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5 major reservoirs

5 major reservoirs. 5 major reservoirs: atmosphere, terrestrial biosphere , oceans (and ocean critters), sediments, earth’s interior. Short term cycle (days->years ) Residence time=(Storage)/(Flux) Long term cycle (millions of years ).

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5 major reservoirs

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  1. 5 major reservoirs

  2. 5 major reservoirs: atmosphere, terrestrial biosphere, oceans (and ocean critters), sediments, earth’s interior

  3. Short term cycle (days->years) Residence time=(Storage)/(Flux) Long term cycle (millions of years)

  4. Earth’s long term climate history: Is any of this due to the long-term, geologic CO2 cycle?

  5. Can mountains change the global climate?

  6. More recent (Pleistocene, Holocene) Climate • in last 1.8 million years (Pleistocene) repeated glacial cycles.

  7. Glacial Consequences • Sea level – Ice ages cause sea level to rise and fall. • Sea level was ~ 100 m lower during the most recent Ice age • If ice sheets melted, coastal regions would be flooded.

  8. Causes of Glaciation (Climate Change) • Long-term causes (millions of years) – Set the stage for ice ages. • Plate tectonics – Controls factors that influence glaciation. • Distribution of continents toward high latitudes. • Sea-level flux by mid-ocean-ridge volume changes. • Oceanic currents. • Atmospheric chemistry. • Changes in greenhouse gas concentrations. • Carbon dioxide (CO2). • Methane (CH4).

  9. Long-Term Climate Change • What causes long-term climate changes? • Volcanic gases trap heat, promote global warming. • Mid-Cretaceous rifting and expanded mid-ocean ridges. • Orogenic uplift consumes CO2 in rock weathering. • Leads to overall climatic cooling. • Uplift of the Himalayas attended Cenozoic cooling.

  10. Causes of Climate Change • Short-term causes (10’s to 100’s ka)– Govern advances and retreats. • Milankovitch Cycles changes in Earth’s orbit

  11. Causes of Climate Change Milankovitch cycles – Climate variation over 10’s to 100’s Ka predicted by cyclic changes in orbital geometry. • These variations lead to excess warming or cooling. • Ice ages result when cooling effects coincide.

  12. Causes of Climate Change • Short-term causes, con’t– Govern advances and retreats. • Changes in albedo (reflectivity). • Volcanic Activity • Sunspot activity • Oceanic thermohaline circulation changes. • atmospheric CO2 concentrations.

  13. Global Climate Change • Methods of Study. • Paleoclimates – Investigations of past climatic variation. • Computer simulations – Modeling past and future changes.

  14. Global Climate Change • Paleoclimates – Past climates are indicated by datable Earth materials that are climate sensitive. • Stratigraphic records – Sequences of rock strata. • Depositional environments are often climate-sensitive. • Coral reefs – Tropical marine. • Glacial tills – Cold and continental.

  15. Global Climate Change • Paleoclimatic evidence: • Paleontological – Faunal assemblages reflect climate. • Assemblage changes record climatic shifts. • Pollen in pond sediments. • Spruce (colder) vs. hemlock (warmer). • Trees (colder, drier) vs. grasses (warmer, wetter).

  16. Global Climate Change • Paleoclimates: • Oxygen isotopes – Two isotopes: 16O and 18O. • 16O water evaporates faster than 18O water. During ice ages… • 16O in seawater evaporates faster. • This water is trapped on land as ice. • Seas become 16O depleted, 18O enriched. • 18O/16O increases in remaining seawater. • Shells grown in this sea will reflect the altered 18O/16O ratio.

  17. Global Climate Change • Paleoclimates: • 16O water evaporates faster than 18O water. During interglacials… • Melting ice returns water to oceans. • 16O returns to oceans. • 18O/16O decreases. • Reflected in shells. • 400 Ka of 18O/16O data are archived in polar-region ice cores.

  18. Global Climate Change • Paleoclimates: • Oxygen isotope ratios are preserved in carbonate shells. • The oxygen in CaCO3 shells mirrors oceanic 18O/16O. • Sea floor sediments preserve ocean chemistry changes.

  19. Global Climate Change • Paleoclimates: • Growth rings – Tree rings can easily be dated. • Ring thickness reflects climatic changes. • Wetter, warmer = thicker; drier, colder = thinner. • Ring widths form time sequences. • Overlapping sequences yield a time scale.

  20. 1. Overview of Climate What Causes the Climate to Vary? Humans Plate Tectonics Volcanic Activity Sun

  21. Anthropogenic Changes • Global warming – Human GHG additions alter climate. • CO2 in the atmosphere has steadily climbed since 1958. • In 1958, CO2 was ~ 315 ppm; in 2000, CO2 was ~ 370 ppm. • Human additions of CO2 and CH4 outstrip natural removals. • Fossil fuel combustion (CO2). • Rice-paddy decay (CH4). • Cow flatulence (CH4).

  22. Th & Friday • Dr. Susan Kaspari (climate scientist)

  23. Exam #6 • Thursday, 8:00 am • This Room • Will cover and readings and lectures on: • Groundwater • Glaciers • Earth System/Climate Change

  24. Glacial Sediment Transport • Glaciers carry sediment of all sizes – lots of it! • Some sediment falls onto the ice from adjacent cliffs. • Some sediment is entrained from erosion of the substrate. • When glacial ice melts, this material is dropped.

  25. Sediment Transport on Ice • Moraines – Unsorted debris dumped by a glacier. • Lateral – Forms along the flank of a valley glacier. • Medial – Mid-ice moraine from merging lateral moraines.

  26. Depositional Landforms • End moraines form at the stable toe of a glacier.

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