As greenhouse gas, methane is more powerful than carbon dioxide, but there is a much more important difference between these two gases. Carbon dioxide emissions are something that we create and that we can control, at least in principle. If we stop burning fossil fuels, then we stop generating CO2. But, with methane, it is another matter. We have no direct control on the huge amounts of methane buried in ice in the permafrost and at the bottom of oceans in the form of "hydrates" or "clathrates."