Background
Nitrogen and oxygen are the major gases in the Earth’s atmosphere. All the remaining gases are trace gases, including carbon dioxide and the other greenhouse gases. Greenhouse gases prevent heat (in the form of infrared radiation) from escaping into space from the Earth’s surface, thus they cause the temperature of the atmosphere to slowly rise over time. Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities (such as the burning fossil fuels) add to the levels of these naturally occurring gases.
Global warming is the observed increase in the average temperature of the Earth’s atmosphere and oceans over the last 150 years. The prevailing scientific opinion is that most of this warming is due to human activities, which have resulted in an increase in greenhouse gasses in the Earth’s atmosphere. Global warming has long been predicted to result from increasing greenhouse gases in the atmosphere. Global surface air temperature has indeed increased in the past century, but at a rate less than 0.1°C/decade. Record global temperatures have been achieved several times in the last several decades, but a new record often exceeds the old record by only a few hundredths of a degree. What relevance, if any, do such small temperature changes have to most people? In the following exercises you will look at the data and examine the significance of these changes yourself.
Objectives
- Analyze data related to atmospheric carbon dioxide levels collected at the Mauna Loa Observatory.
- Analyze data related to atmospheric carbon dioxide in the past collected from Antarctic ice cores.
Assignment Instructions
Part 1: Atmospheric Carbon Dioxide
The more carbon dioxide and the other greenhouse gases in the atmosphere, the more heat from the sun is trapped in the atmosphere.
Visit the following resource: http://keelingcurve.ucsd.edu/
The graph you see on the website above is known as the Keeling Curve. This graph is produced from measurements of carbon dioxide levels in the atmosphere from March, 1958 collected at the Mauna Loa observatory on the island of Hawai’i. This site is thought to be the least polluted air on the Earth because there is no source of air pollution upwind for thousands of miles from Mauna Loa.
On the Keeling Curve page, make sure you are on the Full Record tab and complete the task and respond to the following questions.
Task: Click on the Keeling Curve graph then save the image or take a screen capture. You will include this graph in your report.
- What does this graph tell us about the changing atmospheric CO2 level since 1958?
- What is the latest CO2 concentration reading?
- What was the CO2 concentration in 1958 when these measurements began?
- By how much as the atmospheric concentration of CO2 increased since the first measurements were made at Mauna Loa in 1958?
- What is the average annual rate of change in CO2 concentration since 1958 (hint - take what you found in 4 and divide by the number of years since 1958)?
Part 2: Carbon Dioxide in the Atmosphere Over Time
Most scientists have said that this increase in CO2 is due to human emissions and the destruction of the rainforests. It is possible that some of the variation could be due to natural variations in carbon dioxide. To fully understand the issues related to greenhouse gases and global change, we need to examine the past to see if CO2 levels have changed over time and if so, to what extent.
Most scientists have said that this increase in CO2 is due to human emissions and the destruction of the rainforests. It is possible that some of the variation could be due to natural variations in carbon dioxide. To fully understand the issues related to greenhouse gases and global change, we need to examine the past to see if CO2 levels have changed over time and if so, to what extent.
We can use ice cores from Antarctica to understand past variations in trace gases. As snow falls it traps small amounts of air in the spaces between the snowflakes. Some of this gas forms small bubbles as the snow metamorphoses into glacial ice. These bubbles become fossil atmospheres providing us with a means to examine the gas content of the atmosphere thousands of years in the past.
On the Keeling Curve page, click on the 1700-PRESENT tab and respond to the following questions.
- Make a statement regarding the annual change in atmospheric CO2 concentrations between 1700 and 1958.
- What data source is used for atmospheric CO2 concentrations between 1700 and 1958?
On the Keeling Curve page, click on the 10K YEARS tab and respond to the following questions.
- Make a statement regarding the annual change in atmospheric CO2 concentrations over the past 10,000 years.
- What are some reasons that are contributing to the dramatic increase in atmospheric CO2 levels in the past 150 years?
On the Keeling Curve page, click on the 800K YEARS tab and respond to the following questions.
- Before the Mauna Kea data collection started in 1958, what was the highest atmospheric CO2 concentration level in the last 800,000 years?
- When you examine the 800,000 year record, it shows that atmospheric CO2 concentration levels fluctuate over time. What is the average amount of time between peak atmospheric CO2 concentration levels?
- What are some reasons that may contribute to fluctuations in atmospheric CO2 levels over the past 800,000 years?
Part 3: Determine your carbon footprint
Go to one of the following sites and calculate your carbon footprint:
- This carbon footprint calculator is powered by the CoolClimate Network at the University of California at Berkeley.
- COTAP’s Carbon Footprint Calculator
Task: Take a screen capture of your carbon footprint calculation. You will include it in your report.
Answer the following questions:
- What did you learn about your carbon footprint?
- What are some things that you can do in your daily life to lower your carbon footprint?
Complete a report for this week's lab.
Your lab report should be 2-3 pages in length and MUST contain the following:
You must use the following template for your lab report: Lab 5 Report Template