ERS103H5 Lecture Notes - Lecture 18: Sea Surface Temperature, Geologic Time Scale, Ordovician
Document Summary
* refer to geological time scale note as guide. H2o, co2 (carbon dioxide), and ch4 (methane) absorb thermal energy and reradiate it, warming the lower atmosphere. A gradual rise through the cambrian, reaching a zenith in the late ordovician. Very high sea levels with continents flooded by shallow seas. Warm and little temperature differences - low thermal gradients. Lower albedo, absence of ice at higher altitudes. Low vertical gradients: deep water not much colder than shallow water. Density of ocean water controlled more by salinity than by temp differences. Reasons for oxygen deficiencies: low temperature gradient/little circulation. Deep waters stagnant, ocean stratified: organic decay removes oxygen - deep waters not replenished, lower solubility of oxygen in warm water. * intense rapid global warming over 200,000 years. From ice core studies, co2 concentration was found from 180 to 280ppm through glacial advances and retreats.
