Green water – the rainwater available to plants in the soil – is indispensable for life on and below the land. But in a new study, we found that widespread pressure on this resource has crossed a critical limit.
The planetary boundaries framework – a concept that scientists first discussed in 2009 – identified nine processes that have remained remarkably steady in the Earth system over the last 11,700 years. These include a relatively stable global climate and an intact biosphere that have allowed civilisations based on agriculture to thrive. Researchers proposed that each of these processes has a boundary that, once crossed, puts the Earth system, or substantial components of it, at risk of upset.