wk 11 - 2/21/11 D. Shaw 3/17/10 2/21/11 About 3.5 Ga,...

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Unformatted text preview: 2/21/11 D. Shaw 3/17/10 2/21/11 About 3.5 Ga, 2/21/11 Layered intrusion Large sill-like body of igneous rock which exhibits vertical layering. These intrusions typically are many kilometers in areal extent to over a kilometer in thickness. While most are Archean (2.5 Ga ) to Proterozoic (0.5 2.5 Ga) in age, 2/21/11 Dating the establishment of Earths magnetic fi eld has implications for identifying conditions  3.9 billion years ago (Ga), Earth was bombarded by heavy radiation from the Sun (protons, , , particles); no life in any form existed.  Around 3.45 Ga, appreciable magnetic field developed around the Earth, and allowed life to  Around 2.30 Ga, Earth developed an oxygen-rich atmosphere. 2/21/11 Moira Jardine, Science 5 March 2010 2/21/11 Informed and Discerning  Scientists ponder why worlds climate is changing; a major cooling widely considered to be inevitable --The New York Times, May 21, 1975  Climatologists said the ice cores left no doubt that the burning of fossil fuels is altering the atmosphere in a substantial and unprecedented way. --The New York Times, Dec. 30, 2005 Thirty years is too short for a global cooling/warming cycle! Issues related to energy/climate sustainability should be considered in time-scale longer the political election cycles. 2/21/11 Assessments of U.S. Energy Sustainability  Continuing reliance of foreign oil is not sustainable Political instability of oil-exporting countries Supply/demand competition caused by increasing global population and prosperity  The fossil fuels (currently at about 80%) will play an important role in the overall energy picture It could be reduced by 20-25% with public support. Renewables cannot replace fossil fuels as the major source of energy But they should play a large role (e.g. 25% in 2050) 2/21/11 Why is SD so difficult?  SD is complex because it involves many problems in addition to technological considerations. 3 aspects economic, social (poverty eradication, equity, life style, etc.), and environment/ecology  Sun/earth energy balance Milankovitch cycle; coronal mass ejection/earth protective magnetic field  Earth is a fascinating complex system Atmosphere 2/21/11 What are the Problems?  Climate change has not motivated the public on energy- related issues....
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wk 11 - 2/21/11 D. Shaw 3/17/10 2/21/11 About 3.5 Ga,...

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