An unusually severe winter occurred in Europe after the continent was

MentorTutoring VeritasKarishma AjiteshArun

I recently encountered this Q while practicing from repeat free mocks from GMAC. (16-Jul-20)
I have rarely seen such an answer choice that directly contradicts the claim.



Eruptions → Cooling in atmosphere




The name of location is irrelevant. Time span mentioned is earlier than the one mentioned in argument.
Most imp: Causal relation as per this choice: E → H (rise in temperature than cooling as mentioned in argument)
So as per argument A → B , but this choice says A → B. Hence this fits my bill.

Is my reasoning valid?

Hello, adkikani. It has been a while since we last crossed paths. I hope you are doing well. Your reasoning is accurate above, with one exception. There is no contradiction of a claim. Rather, the goal is to contradict or weaken a conclusion, and this question type comes up frequently. In any case, we need to zero in on the conclusion that major eruptions cause the atmosphere to become cooler than it would be otherwise. Choice (C) presents such a large or major eruption, only this one caused the atmosphere to become warmer than was expected. It is a complete contradiction of the argument, so it is a perfect answer.

Thank you for tagging me, and good luck with your studies.

- Andrew

Conclusion: Thus, it is evident that major eruptions cause the atmosphere to become cooler than it would be otherwise

Which of the following statements, if true, most seriously weakens the argument above?

A. The cooling effect triggered by volcanic eruptions in 1985 was counteracted by an unusual warming of Pacific waters.
Out of scope – It doesn’t matter what happens after the volcanic eruptions.

B. There is a strong statistical link between volcanic eruptions and the severity of the rainy season in India.
Out of scope – not only too narrow in scope but also don’t care about another weather pattern that occurs after eruptions

C. A few months after El Chichón's large eruption in April 1982, air temperatures throughout the region remained higher than expected, given the long-term weather trends.
The conclusion states major eruptions = atmosphere cooler, but this gives an example that it is not the case. Eruption = atmosphere hotter. More specifically, "...the region remained higher than expected..." so it was not only higher immediately after the eruption, but also higher some time (i.e., a few months) after the eruption

D. The climatic effects of major volcanic eruptions can temporarily mask the general warming trend resulting from an excess of carbon dioxide in the atmosphere.
This almost seems support the conclusion. The conclusion states major eruptions = atmosphere cooler. This says eruptions temporarily mask the general warming; thus, it does get cooler (albeit temporarily). If it’s cooler for a second or for a few years after an eruption, it is cooler.

E. Three months after an early springtime eruption in South America during the late 19th century, sea surface temperatures near the coast began to fall.
Got trapped by this one. Originally thought that this weakens the argument because it shows that the eruption in the stimulus was an exception and it didn’t cool after the eruption. But it technically did cool. Just later. More specifically, 3 months later…

GMATNinja in c - it says "higher than expected" what if they expected -100 but instead it was higher -50?

Posted from my mobile device

The actual temperatures involved don't matter that much -- what matters is the relative values of the temperatures.

The author concludes that "major eruptions cause the atmosphere to become cooler than it would be otherwise." He/she uses the Laki Volcano eruption as an example to support this conclusion. After the volcano erupted, there was an "unusually severe winter" in Europe. What does "unusually severe" mean in terms of absolute temperature? We have no idea. The only thing that we know is that it was colder than usual.

In (C), we get an example that goes against the author's conclusion:

Instead of an unusually cold period after an eruption, there was an unexpectedly warm period after this particular event. Not only that, but these expectations were based on "long-term weather trends" -- in other words, people expected a normal, or "usual," temperature given the trends of the area.

This weakens the author's argument by showing that the author may have generalized too much from just one, cherry-picked example.

Again, it really doesn't matter whether people expected 50 degrees and got 100 degrees, or expected -100 degrees and got -50 degrees. The important thing is that people expected "usual" weather patterns, and that the weather was warmer than expected.

So (C) is the correct answer.

I hope that helps!

- Analysis of eruption

Pre-thinking: eruption —> blue haze —> cooling —> winter (the overall atmosphere becomes cooler)

C —> Correct because it proves that cooling by eruption is a temporary phenomenon as the temperature becomes higher after a few months

D —> Wrong because effect of CO2 is out of scope. We want the effect of heating/cooling by eruption

The argument claims that major volcanic eruptions cause the atmosphere to become cooler. To weaken this argument, we need to find a statement that contradicts or undermines the claim.

Option (A) states that the cooling effect triggered by volcanic eruptions in 1985 was counteracted by an unusual warming of Pacific waters. This weakens the argument because it suggests that other factors, such as warming Pacific waters, can counteract or nullify the cooling effect of volcanic eruptions.

Option (B) discusses a statistical link between volcanic eruptions and the severity of rainy seasons in India. While this statement is about the effects of volcanic eruptions, it doesn't directly weaken the argument about cooling effects in Europe. Therefore, it is less relevant.

Option (C) provides evidence that after the eruption of El Chichón in April 1982, air temperatures throughout the region remained higher than expected, contrary to the argument's claim of cooling effects. This directly contradicts the argument and weakens it significantly.

Option (D) suggests that the climatic effects of major volcanic eruptions can temporarily mask the general warming trend resulting from excess carbon dioxide in the atmosphere. Although this statement doesn't directly address the cooling effects mentioned in the argument, it introduces the idea that volcanic eruptions can have complex and varied effects on climate, which weakens the argument's oversimplified view.

Option (E) states that sea surface temperatures near the coast began to fall after an early springtime eruption in South America during the late 19th century. This statement is unrelated to the argument about European winter and cooling effects, so it doesn't significantly weaken the argument.

In conclusion, option (C) is the statement that most seriously weakens the argument because it directly contradicts the claim of cooling effects following a major volcanic eruption.