Q18 - In recent years the climate

[sheffieldjordan]

Could someone please explain why (C) is correct?

The paradox is that the weather in northern Asia is such that one would expect increased crop yields. Yet, scientists expect a decrease in crop yields next year.
(C) explains that the recent weather has been too cool and dry for insects pests to become established.

How would that resolve the paradox and explain the scientists' contrary expectation?

Must one assume that the insect pests become established only when crop yields are increasing?


Thanks.

[patrice.antoine]

I think (C) explains the paradox because it's saying the weather of past (cooler and dryer) has prevented crop insects from populating the area. If the direct opposite occurs (higher temperature and humidity) more insects will start populating the area to feast on those crops and as a result, decrease the region's crops.

We're to assume that the higher the temperature/humidity ---> more crop insects ---> more crop insects will feed on crops ---> less yield of crops.

(C) helps capture this assumption and justifies the conclusion perfectly.

[bostonphoenix]

I narrowed down to C and E and flipped a coin and went with C.

I dont understand why E is wrong.

We are asked to resolve a paradox that says that yield will go down. If we can't farm year round as a result of the increase in temperature and humidity wouldn't this give us a reason why overall yield is down?

[nbayar1212]

I was in the same boat with regards to E) but after thinking about it a bit more I think the issue is that it doesn't explain why the yields would be DECREASING; it only serves to explain why they could possibly stay the same.

E says that the recent climate prevents crops from being farmed in the winter....OK fine, but that just means that if the climate continues, crops will continue to not be farmed during the winter but the question remains: why will crop yields go down?

C on the other hand implies that the new climate will be favorable to pests in new ways which would explain why crops yields will decrease despite the favorable weather i.e. new pests will also begin to thrive and lower crop yields.

[rtrombley]

E is wrong for a few reasons.

"Many" does not mean "Most." Many crops may be unable to grow in the winter, but who is to say that these crops were the ones whose yields increased during the higher temperature / humidity. In essence, the paradox could still exists as aggregate yield increase could still be expected to increase.

The main reason E is wrong is because the timulus talks about future climate, not recent climate. Recent climate is not relevant to future projections. Perhaps the plants that couldn't be farmed in winter currently will now be able to be farmed in the winter due to warmer climate / better humidity; this could deepen the discrepancy as to why annual yields would not increase during the next century.

[christine.defenbaugh]

Lots of really great discussion here! Let's crack this Explain the Discrepancy question from the top!

We've got two things that seem really weird together, and we want an answer choice that could explain how they might both be true. In other words, we want something that makes the two things seem less weird together!

Thing 1: recent climate cool and dry, but on the days that were hotter/wetter, most crops increased.
Thing 2: if the climate matches that hotter/wetter range most of the time, then most crops will decrease.

Well, that's weird. You'd think the future crops would increase with that hotter/wetter general climate, just like they do now on random hotter/wetter days, but the scientists are saying the opposite. Weird!

But wait! (C) gives us a possible explanation. If there were nasty pests that the current cool/dry climate generally keep away, then it might be that shifting the whole general climate hotter/wetter would allow these pests to do their worst! So, the hotter/wetter climate might make the plants grow more, but then get all eaten up by the pests! patrice.antoine had this explanation on lock!



Nothing else offers an explanation for how these two things could both be true at the same time. In fact, most of the answers just make the situation weirder!

Still weird, or even weirder!
(A) - Who cares about Southern Asia? Even if this is true, our situation is still weird!
(B) - So the hotter/wetter climate would mean more CO2, which ought to mean increased crops! That makes our situation even weirder.
(D) - This suggests the hotter/wetter climate would cause the plants to flourish. That makes the prediction of decrease even weirder!
(E) - rtrombley is completely right to note that this is about the recent climate - and if the recent climate meant some crops couldn't be farmed during winter, maybe the hotter/wetter future climate would enable that. But if that were all true, then the future should have increased crops, not decreased! This makes our situation even weirder!

I would be careful about over-relying on the distinction between "many" and "most" here though. Explanation answers for paradoxes do not have to definitively prove that the weird situation will happen. They simply must offer a plausible possible explanation that could make the two things not weird together. So, if (E) had been about the future climate, and therefore said that many crops in the future climate would not function in the winter, that would have been a potential explanation for the predictions of future decrease.

I hope this helps clear up a few things!

[thompson.simonm]

This question aggravated me, though I was likely just over thinking it. I interpreted "crop insect pests" to be pests of crop insects. Therefore, I assumed that the return of these pests of crop insects would only increase the likelihood that the crops would flourish, no longer beleaguered by "crop insects." Ah well.

[crocca]

^^ I also thought of it as pests of crop insects, and since they aren't established, the crop insects will eat the crops unbothered and cause lower crop yields.

What I do not understand about the explanations given above is how do they account for the higher yields in the years before? If pests are established in hot and humid temperatures, wouldn't they have been established in the previous years of heat and humidity, and thus have caused the crop yields from those previous years to not be that great too?