Note_-_Chapter_19 - Global Change in the Earth System Global change Geology verifies that Earth changes constantly Why does it change constantly A

Note_-_Chapter_19 - Global Change in the Earth System...

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Global Change in the Earth System Global change - Geology verifies that Earth changes constantly - Why does it change constantly? - A plastic asthenosphere permits tectonic plate motion - A star is close enough to warm Earth and its atmosphere - Liquid water is possible; thus, weathering and erosion - Biotic evolution continually modifies the biosphere The Earth system - Life on Earth is due to interactions among the: - Lithosphere - Atmosphere - Hydrosphere - Biosphere - The “Earth System” is composed of these physical components interacting with the biosphere - The interlinkage of the physical and the biological: - Global changes transform or modify both realms - There are many ways to describe changes: - Gradual change - Catastrophic change - Unidirectional change - Cyclic change Unidirectional changes - Evolution of the solid Earth: - Planetesimal accretion - Melting and differentiation - Formation of the Moon: - Mars-sized protoplanet collides - Mantle blasted into space - Debris coalesced to form the Moon - Evolution of the atmosphere and oceans: - Volcanic gases created an early atmosphere - CO 2 , H 2 O, N 2 - Liquid water condensed to form the oceans - Photosynthetic organisms appeared - O 2 becomes a significant component of the atmosphere - Evolution of life - Life appeared on Earth before 3.8 Ga - Multicellular organisms appeared in Late Proterozoic and early Phanerozoic - Life inhabits all regions, within a few km of Earth’s surface
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Physical cycles - The supercontinent cycle: - Plate tectonics drives continental movement - Ocean basins open and close - Continental landmasses collide and rift apart - Supercontinents (like Pangaea) have formed several times - SL has risen and fallen many times over Earth’s history - +/- 300 meters during the Phanerozoic - Transgression (SL rise): shorelines move landward - Regression (SL fall): shoreline move seaward - Sedimentary rocks preserve evidence of sea-level change - Sea-level cycles are bounded by unconformities Biogeochemical cycles - Chemical fluxes between living and nonliving - Involve storage and transfer between reservoirs - Nonliving reservoirs: - Atmosphere - Lithosphere - Hydrosphere - Living reservoir - All living organisms: - Microbes - Plants - Animals The carbon cycle - A biogeochemical cycle that regulates climate - Volcanic CO 2 adds carbon to the atmosphere - Atmospheric CO 2 is removed in several ways: - It dissolves in water as carbonic acid and bicarbonate - Photosynthesis removes CO 2 - Weathering - Carbon may be stored for long periods of time - Limestones - Fossil fuels (coal and oil) - Organic shales - Methane hydrates - Carbon is returned to the atmosphere - Biotic respiration creates CO 2 from organic matter - Rapid oxidation (burning) of organic matter creates CO 2 - Metamorphism of carbonate rocks liberate CO 2 - Degassing removes dissolved CO 2 from water
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Global climate change -
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