Understanding Greenhouse Gases
Planet Earth is warm enough to sustain life thanks to gases in the planet’s atmosphere that hold heat. These gases are called greenhouse gases because they act just like a greenhouse — trapping the heat inside the planet’s atmosphere, making the average temperature on Earth 59 degrees Fahrenheit (15 degrees Celsius). Humans have increased the amount of greenhouse gases in the atmosphere by about 35 percent. The more greenhouse gases in the atmosphere, the warmer the average temperature gets.
The main greenhouse gases
The two major greenhouse gases both occur naturally and can be increased due to human activity.
Carbon dioxide (CO2): Responsible for 63 percent of global warming over time, and 91 percent in the last 5 years, this gas is produced from burning fossil fuels, such as coal and oil. It also occurs naturally as it flows in a cycle between oceans, soil, plants and animals.
Methane (CH4): Responsible for 19 percent of global warming, this gas is produced by rotting garbage and wastewater, gas from livestock, and rice crops. Swamps and anything that decomposes without air naturally creates methane.
Two main sources of greenhouse gases
Energy use: Humans derive energy from burning fossil fuels, which releases almost three quarters of all human-produced greenhouse gases into the atmosphere. Half of all fossil fuels are burned to provide electricity and heat; the next big users of fossil fuels are manufacturing and transportation.
Land use: How humans remove forests and use land contributes over one quarter of all human-produced greenhouse gases to the atmosphere. Trees absorb carbon dioxide from the atmosphere, so logging and clearing forest land for agriculture and development means more carbon dioxide stays in the air.