Greenhouse Gases: Methane

Alaskan Tundra

Global warming has been most dramatic in the Arctic, where temperatures have risen almost twice as much as the global average. The vast tundra (Arctic plains) of Alaska, Siberia, and other subpolar regions contains a layer of frozen subsoil called permafrost. The area of frozen ground has decreased due to rising temperatures, and scientists are concerned that as the permafrost melts it will release large amounts of methane, a potent greenhouse gas, into the atmosphere. This would accelerate global warming.

       Methane is emitted into the atmosphere during the mining of coal and the production and transport of natural gas and oil. Methane also comes from rotting organic matter in landfills, rice paddies, and wetlands, as well as from certain animals, especially cows, as a byproduct of digestion. Live plants also emit small amounts of methane.

       Scientists are increasingly concerned about the release of methane and carbon dioxide from melting permafrost, areas of frozen ground in the tundra (Arctic plains) of Alaska, Siberia, and other subpolar regions. Temperatures in the top layer of permafrost have increased, leading to a decrease in the area of seasonally frozen ground. Methane released from these areas as they melt would contribute to further warming and further melting, in what scientists call a feedback process.

      Since the beginning of the Industrial Revolution, the amount of methane in the atmosphere has more than doubled. Methane traps nearly 30 times more heat than the same amount of carbon dioxide. Compared to carbon dioxide, methane appears in lower concentrations in the atmosphere and remains in the atmosphere for a shorter time. In total, methane contributes about a third as much as carbon dioxide to global warming.