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12B. ClimateChange

S originally agreed then backed out adopted in 2001

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Unformatted text preview: on fossil fuels United Nations Kyoto Protocol 1997, 2001 International agreement in 1997 to reduce emissions of greenhouse gases, especially carbon dioxide U.S. originally agreed then backed out Adopted in 2001 by 180 nations – say economic impact minimal and need extreme Bush argues it is too expensive and excludes developing countries, BUT… The U.S. is responsible for 25% of current greenhouse gas emissions! Climate of the last million years For the past million years, we are able to resolve rapid, short-term fluctuations from cold to warm. During glacial period, The Earth’s average temperature was10°C; rit has averaged 15°C in the Holocene and is 15.8°C today Climate Trends (continued) •  New evidence suggests that most of the warming over the past 50 years is due to human activities. •  Human activities has altered the chemical composition of the atmosphere through the buildup of greenhouse gases primarily carbon dioxide, methane, and nitrous oxide. Anthropogenic Greenhouse Gas Increases •  For N. Hemisphere (most of the world's population) 2005 was hottest year on record since 1880, earliest year which reliable instrumental records were available. •  Heat-trapping emissions are driving the climate about three times more strongly now then they were in 1950. •  Major glacial events = ice age –  When glaciers grow and advance –  Last several million years –  Have occurred at various times in the last billion years –  Results in drop in global sea-level •  Earth currently in interglacial period –  10% of Earth currently ice covered –  Ice sheets may advance again in future North American portion of last ice age Coring Continental Ice Ice cores with climate records of the last ~400,000 yrs have been collected in the ice sheets of Greenland and Antarctica. Working With Glacial Ice Layering in the ice provides a time record, just like varved lake sediments. Geologists examine the stable isotope compositions and trapped gas contents (CO2 and CH4) of ice cores. Temperature variations recorded in the Vostok ice core, Antarctica Viking Expansion during Medieval Warm Period: Travel from Norway to Iceland and Greenland from 800-1200 Price of wheat went way up! Climate Trends Climate is influences by many fact...
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