But if that is true, then the methane spike at the end of the ice age must have been caused by something else.

ECONOMIST: Methane and climate change

As land repeatedly surfaced and receded, the remains of marine creatures got mixed up with those of terrestrials, forming one big Ice Age graveyard: sea cows, prehistoric sharks, spike-tailed armadillos the size of refrigerators.

NEWYORKER: Bones of Contention

Mark Maslin of the Environmental Change Research Centre at University College, London, believes that the spike was caused mainly by emissions from tropical wetlands and peat bogs that formed as the ice retreated.

ECONOMIST: Methane and climate change