A comprehensive scientific assessment in 2015 found that human activity has already breached four of the planetary boundaries. Greenhouse gas emissions are brewing a hotter climate, the sixth mass extinction of species is unpicking the web of life that makes up the global biosphere, intensive farming is polluting the environment and natural habitats are being destroyed on a significant scale. Earlier in 2022, researchers announced that a fifth planetary boundary had been crossed with the emission and accumulation of chemical pollution and plastics.

So far, it has been suggested that human use of freshwater is still within safe limits globally. But earlier assessments only considered the extraction of what is called blue water – that which flows in rivers and resides in underground aquifers. Even then, regional boundaries are likely to have been crossed in many river basins due to a sixfold increase in the extraction of blue water over the past century. Besides irrigating crops to sate growing demand from people and livestock, population growth and higher standards of living have raised global domestic and industrial water consumption, disrupting aquatic ecosystems and decimating the life within them.