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The carbon cycle is a natural process through which carbon circulates throughout our environment. Part of the cycle actually occurs outside the cycle per se. A certain amount of pure carbon becomes fixed in sinks below the ground and oceans: plants and animals die, and sometimes become buried before decay is complete; under certain conditions of pressure and temperature as well as anaerobic decay they ultimately compress into substances such as coal, peat, natural gas, and oil, substances we now call fossil fuels. Over 300 million years ago, this process was very robust. Large amounts of coal were being laid down. In fact, this era took its name–the Carboniferous Period–from this activity.

Today, we are rapidly using these fossil fuels to power our factories, homes, and daily lives. Estimates say that 90 percent of the energy we use in the United States alone comes from fossil fuels.

The problem is that when the carbon in fossil fuels burns, its molecules unite with oxygen to form carbon dioxide, a greenhouse gas. And, ever since the dawn of the Industrial Age, atmospheric levels of carbon dioxide have exploded.

The longest continuous record of atmospheric carbon dioxide concentrations is compiled by scientists working on Mauna Loa in Hawaii. Their data shows that--between 1959 and 2004--the concentration of carbon dioxide in the atmosphere increased from about 317 parts per million (ppm) to 377 ppm. And that figure continues to rise, increasing the chances that the warming of our planet and the climate change it generates will at least continue, if not accelerate, in the coming years.

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Learning Objective

After listening to this podcast, students will be able to describe the relationship between the burning of fossil fuels, t he production of greenhouse gases, and the carbon cycle.

Standards Addressed
Can be used with existing lesson plans on

Carbon cycle, greenhouse gases, fossils, geography

Additional ways to use this asset to enrich your curriculum
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