The four ‘Global Commons’ – the Atmosphere, Antarctica, the High Seas (Oceans) and Outer Space – are in international law identified and recognised as falling outside the jurisdiction of any state. Whilst crucial to mankind and the global ecosystem as a whole, the commons are severely impacted by the current anthropogenic climate change. This thesis argues that the global commons have a weak legal protection today. Given the significance of the global commons for the achievement of sustainable development, exploring possibilities to strengthen such protection through international law is crucial to secure the future of our world. The purpose of this thesis is to highlight the issues relating to the current legal protection of the global commons and to address them in the perspective of international law and sustainable development as intersecting conceptual and theoretical frameworks. By applying and analysing the acknowledged New Delhi Declaration of Principles of International Law Relating to Sustainable Development, this thesis will aim to provide insights, and maybe even a fresh point of view, as to how legal instruments could be structured and implemented in the strive for more effective and sustainable protection of the global commons.