Monday June 27, 2022
The Conversation —
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.
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.