Life support systems on Earth face greater risks and uncertainties than ever before, and most of the main safety limits have already been exceeded as a result of human interventions across the planet, according to a scientific study released this Wednesday (13).
In a sort of “health check-up” of the planet published in the journal Science Advances, an international team of 29 experts concluded that Earth is currently “well outside the safe operating space for humanity” due to human activity.
The study, which expands on a 2015 report, states that the world has already surpassed 6 of 9 “planetary boundaries” — safe limits for human life in areas such as the integrity of the biosphere, climate change, and the use and availability of freshwater.
In total, the study states, 8 of the 9 borders are under greater pressure than that seen in the 2015 assessment, increasing the risk of dramatic changes in Earth’s living conditions. The ozone layer is the only issue to improve.
“We don’t know whether we can thrive under large, dramatic changes to our conditions,” said study lead author Katherine Richardson of the University of Copenhagen.
The authors assert that crossing borders does not represent a tipping point at which human civilization will simply collapse, but could bring irreversible changes to Earth’s life support systems.
“We can think of the Earth as a human body and planetary boundaries as blood pressure. Above 120/80 [na medição da pressão sanguínea] It doesn’t necessarily indicate a heart attack, but it does increase the risk,” Richardson said.
Scientists have sounded the alarm about the rise in deforestation, the excessive consumption of plants as fuel, the proliferation of products such as plastic, genetically modified organisms and synthetic chemicals.
Of the nine limits evaluated, only ocean acidification, ozone layer destruction and atmospheric pollution — mainly with soot-like particles — were considered still within safe limits. The ocean acidification ceiling, however, is close to being surpassed.
The atmospheric concentration of carbon dioxide, the main greenhouse gas, has increased to around 417 ppm (parts per million), significantly higher than the safe level of 350 ppm.
The current rate of species extinction is also estimated to be at least tens of times faster than the average rate of the last 10 million years, meaning that the planet has already surpassed the safe boundary for genetic diversity.
“In my career I have never relied on as much evidence as I do today,” said Johan Rockström, co-author of the study and director of the Potsdam Institute for Climate Impact Research.