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GEO302C-L28 - b Millennial Oscillations during glacial...

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GEO302C 03/31/08 Lecture 28: Millennial Changes: Delta 18O in Ice Sheets Homework Definitions Dates Important People 1. Climate change at different time scales a. Tectonic: longest scale- hundreds of millions of years b. Orbital: tens to hundreds of thousands of years- cycles c. Millennial: thousands of years- oscillations 2. Oscillations recorded in Greenland Ice Cores a. Delta18O and dust help to date ice b. Early studies in 1970 c. Lots of dust mean climate was windier and more polluted d. Underlying trend of graduate glacial- interglacial changes 3. Millennial Oscillations a. Younger Dryas- during the last deglaciation i. 1500 yrs long ii. Abrupt beginnings and endings (about 10 yrs)
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Unformatted text preview: b. Millennial Oscillations during glacial period vs. interglacial i. Very wide spacing and amplitude ii. Average spacing: 1500 yrs iii. Called Dansgaard-Oeschger cycles 4. Oxygen isotope ratios in Ice and Ocean Cores a. Ocean Cores i. D18O signals 2 influences: Temp. Change and Ice volume b. Ice cores i. D18O signals reflect several influences: ii. Temperature of snowfall iii. Source of moisture iv. Transport paths v. Season of precipitation c. Relationship i. Correlation, as marine D18O becomes more positive, D18O in ice cores become more negative...
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