Carbon Cycle

Objectives

• Discuss role of photosynthesis and respiration in C cycle
• Describe what has lead to increased CO2 in atmosphere

Recycling of carbon is important because organisms do not synthesize carbon atoms.

Carbon must be recycled through organisms or it will stay in the atmosphere.

In the atmosphere, carbon exists primarily as carbon dioxide.

Cellular respiration releases carbon dioxide into the atmosphere, and photosynthesis removes it to make organic compounds.

Other things that release CO2

• Decomposition of dead organisms
• Burning organic material
• Eruption of volcanoes
• Production of cement (heating limestone)
• Warmed ocean water releases CO2

Because of humans, there is more carbon in the atmosphere now than there was thousands of years ago.

Carbon cycles quickly between organisms and the atmosphere.

Carbon cycles slowly through processes like sedimentation. Carbon can be stored in rock for millions of years.