Greenhouse Effects
Greenhouse Gases in Earth's Atmosphere
A greenhouse gas (or GHG) is any gas in the atmosphere that absorbs and releases heat, thereby keeping the planet's atmosphere warmer than it would otherwise be. The most important greenhouse gases in the earth's atmosphere are water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone.
Greenhouse gases occur naturally in the Earth's atmosphere, but human activities, such as burning fossil fuels, increase levels of greenhouse gases in the atmosphere, causing global warming and climate change. The Kyoto Protocol is an international treaty aimed at controlling the release of greenhouse gases from human activities.
It should be noted that different greenhouse gases remain in the atmosphere for different periods of time and absorb different amounts of heat. The "Global Warming Potential" (GWP) of a greenhouse gas indicates how much heat a gas causes over a certain period (usually 100 years). Based on CO2 as index 1, GWP calculates the greenhouse gas potential of the other gases produced by combustion. For example, 1 kg of methane over a period of 100 years causes 25 times the warming compared to 1 kg of CO2. This means that methane has a GWP value of 25.
