has not this gas been released over the course of earths history?How can climate change be linked to a rise in methane emissions in the polar regions?Methane is an effect when organic material is rotting and/or decaying. In the polar region (e.g. the tundra of Siberia) former trees and vegetation is frozen and the organic matter is not decaying. As Temperature increase and go above 0 degrees Celsius the rotting process starts and methane gas is set free into the atmosphere. As methane itself is a green house gas expected to be 4 - 5 times more effective then CO2 it will work as a multiplier in the rise of temperature.
There was a television report with Alan Alda in the US where he visited this tundra area in Canada and is it was directly shown using old caverns which were formerly frozen and now are above freezing point.
You may find it on the PBS website (Public Broadcasting System/USA).
You are correct: methane gas has been released over the last century but a part of potential gas has been stored in %26quot;un-trotten/un-decayed%26quot; organic material in the polar/tundra regions of the world.How can climate change be linked to a rise in methane emissions in the polar regions?Large swings in polar concentrations of methane in polar regions are not unprecedented for historical times, even during the preindustrial part. At least one study has suggested that it may be due to a tropical source sometimes. http://www.springerlink.com/content/8731
Some are concerned that polar CH4 (methane) could act as a positive feedback mechanism, and cause run away global warming, but additional CH4 has a logarithmic greenhouse effect on global warming. http://en.wikipedia.org/wiki/Beer%E2%80%
Thus, additional CH4 comes to have less and less effect, not a run away effect.
The primary effect of methane as a greenhouse gas is at the 3.3 um range: http://en.wikipedia.org/wiki/Beer%E2%80%
However, that effect is somewhat limited by atmospheric water, and the fact that very little energy is present in that range anyway.
