De Brún was a member of the Regional Policy Committee in the European Parliament and a substitute member of the Environment Committee. Within the EU parliament she focused on environmental issues. She was part of an EU delegation that attended the 2011 Durban Climate Change Conference.Summary Note: Delegation to the 17th Session of the Conference on Climate Change. She was critical of the final report of the conference saying "We need to recognise that even the best possible outcome from Durban still only takes us half way down the road we need to travel".Conference backs 'fragile' deal on climate change . Irish Times, 12 December 2011.
