A team of climate scientists introduced the term “planetary boundaries” almost 15 years ago, to identify important systems that were at risk of becoming unstable due to human activity.

They looked at systems such as climate, biodiversity and fresh water to determine the limits of what they called a “safe operating area” for civilization, writes Bloomberg.

A major update, which is published today in the journal Nature, describes how much nature can withstand before it turns on us. Seven of the eight global boundaries have already been crossed by humans, the authors state.

The researchers present their new work in the hope that business and the authorities will develop tools to adapt their practices to the scientifically determined limit values.

We simply must have science-based goals that go far beyond the climate for all the planetary boundaries, in order to have a stable and robust system, also to deal with the climate crisis, says Professor Johan Rockstrom, director of the Potsdam Institute for Climate Impact Research in Germany and co-author of the new and original work.

The new analysis also contains criteria for “justice” for the many millions of people who are at risk today, for the billions who will come in the future and for the world’s countless species and ecosystems.

For some systems, such as the climate, this “fairness analysis” requires stricter limits than geophysical stability factors alone would provide. The warming limit of 1.5 °C laid down in the Paris Agreement is too high for humanitarian reasons, the authors write and at the same time claim that tens of millions of people are now exposed to dangerous heat.

The world has become 1.2 degrees warmer since industrialisation. The researchers believe that within 1.5 °C, more than 200 million people – mainly poor, vulnerable and marginalised communities – can expect to be exposed to “unprecedented heat”.

The aim is to reduce the global average temperature increase to below 1°C, but since that is not possible in the short term, the individual countries must deal with the consequences themselves. And that means that “adaptations and compensation to reduce damage sensitivity and vulnerability will be necessary”.

The authors are calling for international compensation for poor countries’ climate-related “losses and damage”, as was agreed during the UN’s climate negotiations last year.

“The scale of the effort required to meet these challenges is unparalleled,” claim the researchers.

Nothing less than a fair global adjustment across all ESBs (earth system boundaries) is required to ensure human welfare, they write. Energy, food, cities and other sectors require a restructuring of politics, economics and technology. It requires a leap in our understanding of how justice, economics, technology and global cooperation can be promoted in favour of a safe and fair future, write the researchers.

The 51 authors are associated with the Earth Commission, a group of natural and social scientists that Professor Rockstrom co-founded to generate science that can inform organisations such as the Science Based Targets Network, which develops policies for businesses and cities.

The aim of the report is to quantify changes at the planetary level that are “mostly driven by social and economic systems that are based on unsustainable resource extraction and consumption”.

The new work is not only based on previous research on the planet’s limits, but also on other assessments of society’s vulnerability to systemic changes, including the UN’s sustainability goals.

An important breakthrough in this paper, the authors write, is the translation of the consideration of social justice into the same units of measurement as the systems we use, such as Celsius for temperature or cubic kilometres for water consumption.

Nitrogen and phosphorus from agriculture, for example, run into waterways and cause oxygen-free “dead zones” in rivers and seas, which in some areas also has consequences for drinking water. The global limit for how much nitrogen is 119 million tonnes a year and 10 million tonnes for phosphorus, according to the report.

In order to overcome air pollution, the researchers have set themselves the goal of minimising the difference in the concentration of aerosols between the northern and southern hemispheres, and to set an upper limit for harmful pollution of small particles. Aerosols from both natural and human sources, from volcanoes to exhaust pipes, cause disease and premature death worldwide.

They also propose two biodiversity targets to limit the destruction of species and ecosystems. The first defines what proportion of the natural ecosystems should be preserved: 50 to 60 percent, which is higher than the status quo of 45 to 50 percent. To ensure that human-impacted areas continue to play an important role, the authors believe that 20–25 percent of every square kilometre of urban areas, agricultural areas and other areas affected by humans should contain elements of natural ecosystems. To prevent the loss of biodiversity in freshwater, the researchers recommend that rivers and streams do not deviate more than 20 percent from the natural monthly water flow.

The focus on the human consequences of a changing planet helps to make the new analysis more concrete than previous editions of the research on the boundaries of the planet, says Professor Kim Cobb, who is director of the Institute at Brown University for Environment and Society and was not involved in the study.

Although there may still be scientific uncertainty related to parts of these systems, we really have no uncertainty related to climate change’s disproportionate consequences for the most vulnerable, she says, and adds:

And that is something I believe we should start from when we make decisions today.

Essentially, the authors are trying to do the same thing for the entire Earth system that has already been done for climate change: generate scientific benchmarks that standard-setting organisations and governments can use to help businesses, cities and others ensure that their operations do not contribute to further systemic environmental change or human harm. The limits may include, but are not the same as, “tipping points” or thresholds that allow the planet to continue to change with or without human intervention.

The ultimate definition of justice today is that all people, and especially future generations, have the right to a stable planet – to be born on a planet that is at least as livable as the planet where their parents were born, concludes Rockstrom.

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