Why does permafrost thaw release methane?

Permafrost is ground that has stayed frozen for at least two consecutive years, and in many Arctic regions it has persisted for thousands of years. It locks away dead plants and animals that were never fully decomposed. When the ground thaws, microbes become active again and break down the organic matter. In waterlogged, low-oxygen conditions, that decomposition produces methane as well as carbon dioxide. This matters because methane is a potent greenhouse gas and can amplify warming in the Arctic.