Carbon and the Atmosphere: My Life as a Greenhouse Gas

Introduction

In the atmosphere, carbon exists primarily in the form of carbon dioxide (CO₂) and methane gas (CH₄). The atmosphere is a large reservoir for carbon dioxide, and because it interfaces with the biosphere, the geosphere, and the hydrosphere, the atmosphere behaves like a Grand Central Station, with carbon dioxide moving into and out of the atmosphere through multiple natural exchange points such as plants, animals, soils, and oceans. Over Earth's history, slow carbon cycles and fast carbon cycles have worked in tandem to stabilize the carbon cycle. Today, however, our use of fossil fuels, such as coal, oil and natural gas, combined with deforestation, are disrupting the carbon cycle by increasing the concentration in the atmosphere. And, as with any complex system, a disruption in one part of the system will often cause a disruption in other parts of the system.

Since we first started burning large amounts of fossil fuels during the Industrial Revolution, the concentration of carbon dioxide in the atmosphere has increased by 39%. Some of this extra carbon dioxide has been absorbed by oceans, soils, and trees, but the rest will stay in the atmosphere for thousands of years. This is significant for our climate because carbon dioxide is the most important gas for controlling Earth's atmospheric temperature. Carbon dioxide and other atmospheric gases—such as methane, water vapor, and nitrous oxide—control Earth's temperature through the greenhouse effect. Without a greenhouse effect, the temperature of Earth would be much colder than it is now.

In this Lab, you will investigate the following essential questions:

• How do carbon dioxide and other greenhouse gases warm our Earth?
• Will there be any consequences for Earth if we continue to burn fossil fuels, and if so, what should we do about it?

In Part A, you will investigate carbon dioxide's capacity to absorb infrared radiation as a greenhouse gas. Then, you will conduct a simple experiment that measures the relationship between added carbon dioxide and temperature change in a plastic soda bottle.
In Part B, you will analyze how concentrations of global carbon dioxide, and temperature have changed since the advent of the Industrial revolution. You will apply systems thinking strategies to identify feedback relationships between a warming atmosphere and changes in the carbon cycle.
In Part C, you will use a carbon footprint to identify the amount of CO₂ your family emits to the atmosphere.

By the end of this investigation, you should be able to:

• Explain how carbon dioxide and other greenhouse gases absorb infrared radiation and warm the atmosphere.
• Describe the relationship between changes in carbon dioxide levels and changes in atmospheric temperature.
• Describe feedback relationships between a warming atmosphere and changes in the carbon cycle.
  

Keeping Track of What You Learn

Throughout these labs, you will find two kinds of questions.

• Checking In questions are intended to keep you engaged and focused on key concepts and to allow you to periodically check if the material is making sense. These questions are often accompanied by hints or answers to let you know if you are on the right track.
• Stop and Think questions are intended to help your teacher assess your understanding of the key concepts and skills you should be learning from the lab activities and readings.