The Earth is exceeding its “safe operating space for humanity” in six of nine key measures of its health, and two of the remaining three are heading in the wrong direction, according to a new study.
The Earth’s climate, biodiversity, land, drinking water, nutrient pollution and “new” chemicals (man-made compounds such as microplastics and nuclear waste) are out of control, a group of international scientists said today. Science Advances magazine in its Wednesday edition. Only ocean acidity, air health and the ozone layer are within limits considered safe, and both ocean and air pollution are heading in the wrong direction, according to the study.
“We are in a very bad situation,” said Johan Rockstrom, co-author of the study and director of the Climate Impact Research Institute in Potsdam, Germany. “We show in this analysis that the planet is losing power of resistance and the patient is sick.”
In 2009, Rockstrom and other researchers created nine different large boundary zones and used scientific measurements to judge the health of the Earth as a whole. Wednesday’s study was an update of the 2015 study and added a sixth factor to the unsafe category. The water went from barely safe to out of bounds due to worsening river runoff and improved measurements and understanding of the problem, Rockstrom explained.
These limits “determine the fate of the planet,” said climatologist Rockstrom. The nine factors have been “scientifically well established” by numerous outside studies, he said.
If Earth can control these nine factors, it could be relatively safe. But it’s not like that, she said.
In most cases, the team uses other peer-reviewed studies to create measurable thresholds for a safe limit. For example, they use 350 parts per million of carbon dioxide in the air, instead of the 1.5 degrees (2.7 degrees Fahrenheit) of warming since the pre-industrial era set in the Paris climate agreement. This year, carbon in the air peaked at 424 parts per million.
The nine factors are intertwined. When the team used computer simulations, they found that worsening one factor, such as climate or biodiversity, led to the degradation of other aspects of the Earth’s environment, while correcting one helped the others. Rockstrom said this was like a simulated stress test for the planet.
The simulations showed “that one of the most powerful means available to humanity to combat climate change” is to clear its lands and save its forests, according to the study. Returning forests to late 20th century levels would provide important natural sinks to store carbon dioxide rather than in the air, where it traps heat, the study notes.
Biodiversity — the number and types of living species — is at one of its most worrisome times and doesn’t get as much attention as other issues, such as climate change, Rockstrom said.
“Biodiversity is critical to keeping the carbon cycle and the water cycle intact,” Rockstrom said. “The biggest headache we have today is the climate crisis and the biodiversity crisis.”
University of Michigan environmental studies dean Jonathan Overpeck, who was not involved in the study, commented that it was “deeply disturbing because of its implications for the planet and people should be concerned.”
“The analysis is balanced in the sense that it raises a flashing red alarm, but is not overly alarmist,” Overpeck said. “And most importantly, there is hope.”
The fact that the ozone layer is the only factor for improvement shows that when the world and its leaders decide to recognize a problem and act on it, it can be solved and “for the most part there are things we know how to do” to improve the remaining problems said Neil Donahue, a professor of chemistry and the environment at Carnegie Mellon University.
Some biodiversity scientists, such as Duke’s Stuart Pimm, have long questioned Rockstrom’s methods and measurements, saying it renders the results meaningless.
But Carnegie Mellon environmental engineering professor Granger Morgan, who was not involved in the study, said: “Experts don’t agree on exactly where the boundaries are, or how much the planet’s different systems can interact, but we can tell. we are getting dangerously close.”
“I have often said that if we don’t quickly reduce the way we are stressing the Earth, we are toast,” Morgan said in an email. “This article says we’re more likely to be toast.”
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