2023 CSAT — Q41

Locate. This is a valid-assumption question: find the argument the statements lean on. The passage: scientists found that warmer, less-snowy winters produce a longer lag between spring events and a “more protracted vernal window,” with ecological consequences — notably, “as the ice melts earlier, the birds don’t return,” delaying/lengthening springtime ecological events.

Test (negate each statement, then check it against three limits — the entities, the cause-and-effect, and the level of certainty). Statement 1 — “global warming is causing spring to come early and for longer durations.” Map it: “warmer winters with less snow” is the warming signal; “a longer lag… a more protracted vernal window” is spring coming early and lasting longer. Same entities, same mechanism, no inflated qualifier. Negate it (“warming is not causing early/longer spring”) and the passage’s central finding is contradicted. VALID. Statement 2 — “early spring and longer spring is not good for bird populations.” Run the cause-and-effect check, which is where this turns. Read the passage’s actual chain: ice melts earlier → the birds don’t return → a delay/lengthening in springtime ecological events. The birds’ non-return is stated as the cause of shifted ecological-event timing — the passage’s interest is the disrupted vernal window. It says nothing about a consequence for the birds — not their health, not their numbers, not their welfare. “Not good for bird populations” asserts a fresh causal claim — that the altered spring harms the population — which the passage never traces. That is a cause the passage never states, and our house rule is explicit that an outcome which merely sounds reasonable (even one that may be true in the world) does not survive that check. The negative valence here is not a hedge on a stated claim; it is a new consequence-on-the-birds. INVALID.

Eliminate by anatomy. This is the trap the boundary test exists to catch: the disruption is real, so “harm to the birds” feels entailed — but the disruption the passage states is to ecological-event timing, not to the bird population. (c) Both and (b) 2 only both seat the invalid Statement 2 as if “the birds don’t return” licensed a welfare verdict on the population — a cause the passage never traces re-read as a stated harm. (d) drops the clean Statement 1 too, reading the passage as demanding more than it does. The transferable rule: a process the passage names as a cause of something else does not, by itself, license a value claim about the actor — to get “not good for birds” you must add a mechanism (harm to the population) the text never states. Only Statement 1 survives. Our key: (a) 1 only — which diverges from UPSC’s official (c); escalated.

Statement 1 — “warmer winters with less snow resulted in a longer lag time between spring events and a more protracted vernal window” maps directly onto “global warming → spring early and longer”: same entities, same warming mechanism, no qualifier inflation → VALID. Statement 2 — the passage’s chain is “As the ice melts earlier, the birds don’t return, causing a delay, or lengthening in springtime ecological events”: the birds’ non-return is stated as a CAUSE of ecological-event timing shifts, NOT as harm to the birds. The passage states no consequence ON bird populations — no welfare, health, or numbers claim. “Not good for bird populations” adds a mechanism (spring-change harms the population) the text never traces → MECHANISM boundary fails → INVALID. Valid St.1 only → CONTESTED key (a), diverging from official (c).

The passage links warmer, less-snowy winters to a longer, more protracted vernal window, and names one ecological knock-on: as the ice melts earlier, the birds don’t return, which delays/lengthens springtime ecological events.

Statement 1 — global warming causes early, longer spring. “Warmer winters with less snow” is the warming driver; “longer lag… more protracted vernal window” is spring arriving early and persisting. Direct fair inference. Valid.

Statement 2 — early/longer spring is not good for bird populations. The passage’s only sentence about the birds is “As the ice melts earlier, the birds don’t return, causing a delay, or lengthening in springtime ecological events.” That places the birds’ non-return as a cause of shifted ecological-event timing — the passage’s subject is the disrupted vernal window. It states no effect on the birds: no harm to their health, numbers, or welfare. “Not good for bird populations” adds a consequence-on-the-birds the text never traces — it invents a cause the passage doesn’t state. A sounds-reasonable outcome is not a boundary the exam respects, and when in doubt we resolve it the stricter way, against the second statement. Invalid.

Only Statement 1 holds. Our answer: (a) 1 only — diverging from the official (c) Both; this is a contested-vs-official escalation, not a clean clear.

This item is the cleanest classroom case of the cause-and-effect boundary. The disruption in the passage is real, so “harm to the birds” feels entailed — and that feeling is exactly the trap of inventing a cause the passage never states. The text runs ice-melt → birds-don’t-return → shifted ecological events; the birds are a cause in that chain, never the thing measured for harm. To reach “not good for bird populations” you must add a claim the passage withholds: that the altered spring damages the population. A disciplined reader stops at the boundary — a process named as a cause of X does not license a value verdict on the actor. UPSC’s official key marks Both, accepting the welfare reading; our standard cannot, because nothing in the text states an effect on the birds. We hold (a) and route the divergence to the founder rather than rubber-stamp (c) against our own house standard.