Abstract. Following the 2015 UNFCCC Conference of Parties in Paris there is renewed interest in understanding and avoiding potentially dangerous climate change. The loss of Arctic sea ice is one of the most directly visible aspects of climate change and the question is frequently asked: when can we expect the Arctic to be ice-free in summer? We argue here that this question may not be the most useful one to inform decisions on climate change mitigation or adaptation in the Arctic. The development of a community-wide consensus on a robust definition of "ice-free", may reduce confusion in the community and amongst the public.