periods. Because correlation does not prove causation. The assumption that the same conditions/causes apply now as in the past is critical for validating the climatologists' claim that similar weather patterns (effect) indicate similar causes—namely, climate change driven by global temperature rises.
 
_______________________________
 
 B. Factors related to global temperatures, such as ocean currents or volcanic activity, did not significantly influence weather patterns during the Pliocene Epoch. 
 
This is the opposite of what we are looking for. B) tells us that global temperatures did not influence the weather patterns in Pliocene Epoch. Eliminate
 
 C. Without evidence of increased global temperatures, the claim that current weather patterns are due to climate change would not be credible. 
 
First of all, this answer choice is an evaluation of an argument rather than an assumption. Second, there is no evidence provided or requested in the augment. The argument does not doubt or require proof of temperatures thus this cannot be the assumption. Is it possible to turn this answer choice into a valid assumption? Yes, a weak one but valid nevertheless. An example of a secondary and valid assumption would have been something such as “The increased global temperatures have been measured correctly and there is undeniable proof of rising temperatures”. This could be a weak assumption if we modify this answer choice. Other similarly weak assumptions could be that no mistakes were made in recording weather patterns, and that data was collected accurately, etc, but all of them are not at the center of the argument and not what usually be the answer on the GMAT. Eliminate.
 
 D. If global temperatures continue to rise, the frequency and severity of these weather patterns will certainly increase. 
 
This is a predictive statement (inference) about future conditions and does not necessarily underpin the argument that current patterns are due to climate change; it’s stating implications of ongoing changes. Eliminate.
 
 E. The mechanisms that caused climate change in the past are fundamentally different from those causing current climate change. 
 
This answer choice contradicts our argument and information given in the premise. We know that the climatologist is arguing that both past and present climate and weather changes are related. Changing to the opposite, would have made this the correct answer choice. Eliminate.

Answer: A

Nutella024 · Answer

Thanks,  Bunuel  for the explanation, please clarify one thing for me. Isn't A already mentioned in the paragraph, so doesn't that make it explicit assumption or a fact

bb · Answer

Hi Nutella024. Thank you for the question. 
A) is not mentioned in the paragraph. A) talks about the cause, which is not stated in the passage text. We need something to tie the 2 events together and to do that we need an assumption that both events have been caused by the same events/cause.

See this component from the explanation: 
Because correlation does not prove causation. The assumption that the same conditions/causes apply now as in the past is critical for validating the climatologists' claim that similar weather patterns (effect) indicate similar causes—namely, climate change driven by global temperature rises.

Nutella024 · Answer

Thanks, BB for the Explanation, Appreciate it!

Goldenfuture · Answer

I was not in favour of option A and was leaning toward B because of this thinking:

The weather pattern being the same is what matters;
the conditions causing the pattern do not necessarily have to be the same.
Option A feels too strongly worded — it says that the conditions that caused the Pliocene weather pattern must also be the same conditions causing the current pattern.
I felt that this level of “must be the same” is not needed for the argument.
Option B seemed more valid because it says that the other factors (ocean currents, volcanic activity etc.) did not significantly influence the weather patterns in the Pliocene.
That would mean:

Higher temperature was indeed the main driver of the pattern then
There were no other major interfering factors

Since the passage’s premise is that higher temperature caused those Pliocene patterns, B felt like a stronger and more relevant assumption to support the logic.

Based on this line of thinking, I believed B made more sense than A, and I wanted to know—purely from a GMAT‐style reasoning perspective that high‐scorers use—why this thinking is incorrect.
 MartyMurray

MartyMurray · Answer

Actually, the conditions are what matters because the conclusion is about the underlying conditions, which the author concludes are "increased global temperatures."
 
The reasoning of the argument is that the presence of similar weather patterns indicates that current conditions are basically the same as those that existed during the Pliocene era. So, the underlying assumption is that the conditions existing currently are basically the same as those that existed during the Pliocene era.

If choice (A) said "exactly the same," then it might be too strong, but for the argument to work, the conditions have to be basically the same.
 
The point of (B) is not entirely clear. So, I can see why you interpreted it that way.

At the same time, we can eliminate (B) because it's basically saying that factors related to temperatures didn't influence weather patterns. In fact, the argument involves the idea that factors related to temperatures did influence weather patterns.

Of course, we all might be aware that what is commonly termed "climate change" is not caused by "volcanic activity." So, (B) may appear to bring up an alternative explanation. At the same time, "ocean currents" are understood to be involved in "climate change."

In short, while (B) is not ideally constructed, we can eliminate it because, in a way, it's contrary to the argument.

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