climate change GEO 102
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School
Illinois State University *
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Course
102
Subject
Geography
Date
Dec 6, 2023
Type
docx
Pages
10
Uploaded by BarristerWolverine2214
Project EDDIE: CLIMATE CHANGE
Student Handout
This module was initially developed by O’Reilly, C.M., D.C. Richardson, and R.D. Gougis. 15 March 2017. Project EDDIE: Climate Change. Project EDDIE Module 8, Version 1. http://cemast.illinoisstate.edu/data-for-students/modules/climate-
change.shtml
. Module development was supported by NSF DEB 1245707.
Learning objectives:
To analyze global temperature data to see if Earth’s average global temperatures are really increasing
To analyze CO
2
data to see if atmospheric levels are really increasing
To correlate CO
2
data with global temperature to see if there is a relationship
To compare current trends with rates of change during pre-historic periods using ice core data
To interpret what these results mean for understanding current climate change
To learn basic shortcuts and graphing in Excel
Why this matters:
Current climate change is affecting many aspects of the environment, with socio-
economic consequences. For example, a warmer climate can allow new diseases to be introduced and persist (e.g. West Nile became established in the United States after an unusually warm winter allowed the mosquitos that carry the virus to survive and spread). We are concerned not only with the actual temperature, but also with the rate that the temperature changes. Very rapid changes make it more likely that species (maybe even including humans!) cannot adapt and will go extinct. Outline:
1.
Discussion of papers read for class and Power Point presentation
2.
Activity A: Determine current rates of air temperature and CO
2
change from modern datasets.
3.
Activity B: Explore whether temperature and CO
2
concentrations are related.
4.
Activity C: Compare current rates to pre-historical rates of change using data from an ice core to investigate how climate has changed in the past. 1
Activity A: How much are temperature and atmospheric CO
2
changing? Changes in air temperature -
Scientists from the Goddard Institute for Space Studies, NASA, compiled temperature datasets from weather stations all over the world to create the dataset you are going to be working with today to answer the question: Is earth “warming”? The data you will use are from years 1880-2013. 1.
Before you conduct your analysis, you should first make your predictions. What slope would indicate a warming Earth? What slope would indicate Earth’s average global temperature was not
changing? What slope would indicate a cooling Earth? Sketch lines in the axes below to show what the expected slopes would be in these different scenarios.
cooling
warming
no change
2.
Getting the air temperature data: These data are compiled by the Goddard Institute for Space Studies, NASA, and are made available via the Earth Policy Institute. http://www.earth-
policy.org/data_center/
Select Climate, Energy and Transportation. The dataset you are looking for is called something similar to “Average Global Temperature, 1880-2014 (Celsius)”, about 15 rows down. Download this excel file and save on your computer in a location where you can find
it again (the Desktop is a good option). 3.
Open up the dataset. Make a scatter plot of temperature change over time. 1860
1880
1900
1920
1940
1960
1980
2000
2020
2040
12.80
13.00
13.20
13.40
13.60
13.80
14.00
14.20
14.40
14.60
14.80
f(x) = 0.01 x + 1.12
R² = 0.77
temp vs time
4.
Now, determine the rate of change. Determining rates of change graphically is straight forward. The average rate of change is just the change in temperature divided by the change in time, or change in y divided by the change in x, or the slope of a line that fits through the data. These are all the same thing. Luckily, Excel can calculate the slope of a line very easily. So, to determine o
C
o
C
o
C
time
time
time
2
the rate of change (slope) add a trend line. When you do this, make sure to select the options to show the equation of the line and the R
2
value. The equation is written in the form y = mx + b
, where m
is the slope and b
is the intercept. The value for m
is the rate of change. The R-squared (R
2
) is a statistic resulting from a linear regression analysis, which is the statistical name for what you just did by adding a trend line. It describes the proportion of variation in the dependent variable explained by the independent variable. When R
2
~1, the data form a perfectly straight line. As the data become more scattered from the line, R
2
decreases toward 0. Higher R-squared values indicate a stronger relationship between the two variables. Record your R
2
value down with your slope.
a.
Equation for the line: y= 0.0066x+1.1197
b.
R
2
= 0.7662
c.
Rate of air temperature change (include units): 0.0066 0
C/year
d.
Given your analysis, is Earth warming? How do you know? Rate of change is positive, so
it is warming 5.
Many scientists claim that drastic changes in global temperature began in the mid-1900s when fossil-fuel-powered transportation became a mainstay for most families. Test this hypothesis by adjusting your trendline so that it only looks at the most recent decades, after personal transportation became common. You can do this by:
Decide on the year in the mid-1900s that you want to begin the trendline. Scroll to that year and select the data (year and temperature) from that year all the way to the most recent year.
Create a Scatter plot just as you did before and add a trendline with the R
2
. Write your answers for (a) and (c) on the board to compare with others. 1870188018901900191019201930194019501960
13.20
13.30
13.40
13.50
13.60
13.70
13.80
13.90
14.00
14.10
14.20
f(x) = 0 x + 6.45
R² = 0.3
1880-1950
1940 1950 1960 1970 1980 1990 2000 2010 2020
13.20
13.40
13.60
13.80
14.00
14.20
14.40
14.60
14.80
f(x) = 0.01 x − 10.55
R² = 0.83
1951-2014
a.
Equation for the line: 1880=1950=y=0.0038x + 6.4518
b.
1051+2014=y= 0.0125x+10.547
c.
R
2
= 1880=1950=0.2966
3
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d.
1951
e.
Rate of air temperature change (include units): 0.0125
0
C/year
f.
Compare the slopes of these two lines (1880 through mid-1900s versus mid-1900s through 2013). Does your analyses support the hypothesis that the rate of global average temperature is greater since the 1950s? Yes, my analysis supports the hypothesis that the rate of global average temperature is greater since the 1950s because temperature keeps increasing as years increase and there is still a positive slope
increasing. As we can see from the graphs, before the 1950s the temperature was all over the place, there was a variety. Now, after the 1950s the temperature has maintained as a steady slope and keep
increasing drastically.
Changes in atmospheric CO
2
- In 1958, Dr. Charles David Keeling (1928-2005), who was a scientist at
Scripps Institute of Oceanography, began collecting data on atmospheric CO
2
concentration at the Mauna Loa Observatory located in Hawaii. This dataset is what allowed us to understand the degree to which climate change is human-caused through our burning of fossil fuels and release of CO
2
into the atmosphere. Due to his scientific achievements, Dr. Keeling was awarded the National Medal of Science
by President George W. Bush in 2002. This is the highest award for lifetime scientific achievement that can be granted in the U.S. Today, you get to analyze this same dataset, except that you have more data that was available to Dr. Keeling and his colleagues, because your dataset extends up to current time.
6.
Getting the atmospheric CO
2
data: The longest measurements of atmospheric CO
2
concentrations
have been done in Mauna Loa, Hawaii. The simplest way to access the data is directly from the Mauna Loa page. http://www.esrl.noaa.gov/gmd/ccgg/trends/
(You can already see some graphs plotted on this page, but since you want to analyze these data yourself to determine a rate of change, you will have to download them.) Select the ‘Data’ tab. Scroll down to the bottom of the page to ‘Data’. Select “Mauna Loa CO
2
annual mean data”
The data will appear as a .txt web page. This is a common format for datasets that are relatively small and easily downloadable. There is a lot of text at the top that describes the dataset. The data are presented as a column of years, the mean CO
2
as ppm (parts per mil, or micromoles per mol of air), and the last column is the estimated uncertainty in the annual mean is the standard deviation.
Since you only need the data, the easiest way to do this is to highlight the data section of the web
page, including the headings (year, mean, unc). Copy. Then paste into Excel, on a new worksheet
in the same file that has the global temperature data. To convert from txt to Excel format, you need to makes sure you have that column highlighted, then go to ‘Text to Columns’ under the Data tab in Excel. In the new window, you should be able to click through as the default settings should work. You should be able to see the data in columns. 4
7.
As you did for air temperature, plot a graph of CO
2
vs time.
1950
1960
1970
1980
1990
2000
2010
2020
2030
0
50
100
150
200
250
300
350
400
450
f(x) = 1.64 x − 2909.48
R² = 0.98
Co2 vs time
mean
Linear (mean)
Linear (mean)
Linear (mean)
8.
Determine the current rate of change for atmospheric CO
2
data by fitting a trend line, as you did for air temperatures. a.
Equation for the line: y=1.6416x – 2909.5
b.
R
2
= 0.983
c.
Rate of air CO
2
change (include units): 1.6416 0
C/year
d.
Based on your analysis, has atmospheric CO
2
concentration increased? How confident are
you in these results? What phenomenon explains the matching patterns of average global temperature and atmospheric CO
2
?
Yes, it is increasing a little as time goes by. I am very confident in my answer because the graph shows a positive slope because it is gradually increasing.
Activity B:
How related are the changes in temperature and CO
2
?
1.
To determine whether a change in CO
2
corresponds well with a change in air temperature, you can plot temperature against CO
2
.To do this, highlight the CO
2
data from 1959 onwards, copy them, and then paste them next to the temperature data from those years. Then make a graph with
CO
2
on the x axis and temperature on the y axis. 5
310
320
330
340
350
360
370
380
390
400
410
13.20
13.40
13.60
13.80
14.00
14.20
14.40
14.60
14.80
f(x) = 0.01 x + 10.95
R² = 0.87
C02 vs time
a.
Equation for the line: y= 0.0094x + 10.945 b.
R
2
= 0.8744
c.
Based on your analysis, could atmospheric CO
2
concentration explain the increase in
average global temperature?
Yes, atmospheric CO2 concentration can explain the increase in average global
temperature because as Co2 increases so does the global temperature and it increases
quickly. I am confident because according to the graph it demonstrates that it is positively
increasing.
Activity C: How do current trends compare to pre-historic rates of change?
An exploration of the Vostok Ice Core - When analyzing Earth’s climate, it is important to remember that Earth is 4.54 billion years old. Our analyses so far have only looked at recent history. How can we compare the recent data to pre-historic time? Are the current rates of change similar or different than those the earth has experienced in the past? To explore this, we can use data taken from ice cores that were drilled at the poles. Hundreds of ice cores have been extracted from polar ice because they contain valuable data on atmospheric chemistry over pre-historic time. These valuable data exist in tiny air bubbles that are trapped in the ice. These air bubbles contain the same gases in the same ratios as the atmosphere at the time when the ice formed. The data you will be analyzing today are from ice cores extracted from the Vostok research station in Antarctica. As you have probably assumed, the depth of the ice core is related to how old the ice is; deep ice is older. There are two other variables that you will be analyzing from the ice cores. The first is temperature, which is reflected by isotopic ratios in the ice of the core so that these isotopic ratios can be converted into air temperatures. The second variable you will analyze is CO
2
concentration, which has been measured from air bubbles trapped in the ice. We can use these data to see
what rates of change were like during this pre-historic period, during which human activity has been minimal. 6
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1.
The Vostok ice core data is available through the Carbon Dioxide Information Analysis Center (CDIAC) http://cdiac.esd.ornl.gov/
. Under the Data dropdown menu, select Climate. Then select Temperature. Then down at the bottom of that page there is a link called “Historic isotopic temperature record from the Vostok Ice core, Antarctica”. Select this link, which provide information about the core location, and then select ‘Digital Data’ on the top of the page. Similar to the CO
2
data, you need to highlight the column headings and then down all the rows, excluding all the text in the starred box. Download the Vostok ice core data to Excel and save it as a new Excel workbook on the desktop. This step is already done for you on the Excel sheet!
2.
Begin with the temperature data, and graph it using ice age as the independent variable. Create a Scatter graph with straight lines between the points. Keep in mind that the x axis refers to how many thousands of years ago, so the time axis moves in the opposite direction as what you are accustomed to based on previous analyses. This is the custom for research that investigates patterns over long time periods. Adjusting the y axis will make the data be more prominent on the graph.
To help you orient to these plots, address the following questions:
a.
Do you think these data are a good representation of pre-historic rates of change? Yes, they are a good representation of pre-historic rates of change because it helps show the
patterns of the temperature over time.
b.
Are we currently in a glacial or interglacial period? We are currently in a interglacial period.
c.
How long does a glacial and interglacial period last?
Glacial: 70,000-90,000 years
Interglacial: 10,000 years
7
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
-65
-63
-61
-59
-57
-55
-53
-51
-49
-47
-45
f(x) = 0 x − 59.12
R² = 0
Vostok Temp vs. Time
3.
Add a trend line to the ice core temperature data and look at the R
2
value. Do you think this line is a good representation of long-term rates of temperature change?
Yes, it Is a good representation of long-term rates of temperature change because it shows the
periods of glacial and interglacial, and it shows a drastic change over the years and how it keeps
changing.
4.
The next step is to calculate what the fastest rate of change might be. To do this, you want to identify a section of your data where the temperature is changing very rapidly. If you hover your mouse over a data point, it will tell you the data values for that particular point. Make note of the data point values at the beginning and end of the time period segments that you think have the steepest slopes:
Then make a new graph of only that time period, and determine the rate of change by fitting a trend line and looking at the slope. 128000
130000
132000
134000
136000
138000
140000
142000
144000
146000
-65
-63
-61
-59
-57
-55
-53
-51
-49
-47
-45
f(x) = − 0 x + 48.13
R² = 0.84
Vostok Temp Rapid Change
Rate of pre-historic temperature change (with units). Write your answer on the board to compare with others.
-0.0008x
0
C/ice yr
5.
To download the Vostok ice core CO
2
data, under the CDIAC website http://cdiac.esd.ornl.gov/
select ‘Atmospheric Trace Gases & Aerosols’. Then select ‘Carbon Dioxide (CO2)’. On the next page there is a link to ‘Vostok, Antarctica (Baronla et al.).’ You can then download the data and convert it into Excel columns in the same way you did previously. Prepare a plot of CO
2
concentration as a function of (gas) age. Plot (gas) age on the x axis and CO
2
on the y axis. 8
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
0
50
100
150
200
250
300
350
f(x) = 0 x + 221.02
R² = 0.03
Vostok vs. Time
a.
According to the CO
2
data from ice cores, during which time frame(s) was there the greatest rate of change in atmospheric CO
2
concentration? How does this change in atmospheric CO
2
concentration correspond to what you see in the ice-core temperature record? The greatest rate of change was in the time frame of 323485 and the lowest was 354372. b.
How do CO
2
concentrations recorded over time in the ice core compared to the current values for today, which you can see on the Mauna Loa web site? The ice core recorded over time compares because they both show an increase and decrease over time. The Mauna Loa has a more constant increase. 6.
Now make a new graph focused only on a time period of rapid change in CO
2
. Determine the rate of change by fitting a trend line and looking at the slope. 320000
325000
330000
335000
340000
345000
350000
355000
360000
0
50
100
150
200
250
300
350
f(x) = − 0 x + 1231.8
R² = 0.75
Vostok Rapid Change
a.
Rate of pre-historic atmospheric CO
2
change (with units)
-0.003x
0
C/ ice yr.
9
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7.
Compare the fastest natural rate of change with the modern rate of change. (Remember to check your units are equivalent).
How do current (i.e., in the past ~200 years) changes in atmospheric CO
2
concentration and average global temperature compare to pre-historic (i.e., in the past hundreds of thousands of years) changes in these variables? What does this suggest about whether recent changes in temperature are due to natural or anthropogenic (human) factors? It is plausible that recent increase in atmospheric carbon dioxide is a result of natural fluctuations and not human-induced?
The modern rate of change is 0.0066
0
C/yr. and the fastest natural rate of change is
1.5371
0
C/yr. Current changes in the atmosphere and average global temperature
compared to pre-historic changes because there have been drastic changes whether it has
been positive or negative, and the Co2 levels have increased while the temperature has
too. What this suggests about whether recent changes in temperature are due to human
factors is that in the years of industrialization 1900s and more, you can tell how the
temperature increased along with Co2 levels. However, nature also changed a lot on its
own because over the years the sun has affected the ice a lot and its melting. I think it can
be plausible that recent increase in atmospheric carbon dioxide is a result of natural
fluctuations and not human-induced because the earth is something that cannot be
controlled, and everything will change a lot or less over the years and sometimes it isn’t
predictable. Therefore, graphs and charts are a good demonstration of showing those
changes over time and seeing what is affecting the increasing or decreasing of
temperature because we can see patterns. 10