U.S. Energy Information Administration (EIA) Energy Kids Website. Nonrenewable Natural Gas.
The main ingredient in natural gas is methane, a gas (or compound) composed of one carbon atom and four hydrogen atoms. Millions of years ago, the remains of plants and animals (diatoms) decayed and built up in thick layers. This decayed matter from plants and animals is called organic material — it was once alive. Over time, the sand and silt changed to rock, covered the organic material, and trapped it beneath the rock. Pressure and heat changed some of this organic material into coal, some into oil (petroleum), and some into natural gas — tiny bubbles of odorless gas.
Burning natural gas produces carbon dioxide which is a greenhouse gas. Greenhouse gases contribute to the "greenhouse effect."
Scientists know with virtual certainty that increasing greenhouse gas concentrations tend to warm the planet, according to the U.S. Environmental Protection Agency, Climate Change State of Knowledge.
As with other fuels, natural gas also affects the environment when it is produced, stored, and transported. Because natural gas is made up mostly of methane (another greenhouse gas), small amounts of methane can sometimes leak into the atmosphere from wells, storage tanks, and pipelines.