Yes, the distinction between population glut and limited lands is important.

I do not believe that there were too many people in Scandinavia for the resources to provide for. Life there wasn't a choice of move away or maybe starve.

The increased population meant too many sons for too little patrimony. Continual subdividing of a jarl's estate would soon reduce each heir to the possession of a tiny farm, as the holding got parcelled out to surviving sons. So the answer was to emigrate, under arms of course.