Notes From 08-25-09

08/25/09 Proxy data: look at fossil record (microfossil or pollen in lake settlements) • Sediment deposited over long periods of time • Core of settlement has record of pollen • shows climate change by slicing core, look @ microfossils of pollen and construct types of trees in that region & determine climate ice cores: taken from glacier or Antarctic ice sheath • drill and take core sample • slice core sample and look at the bubbles in the ice; can reconstruct when core was laid down isotope abundance (tool used) • carbon 12 (stable isotope of carbon) • carbon 13 (“) not as abundant as 12C • important tool for climate change • oxygen in water (temperature) can be used to study climate modeling • constructed using known temperature over period of time • hindcasting: ex: known temperature and known greenhouse gas – able to identify future changes • also important management tool What’s happening with the climate? • CO2 increasing over centuries, esp. around mid-1800s due to Industrial Revolution 13C • • • •

12 & 13 behave differently; 12C is lighter Any RX that involves C; lighter isotope favored Ex: plant intake of C. plants will have more 12C based on diffusion alone. More favoring of 12C during photosynthesis. Fossil fuels – C taken from atmosphere & deposited long time ago

Global carbon budget: • About twice as much C stored in soils than in atmosphere • Deep ocean – huge reservoir for C storage • Almost 7x more carbon in fossil fuels than in atmosphere • Releasing the C from its storage reservoirs will increase C levels in the atmosphere to extreme proportions Tectonic effects cause climate change • Glaciers important in controlling climate

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Glaciers are land ice – continents must be near poles to form glacier (ex: Antarctica @ S.P.) Volcanoes effect short-term climate change; major eruptions cause cooling due to releasing ash into stratosphere which blocks sunlight

*Milankovitch theory – Earth’s movement around sun causes change in climate • Eccentricity – radiation proportional to the square of the distance from the sun, not the actual distance • Obliquity • Precession • burning fossil fuels is changing climate so may override these changes in the future