Underlying the northern arctic coast of Alaska is a thick layer of permafrost. As water melts and pools on top of the permafrost, thaw lakes are formed. Much of the North Slope of Alaska is covered in such thaw lakes. As they decompose organic material, the bacteria and other microorganisms living in thaw lakes produce either carbon dioxide or methane, depending on the conditions. Methane is a highly potent greenhouse gas with a global warming potential 22 times that of carbon dioxide, and increased microbial activity in thawing permafrost areas could lead to changes in the atmosphere due to the increased release of methane.