Kirsten served as Chief of Policy Analysis and Innovation for UNOCHA (2013-2015); Head of the Advocacy and Visual Media Unit (2009-2011); Head of the Global Challenges Unit (2007-2009); and as a humanitarian affairs officer from 2002-2007, coordinating responses to the 2006 security crisis in Timor-Leste, the 2005 Pakistan Earthquake, Hurricane Katrina, and the 2004 Indonesian Tsunami. Additionally, she served as humanitarian advisor to UN Special Envoy for Haiti, President William Clinton in 2010.