Icelandinc membership will take place through a treaty. Any power that citizens have over their government entering into international treaties applies to Icelandic membership.

This is why I think Croatia will not join the EU: there's nothing to prevent Croatia's accession treaty from being defeated either by the Slovenian parliament, or the Slovenian people in a referendum.

The peak-to-trough part of the business cycle is an outlier. Carnot would have died laughing.