An unusually severe winter occurred in Europe after the continent was blanketed by a blue haze resulting from the eruption...
GMAT Critical Reasoning : (CR) Questions
An unusually severe winter occurred in Europe after the continent was blanketed by a blue haze resulting from the eruption of the Laki Volcano in the European republic of Iceland in the summer of 1984. 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?
Passage Analysis:
| Text from Passage | Analysis |
| An unusually severe winter occurred in Europe after the continent was blanketed by a blue haze resulting from the eruption of the Laki Volcano in the European republic of Iceland in the summer of 1984. |
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| Thus, it is evident that major eruptions cause the atmosphere to become cooler than it would be otherwise. |
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Argument Flow:
The argument starts with one specific example (Iceland volcano → blue haze → severe winter) and then jumps to a broad general rule about all major eruptions causing cooling
Main Conclusion:
Major volcanic eruptions cause the atmosphere to become cooler than it would be otherwise
Logical Structure:
This is a classic case of drawing a sweeping conclusion from just one example. The author assumes that because one volcanic eruption was followed by cold weather, all major eruptions must cause atmospheric cooling. We have: Single Case (Iceland 1984) → General Rule (All major eruptions cool atmosphere)
Prethinking:
Question type:
Weaken - We need to find information that reduces our belief in the conclusion that major volcanic eruptions cause atmospheric cooling
Precision of Claims
The conclusion makes a broad causal claim about 'major eruptions' based on one specific example (Laki 1984). The author assumes this single case represents a general pattern.
Strategy
To weaken this argument, we need to find information that shows the conclusion doesn't necessarily follow from the evidence. We can attack the causal relationship by showing: (1) alternative explanations for the severe winter, (2) that this volcano/winter connection might be coincidental, or (3) that major eruptions typically don't cause cooling. We must respect the facts - the volcano did erupt, there was a blue haze, and there was a severe winter.
This discusses volcanic eruptions in 1985 where the cooling effect was counteracted by Pacific water warming. This doesn't weaken the argument because it actually supports the idea that eruptions do cause cooling - it just mentions another factor that counteracted it. The author's conclusion about eruptions causing cooling remains intact.
This mentions a statistical link between volcanic eruptions and rainy seasons in India. This is completely irrelevant to the argument about atmospheric cooling. Rain patterns don't address whether eruptions cause temperature changes, so this neither strengthens nor weakens the cooling claim.
This describes El Chichón's large eruption in April 1982, after which air temperatures remained higher than expected rather than cooler. This directly contradicts the author's conclusion by showing a major eruption that did not cause cooling. If major eruptions always cause atmospheric cooling as claimed, then we shouldn't see a case where a large eruption is followed by higher-than-expected temperatures. This creates serious doubt about the generalizability of the Iceland example.
This states that volcanic eruptions can temporarily mask general warming trends from carbon dioxide. This actually supports the author's conclusion by confirming that eruptions do have a cooling effect - it just notes that this cooling can mask other warming. This strengthens rather than weakens the argument.
This describes a 19th-century eruption followed by falling sea surface temperatures. This supports the author's conclusion by providing another example of an eruption followed by cooling (lower sea temperatures). This strengthens the argument by showing the pattern holds in other cases.