The paper argues for the development of open science in Africa as a means of energising national science systems and their roles in supporting public and private sectors and the general public. It focuses on the complexity of the social and economic challenges created by climate change and the demographic explosion and the difficulty of confronting them in the absence of an adequate digital infrastructure. Although a well-coordinated, federated multi-state open science system would be a means of overcoming this barrier, African science systems largely operate independently of each other, creating siloes of incompatible policies, practices and data sets that are not mutually consistent or inter-operable. Africa's linguistic chasms of English, French, Portuguese, Spanish and indigenous languages create further barriers. As international science moves towards greater openness and data sharing to address the complexity inherent in major global challenges, Africa's stance needs radical overhaul. The paper draws on the questionnaire data from 15 African Science Granting Councils and the state-of-the-art Report to them on "Open Science in Research and Innovation for Development in Africa". It concludes that a well-developed Open Science system for Africa, would develop and enhance collaborations and partnerships among Africans to tackle the challenges that they face and accelerate innovation and development.