by B. Van Vliet-Lanoé & A. Gudmundsson, Feb 2020, in ResearchGate

Permafrost developed from Termination Ia (Bölling interstadial, 14.5 cal ka BP) in Northern Iceland, in answer to deglaciation. Permafrost persisted or even re-extended during the Preboreal cooling events (at 11.2, 10.3 and 9.3 cal ka BP) synchronic with pulsated glacial advances. It disappeared below 1000 masl during the Thermal Optimum (8-5 cal ka BP). The present-day re-extent was controlled with the cooling related with the Little Ice Age and particularily the Maunder solar Minimum. Continuous permafrost is stable above 1000 masl, but is today melting between 900 and 800 masl. Discontinuous permafrost is vanishing today with the recent climate warming (from 1970), especially in palsa bogs, and on valley slopes with thermokarstic mass wasting.