Harro has published numerous book chapters and articles in peer-reviewed academic journals, including Climatic Change, Climate Policy, Energy Policy, Global Environmental Change, Global Environmental Politics, Journal of Environmental Law, Nature Climate Change, New York University Journal of International Law & Politics, Policy Sciences, and Stanford Environmental Law Journal. He is author of The Fragmentation of Global Climate Governance (Edward Elgar, 2014), and co-editor of Climate Change Policy in the European Union (Cambridge University Press, 2010). He is Editor of the journal Review of European, Comparative and International Environmental Law (RECIEL), Associate Editor of the Carbon & Climate Law Review (CCLR), and sits on the Editorial Board of International Environmental Agreements: Politics, Law and Economics.

Harro holds a PhD (cum laude) from the VU University Amsterdam (2013), and an MA in law (specialization: international law) from VU University Amsterdam (2002).