In another worrying study, humans have crossed seven of the nine "safe limits" that make human life possible on Earth. In 2009, a team of global scientists had introduced the concept of planetary boundaries, which humans should not cross if they want the earth to remain hospitable to civilisation.

They are: climate change, biosphere integrity, land-system change, freshwater use, biogeochemical flows (nitrogen and phosphorus), ocean acidification, atmospheric aerosol pollution, stratospheric ozone depletion, and release of novel chemicals (including heavy metals, radioactive materials, plastics, and more).