Reading Comprehension

PT109 · S2 · P3 · Q19 Atmospheric CO2

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Experts anticipate that global atmospheric concentrations of carbon dioxide (CO2) will have doubled by the end of the twenty-first century.

Topic

The potential effects of elevated CO2 levels on agriculture and global warming.

Framework

Challenge Position

Main Point

While some initially believed that increased CO2 levels could lead to lush agricultural growth and aid in decreasing global warming, research suggests that it might actually disrupt ecosystems, decrease crop yields, and exacerbate global warming. *The Most Valuable Sentence: (start of paragraph 3).*

P1: Introduction to CO2's Anticipated Impact

This paragraph sets up an initial optimistic view that increased CO2 levels might boost plant growth and lessen global warming by enhancing photosynthetic rates and trapping more carbon.

P2: Challenge to the Optimistic View

Recent studies show that while plant growth could increase with more CO2, it would vary between species, potentially reducing agricultural yields and harming ecosystem stability. For example, certain crops might suffer compared to weeds, leading to ecological changes and increased wildfire risks.

P3: Doubts About CO2 Reducing Global Warming

The paragraph discusses how in some conditions, such as warming tundras, enhanced plant growth won’t offset CO2 emissions from decomposing peat, hence the increased uptake of CO2 might not significantly curb global warming.

19.

The author would be most likely to agree with which one of the following statements about the conclusions drawn on the basis of the research on plant growth mentioned in the first paragraph of the passage?

Correct
The conclusions are correct in
Why this is right
Sneaky, sneaky, LSAT. Usually, Author's Opinion questions reward us for understanding the author's stance on certain big topics in the passage. The author's stance on the conclusions being reached in the 1st paragraph is one of big ol' disagreement. The whole passage is Challenge Position, because the author spends a paragraph each shooting down these two conclusions. But this answer represents a Concession, an area of agreement with the author's opponents. In the 2nd paragraph, the author definitely acknowledges that in a world with more atmospheric CO2, the photosynthetic rates of certain plants will increase: while a number of recent studies confirm [the conclusion] that plant growth would be generally enhanced in an atmosphere rich in CO2, they also suggest that increased CO2 would differentially increase the growth rate of different species of plants. Later in the 2nd: studies have shown that within rangeland regions, a weedy grass grows much better with plentiful CO2 than do three other grasses. The language of "growth rate" and "photosynthetic rate" are synonyms. A plant metabolizes and grows by using photosynthesis. In the 2nd paragraph the author is saying, "While I agree that more CO2 in the atmosphere will mean that some plants have higher photosynthetic rates and thus grow more and grow faster, you should realize that you won't get agricultural abundance out of this. The plants that will be helped by more CO2 aren't necessarily the good ones." The first half of that is the concession stated in this answer choice.
Skill tested: Author Opinion · how this choice captures the passage's function is the move to repeat next time.
73% picked this
The conclusions are correct in
Too Strong / Opposite: guarantee crops
The author's point in the 2nd paragraph is that crops will do worse in this world of more CO2. Sugarcane and corn are currently have advantages over other plants because they are more efficient with how they do photosynthesis (they can get more energy out of the available atmospheric CO2 than can other plants). But if the atmosphere gets juiced with lots of CO2 fuel, then sugarcane and corn will no longer have a competitive advantage. So crappy plants like weeds will be able to grow as fast and as plentiful as crop plants. So not only is the author never saying something extreme like "more CO2 will guarantee abundant crops", she is actually suggesting the opposite.
2% picked this
The conclusions are correct in
Opposite
In the 3rd paragraph, the author is disagreeing with the conclusion that increased plant growth will reverse global warming. She's saying that the increased intake of CO2 by plants will be more than offset by the increased emission of CO2 by decomposing dead plants, which are currently shielded by the permafrost. In a warmer world, increased plant growth would not compensate for this rapid increase in decomposition rates.
2% picked this
The conclusions are incorrect in
Opposite
This is the reverse of (A). In the 2nd and 3rd paragraphs, the author acknowledges that as CO2 in the atmosphere goes up, some plants will start to photosynthesize more, leading to more plant growth. In the 2nd paragraph, she is saying, "Just be aware that this increased plant growth will mainly be crappy plants like weeds, not cool plants like sugarcane and corn." In the 3rd paragraph, she is saying, "Just be aware that having more plants to suck up CO2 is not going to make up for the fact that in a world where the permafrost melts, there is going to be tons of CO2 released by decomposing peat."
17% picked this
The conclusions are incorrect in
Opposite / Violates Common Sense
The author thinks it's correct that vegetation can draw CO2 from the atmosphere. In fact, that's just a common sense truth we all know. It's one of the first things we learn about plants: they suck in CO2 and give out oxygen. In the second to last sentence of the passage, the author acknowledges such a thing: In a warmer world, increased plant growth, which could absorb CO2 from the atmosphere ...
7% picked this

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