Scientists studying climate change have found that global warming not

Question

Scientists studying climate change have found that global warming not only increases the temperature of the planet but also leads, on average, to an earlier arrival of the spring season and a later arrival of the autumn season. Though some argue that this effect on the seasons is advantageous because it increases the length of the summer growing season, leaders of the World Wildlife Fund fear that many animal species will not be able to adapt to the altered season lengths and will thus soon face extinction.
 
Which of the following, if true, provides the best evidence in support of the view held by the leaders of the World Wildlife Fund?

(A) When spring arrives earlier than usual, most species of hibernating mammals are forced to emerge from hibernation earlier than usual and to find alternative food sources to supplement their regular diets.

(B) As the planet's temperature rises, the average global sea surface temperature also rises, endangering several marine organisms that reside near the sea surface and that can only survive within very narrow temperature windows.

(C) Many species of salmon rely on seasonal changes in temperature to signal the start of their annual migrations and will leave their freshwater birthplaces early if spring arrives early; as a result, the populations of several types of freshwater insects consumed by those species of salmon will grow exponentially, infesting thousands of acres of crops on which humans rely.

(D) The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature.

(E) As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that will likely endanger hundreds of animal species.

Verbal Question of The Day: Day 28: Critical Reasoning 
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GMATNinja · Accepted Answer

And we have some healthy debate going on here! Always a good thing.

The conclusion, which is contained within the view held by the leaders of the World Wildlife Fund, is that many animal species will soon face extinction. So let's start by figuring out: why do the leaders of the WWF fear that this will happen?

We are told that, based on scientific studies, global warming increases the temperature of the planet AND leads to an earlier arrival of the spring season and a later arrival of the autumn season. Is that change to the seasons necessarily a bad thing (or something WWF leaders should fear)? Some even argue that this change can be beneficial because "it increases the length of the summer growing season", so why are the WWF leaders fearful?

WWF leaders fear that many animal species will not be able to adapt to the altered season lengths and that, as a result, those animal species will soon face extinction. This view would be supported by any evidence showing how altered season lengths could lead to an animal's extinction.

Let's see if any of the answer choices provide such support:

(A) This evidence demonstrates how altered season lengths can affect an animal, but it does not show that the change would affect the animal's ability to survive. Sure, the animals would be "forced" to find alternative food supplies, but there's no indication that they would fail to find those food sources. You'd have to make a huge assumption in order to conclude that this would contribute to extinctions. (A) can be eliminated.

(B) This example shows how the increase in the temperature of the planet can endanger certain species, but leaders of the WWF are concerned about the altered season lengths, not about the increase in the temperature of the planet. This evidence suggests that global warming can be dangerous for certain species, but it does not support the reasoning of the WWF leaders. (B) can be eliminated.

(C) Here is an example of how the altered season lengths could have a negative impact on one species of animal: humans. However, it does not suggest that humans will be unable to adapt to the changes or unable to survive as a species because of the changes, so choice (C) can be eliminated.

(D) As with choice (A), we have an example of how altered season lengths can affect an animal (the metamorphosis of caterpillars into butterflies is triggered by seasonal changes in temperature). But choice (D) also tells us how the effect on one animal will indirectly affect another animal: "the young of many species of birds and rodents feed exclusively on caterpillars". If caterpillars are the ONLY source of food for the young of many bird and rodent species and if caterpillars morph into butterflies earlier because of the early arrival of spring, then it's possible that all or most of the caterpillars will turn into butterflies before the young are hatched. This effect could severely diminish the survival rate of those young who have lost their only source of food.

We certainly don't know for sure if the affected bird and rodents will be unable to adapt and survive, but choice (D) provides a solid example of how altered season lengths could lead to the extinction of certain species. Therefore, choice (D) definitely supports the view held by the WWF leaders.

We certainly don't know for sure if the affected bird and rodents will be unable to adapt and survive, but choice (D) provides a solid example of how altered season lengths could lead to the extinction of certain species. Therefore, choice (D) definitely supports the view held by the WWF leaders.

(E) This example shows a possible negative impact of the altered season lengths. However, choice (E) illustrates a GRADUAL change, suggesting that it will NOT cause any animals to face extinction anytime soon. Furthermore, this example does not show how animals will be unable to adapt to the altered season lengths and thus unable to survive. Rather, this scenario demonstrates how the altered season lengths will impact the temperature of the planet, which in turn will endanger many animal species. Although this evidence might contribute to the fears of the WWF leaders (because of the indirect effect on many animal species), it does not show us how an inability to adapt to the altered season lengths could lead to extinction. Choice (E) can be eliminated.

Choice (D) provides the best evidence in support of the view held by the leaders of the World Wildlife Fund and thus is the best answer.

niks18 · Answer

Correct me if I am wrong here -

WWF's conclusion is that  animal species  will not be able to adapt and will face extinction if  summer growing season  is extended
The option that provides impact of extended growing season on animal species in "general, and not about any specific animal will be Correct

(A) When spring arrives earlier than usual, most species of hibernating mammals are forced to emerge from hibernation earlier than usual and to find alternative food sources to supplement their regular diets.--- this option does not talk about extinction. It only implies that alternate food sources will have to be identified and that means if alternate food sources are identified, then species can survive . hence incorrect
(B) As the planet's temperature rises, the average global sea surface temperature also rises, endangering several marine organisms that reside near the sea surface and that can only survive within very narrow temperature windows. -- the option talks only about marine organisms. we don't have information about other animal species . Hence incorrect
(C) Many species of salmon rely on seasonal changes in temperature to signal the start of their annual migrations and will leave their freshwater birthplaces early if spring arrives early; as a result, the populations of several types of freshwater insects consumed by those species of salmon will grow exponentially, infesting thousands of acres of crops on which humans rely.--- gives information only about salmon . Hence incorrect
(D) The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature.--- talks about birds & rodents. no info about other animal species . Hence incorrect
(E) As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that will likely endanger hundreds of animal species. --- This option provides evidence about impact of increase in summer growing season on animal species.  Hence Correct

Option  E

gmatexam439 · Answer

Scientists studying climate change have found that global warming not only increases the temperature of the planet but also leads, on average, to an earlier arrival of the spring season and a later arrival of the autumn season. Though some argue that this effect on the seasons is advantageous because it increases the length of the summer growing season, leaders of the World Wildlife Fund fear that many animal species will not be able to adapt to the altered season lengths and will thus soon face extinction.
 
Which of the following, if true, provides the best evidence in support of the view held by the leaders of the World Wildlife Fund?
 
(A) When spring arrives earlier than usual, most species of hibernating mammals are forced to emerge from hibernation earlier than usual and to find alternative food sources to supplement their regular diets. - Finding an alternate may or may not endanger the species. Plus this option is too specific, by taking into account only the mammals. 
(B) As the planet's temperature rises, the average global sea surface temperature also rises, endangering several marine organisms that reside near the sea surface and that can only survive within very narrow temperature windows.  This option takes into account the temperature's rise. If the option had talked about "the longer summer makes the temperature even more", the option would have made sense w.r.t. argument. 
(C) Many species of salmon rely on seasonal changes in temperature to signal the start of their annual migrations and will leave their freshwater birthplaces early if spring arrives early; as a result, the populations of several types of freshwater insects consumed by those species of salmon will grow exponentially, infesting thousands of acres of crops on which humans rely. - This option wrongly says that humans will be endangered. 
(D) The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature. - The argument is not talking about the food of young birds. 
(E) As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that will likely endanger hundreds of animal species. - Makes sense. The extended summer will increase temperature that will in turn endanger the species. Note: It doesn't talk about a specific specie unlike A and B.Therefore Correct

Please let me know if i am going in the wrong direction.

Leo8 · Answer

Scientists studying climate change have found that global warming not only increases the temperature of the planet but also leads, on average, to an earlier arrival of the spring season and a later arrival of the autumn season.

Though some argue that this effect on the seasons is advantageous because it increases the length of the summer growing season, 
leaders of the World Wildlife Fund fear that many animal species will not be able to adapt to the altered season lengths and   will thus soon face extinction.

Which of the following, if true, provides the best evidence in support of the view held by the leaders of the World Wildlife Fund?

(D) The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature.

(E) As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that will   likely endanger hundreds of animal species.

I prefer D over E because the leaders fear that extinction will soon happen ( no uncertainty)

however E shows the likelihood of the endangerment

RaguramanS · Answer

Scientists studying climate change have found that global warming not only increases the temperature of the planet but also leads, on average, to an earlier arrival of the spring season and a later arrival of the autumn season. Though some argue that this effect on the seasons is advantageous because it increases the length of the summer growing season, leaders of the World Wildlife Fund fear that many animal species will not be able to adapt to the altered season lengths and will thus soon face extinction.

Keyword: Strengthen
Conclusion: Many animal species will extinct because of change in climate.

(A) When spring arrives earlier than usual, most species of hibernating mammals are forced to emerge from hibernation earlier than usual and to find alternative food sources to supplement their regular diets.
Doesn't support extinction. Since the animals looks for alternative ways of its survival  Wrong

(B) As the planet's temperature rises, the average global sea surface temperature also rises, endangering several marine organisms that reside near the sea surface and that can only survive within very narrow temperature windows.
Endangering several Marine organisms  Contender

(C) Many species of salmon rely on seasonal changes in temperature to signal the start of their annual migrations and will leave their freshwater birthplaces early if spring arrives early; as a result, the populations of several types of freshwater insects consumed by those species of salmon will grow exponentially, infesting thousands of acres of crops on which humans rely.
The option deals with some impacts but not extinction  Wrong

(D) The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature.
The option deals with some impacts but not extinction  Wrong

(E) As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that  will likely endanger   hundreds of animal species.
In this option, the phrase " will likely endanger" is used. The option deals with extinction.  Contender

Between (B) and (E),
B is the better bet 
In the option E the author uses the word will likely, indicates there is some chance for the survival.

pushpitkc · Answer

The conclusion of this argument, that we are asked to strengthen by providing evidence is
 Many species won't be able to adapt to altered season lengths and face extinction

Of the available options Option D and E provide such evidence(of causing extinction)

But  Option D  is a clear winner, as it provides evidence to strengthen the conclusion.
It says If the young of many species(rodents and birds) feeds on the caterpillars and due to longer autumn season, 
the caterpillars won't become butterflies and eventually, butterflies will become extinct.

teaserbae · Answer

VeritasKarishma   GMATNinja   nightblade354   GMATNinja two 
Can you please what seasonal change in temperature mean in D ?
In D change in seasonal length is not taken into consideration so how it is correct ?

KrunaliG · Answer

Still unable to understand the OA which states D as the correct answer. 
According to me E should be the correct answer!

Posted from my mobile device

AKY13 · Answer

Hi Gmatninja,
In D, why are we overseeing the possibility of this change - in timing of season - being beneficial for the rodents. We are ruling out a possibility that because of the change in the timing of season, the hatching of the young ones of rodents match exactly the timing of metamorphosis to have more food than required amount. However this may create an imbalance in food chain but we are not interested in that event. Nowhere in this option, it is mentioned that the change in season timing has an adverse effect. 
Am I missing something; pls help.

cristianosubo · Answer

I completely go along with your thought process AKY13. There is no indication that this change in metamorphosis will have a negative or a positive effect as an exclusive food source to its prey. How can we assume that the effect has to be negative for sure?

KarishmaB · Answer

Global warming has two impacts:
1. Increase in temp
2. Early spring and late autumn so longer summer 
(So hotter and longer summer!)

Some say that this effect on the seasons is advantageous (longer growing season) but WWF leaders fear that many animal species will not be able to adapt to the altered season lengths.

We need to evidence to support the view of WWF leaders. Note that the view is on impact of season length, not increased temp. So any option that tells us about the impact of increased temp should be ignored. We need to see how change in season length impacts animals.

(A) When spring arrives earlier than usual, most species of hibernating mammals are forced to emerge from hibernation earlier than usual and to find alternative food sources to supplement their regular diets.

Yes, many mammals may be forced to find alternative food sources but it doesn't mean that those sources will not be available. In fact, with long growing seasons, there may actually be additional sources of food available. Hence, we cannot deduce anything from this option.

(B) As the planet's temperature rises, the average global sea surface temperature also rises, endangering several marine organisms that reside near the sea surface and that can only survive within very narrow temperature windows.

This option talks about the impact of increase in planet's temperature. We are to ignore that.

(C) Many species of salmon rely on seasonal changes in temperature to signal the start of their annual migrations and will leave their freshwater birthplaces early if spring arrives early; as a result, the populations of several types of freshwater insects consumed by those species of salmon will grow exponentially, infesting thousands of acres of crops on which humans rely.

This tells us how human crops will be impacted by seasonal changes. If anything, several insects seem to be flourishing as per this option.

(D) The young of many species of birds and rodents feed exclusively on caterpillars, whose metamorphosis into butterflies is triggered by seasonal changes in temperature.

Here is the correct option - it says that the young of many feed EXCLUSIVELY on caterpillars. If seasonal changes trigger their metamorphosis into butterflies, early spring will mean early metamorphosis (from caterpillars, they will turn into butterflies early) and hence the food source (caterpillars) of the young of many species will dwindle. This could lead to a severe impact on animal population because of seasonal changes.

(E) As the length of the summer growing season increases, the amount of carbon emissions produced by humans gradually increases, exacerbating the increase in global temperatures that will likely endanger hundreds of animal species.

This options tells us that seasonal changes could gradually lead to further increase in global temperatures. This increase in temp could endanger many animal species. This option tells us that animals will not be able to adapt to increase in temp. We need to look for an option that tells us how animals will not be able to adapt to seasonal changes. So we are certainly looking for a more direct impact.

Answer (D)

AKY13 · Answer

Hi Karishma,
I re-pasting my reasoning against D as the correct answer. Can you pls specifically find the flaws in my reasoning.

"In D, why are we overseeing the possibility of this change - in timing of season - being beneficial for the rodents. We are ruling out a possibility that because of the change in the timing of season, the hatching of the young ones of rodents match exactly the timing of metamorphosis to have more food than required amount. However this may create an imbalance in food chain but we are not interested in that event. Nowhere in this option, it is mentioned that the change in season timing has an adverse effect. "

Desertchampion · Answer

Most of the answer choices show a less than desirable effect. What we are looking for here is an extinction of species due to the altered seasons. Answer choice (D) is the only one that indicates this.

Because the caterpillars are the  only  source of food and because their metamorphosis into butterflies is triggered by seasonal changes and thus will be altered, this will leave many species of birds and rodents without caterpillars to eat, which will cause them to starve and die.

Please send kudos if this helped in any way!

AndrewN · Answer

Key points : This is a type of  strengthen  question, but with a focus on evidence and the "view" of the leaders.
 Breakdown : To support a view, we must pinpoint what exactly that view may be. Here, the leaders "fear that many animal species will not be able to adapt to the altered season lengths." Why did I stop there? Because the rest of the final line of the paragraph is a conclusion: many animal species "will thus face extinction." The correct answer, then, ought to deal with changing season lengths.

Answers : As I do in all my Verbal analyses, I prefer to focus solely on weak points of the answer choices to decide what to toss out and what to keep, even if temporarily.

(A)  forced to find alternative food sources to supplement their regular diets

Analysis: I was with this answer up to the part after "forced," when it suddenly turns from the animals facing impending doom to their experiencing some discomfort. Finding another food source could be on the right track, but  supplement  is the final nail in the coffin of this response. To support the view, the evidence needs to paint a more dire picture for the animals. Red light.

(B)  temperature rises... temperature also rises

Analysis: In a hurry, a test-taker might latch onto the fragile environment of the marine organisms mentioned. However, this response is a pure  distraction , swapping out any information about changing season lengths with that of rising temperatures. An unrelated weather phenomenon has  nothing to do with the view of the leaders , and thus cannot support their position. Red light.

(C)  populations of... freshwater insects...

Analysis: As we saw with choice (A), this response starts out okay, mentioning "seasonal changes" and how they affect wildlife behavior. But then the focus shifts to insects and the problems they will pose to humans, which, again, has  no connection to the view of the leaders . Red light.

(D) many species... feed exclusively on caterpillars,   seasonal changes

Analysis: This response is unassuming, but it does touch on the dangers that the young of  many species , not just a single organism, will face because of the culprit in question,  seasonal changes . Although I would tick both boxes, I am not ready to get behind this one all the way, especially with just one more response to go. Yellow light.

(E)  carbon emissions... increase in global temperatures

Analysis: This is the sort of answer that, in my view, warrants a glance back up at the paragraph, since it mentions both seasonal change and danger to wildlife. The paragraph states that the leaders of the World Wildlife Fund "fear that many animal species will not be able to adapt to the altered season lengths." There is a vague threat to the animals in this response, but not only does the embedded "that" clause indicate that "global temperatures" will do the damage, but a close reading after that also reveals that  it does not illustrate how animals will need to adapt , a necessary component of the correct response. This answer seems second best. Tread carefully. Yellow light.

Guessing : Probably the easiest responses to eliminate are (A) and (C), since both of them mention seasonal changes without really delivering on the harm such changes will cause "many animal species." Meanwhile, choice (B) paints a grim picture for certain marine organisms, but the problem lies with its focus on rising temperatures instead of changing season lengths. Between (D) or (E), the latter answer looks fine on an initial read, but then fizzles out near the end with rising temperatures again causing harm to the animals, which are never given the opportunity to adapt to anything. Choice (D) is the hardest answer to argue against, so it must be correct.

Happy studies!

- Andrew

komalpatna · Answer

Passage clearly mentions not adopt the alterered season and face extinction: see which option provide example for this. Only D does.

Pls Kudoes!!!

Beqa · Answer

I do not entirely agree with both the OA and any explanation given above.

Logically, both choices A and D say the same thing: The lengthened summer may have some impact on some species. But both also do not provide enough information to prove that the effect is  "will not be able to adapt to the altered season lengths and will thus soon face extinction" .

The answer choice should explicitly say that

Without this information, one is left with the doubt: If the metamorphosis is triggered when fall comes, then the food is more than enough for many species. I am pretty sure that this kind of ambiguous answer choice does not appear in actual GMAT questions.

AndrewN · Answer

Speaking of doubts, I doubt all this ink would have been spilled,  Beqa , if this were an  unofficial  question. This one has appeared in the OG Diagnostic Test for many editions, as far back as I can remember (the 2015 edition was where I started). It is okay not to agree with what anyone has written above, and I agree that the answer choices could be improved for clarity, but remember, you can only go by what is on the page (or screen). Look to eliminate what you can and then take a stab at the answer with whatever is left in your mind. If GMAC™ always created perfectly linear questions and answer choices, the GMAT™ would prove much easier to decode. Expect the unexpected sometimes.

Good luck with your studies.

- Andrew

AndrewN · Answer

My apology,  Beqa . I think I was getting this question confused with a Sentence Correction question from the OG that also references the World Wildlife Fund. Perhaps I should have consulted my OG before posting.

- Andrew

ILIAF · Answer

Between E & D, I didn't really like any of the two options. Though I agree that D is a better choice, what prevented me from choosing this one is conclusion that states that MANY of the species will not be able to adapt. In D the scope is limited to species of birds and rodents. They still may account for minority. Is my logic correct or Do I overcomplicate? Because I thought of this problem as sample/population scenario.

Scientists studying climate change have found that global warming not

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Scientists studying climate change have found that global warming not

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