GlobalClimateChangeLab.v2-studenthandout
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GEOL 121 Name_________________________________ Lab Section ____________
GLOBAL CLIMATE CHANGE LAB
Student Handout
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 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 difficult for humans to adapt and more likely that other species cannot adapt and will go extinct. 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 1880-2022. 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 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. time
time
time
GEOL 121 Global Climate Change Lab
Getting the air temperature data: These data are compiled by the Goddard Institute for Space Studies, NASA, and are made available at https://data.giss.nasa.gov/gistemp/
. For this lab, the data has been organized into an Excel spreadsheet for you, which you can find on the lab Canvas page. Open up the Global Temperature dataset by selecting the correct tab at the bottom of the spreadsheet.
2.
Examine Graph A.
Describe in words how global temperature has changed between 1880 and 2022. Over the time the average temperature has increased since 1880 to 2022. The graph shows an exponential increase over time. 3.
We will now determine the rate of temperature change. Determining rates of change graphically is straightforward. 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. Excel can calculate the slope of a line very easily. In Graph B
, a linear trendline has been added to the global temperature data (
black dashed line
). The equation for the trendline is also shown (outlined in black). The equation is written in the form y = mx + b
, where m
is the slope and b
is the intercept. Another name for the slope (
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 we just did by adding a trendline. 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 the R
2
value down with your slope. a.
Equation for the line: y=0.0077x-15.053 b.
R
2
= 0.763 c.
Rate of air temperature change (include units): .8735ºC every 100 years 2
GEOL 121 Global Climate Change Lab
d.
Given your analysis, is Earth warming? How do you know? Yes because there is a positive slope/ increasing 4.
Many scientists suggest that drastic changes in global temperature began in the mid-1900s when fossil-fuel-powered transportation became a mainstay for most families. We can test this hypothesis by adjusting the trendline so that it only looks at the most recent decades, after personal transportation became common. The red solid line
on Graph B
only includes data from 1965-2022. Record the values for the red solid trendline below. a.
Equation for the line: 0.0183x-36.109 b.
R
2
= 0.9194 c.
Rate of air temperature change (include units): .959 d.
Compare the slopes of these two lines (1880 through 2022 (black) versus 1965 through 2022 (red)). Does your analyses support the hypothesis that the rate of global average temperature is greater in recent decades? Yes it does. The average temperature has increased by .0855ºC 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 3
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GEOL 121 Global Climate Change Lab
can be granted in the U.S. Today, you get to analyze this same dataset, except that you have more data than was available to Dr. Keeling and his colleagues, because your dataset extends up to current time. 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/ For this lab, the data has been organized into an Excel spreadsheet for you, which you can find on the lab Canvas page. Open up the dataset by selecting the Mauna Loa CO
2
tab at the bottom of the spreadsheet. 1.
Examine Graph C. Describe in words how atmospheric CO
2 has changed between 1959 and 2022. The average has increased dramatically since 1959. It has increased by .99 since then. 2.
The black dashed line on Graph C
is a linear trendline applied to the CO
2
data. Record the equation and R
2
for this trendline below. Determine the current rate of change for atmospheric CO
2
data, as you did for air temperatures. a.
Equation for the line: 1.6244x-2875.2 b.
R
2
= .9818 c.
Rate of air CO
2
change (include units): .99 d.
Based on your analysis, has atmospheric CO
2
concentration increased? How confident are you in these results? Yes because the slope is positive. I feel very confident 4
GEOL 121 Global Climate Change Lab
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
.This is done for you in Graph D
. Describe in words the relationship between atmospheric CO
2
and global temperature. The relationship is they both increase as the other does. As the average CO2 goes up, so does the average temperature. 2.
The blue solid line is a linear trend line through the CO
2
and temperature data. Record the equation and R
2
below. a.
Equation for the line: 0.0104x-3.3726 5
GEOL 121 Global Climate Change Lab
b.
R
2
= 0.9259 c.
Based on your analysis, could atmospheric CO
2
concentration explain the increase in average global temperature? How strong is the relationship between CO
2
and temperature? How can you tell? Yes, as the CO2 levels increase, so does the temperature. The relationship is strong because they are both positive slopes. 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. The Vostok ice core data is available through the Carbon Dioxide Information Analysis Center (CDIAC) http://cdiac.esd.ornl.gov/
. For this lab, the data has been organized into the Excel spreadsheet for you in the Vostok CO
2
and Vostok Temp tabs. 6
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GEOL 121 Global Climate Change Lab
In these data, temperature is calculated from the ‘delta D’ content. Deuterium, or delta D, stands for the relative proportion of two types of hydrogen (
2
H: 1
H). Changes in the proportion of these two types of hydrogen in ice-water correlate to the amount of evaporation and the temperature of the atmosphere. In the next column, paleo-temperatures at Vostok are calculated based on the formula describing the empirical relationship between temperature and deuterium concentration: Temperature (in degrees C) = -55.5 + (delta D + 440) / 6 1.
Begin with the temperature data, and examine Graph E
. Keep in mind that the x axis refers to how many years ago; so the years go up as you go back in time. This is the custom for research that investigates patterns over long time periods. Describe in words how Antarctic temperature has changed over the last 420,000 years. We see a pattern of intense warming and intense cooling periods. These periods are the earth sequestering to the over stimulation of temperature increase and decrease. Right now the earth is in the middle of a warming period. 2.
On this graph, the colder times correspond to glacial periods (ice ages) and the warmer times correspond to interglacial periods. a.
Are we currently in a glacial or interglacial period? I would say we are in a interglacial period b.
Approximately, how long does a glacial and interglacial period last? i.
Glacial: about 74,000 years ii.
Interglacial: about 26,000 years
7
GEOL 121 Global Climate Change Lab
3.
On Graph F
a trend line has been added to the ice core temperature data (black dashed line). Take a look at the R
2
value. Do you think this line is a good representation of long-term rates of temperature change? I would say that it is not because the graph would suggest that our climate is never changing when it is constantly 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. What are the data point values at the beginning and end of the time period segments that you think have the steepest slopes: -63º—->-51º 5.
The time periods with the greatest rate of temperature change tend to be at the end of the glacial periods. These are call deglaciations. The red solid line and the blue solid line on Graph F are trend lines fit to the data during the two most recent deglaciations. (Note that the slopes of these lines are negative because the time on this graph increases as we go back in time.) What are the rates of pre-historic temperature change (with units) during each of these deglaciations? Blue line =.9789 8
GEOL 121 Global Climate Change Lab
Red line= .9440 6.
How do these rates of temperature change compare to what you found for the recent global temperature in Activity A? There is a much more rapid increase in temperature in the recent years compared to temps through 3me Now move to the Vostok ice core CO
2
data 7.
Examine Graph G
. This is a plot of CO
2
concentration as a function of (gas) age. Describe in words how CO
2
has changed over the last 420,000 years. There were many ups and downs but now we are where we were about 420,000 years ago 9
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GEOL 121 Global Climate Change Lab
8.
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 happened about 130,000-140,000 years ago and this directly relates to the greatest increase in temperature 9.
How do the CO
2
concentrations recorded over time in the ice core compare to the current values for today, which you can see in the Mauna Loa data? The major up and down fluctuations in CO2 data correlates with the major fluctuations seen in global temperature data 10.
Linear trendlines have been added to the Vostok CO
2
data in Graph H
. The black dashed line includes all of the data. The red and blue solid lines just include the two most recent deglaciations (same time periods that we included for the Antarctic temperature). What are the rates of pre-historic atmospheric CO
2
change (with units) for the two deglaciations: Blue line=.9658 Red line= .9705 11.
How do these natural rates of change compare with the modern rate of change? 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? 10
GEOL 121 Global Climate Change Lab
Atmospheric CO2 has greatly increased in the recent years. This shows that this is a anthropogenic factor . As humans have greatly increased the atmospheric CO2 much higher than anytime in history 12.
If atmospheric CO
2
concentrations continue to rise in the future, how would you expect global temperatures to change? You would expect it to increase a great amount as seen in the past because they are related 13.
What is still unclear about changing global temperatures and the relationship between atmospheric CO
2
and global temperature? What questions do you have? I don’t have any questions
11