Topic 1.4: The Carbon Cycle

Vocabulary flashcards covering key terms, processes, sinks, sources, and reservoirs in the AP Environmental Science Topic 1.4 Carbon Cycle lecture.

Carbon Cycle

The movement of carbon-containing molecules, primarily carbon dioxide ($CO_2$), glucose, and methane ($CH_4$), between carbon sources and sinks across Earth systems.

Carbon Sink

A carbon reservoir that stores more carbon than it releases, removing carbon dioxide ($CO_2$) from the atmosphere and mitigating climate change.

Carbon Source

A process or reservoir that releases more carbon into the atmosphere than it stores, increasing atmospheric carbon dioxide ($CO_2$) concentrations.

Photosynthesis

A quick biological process carried out by plants, algae, and phytoplankton that removes carbon dioxide ($CO_2$) from the atmosphere and converts it into glucose.

Cellular Respiration

A process performed by all living organisms to break down glucose using oxygen to release energy, producing carbon dioxide ($CO_2$) as a byproduct and releasing it back into the atmosphere.

Direct Exchange

The quick, continuous movement of carbon dioxide ($CO_2$) gas back and forth directly between the atmosphere and the ocean surface in roughly equal directions.

Sedimentation

The process where dead organisms, algae, or shells sink to the ocean floor and are broken down under water pressure into small pieces called organic sediments.

Burial

A very slow geological process occurring over thousands to millions of years where accumulated sediments are compressed by overlying water or rock layers into sedimentary rock or fossil fuels.

Fossil Fuels

Long-term underground carbon storage reserves—including coal, oil, and natural gas—formed from the ancient burial and compression of dead organic matter such as ferns and phytoplankton.

Extraction and Combustion

The human process of digging up or drilling fossil fuels and burning them for energy, resulting in a very rapid release of carbon dioxide ($CO_2$) into the atmosphere.

Methane ($CH_4$)

A powerful greenhouse gas released into the atmosphere primarily through animal agriculture via livestock burps and farts.

Calcium Carbonate ($CaCO_3$)

The carbon-containing compound created by coral reefs and marine organisms to build their protective shells.

Ocean Acidification

The lowering of ocean pH caused by increased levels of atmospheric carbon dioxide ($CO_2$) dissolving directly into ocean waters.