1. Revised by Daniel Brown
Carbon Cycle Basics
Ranga Myneni
Boston University
Revised by Daniel Brown
Egon Schiele ( )
Autumn Sun 1
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2. Carbon Pools
Carbon is stored on our planet in the following major pools:
as organic molecules in living and dead organisms found in the biosphere;
as the gas carbon dioxide in the atmosphere;
as organic matter in soils;
in the lithosphere as fossil fuels and sedimentary rock deposits such as limestone, dolomite and chalk;
in the oceans as dissolved atmospheric carbon dioxide and as calcium carbonate shells in marine organisms.
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3. Global Carbon Cycle
Carbon is exchanged between the active pools due to various processes –
photosynthesis and respiration between the land and the atmosphere, and
diffusion between the ocean and the atmosphere.
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4. Atmospheric CO2 Concentration-2
In 1958, the concentration of CO2 was about 315 ppmv, and the growth rate was
about 0.6 ppmv/yr. This growth rate has generally been increasing since then; it
averaged 0.83 ppmv/yr in the 1960s, 1.28 ppmv/yr during the 1970s, and 1.53
ppmv/yr during the 1980s. The concentration in 2006 was over 380 ppmv.
The annual cycle in the Mauna Loa record is due to the seasonality of vegetation.
In early spring, the concentration of CO2 is at its maximum, and as the plants
green-up, the concentration drops, reaching a minimum value towards the end of
the summer, and when leaves fall, it starts to build up again. This swing in the
amplitude is most pronounced in the records from the northern high latitudes,
where it can be as large as 15 ppmv.
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5. Atmospheric CO2 Concentration-3
There are at least three arguments to be made for the case that the observed
increase in atmospheric CO2 concentration is due to emissions related to human
activity.
The rise in atmospheric CO2 concentration closely follows the increase in
emissions related to fossil fuel burning.
(2) The inter-hemispheric gradient in atmospheric CO2 concentration is growing
in parallel with CO2 emissions. That is, there is more land mass in the
Northern hemisphere, and therefore more human activity, and thus, higher
emissions, which is reflected in the CO2 growth in the Northern hemisphere
(compared to the SH).
(3) Fossil fuels and biospheric carbon are low in Carbon 13 (an isotope). The ratio
of carbon 13 to carbon 12 in the atmosphere has been decreasing.
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6. Graphing Parent Functions Linear Quadratic Square root Exponential
We can use graphs to predict what we think the trend line for the concentration of CO2 will look like.
Parent Functions
Linear
Quadratic
Square root
Exponential
Sinusoidal

7. Parent Functions 1) Linear
What is true about the rate of any linear function?
Will this be true for the concentration of CO2 emissions?

8. Parent Functions 2) Quadratic
Would a quadratic function better model the concentration of CO2?

9. Parent Functions 3) Square Root
Would a square root function better model the concentration of CO2?
How might we use a square root function model in the future?

10. Parent Functions 4)Exponential
Would a exponential function better model the concentration of CO2?

11. Parent Functions 5)Sinusodial
Would a sinusoidal function model the concentration of CO2?
Do you think the amount of CO2 fluctuates over time like the graph?

12. Prediction of Atmospheric CO2 Concentration
What do you predict a graph of the concentration of CO2 in the atmosphere over the past 400,000 years will look like?
Is the concentration always increasing?
Does the concentration increase sometimes and decrease at other times?

13. Historical Atmospheric CO2 Concentration
This figures shows that the concentration of CO2 has never been grater than 300
ppmv for the past 400,000 years.
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14. Prediction of Atmospheric CO2 Concentration
What do you predict a graph of the direct measurements of the concentration of CO2 in the atmosphere will look like?
Recall that in 1958, the concentration of CO2 was about 315 ppmv, and the growth rate was about 0.6 ppmv/yr. Also, The concentration in 2006 was over 380 ppmv.
Start your graph for the year 1958 and predict all the way up to 2050

15. Atmospheric CO2 Concentration-1
Accurate and direct measurements of the concentration of CO2 in the atmosphere
began in 1957 at the South Pole and in 1958 at Mauna Loa, Hawaii.
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16. Prediction of Global Average Temperature
What do you predict a graph of the global average temperature will look like?

18. Combining Graphs
If we plot a graph of the concentration of CO2 in the atmosphere along with the global average temperature, what will the graph look like?
Make your X-Axis time from 1900 to 2010
Make one side of your y-axis CO2 concentration, and make the other global average temperature