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Long-Term Climate Change.docx

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Department
Life Sciences
Course
LIFESCI 2H03
Professor
Luc Bernier
Semester
Winter

Description
January 30 , 2013 Life Sci 2H03: Environmental Life Sciences Climate Change: Long-Term Climate Record & Forcings Climate Change What Causes Climate? - surface of the Earth is unequally heated by the sun - large portion is reverted back to the earth surface - two major forcings: amount of energy we’re receiving from the sun and the redistribution by GHG - because the sun is directly overhead of the equator there is a net positive balance - there is less incoming solar radiation at the poles because the sun is at an angle, far more energy is being loss in terms of infrared variation - balance between the equators and the poles, their function is to redistribute the excess of energy from the lower latitudes to the higher ones - as the energy is redistributed, the major vector is water in the forms of ocean currents and atmospheric circulation - water raises in the equator and dries as it drops on the suptropical highs, classes with cold dry areas near the poles resulting in precipitation in areas of the subpolar lows - no gains or losses in the radiation budget it is in balance What are Climate Feedbacks - climate forcing makes initial change in climate - feedbacks can: amplify or dampen effect of initial change Positive Vegetation-Climate Feedback The Faint Young Sun Paradox - nuclear fusion was not as strong as it is now - gradually gained luminosity - based on the temperatures generated by lower luminosity, Earth would have been completely glaciated if the atmosphere would have been the same as today (same composition of atmosphere in terms of GHG) - what could have contributed to more moderate temperatures? A CO 2Rich Early Atmosphere? - given the luminosity without gases temperature would have been along the lines of -40 C covering Earth in a thick ice sheet - in an atmosphere rich in GHG Earth would have had a significantly higher temperature - weaker solar radiation is balanced by stronger greenhouse gas effect Faint Young Sun - as luminosity increased over time, the levels of greenhouse gases must have decreased so that the conditions would have remained in the liveable range The Gaia Hypothesis & the Faint Young Sun Paradox - played a role in capturing more carbon dioxide from the atmosphere due to photosynthesis - transferred from terrestrial habitats to the sea-floor and trapped in the sea floor surface reducing concentration of CO 2 Chemical Weathering & CO 2 - plausible explanation for changes in CO level2 Carbon Cycles Constantly between Earth’s Interior and its Surface - with all the volcanic activity there is a lot of carbon dioxide released - mechanicms that capture atmospheric volcanic CO and return2 it back to the surface - leading to smaller changes in Earth’s climate Hydrolysis & Removal of CO from 2he Atmosphere - e.g. Dissolution of CaSiO (w3llastonite) - rocks that are rich in silicate - all biproducts of the reaction will
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