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 well-designed experiment compares CO2 impacts on salt water and fresh water. In a short demonstration, students examine how distilled water (i.e., pure water without any dissolved ions or compounds) and seawater are affected differently by increasing carbon dioxide in the air.

This PBS video shows how Klaus Lackner, a geophysicist at Columbia University, is trying to tackle the problem of rising atmospheric CO2 levels by using an idea inspired by his daughter's 8th-grade science fair project.

This is a video that discusses how climate feedbacks influence global warming.

This video describes the foundation Plant for the Planet, a foundation created by a 9-year-old German boy, Felix. This foundation has planted more than 500,000 trees in Germany, which he says help sequester carbon and reduce greenhouse gas emissions. The student rallies, first his community and then other children, to plant millions of trees to offset our energy-use emissions.

In this video from the Polaris Project Website, American and Siberian university students participating in the project describe their research on permafrost.

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

This NASA animation on land cover change zooms into Rondonia, Brazil. It starts with a Landsat satellite image taken in 1975 and dissolves into a second image of the same region taken in 2009 indicating that there has been a significant amount of land use change.

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

In this activity, students work in groups, plotting carbon dioxide concentrations over time on overheads and estimating the rate of change over five years. Stacked together, the overheads for the whole class show an increase on carbon dioxide over five years and annual variation driven by photosynthesis. This exercise enables students to practice basic quantitative skills and understand how important sampling intervals can be when studying changes over time. A goal is to see how small sample size may give incomplete picture of data.

This activity introduces students to different forms of energy, energy transformations, energy storage, and the flow of energy through systems. Students learn that most energy can be traced back to nuclear fusion on the sun.