Scientists know with "virtual certainty" that the composition of Earth's atmosphere is changing. Ever since the dawn of the Industrial Age, the levels of greenhouse gases such as carbon dioxide have been rising. The buildup of these gases in the atmosphere has increased at the same time human activities that release these gases (such as burning fossil fuels) have also been on the upswing.

Scientists say that human activities release roughly 7.1 GtC (7.8 billion tons of carbon) each year. (GtC stands for "gigatons of carbon," with a gigaton equaling approximately 1 billion tons) Approximately 3.2 GtC (3.5 billion tons) of this remains in the atmosphere and another 2.0 GtC (2.3 billion tons) diffuses into the oceans. (They aren't sure what happens to the remaining 1.9 GtC, though.) Clearly, this process is pumping a great deal of carbon dioxide into our atmosphere ... which, at 3479 ppm (parts per million) is higher than it has been in 400,000 years. Carbon dioxide concentration has varied in a range of 180 to 280 ppm for 400,000 years.

Scientists can clearly demonstrate that Earth's temperature has also been rising. In the years between 1906 and 2005, it increased about 1.0 - 1.7°F in both hemispheres and over its oceans. Scientists also know that increased concentrations of greenhouse gases in our atmosphere tend to warm the planet. They therefore think that the rising levels of greenhouse gases in the atmosphere are contributing to climate change.

In essence, what they are saying is that what we do now is having a direct effect on our atmosphere and our environment. And because the full effect of what we are doing will not be known for decades and decades, it is important to take stock now to see what we can do to avoid an even more-unimaginable climate crisis in the future.

Human Activity and Climate Change

Tackling the Global Warming Challenge

Are the Increases in Atmospheric Carbon Dioxide and Other Greenhouse Gases During the Industrial Era Caused by Human Activities?

How do Human Activities Contribute to Climate Change and How do They Compare with Natural Influences?

After working with this interactive, students will be able to identify human activities that produce greenhouse gases.

• Identify and describe a range of local issues that have an impact on people in other places. (MD 6.0-B. 1a (Grade 6,7,8))
• Humans cause global climate change through fossil fuel combustion, land-use changes, agricultural practices, and industrial processes. (NSF.9.3)
• Life on Earth, including microbes, plants and animals such as humans, can influence climate substantially and has throughout the evolution of life on the planet. (NOAA 1f)
• The atmosphere covers the entire surface of Earth; thus, activities that effect climate (e.g., energy use leading to greenhouse gas release into the atmosphere) in one region affect human beings and other species worldwide. (NOAA 7e)

Greenhouse gases; greenhouse effect; carbon footprint

• Where we are Now Before students experience this interactive, involve them in this activity: NOAA maintains a Global Climate Dashboard on its Climate Change site. The dashboard provides a window on the world climate situation. Students can adjust sliders to review current and historic data about climate factors such as temperature, carbon dioxide levels, and sea levels. Encourage students to experiment with the dashboard, clicking on various factors to see more information. Based on their experimentation, discuss reasons why many groups are calling for action now to curb or change human activities that affect our climate.
• Calculate your Impact After students experience this interactive, involve them in this activity: A carbon footprint is the "weight" of your activities measured by the amount of greenhouse gases produced by completing them or providing the power to complete them; it is measured in units of carbon dioxide. What is your carbon footprint? How about your school's? The EPA has prepared this carbon footprint calculator to help you find out. By responding to a series of questions, you can calculate carbon savings for your class, your school, and by all students throughout the country.
• The "Why" behind the Numbers After students experience this interactive, involve them in this activity: Analyze the factors involved in this interactive (trees, cars, buses, streetlights, and homes) to find out the processes through which these items have a carbon "cost." For example, homes use electricity, but how does carbon figure into that? Need tips on how and why each factor adds to or subtracts from our carbon footprint? Check out this Nature Conservancy site.