ACT (Enhanced)ScienceEasy
A climate scientist is analyzing tree ring data to reconstruct historical climate patterns. Wider tree rings generally indicate periods of favorable growth conditions (e.g., adequate rainfall, moderate temperatures), while narrower rings suggest less favorable conditions. If a section of tree rings shows a consistent pattern of narrow rings for 15 consecutive years, followed by a sudden shift to significantly wider rings for the next 20 years, what is the most reasonable inference about the climate in that region?
- AA sustained period of high winds followed by a period of volcanic activity.
- BA period of unusually cold temperatures followed by a period of decreased precipitation.
- CA prolonged period of drought followed by a period of increased precipitation and/or warmer temperatures.
- DA steady increase in atmospheric carbon dioxide over 35 years.
Show answer & explanationAnswer & explanation
Correct answer: C. A prolonged period of drought followed by a period of increased precipitation and/or warmer temperatures.
Narrow tree rings indicate poor growth conditions, often associated with drought or cold. Wider rings indicate favorable conditions, typically linked to ample water and moderate temperatures. The observed pattern directly supports a shift from unfavorable to favorable conditions.
Why the other options are wrong
- A. High winds might affect growth, but volcanic activity typically leads to cooling, which would result in narrow, not wide, rings.
- B. This contradicts the interpretation of wide rings indicating favorable conditions.
- D. While CO2 can affect growth, the sudden shift suggests a more immediate climatic change than a steady, long-term trend.
Dendroclimatology
The study of past climates using tree rings. Tree ring width, density, and chemical composition can provide information about environmental conditions during the tree's life.
- Wider rings typically indicate favorable growth (e.g., sufficient moisture, mild temperatures).
- Narrower rings typically indicate unfavorable growth (e.g., drought, extreme cold).
- Each ring represents one year of growth.
Memory trick: Rings Tell What the Year Brought