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GLACIAL LANDSCAPES ** Climate Change: * climate & weather don't stay the same, they change day to day, year to year, millennium to millennium * there are daily & monthly & annual averages, SO * climate change is a significant change in these averages over hundreds of thousands of years * climate system ; the interaction of all spheres (atmosphere, lithosphere, biosphere, hydrosphere) * when change occurs in one sphere, it usually affects the other spheres * Evidence of climate change : * sea-floor sediments - ancient fossil remains that do not normally live in this area * tree rings * palynology(study of fossil pollens)-ancient tree pollen is of a different species than today * geologic formations(coal deposits) - coal deposits indicate tropical weather * historical records * Climate change theories: * Non-human Induced Causes: * Plate tectonics: move into or out of a climate * Volcanic activity: increased amount of dust & ash in atmosphere affects T°'s * Astronomical theory 1) eccentricity : change in the shape of earthe’s orbit 2) obliquity : change in angle of earth’s axis 3) Axial precession : Wobbling of the earth’s axis Solar Variation- (sunspots and solar flares) * Timing of recent changes 1) before 3 MYBP warmer; then begin a series of glacial advances and retreats (about 20) until 12,000 YBP; last advance melted between 18,000 - 12,000 YBP 2) 12,000 YBP --- still cool with boreal forests in GA 3) 7,000 YBP --- warmer & dry, prairies farther east than present
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4) up to 2000 YBP --- gradual cooling 5) 1000-1200 AD (800 YBP) --- slight warming trend
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