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3-16 & 3-18

3-16 & 3-18 - CLIMATIC CHANGE climate is dynamic it...

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CLIMATIC CHANGE ** climate is dynamic , it doesn't stay the same ** there are daily & monthly & annual averages, SO ** climate change is a significant change in these averages over tens or hundreds of thousands of years ** climate system ; the interaction of all spheres (atmosphere, lithosphere, biosphere, hydrosphere) * when change occurs in one sphere, it affects the other spheres ** climates have changed in the past at various times & scales, so will probably continue to change *** Evidence of climate change : Seafloor sediments , Oxygen isotope analysis , Tree rings , Palynology , Geology , Historical Records sea floor sediments : change in marine life due to changing climate; the relative abundance of warm- and color water species, or morphological variations in a particular species resulting from environmental factors/change. oxygen isotope analysis: the ratio of 18 O to 16 O in calcareous marine microfauna & from ice cores can indicate glacial vs. inter-glacial periods * this ratio depends on the ocean water T° * 18 O doesn’t evaporate out of the seawater as easily as 16 O under colder water conditions, thus more 18 O will be left in ocean water & thus more will combine with CaCO 3 when it recrystallizes to form shell material * SO, when T°s are colder the ratio: - in ice cores is more 16 O than 18 O than under warmer conditions and in seashells is more 18 O than 16 O than under warmer conditions tree rings: indicates dry vs. wet periods; relatively short-term * wider rings usually indicate wetter periods & narrower rings drier palynology (study of fossil pollens): indicate wet vs dry and cool vs warm
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periods by type of plant pollen; certain species may only exist in warm weather, others in cold (tropical plants vs spruce or fir of subpolar region) EX: pollen of spruce species now only found in Canada are found in soil records in Georgia from period of last Ice Age (15,000 ybp) geologic formations : certain formations will only form under certain climatic conditions, for example coal deposits result from areas of thick vegetation, usually rainforest human historical records : anecdotes & observations written down by people about abnormal weather patterns, like a warmer or colder winter than normal * can only go back for relatively for short period of time Changes in ability of oceans to store CO2, & heat Changes in ocean currents : directions and/or temperatures, Changes in average sea level : change amount of CO2 & heat stored Changes in l evels of photosynthesis activity : affect CO2 levels Changes in storage of carbon in soils : affect CO2 levels Changes in cloud cover : change temps at the Earth’s surface *** Climate change theories: * Non-human Induced Causes : Plate tectonics : land area may "move" into a different climate; could "trigger" a local glacial period, or inter-glacial period Volcanic activity : increases dust & ash in atmosphere, blocking-out sunshine --> decreasing T°, potentially increasing size of ice masses Astronomical theory Eccentricity : changing the shape of Earth’s orbit; average period of about 95,800 years; varies solar receipt Obliquity : changes in
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3-16 & 3-18 - CLIMATIC CHANGE climate is dynamic it...

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