Shows evidence of historical changes in distribution of vegetation types and dominant species C. Tree-ring analysis 1. In climates with a pronounced winter or dry season, plants grow during only part of the year and go dormant. This leaves annuals rings in the wood. Scientists extract cores from trees and analyze the variation in ring-widths to make educated guesses about past climates. Wide rings usually mean plenty of moisture and warmth.
Narrow rings imply drought, or possibly short growing season.
D. Historical record 1. Abrupt cooling around 1200 A.D. brought a swift demise to Norse dominance and Anasazi culture. Glaciers in the Alps advance to lower elevations. Show curve of gradual warming during this period, especially since 1980. Theories to account for climate change.