A new study funded by the European Union and Germany warns that out of nine crucial indicators measuring Earth's health, six have exceeded safe limits, with two more trending in a dangerous direction. As the study describes, Earth is now akin to a "patient."
In 2009, Johan Rockstrom, director of the Potsdam Institute for Climate Impact Research in Germany, and his team introduced these nine indicators to gauge the overall health of the planet for human habitation. The indicators include climate change, novel entity pollution (like microplastics, nuclear waste, and synthetic compounds), ozone depletion, air pollution (atmospheric aerosol loading), ocean acidification, freshwater changes, land system alterations, biosphere integrity (biodiversity), and biogeochemical flows.
Three of these indicators were beyond safe limits in 2009. By 2015, the number of "red light" indicators rose to four. The latest research, published in the journal "Science Advances" this Wednesday, updates these findings, revealing that six indicators are now in the red.
The new report identifies biodiversity, climate change, novel entity pollution, biogeochemical flows, land, and freshwater as the six indicators that have breached the "safe operating space for humanity." The first four of these are at the highest risk levels. While the ocean and air remain within safe limits, they are trending toward danger. Ozone is the only indicator showing improvement.
Biogeochemical flows reflect human disturbances in global elemental cycles. The study considers nitrogen and phosphorus as essential life components, and their global cycles have been significantly altered by agricultural and industrial activities.
Compared to 2015, two additional "red light" indicators have emerged: freshwater health and novel entity pollution. Rockstrom, one of the report's co-authors, attributes this to deteriorating river flow conditions and a deeper understanding of the issues, leading to the water indicator moving from "barely safe" to "beyond bounds." Improved measurement methods and data have also allowed for the quantification of novel entity pollution levels for the first time.
The Stockholm Resilience Center suggests that crossing these boundaries increases the risk of "large-scale abrupt or irreversible environmental changes." Katherine Richardson of the University of Copenhagen, another co-author, likens the Earth to a human body, with the "safe boundaries" being akin to normal blood pressure standards. Exceeding these standards doesn't necessarily mean an imminent heart attack but does elevate the risk, emphasizing the need to lower these "pressures."
The report notes that these nine indicators are interconnected. Computer simulations by the research team revealed that the deterioration of a single indicator, such as climate or biodiversity, could lead to the decline of others. Conversely, addressing one issue can also benefit others.
The report suggests that sustainable land use and forest conservation might be among the most potent tools humans currently have to combat climate change. Encouraging biodiversity could also reduce pollution and improve water health.
The two most concerning indicators for researchers are the climate crisis and the biodiversity crisis. Rockstrom points out that the biodiversity crisis is particularly alarming because it doesn't receive as much attention as climate change, even though it's fundamental to maintaining carbon and water cycles.
The ozone layer is the only indicator showing significant improvement, largely due to global initiatives like the 1987 Montreal Protocol. This recovery suggests that other indicators, even if they've only slightly crossed their boundaries, can also be restored.
Jonathan Overpeck, the director of environmental studies at the University of Michigan, who wasn't involved in the study, endorses the report, calling its analysis "balanced." The findings appear as a flashing red alert, but it's not alarmist. "People should be concerned, but more importantly, there's still hope," he said.
However, there's some disagreement among scientists about the measurement methods and models used in the European study. Granger Morgan, a professor of environmental engineering at Carnegie Mellon University, says experts haven't reached a consensus on where exactly Earth's limits lie or the extent to which different systems on Earth might interact. Yet, he admits, "We are indeed dangerously close to the limits."