GEOL 2207 Lecture Notes - Ocean Current, Ellipse, Pleistocene
Document Summary
Earth"s orbit around the sun is an ellipse, not a perfect circle. The orbit stretches from circular to elliptical on a 100 ka cycle. Other contributors: drawdown of atmospheric greenhouse gases, increased surface albedo* Snow, white, high albedo, reflecting a lot of the solar radiation: configuration of continents and ocean circulation, atmospheric dust and aerosols (volcanic eruptions) As glaciers get bigger, fewer vegetation, increases albedo, reflects more, more cooler, accumulating more snow. Low temperatures coincide with major continental glaciations; high temperatures with interglacial periods. Climate fluctuates in cycles of about 100,000 years. Last major interglacial 125,000 years ago: global sea-level 5-7m higher than today. Rapid fluctuations between 15 and 11,000 years ago: younger dryas (12. 8-11. 6 ka) period of severe cold, rapid warming after 1. 6 ka. Slow cooling began 7000 years ago: culminated in little ice age (14th 19th century) Complex warming and cooling trends over the past 100 years.
