Copy of Lab 10 Carbon and Climate
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106
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Dec 6, 2023
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GEOSCI/ENVIR ST 106: Environmental Geology
Lab 10: The Carbon cycle and Climate
Assignment overview:
The carbon cycle is responsible for the movement of carbon between
various reservoirs in the Earth: the ocean, atmosphere, soil, rocks, and life. Because Earth’s
temperature is sensitive to the amount of carbon-bearing molecules in the atmosphere (carbon
dioxide, methane, and more), understanding how Earth’s carbon cycle works is critical for
understanding how Earth’s climate is going to change in the future. In this lab, you will explore
the processes that influence carbon concentrations in the atmosphere.
Instructions:
Fill out each red highlighted field (_________) according to each question’s
instructions.
Submission:
To submit the assignment on Canvas, use the following steps:
1.
In Google Docs, generate a PDF: File → Download as → PDF Document
2.
In Google Docs, use Share → Get Shareable Link, and copy the link address
3.
In Canvas, upload your PDF to the assignment.
4.
In Canvas, paste the link address to your Google Doc in the assignment comments.
Potentially useful things:
This lab will require doing some calculations involving multiplication
and division. To arrive at the right answers, it will be helpful to carefully keep track of the units in
your calculations. To help with this, you may find the following numerical conversions useful. It
will also be useful to review the information on these topics that was covered in lecture.
1°C = 1.8°F
1 ppm = 1 part per million = 10
-6
= 0.000001
1 ppb = 1 part per billion = 10
-9
= 0.000000001
1 ppt = 1 part per trillion = 10
-12
= 0.000000000001
1 ton = 10
3
kg = 1,000 kg
1 Gigaton = 10
12
kg = 1,000,000,000,000 kg
1
Figure 1.
Net Primary Productivity (NPP) on land in units of grams of carbon (g C) per
m
2
of the Earth’s surface per year. Figure from Haberl et al. (2007).
Figure 2.
Net Primary Productivity (NPP) in the ocean in units of grams of carbon per m
2
of the Earth’s surface per year. Figure from NASA Goddard Agency.
2
1. Net Primary Productivity (NPP) is a quantity that describes how quickly organic material is
generated through the growth of plants and animals. NPP has units of the mass of carbon
(g of C) per square meter (m
2
) of the Earth’s surface per year. In other words, it’s a proxy for
the rate at which new life is growing. For example, if the only thing growing in a 1 m
2
garden
were a cantaloupe, and if that cantaloupe grew and gained 1000 g of carbon over one year,
then that little garden patch would have a NPP of 1000 g of carbon per m
2
per year. These
are the units of NPP in Figures 1 and 2, which show global maps of NPP on land and in the
oceans, respectively.
(a) Examine Figure 1. In what region on land does the highest NPP tend to be found?
What is the maximum value NPP reaches on land? Based on the material discussed in
lecture, why does NPP tend to be highest there? (3 points)
Location: __Northern South America, Brazil_______
Maximum value: ___1200-1500______
Reason: Amazon rainforest
(b) Examine Figure 2. In what region in the oceans does the highest NPP tend to be found?
What is the maximum value NPP reaches in the oceans? Based on the material discussed
in lecture, why does NPP tend to be highest there? (3 points)
Location: ____Coasts of China_____
Maximum value: ____800_____
Reason: ____deep ocean water gets pushed up by the coasts so organic matter or marine
snow gets pushed up to the surface and allows life to flourish_____
(c) Where is NPP higher on average: On land or in the ocean? (1 point)
____land_____
3
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Figure 3.
Measurements at Mauna Loa in Hawaii show a steady increase in atmospheric
carbon dioxide (CO
2
) concentrations since the mid-20
th
century. The red line shows the
concentration each month, and the black line shows a smoothed moving average
through the data.
2. (a) The red line in Figure 3 shows measurements of atmospheric carbon dioxide (CO
2
)
concentrations measured at Mauna Loa, Hawaii, from 1958 to the present. Based on the data
in this figure, what is the current atmospheric CO
2
concentration? Be sure to report the most
recent value in this figure and to include the units in your answer. (1 point)
____A little over 410 ppm _____
(b) What is the current mass of carbon dioxide in the atmosphere? To calculate this, multiply the
mass of the atmosphere (~5.1·10
18
kg) by the atmospheric CO
2
concentration that you
measured in the previous question and the fraction of a CO
2
molecule’s mass that is carbon
(i.e., the molar mass of carbon (12 g/mol) and the molar mass of CO
2
(44 g/mol)). In this
equation, be sure to represent the concentration as a fraction. For example, if half of the
atmosphere were made of CO
2
, the value to use for atmospheric CO
2
concentration in this
equation would be 0.5. (1 point)
𝑀??? ?? ?????? ?𝑖??𝑖?? = (𝑀??? ?? ??????ℎ???)(𝐶𝑂
2
??????????𝑖??)
𝑀???? ???? ?? 𝐶
𝑀???? ???? ?? 𝐶𝑂
2
__(5.1*10^6)(410*10^-6)(12/44)=570.3 gigatons _______
4
(c) How much have atmospheric CO
2
concentrations
increased since this monitoring program
began in 1958? (1 point)
____about 100ppm_____
(d) What was the mass of the carbon dioxide in the atmosphere in 1958? Use the same formula
you used in part (b) above, but with the peak 1958 concentration. How much CO
2
has been
added to the atmosphere since 1958? As in part (a), be sure to include the units. (2 points)
Mass of atmospheric CO
2
in 1958: ____(5.1*10^6)(315*10^-6)(12/44)=438.1 gigatons_____
Extra mass of CO
2
added between 1958 and the present: ____132.2 gigatons_____
5
Figure 4.
Carbon fluxes to and from the atmosphere (image from Figure 18.1 in the
textbook, Montgomery (2019),
Environmental Geology
, 11th edition). Numbers in this
figure represent the rate at which carbon is transferred between reservoirs in units of
billions of tons of carbon per year.
3. As discussed in lecture earlier this semester, the residence time is defined as the length of
time a given object stays in a given reservoir before leaving it. For example, the average
residence time of a water molecule in the ocean is about 1000 years. The average residence
time is calculated as the mass of the reservoir divided by the rate at which new mass comes into
the reservoir.
𝑅??𝑖????? ?𝑖?? (?????) =
𝑀??? ?? ???????𝑖? (??)
𝑅??? ?? ?ℎ𝑖?ℎ ???? 𝑖? ????? ?? ???????𝑖? (??/????)
(a) Examine Figure 4 closely. Pay special attention to how the figure shows carbon being added
to and removed from the atmosphere. How much more carbon is added to the atmosphere
each year than is removed from it? (1 points)
____197-194=3 billions of tons of carbon per year._____
(b) Given your answers to the preceding questions and the information in Figure 4, what is the
current average residence time of carbon in the atmospheric reservoir? (2 points)
____1.7*10^6 years_____
6
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Figure 1.
Anomalies in July global average temperature from 1880 to 2019. Here, the
y-axis indicates the difference between each year’s global average July temperature and
the 20
th
century’s average July global temperature. For example, a value of 0.2°C in a
given year indicates that July that year was 0.2°C hotter than the 20
th
century average.
See the following link for a zoomable version of this figure that can help you identify
each year’s anomaly.
https://www.climate.gov/news-features/understanding-climate/climate-change-global-tem
perature
4. (a) Follow the link in the caption to Figure 1. In the article the link takes you to, zoom in
on the data in the first figure, which shows the same data as Figure 1 here in the lab. Scroll
your cursor over the bars in this graph to reveal a text box with the temperature anomaly.
Which year was coldest? Which year was hottest? How much colder and how much hotter
were those years than the 20
th
century average? (2 points)
____The coldest year was 1917, and the warmest was 2016. 1917 was 0.64 below the average
and 2016 was 1.33 above the average._____
(b) What are the five hottest years in this record? (1 points)
____2016, 2017, 2020, 2023, 2019_____
(c) When was the most recent year temperatures were lower than the 20
th
century average?
(1 point)
7
____1979_____
Figure 2.
Rate of change in temperature between 1990 and 2019. Here, the units are
degrees Fahrenheit per decade.
5. (a) Examine the map in Figure 2. Based on these data, what part of Earth warmed the
most between 1990 and 2019, and at approximately what rate? (1 point)
____The arctic and eastern europe at about 1F/decade warming._____
(b) What geographic region cooled the most over this time, and at approximately what rate?
(1 point)
____The bottom of south america at approximately 0.5 F/decade warming._____
8
EXTRA CREDIT
Table 1.
Global warming potentials of different greenhouse gases and their atmospheric
concentrations. (Concentrations are listed in parts per million (ppm), parts per billion (ppb),
or parts per trillion (ppt). See Unit Conversions on the lab’s first page.) These numbers
quantify the capacity of a certain amount of a gas to induce a certain amount of warming
over 100 years, relative to the warming induced by the same amount of carbon dioxide over
the same time.
Gas
Global warming potential
Concentration
Carbon dioxide (CO
2
)
1
415 ppm
CFC-11
5350
225 ppt
Methane (CH
4
)
34
1850 ppb
Nitrous oxide (N
2
O)
298
330 ppb
6. (a) Some greenhouse gases are more efficient at absorbing Earth’s emitted radiation than
others, which means that they generate more warming per molecule. This amount of warming
each type of gas generates is known as its global warming potential. Table 1 shows the global
warming potential of several greenhouse gases relative to that of carbon dioxide over a
100-year interval; that is, each gas’s warming potential has been scaled to that of carbon
dioxide. For example, one molecule of methane warms the Earth about 34 times more than one
molecule of carbon dioxide does. By definition, under this scaling, the global warming potential
of carbon dioxide is 1.
In the atmosphere, the amount of warming accomplished by a given gas depends on its global
warming potential as well as how much of that gas is in the atmosphere—i.e., its concentration.
For a given gas, this can be calculated as the product of its global warming potential and its
concentration. Use the information in Table 1 to calculate the ratio of the warming produced by
carbon dioxide to the produced by each of the other gases. (3 points)
Ratio of warming by CO
2
to warming by CFC-11: ____1:5350_____
Ratio of warming by CO
2
to warming by CH
4
: ____1:34_____
Ratio of warming by CO
2
to warming by N
2
O: ____1:298_____
(b) Based on your answer to part (a), list the four gases in Table 1 in order from the largest
influence on Earth’s climate to the smallest. (1 point)
___CFC-11, nitrous oxide, methane, carbon dioxide ______
9
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(c) Global climate models project that carbon dioxide concentrations may reach 600-1000 ppm
by the year 2100. How much warming would that much carbon dioxide generate relative to the
amount of warming currently generated by carbon dioxide? Express the upper and lower
bounds on this range as the ratio between the amount of warming that this carbon dioxide will
produce to the amount of warming carbon dioxide currently produces. (2 points)
___CO2 with concentrations of 600-1000ppm have a warming potential of 1.45-2.45. With the
lower bound being warming with 600ppm and the upper bound warming at 1000ppm. It is in a
1:1.45 ratio relative to right now to a 1:2.45 ratio______
References
Bogdanova, S. V., Pisarevsky, S. A., & Li, Z. X. (2009). Assembly and breakup of Rodinia
(some results of IGCP Project 440).
Stratigraphy and Geological Correlation
,
17
(3), 259.
Haberl, H., Erb, K. H., Krausmann, F., Gaube, V., Bondeau, A., Plutzar, C., ... &
Fischer-Kowalski, M. (2007). Quantifying and mapping the human appropriation of net
primary production in earth's terrestrial ecosystems.
Proceedings of the National
Academy of Sciences
, 104(31), 12942-12947.
10