在塞尔维亚，大量的沼气（一种对温室效应影响极大的气体）都被封存在曾被称为“永久冻土”的地区，因为人们相信这些地区的土地都将永久处于封冻状态。
In Siberia, vast quantities of methane, an extremely potent greenhouse gas, are locked up in what used to be called “permafrost” – regions in which it was assumed that the ground was permanently frozen.