Biodiversity loss. Land use. Freshwater use. Nitrogen and phosphorus cycles. Stratospheric ozone. Ocean acidification. Climate change. Chemical Pollution. Aerosol loading in the atmosphere.
A team of 30 scientists across the globe have determined that the nine environmental processes named above must remain within specific limits, otherwise the “safe operating space” within which humankind can exist on Earth will be threatened. Amid some controversy, the group has set numeric limits for seven of the nine so far (chemical pollution and aerosol loading are still being pinned down). And the researchers have determined that the world has already crossed the boundary in three cases: biodiversity loss, the nitrogen cycle and climate change.