Chapter10_post

Chapter10_post - Ch. 10-Climate, Climate Change, and...

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Ch. 10--Climate, Climate Change, and Weather Principles Controls on Global Climate Change Amount of incoming solar radiation controlled by Earth’s orbital parameters: Eccentricity Tilt Wobble Amount of heat retained controlled by: Surface reflectivity Greenhouse effect Circulation Patterns How ancient temperatures are measured Earth’s climate history over the last 500 million and 500 thousand years Sources of greenhouse gases Recent trends in global greenhouse gas abundance and global temperatures Expected effects of global warming (increased land and ocean temperatures, precipitation changes, arctic thaw, sea level rise, changes in ocean circulation patterns Expected impacts to human lives and lifestyles Mitigation strategies Weather principles Heat transfer Atmospheric layers Horizontal and vertical air movement Global air circulation patterns Fronts The hydrologic cycle Precipitation
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A refresher: days and seasons on Earth
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Earth’s Orbital Parameters Eccentricity—describes the shape of Earth’s orbit around the Sun (circular to elliptical) Tilt (a.k.a. ―obliquity‖)– the angle of Earth’s spin axis. It varies from 21.5-24.5 degrees Wobble (a.k.a. ―precession‖)—changes in the direction of tilt of Earth’s spin axis
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Glacial Advance and Retreat: Milankovitch’s Theory • These orbital parameters are not fixed. In fact, they vary cyclicly through time, and are responsible for driving changes in Earth’s climate. • These Milankovitch cycles affect how much radiation is received at the poles, which in turn strongly affects the extent of glacial surfaces on Earth • Eccentricity: 100,000 yr cycle • Tilt: 41,000 yr cycle • Wobble: 19,000-23,000 yr cycle
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How do we measure ancient temperatures? Answer: Past global temperatures are estimated from oxygen- isotope ratios ( 18 O: 16 O) Light Heavy Water vapor (H 2 O) with 16 O condenses slower Water vapor (H 2 O) with 18 O condenses faster 8 neutrons 10 neutrons
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How do we measure ancient temperatures?
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How do we measure ancient temperatures? Oxygen-isotope ratios ( 18 O: 16 O) are preserved in glacial ice or sedimentary material (which contains marine organisms’ shells)
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Last 500,000,000 years of climate history Data of Veizer et al . (1999), http://en.wikipedia.org/wiki/Image:Phanerozoic_Climate_Change.png
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Last 500,000 Years of Climate History Climate change was dominated by the 100,000 year cycle, with glacial periods lasting 70-100 thousand years punctuated by brief warm interglacials lasting 10-20 thousand years
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The glacial ice masses were at peak extent ~20,000 years ago, covering ~27% of today’s land, including all of Canada and part of the northeastern US. Sea level was 130 m lower than
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This note was uploaded on 02/02/2010 for the course GEO 107 taught by Professor Stidham during the Fall '08 term at SUNY Stony Brook.

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Chapter10_post - Ch. 10-Climate, Climate Change, and...

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