Humans have crossed 6 out of 9 Planetary Boundaries including ‘climate change’

By Vivek Saini 

A new study published in Science Advances shows that six out of the nine “planetary boundaries” have been violated as a result of human-caused pollution and degradation of the natural world. This involves the planetary limits theory, according to which, Earth has an operating system destabilized by humanity, jeopardizing the planet’s habitability. Scientists have warned that the planet’s life support systems have been degraded to the point where it is “well outside the safe operating space for humanity.” 

The planetary boundaries are the limitations of essential global systems, such as climate, water, and animal diversity, beyond which their ability to sustain a healthy planet is threatened.

What are Planetary boundaries

A group of worldwide researchers first put forth the planetary boundaries framework in a study published in Nature in 2009. Several of the same authors published a revised version of the theory in 2015. These older versions, however, contained numerous information gaps. For example, at the time, it was unclear what the quantitative boundaries were for novel creatures, atmospheric aerosol loading, and the biosphere’s functional integrity boundary.

The revised framework now includes quantitative boundaries for the nine Earth systems. The novel entities boundary, for example, uses a finding from a 2022 paper to define the limit, noting that industries are now developing and manufacturing synthetic chemicals and other man-made pollutants far faster than governments’ ability to assess and monitor their risks and impacts, causing humanity to fly blind and constituting a boundary-crossing. The researchers also point out that enough aerosol loading violations have happened at the regional level, such as the brown cloud of pollution above Asia, to quantify that boundary-crossing.

The framework for planetary boundaries is based on Earth system science. It outlines nine processes that are crucial to the overall stability and resilience of the Earth system. Human activity is currently causing significant disruption to all of them. The framework aims to define and quantify anthropogenic disturbance levels that, if met, would allow Earth to continue in a “Holocene-like” interglacial state. In such a condition, global environmental functions and life-support systems stay identical to those observed during the previous 10,000 years rather than evolving into a state without precedent in human history.

First complete ‘scientific health check’ for the planet

The ability of Earth to support human society, according to the report, is dependent on nine fundamental “planetary boundaries,” or global systems, that are critical markers of its health. Humans have exceeded six of these nine limits: 

• Climate change
• Biosphere integrity (including biodiversity)
• Freshwater availability
• Land use
• Nutrient pollution, and
• Novel entities (meaning man-made pollutants, including microplastics and radioactive waste).

Only Ocean acidification, Air pollution, and Ozone depletion are exempt from the restrictions. Only the last of them is improving, thanks to the success of the Montreal Protocol, an international agreement. Countries have decreased their ozone-depleting chemicals under this agreement, allowing the protective ozone layer in the atmosphere to recover.

“Crossing six of the nine boundaries isn’t a guarantee of disaster,” Katherine Richardson, principal author of the study and Earth systems scientist at the University of Copenhagen in Denmark, said, “It’s like your blood pressure; it’s a wake-up call.” If your blood pressure is higher than 120/80, it does not necessarily indicate that you will have a heart attack. But it does warn you that the risk is too big, and you attempt to ignore it.”

According to the Guardian’s Damian Carrington, the multinational consortium of experts who did the research, which drew on 2,000 studies, deems it the “first scientific health check for the entire planet.” The “most concerning” discovery, they claim, is that all four biological boundaries, which encompass living things, are already at or near the most dangerous levels.

Current status of control variables for all nine planetary boundaries.

Concerns over human habitability on earth 

Together, the stability of these nine processes is necessary to keep the delicate balance between the Earth’s atmosphere, oceans, and ecosystems that has allowed human civilizations to evolve. But they are also the processes that human activity has most significantly influenced.

Human-caused pollution and degradation of the natural world have violated six out of nine “planetary boundaries”. The planetary boundaries are the points at which major global systems, like those controlling climate, water, and species diversity, risk losing their ability to sustain a healthy planet. The systems have been far removed from the secure and stable condition that prevailed from the end of the last ice age until the beginning of the Industrial Revolution, roughly 10,000 years ago. This is because the limits have been shattered, and during this historical period, known as the Holocene, modern civilization emerged.

The “most worrying” discovery, according to the experts, was that all four biological limits, which protect the living world, were at or very near the maximum risk threshold. Because it provides resilience by offsetting some physical changes, such as trees absorbing carbon dioxide pollution, the living world is essential to the Earth. According to scientists, the planetary boundaries are not irreversible tipping points beyond which sudden and significant deterioration happens. The risks of severe changes to the Earth’s physical, biological, and chemical life support systems increase significantly after these points.

The researchers estimated a threshold beyond which we risk sending the Earth spiraling into a state that hasn’t been experienced for the entirety of human existence, bringing about extreme change that could crash civilization and endanger humanity. This threshold is where we risk sending the Earth spiraling into a state that hasn’t been experienced for the entirety of human existence.

References:

1. https://www.science.org/doi/10.1126/sciadv.adh2458
2. https://www.science.org/doi/10.1126/science.1259855
3. https://www.nature.com/articles/461472a
4. https://pubs.acs.org/doi/10.1021/acs.est.1c04158
5. https://www.nature.com/articles/s43017-019-0005-6
6. https://www.science.org/doi/abs/10.1126/science.aad2622
7. https://news.mongabay.com/2023/09/new-study-shows-earth-may-be-past-the-safe-operating-space-for-humanity/
8. https://www.theguardian.com/environment/2023/sep/13/earth-well-outside-safe-operating-space-for-humanity-scientists-find
9. Image source: https://www.science.org/doi/10.1126/sciadv.adh2458

Banner image source: https://www.pexels.com/photo/bird-s-eye-photography-of-ocean-and-mountains-1130268/