Climatologist Michael Mann and his colleagues have graphed a thousand-year period (the famous "hockey stick" chart)that shows how __________ were more or less constant until they spiked __________.

Question

Quizplus · Accepted Answer

The "hockey stick" chart shows a constant temperature for the first 900 years, with a sudden spike in the past half-century, indicating that global temperatures have been relatively stable until recently. This makes option C the correct choice. Options A and B include incorrect details about CO₂ levels and carbon monoxide, which were not the focus of Mann's research. Option D mentions organic matter levels, which were not measured in the study.

Climatologist Michael Mann and His Colleagues Have Graphed a Thousand-Year