The limits of life, breaking them
Most people have grown accustomed to ignoring scientists' warnings about the poor relationship between the human species and the planet. Many hear or read these news stories with indifference, sometimes with apprehension or laziness, and even hostility. Anti-scientific discourses and attitudes opposed to or suspicious of knowledge, study, and culture have become commonplace and are represented by a good handful of world leaders, with the inevitable US president at the forefront. Discrediting science, culture, and knowledge is a good way to move toward uninformed, confused, easily deceived, and therefore docile societies.
Last week, the annual report of the PIK, the acronym for the Potsdam Institute for Climate Impact Research, was released. Its international team of researchers, led by University of Potsdam Professor Johan Rockström, has been studying the risk of disrupting the Earth's natural balance and resilience since 2009. Their starting point is that the planet's climate became stable 11,000 years ago (the Holocene), which has enabled, during this time, the development of agriculture and livestock, the domestication of animals, and ultimately the construction of the modern world. The question PIK scientists are striving to answer is when this stability might be threatened by the impact of human activity on nature.
To answer this question, they defined nine interconnected limits that, considered together, define the safe operating space for life on Earth. These nine limits are: climate change, biodiversity loss, land use, freshwater use, biogeochemical cycles, chemical pollution, ocean acidification, atmospheric aerosols, and the ozone layer. The 2025 review found that, of the nine limits, the first seven have already been breached. The last on the list to enter the unsafe zone was ocean acidification, that is, the acidity index of marine waters. Only the last two (atmospheric aerosols and the ozone layer) remain within the safe zone. But the other seven show, with each review, a greater and more accelerated tendency toward deterioration.
The violation of each of these limits does not automatically entail catastrophic change, but it does point to a situation of danger to life on our planet. Rockström insists that "the diagnosis is serious, but there is a cure; failure is not inevitable." Feeling this way is comforting, but perhaps it's the wrong message, because the immediate response of governments, which are the ones that can take significant steps to correct this course, is to relax: China has just announced that it will reduce CO₂ emissions... starting in 2035. Meanwhile, PIK scientists warn us that we are living like a house, as if the house were threatening to fall on us, and we don't even have enough water.