Central European I-M223 Co-Migrated With Scandinavian I-M253 Following Last Ice Age

I found this (Germanic Origins From the Perspective of the Y Chromosome, Michael Robert St. Clair, University of California, Berkeley, Spring 2012) while researching for information on my Dad's I2b1 (I-M223) Hg. On page 47, it says regarding my Dad's Hg:

The frequency of the I-M223 mutation peaks in Germany and the Netherlands, and is present in about 10% of men in both countries. Rootsi and others suggest that the the Central European I-Group (I-M223) co-migrated with the Scandinavian I-Group (I-M253) from an Iberian refuge area following the last ice age.

This paper further goes to report that Hg I (both I1 and I2 branches which are further subdivided into regional I-Groups - Scandinavian, Balkan, Sardinian and Central European) is found almost exclusively in Europe and has been in Europe since the Paleolithic. The paper discusses other major European Y-Hg's too.