Not only does global warming threaten life on earth, but also dwindling freshwater reserves, environmental pollution and the reduction in biodiversity. The “Earth Commission”, an international association of scientists, warns of this. In their study in the journal Nature the group led by Johan Rockström from the Potsdam Institute for Climate Impact Research (PIK) writes that seven out of eight “safe and just boundaries” of the Earth system have already been exceeded.
From the point of view of the more than 40 scientists, people with their current way of life are endangering the stability and resilience of the entire planet. “That’s why, for the first time, we are presenting quantifiable numbers and a solid scientific basis to assess the state of our planet in terms of human well-being and equity,” Rockstrom said.
The study is based on the concept of planetary boundaries proposed by Rockström and colleagues in 2009, crossing which threatens the stability of ecosystems on Earth. The concept was supplemented by criteria for a safe and just space for civilisation, which the British economist Kate Raworth described in 2012.
“One must not delude oneself that the planetary boundaries are scientifically determinable”
On a stable earth there are feedbacks that cushion disturbances. If this balancing system is permanently disrupted, there is a risk of existential and irreversible damage, such as an increasing number of deaths, displacement of people, loss of food, water or food security as well as chronic diseases, injuries or malnutrition.
In the case of biodiversity, for example, the authors of the study believe that two limits have already been exceeded: 50 to 60 percent of the land area would have to be left in its natural state or managed sustainably so that the natural services provided by ecosystems, such as pollination, fresh water and fresh air, are preserved. Currently, this only applies to 45 to 50 percent of the land area. And the requirement that 20 to 25 percent of every square kilometer should be covered by largely natural vegetation is met on only a third of the land area affected by humans.
In order to preserve the ecosystems in and around rivers and inland waters, their water level should only fluctuate by around 20 percent of the water volume. On about a third of the land area this is not the case. In addition, only as much groundwater should be removed as can form again. This limit is currently being broken on 47 percent of the world’s land areas.
The justice concept of the new approach includes three aspects of justice in the use of the global commons: towards other living beings and ecosystems, towards the next generations and towards the globally distributed members of the current generation.
The concept of justice comes into play, for example, in the case of climate change: while scientists still classify warming by 1.5 degrees as “certain” compared to the pre-industrial age, they see warming by a maximum of one degree as “fair”. The authors of the study write that even as things stand today, with global warming of around 1.2 degrees compared to pre-industrial times, tens of millions of people are massively affected by climate change. This number will increase dramatically with every tenth of a degree of additional warming.
“I think it’s very, very important to add the perspective of justice. However, one shouldn’t delude oneself into thinking that the planetary boundaries can be scientifically precisely determined,” says Katrin Böhning-Gaese, Director of the Senckenberg Research Center for Biodiversity and Climate. The image of the planetary boundaries suggests that there are tipping points at which the earth system tilts from a safe and habitable state to an uninhabitable state. However, according to Böhning-Gaese, there does not seem to be a safe area when it comes to biodiversity. “On the contrary, with every lost species, we seem to lose ecosystem functions, sometimes more and sometimes less. Above all, the robustness and stability of ecosystems suffer with every lost species.”
According to the researchers, a just global transformation of all earth systems is required to ensure human well-being. “Such transformations must take place systemically in the areas of energy, nutrition, cities and other areas,” write the authors of the study, and they must also benefit poor people. “It is crystal clear,” says Katrin Böhning-Gaese, “that the earth’s resources are limited and that we as humanity have to operate within these limits.”