Humans exceeded 7 of the 9 'safe limits' for life on Earth: Study

Humans have crossed seven of the nine "safe limits" that allow for human life on earth, according to a new study.

In 2009, a team of global scientists had introduced the concept of planetary boundaries, that 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).

In a new report published in the journal Nature, scientists found that seven of these thresholds, including climate change, biodiversity, land-system change, and biogeochemical flows (nitrogen and phosphorus imbalance), have been crossed.

The study, developed by an international science commission engaging more than 40 researchers from across the globe, showed that humans are taking colossal risks with the future of civilization and everything that lives on Earth.

For example, human activities are altering water flows, excessive amounts of nutrients are released into waterways from fertiliser use, and limited natural areas are left.

The world has already passed the safe and just climate boundary, which is set at 1 degrees Celsius above pre-industrial temperature levels, as tens of millions of people are already harmed by the current level of climate change.

Further, the rising temperatures are melting away large ice-sheets of Greenland, and increasing deforestation in the Amazon forest - all which are likely to lift oceans by metres, releasing billions of tonnes of carbon dioxide and methane.

"Our results are quite concerning. This means that unless a timely transformation occurs, it is most likely that irreversible tipping points and widespread impacts on human well-being will be unavoidable," said lead author Prof. Johan Rockstrom, Earth Commission Co-Chair.

"Avoiding that scenario is crucial if we want to secure a safe and just future for current and future generations," added Rockstrom, who is also Director of the Potsdam Institute for Climate Impact Research in Germany.

The scientists also delivered the first quantification of safe and just Earth system boundaries on a global and local level for several biophysical processes and systems that regulate the state of the Earth system.

"The Earth system is in danger -- many tipping elements are about to cross their tipping points," said co-author Dahe Qin, director of the Chinese Academy of Science's influential Academic Committee.

The scientists called for setting just targets to prevent significant harm and guarantee access to resources to people and for as well as just transformations to achieve those targets.