Power14_GlobalChange - Oct 31-Happy Halloween Global change...

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1 Oct. 31--Happy Halloween! Global change Atmosphere, climate, biosphere Systems, positive and negative feedbacks Alternate ecosystem states --Pleistocene steppe-->tundra --Hudson Bay marsh-->mudflat Sustainability, Resilience 2 Antarctic ice core archives climate and atmospheric composition over past 740,000 years This ice is about 491,0000 years old 3 The concentration of CO2 in air today is higher than it has been in the last 650,000 years, and probably since it has been in the last 50 my. CO 2 ( ppm ) Before 1850 274 1958 (Keeling) 316 2005 370 2075 (est.) 540 4 1995-2004 vs 1940-1980 5 Evidence of global warming •Glacier shrinkage on mountains around the globe •Permafrost melting in Arctic •Acceleration of Greenland deglaciation due to moulins •Warming of upper layers of the ocean •Melt of Arctic sea ice-- opening of the Northwest Passage 6 Melting permafrost, ‘drunken trees’
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7 Chapin, Zimov 8 Thermokarst lakes Water will be more heterogeneously distributed in Arctic landscape 9 The area burned in western North America has doubled in the last 40 years 10 System : group of entities united by interaction or interdependence to form or act as an entire unit Feedback Loops can enhance or buffer changes that occur in a system. Positive feedback : change (increase or decrease) in some variable results in the same type of change (increase or decrease) in a second variable, Enhancing or amplify changes; destabilizing a system by moving a it away from equilibrium.
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