Barthel formally retired at the end of 2018, but he plans to continue working part-time.

A festive retirement concert took place in December 2018, in the Groningen Oosterpoort concert hall. The Groningen student symphony orchestra Mira, conducted by Pieter Bosma, played the Academic Fest Ouverture by Brahms, Tchaikovsky’s first piano concerto (with soloist Martin Oei) and Dvorak’s 7th symphony (picture: Elmer Spaargaren).