Examkin

Soru

Zorluk: OrtaWeaken

Paleoclimatologist: Core samples extracted from the Ellesmere Ice Shelf reveal an abrupt spike in micro-charcoal particle density dating to approximately 8,200 years ago. Because regional boreal forests produce high concentrations of airborne charcoal only during prolonged periods of severe drought and wildfire, researchers conclude that a catastrophic multi-decade megadrought afflicted the adjacent subarctic mainland during this era.

Which of the following statements, if true, most undermine the paleoclimatologist's conclusion? Select all that apply.

  1. Around 8,200 years ago, annual snowfall over the Ellesmere Ice Shelf dropped by over 80 percent, dramatically reducing ice accumulation and concentrating standard atmospheric particulates into dense bands.Cevap
  2. B
    Subarctic lake sediment cores from the adjacent mainland indicate that moisture-sensitive coniferous trees were widely replaced by drought-hardy shrubs approximately 8,200 years ago.
  3. Geochemical analysis of the micro-charcoal in the ice layers shows an elemental composition characteristic of basaltic volcanic combustions from a distant ocean ridge rather than organic wood fires.Cevap
  4. D
    Undisturbed modern boreal forests occasionally generate trace amounts of airborne charcoal during brief localized lightning strikes that occur outside of drought conditions.
  5. E
    Human hunter-gatherer populations inhabiting the subarctic mainland established permanent coastal settlements several centuries after the charcoal spike occurred.

Cevap

The statements establishing that a severe reduction in snowfall concentrated baseline atmospheric particles and that the charcoal originated from volcanic basalt rather than forest combustion both undermine the conclusion.
The argument assumes that an elevated density of charcoal particles in the ice core must reflect increased mainland forest burning caused by drought. The statement regarding reduced snowfall demonstrates an accumulation artifact where low precipitation concentrates normal baseline particles into high-density layers without any increase in fire activity. Similarly, the statement identifying a volcanic origin demonstrates that the charcoal did not come from burning boreal trees, severing the link to mainland forest conditions.

Adım Adım Çözüm

1
Identify the main conclusion and core premises of the argument.
The premise is that an ice core shows a spike in micro-charcoal density and boreal forests produce high airborne charcoal during severe drought; the conclusion is that a catastrophic megadrought afflicted the adjacent mainland.
Isolating the conclusion allows detection of the key assumptions linking charcoal density in ice to regional drought conditions.
2
Identify the unstated assumptions and vulnerabilities in the author's reasoning.
The author assumes that high particle density reflects higher total charcoal output rather than an ice-accumulation artifact, and that the charcoal necessarily originated from regional mainland forest fires.
Weaken questions require identifying logical gaps or alternative explanations that break the link between the evidence and the conclusion.
3
Evaluate the answer choices to identify all statements that introduce facts undermining these key assumptions.
The statement showing reduced snowfall caused particle concentration and the statement showing a volcanic origin for the charcoal each independently undermine the author's causal claim.
Both findings provide alternative explanations that account for the data without requiring a mainland drought.

Anahtar Kavram

Alternative Causal Explanations and Data Measurement Confounders
Tahmini Süre:1m 30s
Bu soruyu puanla

Konular

Weaken

Bu konudan daha fazla soru