OLIGOFRENI 60 %

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OLIGOFRENI 60 BIRDS AND PEANUT 70
NEPTUNE 77 FEMTO-PARSEC 75
DINOSAURS 60
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FIGURE 4-11
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FIGURE 4-12
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FIGURE 4-8
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FIGURE 4C
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FIGURE 4-9
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TABLE 4-3
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Figure 12
geology.asu.edu/reynolds/ glg103/sample_site.ht
m
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Sedimentary means of, or related to, sediment.
Sedimentary rock is rock formed from sediment.
image- Rob Fensome, Geological Survey of Canada
(Atlantic
Figure 11
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TABLE 4-2
lt 2 mm
lt 60 µm (0.06 mm)
lt 2 µm (0.002 mm)
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TABLE 4-1
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Summary
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(No Transcript)
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How did climate and CO2 levels change in Earths
history?Climate proxy records Ice cores from
glaciers as source of paleoclimate information
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Pleistocene Ice Ages
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• OLIGOFRENI 60
• BIRDS AND PEANUT 70
• NEPTUNE 77
• FEMTO-PARSEC 75
• DINOSAURS 60

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Sun more active than for a millennium
Lockwood, Physical Review Letters
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National Geographic
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1997
2000
Source AWI, NOAA
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(No Transcript)
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Arctic Ocean Meltdown Sea ice in the Arctic
Circle is decreasing at a rate of 37,000 km2 per
year and is now about 40 thinner than it was 4
decades ago. this sea ice recession has major
implications, from loss of polar bear habitat and
increased precipitation over parts of the Arctic,
to a theorized influx of fresh water into the
North Atlantic that could cut off the ocean
"conveyor belt" that transports heat around the
globe and helps govern the Earths climate
(Ruddiman)
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Pre-Cenozoic Climate Records
Temperature and precipitation for the past
half-billion years of Earth history, based on
isotopic and other indicators. General times of
very low temperatures, and possible ice ages, are
shown with a G.
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The Warm Middle Cretaceous

• During the Middle Cretaceous, the climate was one
  of the warmest in the Earths history. Evidence
• Warm-water marine faunas were widespread.
• Coral reefs grew 5-15 closer to the poles than
  today.
• Vegetation zones were displaced about 15
  poleward of their present position.
• Peat and coal deposits formed at high latitudes.
• Dinosaurs preferring warm climates ranged N of
  the Arctic Circle.
• Sea level was 100-200 m higher, implying the
  absence of polar ice sheets.
• Isotopic measurements of deep-sea deposits
  indicate that deep ocean waters were 15-20C
  warmer than now.
• Based on this evidence, global temperature is
  estimated to have been 6-14C milder than today.
  The temperature difference between the poles and
  the equator may have been as little as 17C
  compared to 41C today.

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The Warm Middle Cretaceous

• Why was the Middle Cretaceous so warm?
• Several factors were likely involved in producing
  such warm conditions
• geography,
• ocean circulation,
• atmospheric composition.
• The greenhouse gas CO2 appears to be a major
  factor.

A geochemical reconstruction of changing
atmospheric CO2 concentration and average global
temperature over the past 100 million years. High
CO2 values and high temperatures in the Middle
Cretaceous contrast with much lower modern
values. Other intervals of higher temperature and
CO2 occurred during the Eocene and the Middle
Pliocene.
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The Warm Middle Cretaceous

• Why was the Middle Cretaceous so warm?
• The most likely source CO2 entering the
  atmosphere is volcanic activity.
• Geologic evidence points to an unusually high
  rate of volcanic activity in the Middle
  Cretaceous.
• Vast outpourings of lava created a succession of
  great undersea plateaus across the central
  Pacific Ocean between 135 and 115 million years
  ago.
• The Ontong-Java plateau (twice the area of
  Alaska and 40 km thick).
• The eruptions could have released enough CO2 to
  raise the atmospheric concentration to 20 times
  the preindustrial value.

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Mantle Convection and Greenhouse Gases

• Recently, geologists have proposed that these
  vast lava outpouring are the result of a
  superplume.
• A superplume would originated from a substantial
  overturn of mantle rock.
• Downgoing slabs of lithosphere can stall near
  670 km depth.
• Hot lower mantle rises to replace the falling
  slabs, inducing a superplume.

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Mantle Convection and Greenhouse Gases

• Why was the Middle Cretaceous so warm?
• If the flushing hypothesis is correct, then
  plate tectonics cools the mantle in two styles
• In ordinary times, heat loss at spreading
  ridges couples with the downward plunge of cool
  lithosphere,
• In extraordinary timeswhen stalled slabs
  flush into the lower mantlesuperplumes would
  allow heat to escape more efficiently from
  Earths lower mantle and core.

• The warm Middle Cretaceous climate was a direct
  consequence of the cooling of the Earths deep
  interior.
• By the end of the Cretaceous, world temperatures
  had fallen substantially below levels reached
  earlier in that period.

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Eocene Warmth and Lithosphere Degassing

• In the Early Eocene, evidence points to warmer
  conditions, probably close to 20C higher than
  today.
• Alligator fossils on Ellesmere Island (at about
  78N latitude).
• Tropical vegetation at up to 45N latitude.
• Tropical marine surface-water organisms at about
  55N.
• Lateritic soils at up to 45N or S.

A geochemical reconstruction of changing
atmospheric CO2 concentration and average global
temperature over the past 100 million years.
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Eocene Warmth and Lithosphere Degassing

• Two processes may have contributed to the higher
  Eocene temperatures
• Greater poleward transfer of heat by the oceans
  (preventing the formation of polar sea ice).
• An increased concentration of CO2 in the
  atmosphere (two to six times the modern value)
  due to volcanism and crustal metamorphism.
• CO2 is released as a byproduct of the
  metamorphic reactions
• Studies show that regional metamorphism of the
  Himalayas may have been contemporaneous with the
  Eocene warming.
• At this time regional metamorphism occurred in
  Greece, Turkey, New Caledonia, Japan, and Western
  North America.

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Uplift, Weathering, and the Carbon Cycle

• Removal of atmospheric CO2 occurs during the
  weathering of orogenically uplifted silicate
  rocks.
• CO2 is removed from the atmosphere when carbonic
  acid is produced.
• As the weak acid decomposes the rocks,
  bicarbonate released by the weathering reactions
  is carried in solution by streams to the sea, and
  is there converted to calcium carbonate by marine
  organisms.

CaSiO3 H2CO3 --gt CaCO3 SiO2 H2O
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Uplift, Weathering, and the Carbon Cycle

• Maintenance of climate equilibrium
• Seafloor spreading controls CO2 generation along
  midocean ridges
• A possibly even larger source of CO2 is
  metamorphism of carbon-rich pelagic sediments
  carried downward in subduction zones.
• At the same time, CO2 is removed from the
  atmosphere by the weathering of surface silicate
  rocks.

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Uplift, Weathering, and the Carbon Cycle

• Maintenance of climate equilibrium
• If seafloor spreading speeds up, more CO2 enters
  the atmosphere, the Earth warms, etc.
• This speeds up the rate of chemical weathering
  of silicate rocks, which removes CO2.
• If spreading slows, less CO2 enters the
  atmosphere, the climate cools, and weathering
  rates decrease.
• Besides weathering, burial of organic carbon is
  another important negative feedback. High erosion
  can lead to rapid sedimentation, with carbon
  being quickly stored rather than being returned
  to the atmosphere
• Also tectonic uplift has been claimed to be the
  driving force behind atmospheric CO2 changes.
  Uplift could increase the rate of CO2 removal by
  increasing weathering processes.

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Continental Uplift and Climatic Change

• The height and form of the continents can
  strongly influence the world climate. Of singular
  importance has been the uplift of the Himalaya
  and Tibetan Plateau over the last 50 million
  years, caused by the collision of the Indian
  plate with Asia. This process has had a major
  effect on the climate of Asia, as well as the
  global circulation patterns. There is evidence
  that by about 8 million years ago (late Miocene)
  the Tibetan Plateau had reached an altitude high
  enough to intensify the Asian monsoon system and
  affect global climate.
• Global climate models have been used to compare
  conditions with a Tibetan Plateau and without
  (prior to uplift). These simulations, supported
  by geologic evidence, point to some major global
  changes

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Continental Uplift and Climatic Change

• Uplift has led to cooling of 8C over land on
  average (Tibet 16C)

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An Outlook to The Next Ice Age
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Maps show the likely ground- level temperature
changes in degrees Fahrenheit, if CO2 in the
atmosphere doubles its preindustrial levels,
then holds for several centuries (top), and if
CO2 quadruples its preindustrial levels over 140
years, then holds over several centuries
(bottom). MAPS GENERATED BY THE GEOPHYSICAL FLUID
DYNAMICS LAB ------------------------------------
------------------------------------
Jerry Mahlman, National Oceanic and Atmospheric
Administration's Geophysical Fluid Dynamics Lab
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U.S. vs. Worldwide CO2 emissions
1996 6085 MtCe
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Carbon Cycle
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CO2 Sequestration Options

• Separate CO2 from flue gas after fossil fuel
  combustion
• Burn fossil fuel with O2 only
• Prevents N2 from entering combustion
• Integrated Gasification-Combined Cycle (IGCC)
  power plant
• Gasify fuel to make syngas (CO and H2)
• Water-Gas shift reaction to CO2 and H2

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Captured CO2 Disposal Options

• Use it in Industrial applications
• Industrial need for CO2 is only 2 of annual
  power plant emissions
• Sequester It

Source Ormerod, 1994
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Deep Aquifer Storage

• Sleipner West Gas Field (North Sea)
• Separate CO2 and CH4
• Sequester CO2 in aquifer 1000 m deep
• Rate of 20,000 tonnes/week
• Equivalent to CO2 produced
  from a 140 MWe power plant
• Cost lt 50/tonne

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Deep Ocean Storage

• Already 140,000 billion tonnes of CO2 in
  ocean
• 90 of worlds CO2 entering ocean nowslowly.
  Will equilibrate over next 1000 years.
• Deep ocean sequetestration avoids large CO2
  peak and high rate of increase.

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Bioremediation of CO2

• Reforestation
• 3-10 dry tonnes CO2/hectare-yr at first
• Need to plant 1-2 Alaskas to mitigate CO2 from
  power plants alone
• Ocean algae fertilization
• Microalgae mitigation of CO2 in Flue Gas

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GreenFuel Bioreactor System

• Claim to be 5x more efficient than algae pond
  system