For the late 20th century, a period of strong greenhouse gas increases, but with diminishing solar influence, variability in ocean warming shown in the profiles falls much further still. (skepticalscience.com)
Coal - seam gas is mostly methane, a very strong greenhouse gas. (ramblingsdc.net)
When the arctic warms the permafrost gives off more methane, which is an even stronger greenhouse gas. (greencarcongress.com)