Proposal: Carbon dioxide and methane in the atmosphere block the escape of heat into space. So emission of these "greenhouse"...
GMAT Critical Reasoning : (CR) Questions
Proposal: Carbon dioxide and methane in the atmosphere block the escape of heat into space. So emission of these "greenhouse" gases contributes to global warming. In order to reduce global warming, emission of greenhouse gases needs to be reduced. Therefore, the methane now emitted from open landfills should instead be burned to produce electricity.
Objection: The burning of methane generates carbon dioxide that is released into the atmosphere.
Which of the following, if true, most adequately counters the objection made to the proposal?
Passage Analysis:
| Text from Passage | Analysis |
|---|---|
| Carbon dioxide and methane in the atmosphere block the escape of heat into space. |
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| So emission of these "greenhouse" gases contributes to global warming. |
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| In order to reduce global warming, emission of greenhouse gases needs to be reduced. |
|
| Therefore, the methane now emitted from open landfills should instead be burned to produce electricity. |
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| Objection: The burning of methane generates carbon dioxide that is released into the atmosphere. |
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Argument Flow:
The argument starts with scientific facts about greenhouse gases, then moves to a general principle about reducing emissions, applies this to a specific proposal about landfill methane, and ends with an objection that challenges the proposal.
Main Conclusion:
Methane from open landfills should be burned to produce electricity rather than released directly into the atmosphere.
Logical Structure:
The author uses a chain of reasoning: greenhouse gases cause warming → we need to reduce emissions → burning landfill methane is one way to do this. However, a critic objects that burning methane still produces CO2, which seemingly defeats the purpose.
Prethinking:
Question type:
Strengthen - We need to find information that makes the proposal (burning landfill methane for electricity) look better despite the objection that burning methane creates CO2
Precision of Claims
The proposal claims burning landfill methane for electricity will help reduce global warming. The objection points out that this process still creates CO2, which is also a greenhouse gas
Strategy
Since the objection says 'but you're still creating CO2 when you burn methane,' we need to find reasons why burning the methane is still better than letting it escape directly. We should look for information that shows either: (1) burning methane creates less greenhouse gas effect overall than letting methane escape, (2) the electricity produced has additional environmental benefits, or (3) there are other advantages that outweigh the CO2 creation
This choice talks about humans and mammals exhaling CO2. While this is true, it doesn't help counter the objection at all. The objection is specifically about whether burning landfill methane is better than letting it escape directly. Information about natural CO2 from breathing doesn't address whether the proposal is environmentally beneficial or not.
The distance between where methane is converted to electricity and the landfills is completely irrelevant to the environmental impact. Whether the conversion happens near or far from the landfills doesn't change the fact that burning methane produces CO2, so this doesn't counter the objection about greenhouse gas emissions at all.
This choice actually works against the proposal! It suggests the electricity from methane would replace fuel that produces NO greenhouse gases. If we're replacing clean fuel with methane burning (which produces CO2), that would be worse for the environment, not better. This strengthens the objection rather than countering it.
This directly counters the objection by establishing that methane is more effective at trapping heat than CO2. If methane blocks heat escape more effectively than CO2, then converting methane to CO2 by burning it actually reduces the overall greenhouse effect. Even though burning produces CO2 (as the objection states), the net result is still better for global warming because we're replacing a more potent greenhouse gas with a less potent one.
This talks about reducing methane emissions through recycling instead of discarding materials. While this might be environmentally good, it doesn't address the specific objection about burning methane producing CO2. The objection challenges the burning proposal specifically, and this choice suggests a completely different approach rather than defending the burning proposal.