Permafrost is permanent on the timescale is years, not on the timescale of interglacial periods. Most of the permafrost we have at the moment thawed in the last

Permafrost is permanent on the timescale is years, not on the timescale of interglacial periods. Most of the permafrost we have at the moment thawed in the last interglacial period and refroze in the last ice age.