EarthLabs > Climate and the Carbon Cycle: Unit Overview > Lab 6: Oceans: Carbon Sink or Source?

The Oceans: Carbon Sink or Source?


Many people have never seen an ocean.

Yet no matter where each of us lives on Planet Earth, we depend on the health of the oceans in so many ways – for food, recreation, jobs, shipping of goods, medicine, and simply for the wonder of ocean exploration and the discoveries yet to be made. But we also depend on the oceans to absorb approximately 92 gigatons of carbon dioxide from the atmosphere each year. As humans have added more and more carbon dioxide to the atmosphere by burning fossil fuels, oceans have responded by absorbing more carbon dioxide. Indeed, the oceans have absorbed about half of all the extra carbon dioxide people have put into the air over the last 150 years!

How do oceans absorb carbon dioxide? Where does the absorbed carbon go? If fossil fuel emissions continue to increase, can oceans continue to absorb greater and greater amounts of carbon dioxide from the atmosphere? Or will carbon uptake by oceans slow down? These are all essential questions that climate scientists and oceanographers are working to answer.

In Part A, you will learn how the oceans "absorb" carbon by considering two ocean processes that "pump" carbon dioxide into the oceans: the physical carbon pump and the biological carbon pump. You will view a PowerPoint that will show you what happens to carbon once it becomes part of the ocean's biological pump.

In Part B, you will explore the role of phytoplankton in ocean uptake of carbon in greater depth by analyzing conditions and locations for its growth. Additionally, you will watch a NASA movie and read an accompanying NASA article about the importance of phytoplankton in the carbon cycle. You will view seasonal and decadal changes in phytoplankton populations using a visualization from the NASA SeaWIFS satellite program.

After completing this investigation, you should be able to:

Keeping Track of What You Learn

Throughout these labs, you will find two kinds of questions. Your teacher will let you know which answers you should record and turn in.

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