Crucial functioning of and human dependence on the global water system

The analysis in this chapter goes deeper into the core functions of the global water system (GWS), the role of water as the bloodstream of the biosphere and the key interactions between scales, including remote linkages or so-called teleconnections. It discusses how various changes in the Earth System could slowly make the GWS less resilient to shocks such as droughts, the key role of bidirectional interactions between water, land and vegetation, and local, regional and planetary boundaries. The chapter highlights three large-scale interactions that indicate long-term responses by the socio-ecological system to land-use changes in terms of so-called tipping points. It finally presents a comparative analysis of water and food security for a number of large river basins in Asia, Africa and South America.