EPS 7 Lecture Notes - Lecture 25: Greenhouse Gas, Megafauna, Runaway Greenhouse Effect
21 Jul 2018
School
Department
Course
Professor
Document Summary
Paleoclimate: the past as guide to the future. Mercury venus earth mars jupiter saturn uranus neptune. Venus: same size as earth, had oceans of water, was a candidate for life, now a runaway greenhouse climate. Venus started out like earth, with an ocean suitable for life. The positive water vapor feedback became so big, that the total feedback parameter was positive. With a positive feedback, venus got hotter and hotter. The oceans boiled and the water vapor escaped to space. Today, its atmosphere is almost entirely co2. Venus (farer from the sun but hotter) 737k. All of earth history: precambrian, 4. 5 gya earth formed, 2. 5 gya great oxygeneation event (snowball earth, 0. 5 gya multicellular life begins. For the first one, it was albedo effect. Somehow gets cold enough that the positive ice-albedo feedback takes over: phanerozoic eon, paleozoic 542 mya: age of weird critters (oceans full of weird creatures) -------- 251 mya: great dying: cause unknown--------: mesozoic age of dinosaurs.
