Scientists are warning that the Earth is “well outside the safe operating space for humanity” due to human interference in the environment.
The assessment was published in the Journal of Science Advances and is based on more than 2,000 scientific studies. It indicates that six of the planet’s “planetary boundaries” have broken and two more are on the edge.
The researchers called it the “first scientific health check for the entire planet.”
The boundaries include systems like land use, biosphere integrity, climate change, Ozone depletion and others. Among these, air pollution and ocean acidification are close to being broken. Meanwhile, climate change, biosphere integrity, land use, freshwater management, biogeochemical flows(the Earth’s nitrogen and phosphate levels) and novel elements (previously called chemical pollution) have exceeded the boundary.
Scientists do not describe the planetary boundaries as a tipping point that cannot be returned from and result in catastrophic and swift changes in the environment. Instead, they say they represent markers that once passed, could fundamentally alter how the planet functions.
To determine the point where the boundary is crossed, scientists examined how the world looked from the end of the last ice age 10,000 years ago until the start of the Industrial Revolution. This period, called the Holocene, was stable geologically speaking, during which the entirety of human civilization rose.
The scientists did not set the boundaries at the points they were before the Industrial Revolution, since the Earth’s biosphere is resilient and can cope with some changes. The boundaries represent estimates of when that resiliency could begin to fail.
“We know for certain that humanity can thrive under the conditions that have been here for 10,000 years,” Katherine Richardson, a professor at the University of Copenhagen and the assessment’s lead official. “We don’t know that we can thrive under major, dramatic alterations.”
Only ozone depletion was solidly within the boundary and is also the only planetary boundary where things seem to be moving in the right direction. In 1985, a hole in the ozone was discovered over Antarctica. By 1987, international treaties had been drafted that cut the use of chlorofluorocarbons (CFCs), the chemicals blamed for the depletion of the ozone, in half, and today, their use is banned in 197 countries. Since the ban, the ozone has been slowly but steadily recovering.
Richardson compared it to a patient with high blood pressure. “That does not indicate a certain heart attack, but it does greatly raise the risk,” she said.
The assessment’s authors say more study is needed to understand how the different planetary boundaries will affect each other as the Earth moves further “into disequilibrium.”