Carbon Cycle

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Carbon Cycle
Also see Chapter 6 of IPCC 2013 http//www.climate
change2013.org/report/full-report/
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Carbon Cycle
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Carbon Cycle
Approximately 0.2 Gtonne/year goes into solid
earth And 0.2 Gt/yr goes into atmosphere from
outgassing Today 2012 approximately 10 Gt/yr are
put into the atomosphere from Fossil fuel
emission and cement manufactoring Thus natural
fluxes from volcanoes and outgassing account for
about 2 of the anthropogenic sources.
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Carbon Cycle
1.6 Gt/yr from deforestation 6.4 Gt/yr from
fossil fuel emission (1994) 1.6/8.00.2020
(deforestation accounts for 20 of total Carbon
flux into atmosphere) Biosphere takes up (2.6 Gt
/yr more ) carbon than it did in preindustrial
times.
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Biosphere takes up (2.6 Gt /yr more ) carbon than
it did in preindustrial times. Preindustrial
RR120 GT/yr Now it is 122.6 Gt/yr
RRContent/lifetime Preindustrial content 597
Gt Now(1994) 763 Gt
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2000-2009 mean land use changes account for about
1.1/8.912 of anthropogenic carbon emissiosn
Figure 6.1 IPCC 2013 WG1AR5
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The atmosphere contains the least amount of
carbon and sediments and rocks contain the most.
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The ultimate removal of carbon from the climate
system is an extremely slow process. In nature
this is balanced by the slow injection of carbon
into the atmosphere by volcanoes and outgassing
near mid ocean ridges. When humans bring carbon
in the form of fossil fuels (coal, natural gas,
oil) to the surface they rapidly disrupt this
balance.
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The annual cycle of vegetation is dominated by
flucuations in the Northern hemisphere.
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Short Term Carbon Cycle
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Short Term Carbon Cycle
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As atmospheric CO2 increases from photosynthesis
or combustion, O2 decreases. O2 is presently
decreasing faster than atmospheric CO2 is
increasing. This indicates the importance of the
oceans in removing CO2 from the atmosphere.
13C/12C ratios in atmospheric CO2 are lower for
human activity than for natural processes.
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Seasonal Cycle is driven by Northern Hemisphere
Vegetation
When the atmospheric carbon dioxide increases
plants are growing or decaying? Circle one.
When the atmospheric carbon dioxide decreases
plants are growing or decaying? Circle one.
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Seasonal Cycle is driven by Northern Hemisphere
Vegetation
When the atmospheric carbon dioxide increases
plants are growing or decaying? Circle one.
When the atmospheric carbon dioxide decreases
plants are growing or decaying? Circle one.
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From www.learner.org/courses/envsci/ Unit 12
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Photosynthesis buffers climate change (i.e. is a
negative feedback)
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Between -10 deg C and 30 deg C The rate of
photosynthesis increases With increasing
temperature.
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Atmospheric carbon dioxide concentrations are
strongly correlated with surface temperatures on
most time scales.
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sunlight
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The solubility of gases like CO2 in water
increases with decreasing temperature.
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Positive climate feedback
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Phytoplankton shell Diatom (SiO2)
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Phytoplankton Shell coccolithophorid (CaCO3
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Zooplankton shell Foraminifer (CaCO3)
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Zooplankton shell Radiolarian SiO2
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More Ice on continents leaves more 18O in oceans
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Ocean Biological Pump. Slowly taking Carbon to
the seafloor for ultimate burial. Most of this
carbon (99) is recycled back to the surface a
very small fraction is removed from the ocean
into the deep earth.
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Coastal Zone Color scanner
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http//earthobservatory.nasa.gov/IOTD/view.php?id
1297
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pH 7.0 is neutral (not acidic not alkaline) less
than 7.0 is acidic greater than 7.0 is alkaline.
pH of 2.0 is highly acidic.
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Long term Carbon Cycle
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Draw a causal loop diagram Describing the
feedback structure at left. Is this a positive
or negative feedback structure?
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All loops are negative feedbacks
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It appears that weathering of carbonate rock does
not remove CO2 from the climate system. However
some of the newly formed CaCO3 IS incorporated
into shells and fall to the bottom of the ocean
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Weather of silicate rock removes CO2 from the
climate system.
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Outgassing is the release of CO2 via volcanic
activity and seafloor spreading. Over the long
term (millions of years) the CO2 flux from
outgassing is in near balance with the removal of
carbon from the subduction of carbonate
sediments. CO2 from outgassing and volcanoes
contributes about 2 to the total global
emissions in 2010.
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Global temperatures would increase with fast sea
floor spreading and decrease with slow sea floor
spreading.
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Small fragmented rocks have much more surface
area compared to large rocks and hence weather
more easily.
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80 of chemically weathered ions in Amazon come
from the Andes. The Andes have been uplifted in
the past 20 Million years.
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Most uplift in the western US region occurred 70
to 45 Myr ago
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Biomass growth (Lichen) on rocks can enhance the
weathering process.
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The end
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Residence Time
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Residence Time
Sourceinflow
Removal Rate outflow
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Residence Time
Sourceinflow
Removal Rate outflow
At equilibrium (steady state)
inflow outflow
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A lake has an annual average outflow of 5
Mgallons per year (5,000,000 gal/yr) and an
annual average content of 10 Mgallons. From this
information estimate the residence time for the
lake. If the annual mean inflow into the lake
increased to 20 Mgallons/yr what would be the new
steady state content of the lake?
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A lake has an annual average outflow of 5
Mgallons per year (5,000,000 gal/yr) and an
annual average content of 10 Mgallons. From this
information estimate the residence time for the
lake. If the annual mean inflow into
the lake increased to 20 Mgallons/yr what would
be the new steady state content of the lake?
20 Mgal/yr2 yr40 Mgal
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CFC-12 has an atmospheric lifetime of 100 yrs.
In the 1980s the emission rate of CFC-12 was 22
ppt/yr. What is the corresponding equilibrium
concentration of CFC-12?
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CFC-12 has an atmospheric lifetime of 100 yrs.
In the 1980s the emission rate of CFC-12 was 22
ppt/yr. What is the corresponding equilibrium
concentration of CFC-12?
22 ppt/yr100yr2200 ppt
Note the highest CFC -12 concentration level
reached was 540 ppt. International agreements to
phase out production and use of CFC-12 ( reduce
emissions) were able to keep levels down.
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CFC-12 has an atmospheric lifetime of 100 yrs.
In the 1980s the emission rate of CFC-12 was 22
ppt/yr. What emission rate (source) would
limit the steady state atmospheric concentration
of CFC-12 to 500 ppt?
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22 ppt/yr100yr2200 ppt
CFC-12 has an atmospheric lifetime of 100 yrs.
In the 1980s the emission rate of CFC-12 was 22
ppt/yr. What emission rate (source) would
limit the steady state atmospheric concentration
of CFC-12 to 500 ppt?
This is less than 25 of the 1980s emission rate.
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water
Porosity the fraction of rock that is pore
space Permeability the ability of a fluid to be
able to flow through a rock formation. Gas, oil,
and water are often trapped in porous rock with
an impermeable cap. Gas on top, then oil, then
water
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From www.learner.org/courses/envsci/ Unit 1
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http//en.wikipedia.org/wiki/FileHubbert_peak_oil
_plot.svg