d. The abundance of greenhouse gases in the atmosphere is controlled by biogeochemical cycles that continually move these components between their ocean, land, life, and atmosphere reservoirs. The abundance of carbon in the atmosphere is reduced through seafloor accumulation of marine sediments and accumulation of plant biomass and is increased through deforestation and the burning of fossil fuels as well as through other processes.

This interactive animation focuses on the carbon cycle and includes embedded videos and captioned images to provide greater clarification and detail of the cycle than would be available by a single static visual alone.

This video segment from 'Earth: The Operators' Manual' explores how we know that today's increased levels of CO2 are caused by humans burning fossil fuels and not by some natural process, such as volcanic out-gassing. Climate scientist Richard Alley provides a detailed step-by-step explanation that examines the physics and chemistry of different "flavors," or isotopes, of carbon in Earth's atmosphere.

In this activity, students learn how carbon cycles through the Earth system by playing an online game.

This narrated slide presentation shows the carbon cycle. It looks at various parts of this biogeochemical sequence by examining carbon reservoirs and how carbon is exchanged among them.

This interactive follows carbon as it moves through various components of the carbon cycle.

In this lab activity, students use a chemical indicator (bromothymol blue) to detect the presence of carbon dioxide in animal and plant respiration and in the burning of fossil fuels and its absence in the products of plant photosynthesis. After completing the five parts of this activity, students compare the colors of the chemical indicator in each part and interpret the results in terms of the qualitative importance of carbon sinks and sources.

This interactive graphic shows the different components of the ocean biological pump, i.e., how carbon in the form of either plankton or particles moves into the ocean's depths. The diagram illustrates the processes at the surface, 0-100 meters, 100-500 meters, and below 500 meters.

In this visualization, students can explore North American fossil fuel CO2 emissions at very fine resolutions of both space and time. The data is provided by the Vulcan emissions data project, a NASA/DOE funded effort under the North American Carbon Program.

This article and slide show from the New York Times, features several scientists from the University of Alaska, Fairbanks, who study the effects of thawing permafrost in Alaska.

This activity from NOAA Earth System Research Laboratory introduces students to the scientific understanding of the greenhouse effect and the carbon cycle. The activity leads them through several interactive tasks to investigate recent trends in atmospheric carbon dioxide. Students analyze scientific data and use scientific reasoning to determine the causes responsible for these recent trends. By studying carbon cycle science in a visual and interactive manner, students can learn firsthand about the reasons behind our changing climate.