Sub-Saharan Africa is confronted with the urgent challenge of ensuring food security in the face of changing demographics, climate change and water vulnerability, which can lead to potential crop failure. Despite the high advocacy for technological solutions, such as irrigation, rainfed agricultural systems, which account for more than 90% of the region's food production, often remain overlooked. This raises the question of which water sources can be sustainably utilized to meet the Sustainable Development Goals. This thesis investigates the significant role of "green water" in addressing these challenges in agricultural production and ecosystem health in the sub-Saharan African region. 

Application of models reveal the pronounced role of green water in African forest systems, regional ecosystems, and food production systems in studying these societal sustainability questions,. The study projects a decrease in precipitation recycling with increasing severity of climate change. The results suggests that regions with lower water efficiency per yield production can significantly increase agricultural yield by tapping into green water sources as improving rainwater management systems, even as land-sourced precipitation is projected to decline more than oceanic sources. 

The thesis argues for adoption of a green water-centric approach to be opted in strategic plans at both local and global levels. Moreover, by capitalizing on green water resources, less developed nations such as sub-Saharan Africa can fulfill their Sustainable Development Goals without the need for significant technological investments and the associated environmental risks.