Earth Has Overshot Key ‘Planetary Boundaries,’ Scientists Warn

Human activity is imperiling eight of the planet’s critical life-support systems and seven of them have already passed into a danger zone, according to a massive review of Earth science conducted jointly by more than 60 researchers and published Wednesday in The Lancet Planetary Health.

Looking at necessities of a livable Earth — including the climate, freshwater systems, biodiversity and soil nutrients — the researchers find almost all have crossed crucial thresholds. The only global system yet to breach safe limits is aerosols, even as small-particle air pollution contributes to 8 million deaths a year.

The new paper builds on a scientific project that began in 2009 ...