GEOL 150Lg Lecture Notes - Lecture 30: Anthropocene, Oligocene, Laurentide Ice Sheet
Document Summary
Proterozoic: sun was weaker, evidence of glaciers in tropics - nearly global glaciaion snowball earth . Long term removal of co2 through silicate weathering. Much of sun"s energy is relected by ice. Ended by gradual buildup of volcanic co2 and other ghgs. Permian: extreme warming, poorly venilated ocean; parts became anoxic (no o2), and water became toxic, at the end there was the largest exincion event ever. High co2 released by frozen methane and volcanism. Low o2 content: dinosaurs well suited to new atmosphere and climate. Cretaceous: tropical hothouse world, oceans warm, intense evaporaion at equator, anoxic zones, global temps ~8 c warmer, high co2 (volcanism), high o2 (plants, high sea levels and no ice, first lowering plants and earliest mammals appeared. Cretaceous-tertiary event: most rapid major exincion event caused by slow climate change from volcanism and rapid change from bolide impact not permanent change, dinosaurs went exinct and mammals survived. Paleocene: high temperatures, high climate sensiivity, rapid co2 spikes.
