CSUEB Environmental Science: Keeling Data Set CO2 Record Analysis

This homework assignment focuses on analyzing the Keeling data set, a long-term record of atmospheric CO2 concentrations from the Mauna Loa Observatory. Students are tasked with examining the data, understanding the units of measurement, identifying maximum and minimum values, and analyzing trends and oscillations. The assignment explores the relationship between CO2 levels and Net Primary Productivity (NPP), considering seasonal variations and the impact of photosynthesis. Students create graphs using Excel, calculate CO2 increase rates over different time periods, and predict future CO2 levels. The assignment covers topics such as seasonality, latitude, and the factors influencing CO2 uptake and release, providing a comprehensive understanding of the dynamics of atmospheric CO2.

Homework Assignment: Keeling Data Set
Modern Atmospheric CO2 Record (39 points)
Monthly atmospheric CO2 data an atmospheric monitoring stations, including the Mauna Loa
Observatory, Hawaii.
You will need access to excel to complete this exercise. If you don’t have it, you can download
office for free here as a CSUEB student:
https://www.csueastbay.edu/news/2015/06/06102015.html
All questions will need to be answered and uploaded into a link in Course Materials Week 7/8.
Unless otherwise stated, all questions are worth 1 point each.
I. Introduction
The measurements of atmospheric carbon dioxide (CO2) concentrations at the Mauna Loa
Observatory are derived from the Scripps Institution of Oceanography's continuous
monitoring program. This record constitutes the longest continuous record of atmospheric
CO2 concentrations available in the world. Monthly averages* of CO2 in water-vapor-free
air are given from March 1958 through present, except for a few interruptions.
A. Atmospheric CO2 Data
Open the Scripps data file that I have attached here. Open it in excel. Familiarize yourself
with the location of the station where the data was collected by checking out the related web
site: https://scrippsco2.ucsd.edu/data/atmospheric_co2/primary_mlo_co2_record.html Note
that there is one parameter, CO2, measured monthly. This website is best accessed NOT
USING SAFARI.
Task 1: Using the web page, scroll down to the Figure of monthly average CO2. Let’s examine
this data set. Answer these questions about the data. I know these are simple questions, but
the trends have significance.
1: What units are CO2 measured in?
Micro-mol CO2 per mole (ppm)
2: What are the maximum and minimum recorded CO2 for the timeframe 1958 – 2020?
Maximum= 414.83 [ppm]
Minimum= 313.21

3: Are the values increasing or decreasing with time?
The values are increasing with time
4: Are the data smooth or ragged as it increases or decreases?
The data are ragged as they increase
5: Do the data have a pattern, other than just continually going up?
The data has pattern other than continually going back. It increases to some maximum
value then decrease then the pattern repeats itself
Task 2:
6: What does the word “oscillation” mean?
Moving back and forth in a regular rhythm
7: What does it mean when we say this graph has regular, short term oscillations?
The data seems to increase to a maximum value and decrease to a minimum value before
repeating the same trend. This increase and decrease happens over a short time span.
Explore what is the cause of the short-period oscillation of CO2? (multiple parts to this
question):
To explore the answer to Q2c, you are to create a chart using the data in the excel file showing
ONLY the last 3 years of the CO2 records SPECIFICALLY January 2017 through January
2020. Recall that this is an "xy scatter plot" and NOT a "line plot" when using Excel's chart
function.
The x-axis should be date and the y-axis concentration of CO2. Note that the months are
listed in the documents as numbers 1= January, 2= February, etc, AND is translated into a
decimal of each year 2000.041 = Jan 2000, etc. Please use the “plotting in excel” document to
help you, and start early so you can ask the professor for help if needed.
This chart should show an xy scatterplot of Date and CO2.
8: Upload your chart to the homework (3 point)

2016.5 2017 2017.5 2018 2018.5 2019 2019.5 2020 2020.5
396.00
398.00
400.00
402.00
404.00
406.00
408.00
410.00
412.00
414.00
416.00
A Scatter Plot CO2 Concentration against Date in
Decimal Months
Decimal Date
concentration of CO^2(ppm)
9: How long is each oscillation? (From minimum to minimum, you can stretch out the graph
to help you see this)
1 year
10: What month(s) do CO2 maxima occur?
May
11: What month(s) do CO2 minima occur?
September
Think about seasonality and how it relates to CO2 uptake through photosynthesis and ocean
absorption. When plants are active and have adequate water, they take CO2 out of the
atmosphere. View this animation
(https://earthobservatory.nasa.gov/global-maps/MOD17A2_M_PSN) showing monthly
variations in net primary productivity and read the explanation.
12: What is Net Primary Productivity (NPP)?
NPP refers to the difference between how much carbon dioxide is taken by vegetation during
photosynthesis and how much carbon dioxide is released during photosynthesis.
13: What are the units of NPP?
Grams per square meter per day
14: What does NPP have to do with Carbon uptake from the atmosphere?
The greater the carbon uptake from the atmosphere the greater the NPP value
15: What does a negative number mean?
A negative value implies that respiration or decomposition is greater than carbon absorption
leading to more carbon release to the atmosphere compared to plant uptake.

16: What color is the negative number?
Tan
17: After viewing this video and reading the explanation, which month(s) do you think have
the GREATEST NPP (Positive CO2 uptake into vegetation)?
June and July
18: After viewing this video and reading the explanation, which month(s) do you think have
the LOWEST NPP?
December, January and February
Now go back and look again at the graph you made of the last three years of the Mauna Loa
CO2 data and compare to the NPP trends with seasons you just looked at.
19: Why might these oscillations occur when they do?
The oscillations occurs the way they do because of seasonal changes which is tied to changes
in the hours of sunlight which influence the time available for the plants to photosynthesize
20: Is Mauna Loa at high latitudes or low latitudes on the planet?
Mauna Loa is a low latitude on the planet
21: If you looked at similar data in the high latitudes of Africa (i.e., at the tip), what months
would you find the highest NPP? (Use the NASA link for this)
March
22: In Southern Africa, what months do you think would have the highest atmospheric CO2
during any single year?
July and August
23: In Canada, what months would you find the highest NPP? (Use the NASA link for this)
June and July
24: In Canada, what months do you think would have the highest atmospheric CO2 during
any single year?
November, December, January and February
25: Explain why and how Canada and Southern Africa differ in this
The two regions are located on opposite latitudes therefore (North and South), therefore
when maximum daylight is maximum in Canada, it minimum in Southern Africa. This
implies that when photosysnthesis is maximum in Canada, it is minimum in Southern Africa.
This explains when NPP is highest in Canada, South Africa has the highest atmospheric CO2
26: Given these places are in different hemispheres, which do you think has a stronger effect
on land plant-derived NPP? Hint: look at the relative land mass of the Northern and
Southern hemispheres.

Length of daylight sunshine influenced by latitude that influence active hours of
photosynthesis.
Task 3: Long-term change in CO2 concentrations measured at Mauna Loa.
27: Create an xy graph of the entire time series. Then add a trendline for the entire time series
and upload it to the homework. (3 pts)
1950 1960 1970 1980 1990 2000 2010 2020 2030
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
450.00
f(x) = 1.57223775817621 x − 2772.59408916883
R² = 0.976812922768599
A Scatter Plot CO2[ppm] Concentration against Date in
Decimal Months
Decimal Months
Concentration of CO2 [ppm]
28: Using the entire data set calculate how much CO2 has increased per year for the time
period 1958-2020. (Hint to get the yearly change divide the total change by the # of years you
are interested in.) This assumes that the rate of increase has been constant since 1958. The
next few questions will test that assumption.
∆ CO2= Average conc of CO2−¿January of final year −Average conc of CO2−¿January initial year
n (number of years)
∆ CO2= 413.37−315.7
2020−1958 =+1.575 ppm/ year
29: Now, do the same calculations for the time period 1958-1979, then 1980-2000, 2001-
2020, then finally for the time period 2010-2020.
∆ CO2 ,1958−1979 concentration=336.23−315.7
1979−1958 =+0.978 ppm/ year (change computed¿ January values)

∆ CO2 ,1980−2000 concentration=369.5−338.7
2000−1980 =+1.54 ppm / year(Change computed ¿average values)
∆ CO2001−2020 concentration= 413.37−370.28
2020−2001 =+2.268 ppm / year (change computed¿ January values)
∆ CO2001−2020 concentration= 413.37−370.28
2020−2001 =+2.268 ppm / year (change computed¿ January values)
∆ CO2010−2020 concentration= 413.37−388.55
2020−2010 =+2.482 ppm / year (change computed ¿ January values)
30: How has the rate of increase changed? Meaning, is there evidence that the rate is actually
systematically increasing or decreasing over the years?
The rate of increase has consistently increased over the years since the computed values have
progressively increased over time.
31: If you wanted to predict the CO2 levels in the atmosphere 30 years in the future, which
calculation would you use? 1958-2020, 1958-1979, 1980-2000, 2001-2020, or 2010-2020?
I would use the 2001-2020
32: Explain your answer to Question 31. (2 pts)
The changes in CO2 concentration are seen to increase with time. This implies that the
changes in a distant past invalidates the use 1958-2020, 1958-1979, 1980-2000. Among the
two choices left, 2001-2020 and 2010-2020, we wish to make a 30 year prediction. 2001-2020
offers a model that takes care of longer years compared to 2010-2020 that only takes care of
10 years variability makes 2001-2020 more suitable.
33: Now that you have the tools, calculate what you predict CO2 levels would be in 2050. (2
pts)
CO2 ,concentration∈2050=CO2 , concentration∈2020+ ( ∆ CO2001−2020 concentration× 30 )
CO2 ,concentration ∈2050=413.37+ ( 2.268 ×30 ) =481.41 [ ppm ]