Currently based in the Netherlands, Tiernan works at Tilburg University as a Digital Skills Trainer in the Research Data Office.

In this role, he supports open science and research data management through a programme of workshops and webinars, including sessions on data anonymization, reproducible research, and good research software practices. His current focus is on developing training and support for research software and he has contributed to a range of national initiatives, including projects with the Netherlands eScience Center and the National Open Science Festival. 

Since 2025 Tiernan is the Managing Editor of the LIBER Quarterly.