Planetary Boundaries Breached


Credit: NASA Goddard

Unsafe Operating Space

Human Forcing

Planet Earth – humanity’s one and only home. What if home were no longer a safe operating space, capable of supporting human civilization as we know it?

This isn’t the premise of a dystopian sci-fi thriller. It’s daily news.

According to NASA’s Goddard Institute of Space Studies, this past summer was Earth’s hottest on record.

Heat kills. Last summer, over 60,000 Europeans perished as the mercury soared. This year’s death toll could be higher. In the southwestern US, almost two dozen died, as temperatures topped 43 degrees C. for 27 days straight. Some of them were migrants, escaping climate catastrophe south of the border.

Heat-related deaths were also reported in China, Myanmar and India.

Heat stokes wildfires. Across Canada, parched forests went up in flames, wafting smoke up and down North America, across the Atlantic to Europe and into the upper troposphere, along with colossal volumes of Earth-warming CO2.

From Tasmania up the eastern coast of Australia, scorching heat triggered bush fires of unprecedented proportion.

Europe’s worst wildfire on record, in Greece, killed almost two dozen.

A hundred perished in the Maui fire in early August.

Over ninety percent of human-generated atmospheric heat has been absorbed by Earth’s oceans. Around the planet, marine heatwaves are dispatching marine life without mercy and sending vast volumes of warm water into the atmosphere, supercharging hurricanes and cyclones that dump rain in Biblical proportions.

In early September, over the course of twenty-four hours, Storm Daniel dumped three-quarters of a meter of rain on the Greek village of Zagora. Days later, almost a half-meter fell on the Libyan town of Al-Bayda. To the east, Derna was washed into the sea.

Cyclone Mocha visited similar devastation on villages in Myanmar and Bangladesh.

In response to the heightening climate crisis, UN Secretary General Antonio Gutteres warns that humanity has “opened the gates of Hell,” and is “hurtling towards disaster, eyes wide open.”

Earlier this month, a team of scientists spelled out humanity’s predicament in drier fashion.

Six out of nine planetary systems key to the survival of the human species have been compromised, the scientific team reported in the journal Science Advances, breaching the estimated boundaries of Earth system stability and resilience and pushing it “well outside of the safe operating space for humanity.”

The GPM spoke with Katherine Richardson, lead author of “Earth beyond six of nine planetary boundaries.”


Estimated indeed. Pinpointing the stable operating boundaries of Earth’s five innate functional systems – climate, biosphere, terrestrial forest cover, surface waters and key nutrient flows – is tricky business. Precisely where safe operating space and zones of ‘increasing’ risk end and unsafe ‘high’ risk zones begin is a highly informed guessing game.

Then there are ‘tipping points’, beyond which self-amplifying system breakdown becomes unstoppable. Earth has likely passed several of these.

Unlike bolide impacts, over and done with in an instant, tipping points are breached in slow motion, over many years. Perhaps centuries.

The scientific paper’s sixth proposed planetary boundary isn’t an innate Earth system at all.

“Novel entities,” the boundary is called. Microplastics, endocrine disruptors, organic pollutants, radioactive waste and genetically modified organisms pose a threat to both natural ecosystems and human health, not to the stability of the planet.

But, the paper’s authors warn, “it remains a scientific challenge to assess how much loading of novel entities Earth system tolerates before irreversibly shifting into a potentially less habitable state.”

Table 1 of their paper, “Current status for the planetary boundaries,” lays out the scientific team’s findings in detail. Among these:  

  • Atmospheric CO2 concentration now sits at 417 parts per million, up from a pre-industrial value of 280, with the planetary boundary set at 350.
  • Biosphere integrity, measured by the rate of species extinction, is at least 100-fold higher than the pre-industrial rate.
  • Human Appropriation of Net Primary Production (HANPP) a measure of the biosphere’s functional integrity, now sits at 30% — up from a pre-industrial value of about 2%. In other words, humanity has commandeered a third of Earth’s natural capacity to process energy and matter, the bedrock of life on Earth.
  • Human industrial agriculture and food production (the main driver of HANPP) have deposited twenty-three million tonnes of phosphorus on Earth’s surface (zero pre-industrially) and almost 200 million tonnes of reactive nitrogen. Both land surface, freshwaters and near-shore marine ecosystems have been affected.
  • Forty percent of Earth’s forests have been eliminated; tropical forest loss: 20% in the Americas, 45% in Africa and 60% in Asia; temperate forest loss: 50% in the Americas, about 60% in Europe and Asia; 30-40% of northern boreal forests gone.
  • Over eighty percent of surface and groundwater systems have been disturbed by human activity.

There is good news in the scientific report: Three out of nine planetary operating boundaries have yet to be transgressed. Stratospheric ozone — shielding Earth’s surface from deadly UV radiation — has “slightly recovered” from the damage caused by CFCs, atmospheric aerosols generated by smokestack emissions and crop burning only pose regional threats, and ocean acidification levels are close to being breached, but not there yet.

What will it take to pull back from Earth systems collapse?

The report’s authors call for “more powerful scientific and policy tools for analyzing the whole of the Earth system with reliability and regularity, and guiding political processes to prevent altering the state of Earth system beyond levels tolerable for today’s societies. [emphasis added].

A tall order. The world’s most powerful nations are great at organizing themselves into competing economic and military blocs, waging interminable wars, fending off refugees and keeping fossil fuels flowing.

Managing Planet Earth as a system, cooperatively, on behalf of all peoples and other living things, is another story.

But Katherine Richardson is optimistic.

Richardson is principal investigator at the Center for Macroecology, Evolution and Climate and Professor of Biological Oceanography at the University of Copenhagen. She co-authored the groundbreaking 2009 paper Planetary Boundaries: Exploring the Safe Operating Space for Humanity, in which the Planetary Boundaries/Safe Operating Space concepts were introduced, and appears alongside many of that paper’s prominent authors in last week’s cautionary update, Earth beyond six of nine planetary boundaries.

Listen to our conversation here: