#1 - Global Reference, Main Point

[Administrator]

Please post your questions below! Thank you!

[sarahzumar]

Why is C wrong?

[Jeremy Press]

Hi Sarah,

In short, C is wrong because, while it's supportable from the passage, it's too narrow to be the main point. Answer choice C is primarily summarizing the second paragraph of the passage, which documents the difference between observed temperatures and what greenhouse theory originally predicted.

One of the things the main point needs to include here is a statement about the author's position on the causal explanation for global warming. The final sentence of the passage nicely sums up the author's position: "changes in the earth's atmosphere have raised its equilibrium temperature, and ... greenhouse gases represent the best explanation of that shift." That "best explanation" position is missing from answer choice C, which merely states that temperature has been "rising in a way that is consistent with the greenhouse theory." Being consistent with a theory is not quite strong enough to capture the causal implication of the last sentence of the passage (that greenhouse gases are causing global warming). Answer choice D better captures that by stating that "the greenhouse effect is a major cause of this warming trend."

I hope this helps!

Jeremy

[appletree]

Hello,
I was a bit thrown off by D because it says "major cause." while the last sentence of the passage says "best explanation."
Could someone please explain why "major cause" does not make the answer incorrect?
Thank you!

[Rachael Wilkenfeld]

Hi appletree,

As used here, the term "explanation" is the same as "cause." The best reason/cause/explanation is essentially the same as saying a "major" cause. In both cases, you are referencing the main mechanism that you think is causing an effect. The main cause of global warming is greenhouse gases is essentially the same as the best explanation for global warming is greenhouse gases. Remember here that we aren't looking for an answer choice that uses the exact same language as the passage, but one that contains logically equivalent descriptions of the main point.

Hope that helps!

[blaisebayno]

Can someone please quote the passage parts that make E correct and that make the other answers incorrect.

[Adam Tyson]

The correct answer here is D, blaisebayno,, not E. It's not just one thing that supports answer D, but the passage as a whole, which is typically the case for Main Point answers. But the final sentence of the passage does sum it all up nicely:

In light of all this, it seems reasonable to conclude that changes in the earth’s atmosphere have raised its equilibrium temperature, and that greenhouse gases represent the best explanation of that shift.

The other answers are wrong for a variety of reasons, but mostly because none of them sum up the passage as well as answer E does. Specifically:

Answer A is wrong because it is the opposite of what the author wants to convey. They are not trying to show problems with the theory, but to support it.

Answer B is wrong because the passage is not about predicting the future. It's about explaining what has happened so far.

Answer C is wrong because the author isn't trying to prove that the theory has been inaccurate. That was just one objection that the author says has been overcome thanks to the inclusion of data about sulfates.

Answer E is wrong because it is not true. The author does not require the theory be combined with the solar fluctuation theory, because they are saying that the solar fluctuation theory doesn't account for the deviation from the average that has been observed.