A study warns we have exceeded seven of the eight variables for maintaining a healthy and just planet.

In 2009, a team of renowned environmental scientists published an “extraordinarily influential” article in Nature magazine arguing that planet-altering human activities could be assembled into nine groups.

Thresholds were calculated for most of them, beyond which the result could spell danger for the planet and its people. At the time the scientists concluded that humanity has crossed three of these nine “planetary boundaries”.

An update on this research by the international scientist group Earth Commission has found that seven out of eight of the original thresholds have now been crossed.

The eight “planetary boundaries” are climate, natural ecosystem area, ecosystem functional integrity, surface water, groundwater, nitrogen, phosphorus, and aerosols.

Adding environmental justice to this list has led the authors to advocate that global warming should be limited to 1°C above pre-industrial levels. This is lower than the 1.5°C target agreed at the 2015 Paris climate conference.

The authors reason that keeping to 1.5°C might well enable the world’s more-affluent people to protect themselves, but it would create significant harm for the most vulnerable.

“Exceeding these boundaries is like entering completely unknown territory with conditions where we don’t know how the planet will behave,” one of the researchers, Daniel Ospina, told the Spanish newspaper El País.