Living in a Carbon World

Introduction: A Carbon Journey

Look around you. Can you see the carbon? Carbon can exist in its pure form, such as a diamond, or in the millions of different kinds of carbon compounds scientists have currently identified. Carbon can be found in all four spheres of the Earth System - the hydrosphere, the atmosphere, the geosphere, and the biosphere. In the biosphere, chemical compounds that contain carbon are the "chemical scaffolds" upon which all life is built and is why carbon is sometimes referred to as the "backbone of life." We also use the carbon from wood to build and heat our homes. Carbon is responsible for combustion in the gas tanks of our cars and in the muscles of our bodies. Yet, this small, six-proton atomic element, which is central to life and gives us fuel for energy, is also contributing to climate change, one of civilization's greatest threats.

Consider the image of a terrestrial and ocean carbon cycle below. Can you identify where carbon exists in these two carbon cycles? Can carbon move back and forth between the terrestrial and ocean carbon cycle? How? What if a change happens in one part of the carbon cycle? How will other parts of the terrestrial and ocean carbon cycle change? These are a few of the important questions you will explore as you work your way through this module.

Because understanding the carbon cycle is key to understanding climate change, many scientists are trying to understand how carbon moves through the carbon cycle. Throughout the module, you will have multiple opportunities to observe scientists doing their research and will have the opportunity to conduct your own research.

The "Essential Questions" of the Carbon Cycle module are:

• How does carbon move through the four spheres of the Earth system and in what forms?
• Where does carbon go, where does it get stored (sequestered) and for how long?
• What is Carbon's connection to sustaining life?
• What is Carbon's role in climate change and the greenhouse effect?

You can begin your carbon journey by watching the NASA video Keeping Up with Carbon.

• Before you begin, make a list of what you think you already know about carbon. Instead of a list, you may want to think about making a word cloud of what you already know about carbon and the carbon cycle. You can use the on-line word cloud program. You can make some words larger if you feel they have more importance in the carbon cycle. At the end of the module, you can made a new word cloud to see how much you have learned.
• As you watch the video, make a list of where on Earth carbon can be found, its relationship to life, climate change and any other carbon fact that interests you.
  

In Part A, you will set up a two-week plant growth experiment that lets you begin to explore the role of trees in storing carbon (also called sequestering carbon) and the factors that might limit that process.

In Part B, you will learn about carbon as an element. Using a ball-and-stick carbon molecule kit and 3-D structures of carbon compounds, you will demonstrate how carbon can bond with other atoms and create many different types of carbon compounds.

After completing this investigation, you should be able to:

• explain why carbon can be transformed into so many different forms of molecules
• explain how carbon compounds are transformed in five chemical reactions that are critical to the carbon cycle: photosynthesis, cell respiration, decomposition, biosynthesis and combustion.
  

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.