Six of Nine Planetary Boundaries Breached, According to Inaugural Planetary Health Check
At the end of 2023, the authors of one of the most consequential papers in climate science heeded their own warnings by establishing Planetary Boundaries Science (PBScience). More than a mere follow up, the international team at PBScience just published the inaugural Planetary Health Check 2024 report.
Much like the wholistic glimpse an annual physical provides of one’s health, the goal of the Planetary Health Check is to provide “health metrics” on a planetary level that will serve to guide ongoing stewardship practices in order to return us to a “safe operating space for humanity”. The document is truly remarkable in its scope, urgency and vision for the future.
Why the Planetary Boundary Framework
“Just as a blood test provides insights into a human body's health and identifies areas of concern, this Planetary Health Check evaluates the 13 control variables across the 9 Planetary Boundary (PB) processes to report on Earth’s stability, resilience, and life-support functions — the overall health of our planet.”
Defined by the conditions during which human civilization has flourished, the Planetary Boundaries framework was established fifteen years ago and continues to be refined as science advances across its many disciplines. The central goal of which remains maintaining the conditions that provide a livable planet for all life-forms.
And yet, part of what makes responding to the climate crisis so challenging is the nuance that exists between local and global issues. Importantly, the “Planetary Boundaries (PBs)” framework provides a global perspective that “complements rather than replaces existing environmental assessment and policy measures.”
Boundaries Breached
Immediate and coordinated global action, involving governments, businesses, and civil society, is essential to return to the Safe Operating Space across all PBs and secure a prosperous future for both people and the planet.
— Planetary Health Check 2024
The “Hothouse Earth” paper helped raise planetary awareness of tipping points within the Earth system at which cascading feedback loops are likely to have irreversible impacts. The Planetary Health Check now goes further by demonstrating how these interrelated systems affect one another and why a wholistic understanding of their correlated impacts is crucial if we are to enact policy measures and regulations capable of reversing current trends.
Of the nine planetary boundaries, six are currently beyond safe levels.
Climate Change
Broadly speaking Climate Change refers to the altering of the Earth’s energy balance. As human activities like greenhouse gas emissions and land-use feed energy into the Earth system at a rate faster than can it be cycled, an energy imbalance arises which traps heat in the atmosphere, raises global temperatures and affects climate patterns in turn. While the typical atmospheric concentration of CO2 of the last 10,000 years was around 280 ppm, today’s concentration at 419 ppm is so high that the goal of reducing it to just 350 ppm, in line with the Paris Climate Agreement, is likely to still produce significant global ice sheet loss and produce massive sea level rise.
Biosphere Integrity
As human activity has flourished, we have increasingly taken more of the energy produced by ecosystems for human use through means such as agriculture, forestry, and urbanization. These same practices have simultaneously reduced overall genetic diversity of the planet, reducing Biosphere Integrity and stifling the planet’s capacity to maintain its chemical cycles. Examples include declining ecosystem services, like natural flood mitigation provided by wetlands, and the decline of pollinator species, a sign indicative of looming crop failures.
Land System Change
The primary drivers of Land System Change include the expansion of livestock grazing, expansion of croplands, and expanding infrastructure and human habitat. Here we start to get a glimpse of just how interconnected each of the PBs truly are. Removing forests to make way for more agriculture drastically depletes critical carbon sinks — ecosystems that are capable of absorbing and storing excess carbon from the atmosphere, inhibits the capacity of the water cycle to generate freshwater through evapotranspiration, and exacerbates habitat loss.
Freshwater Change
Tracking Freshwater Change involves two primary variables: blue water and green water. Blue water includes all surface freshwater in lakes, rivers, and reservoirs. Green water refers to groundwater that provides soil moisture and feeds plants. Disruptions to blue and green water levels are driven by household and industrial water use, as well as irrigation for agriculture. As these disturbances worsen, they contribute to droughts, create conditions for more violent forest fires, and disrupt our ability to grow crops. Currently, nearly one fifth of global land area is experiencing deviations above safe levels for both blue and green water.
Biogeochemical Flows
Similar to Biosphere Integrity, tracking Biogeochemical Flows refers to global nutrient cycles of phosphorous and nitrogen. Key nutrients responsible for plant growth, the Earth system has seen massive inputs of both, primarily from an increased reliance on industrial fertilizers (due in large part to depleted green water and soil health). Measured in teragrams, equal to one million metric tons, safe levels for phosphorous and nitrogen are approximately 11 Tg and 62 Tg per year. Currently, human activity is responsible for doubling and tripling the planetary boundaries of each, respectively.
Introduction of Novel Entities
Unlike the comparisons of other PBs to baselines prior to human activity, the Introduction of Novel Entities encapsulates uniquely human contributions to the Earth system in the form of synthetic chemicals and substances such as microplastics, organic pollutants like antibiotics, and forever chemicals like PFAs. Following the precautionary principle, the PB for synthetic chemicals without adequate safety testing is ideally 0%. However, currently “over 80,000 chemicals have been registered for use since the Toxic Substances Control Act (TSCA) was enacted in 1976, yet the majority have not undergone regulatory testing.” These synthetic entities are responsible for trapping additional heat in the atmosphere like CO2, species loss in the form of pesticide use, as well as causing physical and toxic harm to both terrestrial and marine life.
Towards a Safe & Just Future
As a climate journalist, part of the challenge is navigating how best to share the most relevant data and stories such that readers aren’t alienated but motivated to act — nor do I want to merely preach to the choir. Personally, I believe it demands a willingness to rigorously confront the science as it is. Not as we wish it to be. But, given the inherently broad aperture of climate science, it’s easy to get overwhelmed by a density of data.
Important as it is to focus our efforts, we also can’t lose sight of the interrelatedness between planetary boundaries. Something the Planetary Health Check makes abundantly clear. If we focus on any issue in isolation, we risk failing to see the deforested region for a single felled tree. Part of what makes the Planetary Health Check so noteworthy, is how it weaves together otherwise disparate environmental concerns.
While providing one of the most comprehensive overviews of the multi-pronged nature of the climate crisis, it doesn’t shy away from also integrating areas typically left for social sciences, specifically social justice.
Building on the PBs framework and its Safe Operating Space, the Earth Commission introduced the Earth System Boundaries in 2023 to delineate a "Safe and Just Operating Space" for humanity. This framework adds a crucial dimension: social justice.
This innovative approach aims not only to preserve the Earth's biophysical systems but also to ensure equitable access to resources and minimize harm to humans and other living beings. By integrating social thresholds, the Earth System Boundaries framework addresses the interdependence of environmental sustainability and human well-being.
Making it clear that humanitarian values must prove integral to any meaningful response to the climate crisis, leaving no room for the very real possibility of an authoritarian eco-fascist alternative, PBScience closes the inaugural Planetary Health Check by providing their broader vision for “A Mission Control for the Planet.”
The approach includes introducing new control variables that focus on human-system interfaces, advancing Earth system simulation models with AI-powered analysis, and developing a near-real-time dashboard with data to guide investments and paths to safety. The PBI also emphasizes the importance of public awareness and scientific understanding, with a communications team working to make these insights widely accessible.
Just as the authors of the “Hothouse Earth” paper acted on their initial message when they formed PBScience, they plan to expand that mission by establishing the Planetary Boundaries Initiative (PBI) with a growing network of partners.
“Turning this knowledge into action requires a diverse range of actors beyond science, including technical support, policymakers, activists, communicators, and more.”
To learn more, and to see how you can get involved, visit planetaryhealthcheck.org. Better yet, I highly recommend folks take a look at the report for themselves.Unlike IPCC reports that are massive and wind up getting removing language like “fossil fuels" because they are the host country’s primary asset, the Planetary Health Check was “written to be accessible to a broad audience” and is based “on rigorous scientific publications — recommended for further reading — to ensure scientific integrity.”
Or, you could just wait a month and let your uncle fill you in at Thanksgiving.