If you read a news story about the environment this autumn, you may have seen a number: seven of nine planetary boundaries breached. A year ago the same stories said six.
Nothing in the atmosphere lurched between those two headlines. What changed is that one boundary, ocean acidification, got reassessed, and the reassessment is more interesting and more hedged than the headline suggests. Understanding why tells you most of what you need to know about the whole framework.
Planetary health is a real academic field with a dated definition and a specific scorecard behind it. It is also a phrase that gets attached to supplements, skincare and diet plans by people who have never read either. The two things are not related.
Here is what the field is, what its nine numbers measure, where its own literature attacks it, and the honest answer to the question readers really want: what does any of this say about my body? That last answer is going to be less satisfying than you expect, and saying so plainly is the point.
Where the term came from
The term got its working definition in 2015, from the Rockefeller Foundation-Lancet Commission on planetary health. The report ran as “Safeguarding human health in the Anthropocene epoch” in The Lancet, volume 386, pages 1973 to 2028, published online on 16 July 2015 with the issue dated 14 November 2015.
The Commission’s formal definition is a mouthful: the achievement of the highest attainable standard of health, wellbeing and equity worldwide, through careful attention both to the human systems the report names as political, economic and social, which shape humanity’s future, and to the Earth’s natural systems that define the safe environmental limits within which people can thrive.
The report also offers a plain-language version, and it is worth quoting exactly. In the words of the Rockefeller Foundation-Lancet Commission: “Put simply, planetary health is the health of human civilisation and the state of the natural systems on which it depends.” The British spelling is the Commission’s own.
Notice the shape of that. It defines a field of study, not a diagnosis, not a diet and not a product category. It is a statement that human health and Earth systems should be studied together, by the same people, in the same frame. Everything else follows from that and nothing in it tells you what to buy.
The nine boundaries, and what each one counts
The quantitative apparatus came first, in 2009. Johan Rockström and 27 co-authors published “A safe operating space for humanity” in Nature, volume 461, pages 472 to 475, on 24 September 2009. They proposed nine Earth system processes with a safe limit on each, and judged three of them already crossed.
A revision led by Will Steffen appeared in Science in 2015, volume 347, article 1259855. According to its abstract, two of the nine were singled out as core boundaries, climate change and biosphere integrity, each judged capable on its own of pushing the Earth system into a new state if it is substantially and persistently transgressed. Four boundaries were assessed as crossed.
The current reference assessment is Richardson and colleagues, “Earth beyond six of nine planetary boundaries,” in Science Advances in 2023, volume 9, article eadh2458. Six crossed.
A boundary is not a topic. It is a specific measurable quantity, called a control variable, with a proposed safe value attached. Here is what each one counts, from the 2023 paper.
Climate change uses two: atmospheric carbon dioxide, with a boundary of 350 parts per million against 417 ppm in 2022, and total human-caused effective radiative forcing, with a boundary of 1 watt per square metre against 2.91 in 2022, measured relative to 1750.
Biosphere integrity also uses two. The genetic side uses the extinction rate, measured in extinctions per million species-years, with a boundary below 10. The functional side, new in 2023, uses human appropriation of net primary production: the share of the planet’s plant growth that people take for themselves.
Stratospheric ozone depletion uses the ozone column in Dobson units. The boundary is 276 DU, meaning less than a 5 percent drop from a preindustrial 290. The 2020 global estimate is 284 DU, inside the safe range. Richardson’s team notes the boundary is still crossed over the Antarctic and southern high latitudes, and only during the three months of Austral spring.
Ocean acidification uses the aragonite saturation state of surface seawater, a measure of how easily shell-building organisms can form carbonate. The boundary is at least 80 percent of a preindustrial global average of 3.44. The 2023 paper puts the current value near 2.8, about 81 percent.
Biogeochemical flows uses four numbers for two nutrients. For phosphorus, boundaries of 11 teragrams per year flowing to the ocean and 6.2 teragrams applied to erodible soils, against current values of 22 and 17.5. For nitrogen, a boundary of 62 teragrams per year of industrial and intentional fixation, against 190.
Freshwater change uses the percentage of the planet’s ice-free land where streamflow or root-zone soil moisture has drifted outside its preindustrial range, with boundaries set at the 95th percentile of that preindustrial variability, roughly 10 and 11 percent.
Land-system change uses forest cover remaining compared with what the Holocene could support, with separate boundaries of 85 percent for boreal, 50 percent for temperate and 85 percent for tropical forest.
Atmospheric aerosol loading uses the difference in aerosol optical depth between the northern and southern hemispheres, because that gap shifts monsoon rainfall. Global mean aerosol optical depth is given as 0.14.
Novel entities covers synthetic chemicals, mobilized radioactive material and human modification of evolution. Richardson’s team is candid that assessing how much of this the Earth system tolerates remains an unsolved scientific problem.
Read that list again and notice what every single entry has in common. They are global aggregates. Not one of them is something you could measure in your neighborhood, your kitchen or your bloodstream.
A boundary is not a cliff edge
This is the most common misreading, and the paper’s own authors correct it.
Richardson and colleagues state flatly that boundary positions do not mark or predict a single threshold shift in the Earth system. They are set where the available evidence suggests further pressure could start reshaping how the planet’s systems feed back on each other. The 2023 update replaced the older phrase “zone of uncertainty” with “zone of increasing risk,” precisely because the issue is not measurement error.
The climate boundary shows how deliberately cautious the numbers are. The team kept 350 ppm as the boundary, with a zone of increasing risk running from 350 to 450 ppm, corresponding roughly to 1 to 2 degrees Celsius of warming. Precaution puts the boundary at the start of that zone. That places it below the 1.5 degree target in the Paris Agreement.
So carbon dioxide crossed its planetary boundary in the late 1980s by this accounting, and the framework’s authors are untroubled by that, because the boundary was never meant to be the point where something snaps.
The seventh boundary, and why the headline is softer than it sounds
The Planetary Health Check is an annual assessment produced by the Potsdam Institute for Climate Impact Research through its PBScience project. Its site states that seven of the nine planetary boundaries have been breached, and a news item dated 21 September 2026 records the 2026 edition launching at New York Climate Week. The Stockholm Resilience Centre, where the framework originated, likewise says seven of nine have been transgressed, and identifies ocean acidification as the one assessed in 2025 as the seventh.
The peer-reviewed paper underneath that is Findlay, Feely, Jiang, Pelletier and Bednaršek, “Ocean Acidification: Another Planetary Boundary Crossed,” in Global Change Biology in 2025, volume 31, article e70238. Note the title. It says another, not the seventh. The seventh framing comes from the assessment reports, not from the paper.
And the paper’s own finding is narrower than the headline. The authors conclude that by 2020 average global ocean conditions had crossed into the uncertainty range around the boundary. Once they propagate uncertainty through their numbers, the current global average sits at a 17.3 percent reduction, plus or minus 5.0, against a boundary of 20 percent, plus or minus 5.3. That is below the boundary’s central value and inside its error bars.
Here is the part worth slowing down for, because two authoritative sources give different numbers and neither is obviously wrong. Richardson’s 2023 team put the current aragonite saturation state at about 2.8, a 19 percent drop from preindustrial. Findlay’s team puts the present-day global mean at 2.90 plus or minus 0.06. Against the same preindustrial value Richardson used, that is a 16 percent drop rather than 19. Against Findlay’s own revised preindustrial figure, with uncertainty propagated, it is the 17.3 percent given above. The paper says plainly that its updated values put ocean acidification slightly further from crossing the boundary than Richardson proposed. The newer paper’s own data move the global average away from the line. Both numbers come from careful work. This article is not going to pick one.
What is firm in Findlay’s paper is regional and definitional, not global:
- Four of seven ocean basins have crossed the 20 percent boundary: the Arctic at 26.0 percent, the north Pacific at 22.1, the Southern Ocean at 21.8 and the north Atlantic at 20.1.
- More than 40 percent of the global surface ocean had crossed by 2020, and up to 60 percent of the subsurface ocean down to 200 metres.
- Suitable habitat has shrunk by 43 percent for tropical and subtropical coral reefs, by up to 61 percent for polar pteropods, and by 13 percent for coastal bivalves.
- The authors propose moving the boundary to a 10 percent reduction, which the entire surface ocean passed by 2000.
So “the seventh boundary has been breached” is defensible, but it rests on regional crossings and on a proposed redefinition of the boundary, not on the global average crossing a fixed line. That distinction almost never survives into news coverage.
One housekeeping note for anyone checking: the Planetary Health Check website is internally inconsistent about its own publication history, describing both the 2025 and 2026 assessments as the second report while calling the 2024 edition the inaugural annual report.
The critics are inside the literature, not outside it
An article that presents this framework without its critics is doing advocacy. The criticism is substantial, peer-reviewed and in some cases from ecologists of considerable standing.
The most thorough account is Frank Biermann and Rakhyun Kim, “The Boundaries of the Planetary Boundary Framework,” in the Annual Review of Environment and Resources, volume 45, pages 497 to 521, 2020. They group objections three ways.
From Earth system science: the choice of control variables, the specific boundary values, and processes left out, with marine systems particularly underrepresented. The single-metric approach to biodiversity draws repeated fire.
On thresholds, their sharpest point. The 2009 paper used the word loosely, which invited the charge that boundary values were arbitrary, since many processes below the global scale show little evidence of threshold behavior at all. The 2015 update conceded that a planetary boundary is not the same thing as a global tipping point. Proponents reply that critics keep conflating the two. Both readings are in the published record.
From development studies: the boundaries are global limits that say nothing about how causes and consequences are distributed. The forest-cover standard is the clearest example, since a country that cleared its forests centuries ago faces no comparable constraint today. Inequality inside countries falls outside the frame entirely, and wealthy economies export much of their ecological impact through trade.
From science and technology studies: boundary values embed judgments about how much risk is acceptable, which is a political question, while being presented as pure natural science. The 2009 assessment was led overwhelmingly by natural scientists without systematic input from governments or civil society. Biermann and Kim close by warning that the operating space of humankind could end up being set by academics rather than by the public.
Two more disputes are worth naming. José Montoya, Ian Donohue and Stuart Pimm, writing in Trends in Ecology & Evolution, volume 33, pages 71 to 73, argued that a safe operating space for biodiversity is vague, encourages harmful policy, and loses all content when anyone tries to repair it. And in Science in 2015, Fernando Jaramillo and Georgia Destouni argued that global freshwater consumption may already have crossed its boundary; Dieter Gerten, Johan Rockström and co-authors replied in the same issue that the claim rests on high estimates of water-cycle components, different definitions of consumption, and extrapolation from a single case study. Two authoritative positions, published side by side, unresolved.
What the framework says about your health
By design, nothing. And that is not a criticism, it is what the framework is.
Richardson and colleagues write that “the planetary boundaries framework is only concerned with the stability and resilience of Earth system, i.e., not human or ecosystem health.” The authors drew that line themselves, in the paper that produced the number in the headlines.
Look again at the control variables: parts per million, watts per square metre, teragrams per year, Dobson units, percentages of ice-free land. There is no dose-response curve linking any of them to an individual person, because none was ever built. Anyone writing “what the planetary boundaries mean for your health” is inventing a bridge the literature does not contain.
This matters practically. If you are worried about an environmental exposure where you live, the planetary boundaries are the wrong tool, and reaching for them will cost you time. Local air quality readings, your water utility’s annual report and your own clinician are the right tools.
Get medical help rather than reading an index if you have new or worsening shortness of breath, chest tightness or a wheeze during a wildfire smoke event, especially with asthma or COPD. The same goes for confusion, fainting or a body temperature you cannot bring down during a heat wave. And if a rash or a cough tracks reliably with a specific place, a workplace or a room in your home, that pattern is worth describing to a clinician or an occupational health specialist, because they can test for things an index cannot. Nothing here is medical advice.
Diet is the one real bridge, and the evidence is observational
There is a genuine connection between this field and individual health, and it runs through food.
The EAT-Lancet Commission published “Food in the Anthropocene” in The Lancet in January 2019, volume 393, pages 447 to 492, proposing a reference diet meant to be healthy and environmentally survivable at once. A second edition exists and is recent: the EAT-Lancet Commission on healthy, sustainable, and just food systems, published in The Lancet on 2 October 2025, volume 406, pages 1625 to 1700, with 24 Commissioners from 17 countries according to the EAT Forum.
The strongest individual-level test comes from Bui and colleagues in the American Journal of Clinical Nutrition in 2024, volume 120, pages 80 to 91. They scored adherence to the reference diet every four years in three long-running US cohorts: 66,692 women in the Nurses’ Health Study from 1986 to 2019, 92,438 in its successor from 1989 to 2019, and 47,274 men in the Health Professionals Follow-up Study from 1986 to 2018. Across 31,330 deaths among women and 23,206 among men, people in the top fifth of adherence had a pooled hazard ratio of 0.77 for death from any cause, with a 95 percent confidence interval of 0.75 to 0.80, against the bottom fifth. Cardiovascular deaths came in at 0.86, cancer at 0.90, neurodegenerative disease at 0.72 and respiratory disease at 0.53.
Those are large, consistent numbers. Now the caveats, which are also large.
This is observational, not randomized. Nobody assigned anyone a diet. The participants are American nurses and health professionals, which is not a cross-section of the country. Diet was self-reported on food questionnaires. And the pattern overlaps heavily with Mediterranean and plant-forward diets that had strong evidence behind them long before EAT-Lancet existed.
So the honest tier for this claim is: well-supported observational association, not established causation. The planetary framing adds an environmental argument to a dietary recommendation that already stood on health grounds. It does not add a new health benefit.
How to read the next headline about this
When one of these numbers reaches you, four questions sort it quickly.
Which boundary, and which control variable? “Climate change boundary crossed” means carbon dioxide above 350 ppm, which has been true for decades. It does not mean something new happened.
Which assessment, and from when? Rockström 2009 said three crossed. Steffen 2015 said four. Richardson 2023 said six. The Planetary Health Check says seven. These are revisions of one framework, not a worsening measured year over year, and a story that does not date its source is not telling you which.
Global average or regional? The ocean acidification case turns on exactly this. Four basins crossed a line the global mean has not clearly crossed.
Did the number move, or did the line move? Findlay’s team proposed shifting the boundary from a 20 percent reduction to 10 percent. Under the new line the crossing happened around 2000. That is a scientific argument about where the limit belongs, not a measurement of fresh damage.
The single most useful thing to take from all of this: planetary boundaries is an accounting system built for governments and institutions, by scientists who said in writing that it is not about human health. Read it as a scorecard for policy. It tells you something real about the planet and nothing about you, and its builders never claimed otherwise.
Sources
- The Lancet, 2015 (full-text PDF hosted by the Yale Center for the Study of Globalization). “Whitmee S, Haines A, Beyrer C, et al. "Safeguarding human health in the Anthropocene epoch: report of The Rockefeller Foundation-Lancet Commission on planetary health." Lancet 386:1973-2028. DOI: 10.1016/S0140-6736(15)60901-1.” ycsg.yale.edu
- Nature, 2009 (PubMed). “Rockstrom J, Steffen W, Noone K, et al. "A safe operating space for humanity." Nature 461(7263):472-475. DOI: 10.1038/461472a.” doi.org
- Science, 2015 (PubMed). “Steffen W, Richardson K, Rockstrom J, et al. "Planetary boundaries: guiding human development on a changing planet." Science 347(6223):1259855. DOI: 10.1126/science.1259855.” doi.org
- Science Advances, 2023 (PubMed / PMC10499318). “Richardson K, Steffen W, Lucht W, et al. "Earth beyond six of nine planetary boundaries." Sci Adv 9(37):eadh2458. DOI: 10.1126/sciadv.adh2458.” doi.org
- Global Change Biology, 2025 (PubMed / PMC12147064). “Findlay HS, Feely RA, Jiang L-Q, Pelletier G, Bednarsek N. "Ocean Acidification: Another Planetary Boundary Crossed." Glob Chang Biol 31(6):e70238. DOI: 10.1111/gcb.70238.” doi.org
- Annual Review of Environment and Resources, 2020 (author copy, Utrecht University repository). “Biermann F, Kim RE. "The Boundaries of the Planetary Boundary Framework: A Critical Appraisal of Approaches to Define a 'Safe Operating Space' for Humanity." 45:497-521. DOI: 10.1146/annurev-environ-012320-080337.” dspace.library.uu.nl
- Trends in Ecology & Evolution, 2018 (PubMed). “Montoya JM, Donohue I, Pimm SL. "Planetary Boundaries for Biodiversity: Implausible Science, Pernicious Policies." 33(2):71-73. DOI: 10.1016/j.tree.2017.10.004.” doi.org
- Science, 2015 (PubMed). “Jaramillo F, Destouni G. "Comment on 'Planetary boundaries: Guiding human development on a changing planet.'" Science 348(6240):1217. DOI: 10.1126/science.aaa9629.” doi.org
- Science, 2015 (PubMed). “Gerten D, Rockstrom J, Heinke J, Steffen W, Richardson K, Cornell S. "Response to Comment on 'Planetary boundaries: Guiding human development on a changing planet.'" Science 348(6240):1217. DOI: 10.1126/science.aab0031.” doi.org
- Potsdam Institute for Climate Impact Research (PBScience). “Planetary Health Check.” planetaryhealthcheck.org
- Stockholm Resilience Centre, Stockholm University. “Planetary boundaries.” stockholmresilience.org
- The Lancet, 2019 (PubMed). “Willett W, Rockstrom J, Loken B, et al. "Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems." Lancet 393(10170):447-492. DOI: 10.1016/S0140-6736(18)31788-4.” doi.org
- The Lancet, 2025 (PubMed). “Rockstrom J, Thilsted SH, Willett WC, et al. "The EAT-Lancet Commission on healthy, sustainable, and just food systems." Lancet 406(10512):1625-1700. DOI: 10.1016/S0140-6736(25)01201-2.” doi.org
- American Journal of Clinical Nutrition, 2024 (PubMed). “Bui LP, Pham TT, Wang F, et al. "Planetary Health Diet Index and risk of total and cause-specific mortality in three prospective cohorts." Am J Clin Nutr 120(1):80-91. DOI: 10.1016/j.ajcnut.2024.03.019.” doi.org
- EAT Forum. “EAT-Lancet Commission.” eatforum.org