ENVS 120 Lecture Notes - Lecture 3: Cherry Picking, Gulf Stream, Dendrochronology
Document Summary
We don"t have actual recorded data, we look for proxies. Rocks formed in tropical conditions in north america (ie: crocs found in. Sediment cores (approx 400,00-800,00 yrs ago) a. b. Scientists drill w tubes, pull entire core, can take slices, see how old slice ice, i. ii. Look for fossils, air bubbles, trapped gas as evidence for climate. The colder the air when the snow fell the more oxygen in the core. Ratio of o2 18 vs 16 explains how oxygen was when it settled out. Tree rings (dendrochronology, approx 1000 yrs ago) a. b. c. Slice through, measure thickness of lines, count back, find out how long ago they occurred. Everything was covered under at least a mile or two of ice. During the ice age, gulf stream shifted east. About 10% of the earth is covered in glaciers. If ice is not stored on land, must be stored in water -> causes rise in sea level.