Audio Transcript Excerpt:
PROFESSOR: 'In dendroclimatology, researchers analyze annual tree-ring widths to reconstruct paleoclimatic temperatures. How

Question

Audio Transcript Excerpt:
PROFESSOR: 'In dendroclimatology, researchers analyze annual tree-ring widths to reconstruct paleoclimatic temperatures. However, a major methodological complication emerged in the late twentieth century known as the 'divergence problem.' Specifically, in certain subarctic circumpolar boreal forest populations—primarily white spruce in Alaska and northern Eurasia—the historical sensitivity of tree-ring growth to temperature broke down after approximately 1960. While instrumental thermistor records recorded dramatic warming, the width and maximum latewood density of these high-latitude trees failed to track the temperature increase, showing an unexpected plateau or decline.'

According to the lecture, what specific phenomenon characterizes the 'divergence problem' in subarctic tree-ring chronologies?

Accepted Answer

High-latitude tree-ring widths and wood density failed to track the post-1960 instrumental warming trend.

Answer

Trees began producing two distinct rings per calendar year due to longer summers.

Answer

Southern deciduous trees migrated into subarctic zones and displaced endemic spruce populations.

Answer

Radiocarbon dating in tree cellulose became distorted by oceanic upwelling.

Practice More TOEFL iBT Detail Identification Questions

More Detail Identification Questions in TOEFL iBT

Practice More TOEFL iBT Detail Identification Questions

More Detail Identification Questions in TOEFL iBT