8 Minutes
A planetary boundary in retreat
Human activity has driven a majority of Earth’s terrestrial surface beyond locally defined safe limits for what researchers now call "functional biosphere integrity." A multinational team led by the Potsdam Institute for Climate Impact Research (PIK), with collaborators at BOKU University Vienna, mapped the planetary boundary for this function in fine spatial and historical detail. The paper, published in One Earth, concludes that roughly 60% of global land area now lies outside its locally defined safe operating space and that 38% is in a high‑risk state. These shifts reflect centuries of land‑use change, most intensively across Europe, Asia and North America.
Human societies depend on the biosphere for food, fiber, fuel and growing ambitions to use biomass for climate mitigation. But that very demand—agriculture, forestry, harvest of residues and expanding biomass energy—reduces the capacity of vegetation to sustain the carbon, water and nitrogen cycles that underpin stable ecosystems.
What is functional biosphere integrity and why it matters
Functional biosphere integrity describes the capacity of plant life and associated ecosystems to capture and reallocate energy from photosynthesis to maintain the material flows—carbon, water and nitrogen—that stabilize Earth system processes. It is a core element of the Planetary Boundaries framework. When vegetation and intact ecosystem structure can no longer sustain these flows, ecosystems become more fragile: carbon sinks weaken, water balances shift, nutrient cycles are disrupted and biodiversity declines.
The 2023 update to the Planetary Boundaries framework emphasized photosynthetically driven energy flows as central to planetary stability. The new PIK‑led study operationalizes that insight by measuring two complementary indicators across space and time: the share of natural biomass productivity appropriated by humans (through harvest, timber, residues and land conversion) and a separate ecosystem instability risk indicator that tracks structural changes in vegetation and imbalances in water, carbon and nitrogen cycles.
Methods: high‑resolution, long‑term modeling
The team used the LPJmL global biosphere model to simulate daily water, carbon and nitrogen fluxes worldwide at roughly half‑degree spatial resolution. LPJmL integrates climate, land cover and human land‑use data to reconstruct annual conditions from 1600 to the present. By combining modeled photosynthetic productivity with historical patterns of harvest and land conversion and by comparing outputs to known ecological thresholds from the literature, the researchers assigned each grid cell to one of three statuses: Safe Operating Space, Zone of Increasing Risk or High Risk Zone.
Two indicators, one picture of stress
- Human appropriation of biomass productivity: This metric quantifies what fraction of natural vegetative productivity is diverted to human uses or lost through cultivation and sealing. Large fractions mean less ecological energy remains to sustain native processes.
- Ecosystem destabilization risk: A multi‑variable indicator that captures structural vegetation change and systemic imbalances in water, carbon and nitrogen cycles—early signals that ecosystems are approaching tipping points.
The combination of these indicators produces a spatially explicit map of where the biosphere’s functional limits have been passed and where risks are escalating.
Historical trajectory and regional patterns
Model runs indicate the first substantial transgressions of local biosphere limits began in the mid‑latitudes around 1600. By 1900, about 37% of land was outside locally defined safe bounds and 14% was high risk. Those fractions have since grown to 60% and 38% respectively. This timeline demonstrates that intensive land use and ecosystem alteration predated the era when anthropogenic climate warming became the dominant planetary stressor; land‑use change has long been reshaping Earth system stability.
Spatially, the strongest overshoots occur in regions with long histories of intensive agriculture and land conversion—Europe, large parts of Asia and much of North America. Tropical regions also show growing pressure where expansion of cropland, pasture and plantations has reduced native productivity and ecosystem integrity.
Implications for climate policy, nature‑based solutions and bioenergy
The study underscores a critical trade‑off: proposals to scale up biomass for energy or carbon removal (for example, bioenergy with carbon capture and storage—BECCS) risk further degrading the very biosphere functions that help regulate climate if they are implemented as large monoculture plantations or reduce remaining natural carbon sinks. As Johan Rockström, director of PIK and a co‑author, argues, policymakers must treat biosphere protection and climate action as a single, integrated challenge. Restoring and preserving natural vegetation, reducing excessive biomass demand, and prioritizing land‑use practices that maintain or enhance photosynthetic energy flows are essential.
Technologies and policies that could reduce pressure on the biosphere include regenerative agriculture, agroforestry, improved harvest efficiency, halting conversion of native ecosystems, and prioritizing low‑biomass climate strategies where feasible. Accurate, high‑resolution models such as LPJmL and advances in satellite remote sensing are critical for identifying hotspots of risk and tracking progress over time.
Expert Insight
Dr. Maya Chen, terrestrial ecologist and adjunct professor at the Institute for Global Environmental Change, comments: "This study is decisive because it links human biomass use directly to loss of the biosphere’s regulating power. It’s not enough to measure CO2 alone; we must measure the energy flows that sustain ecosystems. For decision makers, the message is clear: scaling up biomass without stringent criteria for biodiversity, soil health and water balance risks undermining carbon sequestration and resilience rather than supporting them."
Dr. Chen adds that actionable steps include targeting the most degraded and marginal lands for restoration, investing in high‑yield sustainable food systems to reduce land demand, and deploying nature‑positive carbon mitigation projects that protect existing carbon‑rich ecosystems.
Broader scientific and policy context
The PIK study builds on multidisciplinary advances in Earth system science and planetary boundaries research. It complements remote sensing assessments of land cover change, empirical studies of ecosystem function, and policy analyses of land‑based mitigation options. By providing an annually resolved, global map of functional biosphere integrity since 1600, the work offers a historical baseline that can help evaluate restoration targets and guide international climate negotiations.
For international climate and biodiversity policy, the key takeaway is that maintaining or restoring functional biosphere integrity amplifies climate mitigation: healthy ecosystems retain carbon, regulate hydrological cycles and buffer climate extremes. Conversely, continued over‑extraction of photosynthetic energy and wholesale land conversion will limit humanity’s options for stabilizing the climate.
Conclusion
The new analysis from PIK and partners shows that most of Earth’s land surface no longer operates within locally defined safe biosphere limits: 60% is outside the safe zone and 38% is in high risk. The drivers are long‑standing—primarily agriculture and other forms of biomass appropriation—and the consequences reach into climate resilience, biodiversity and human well‑being. Restoring photosynthetically driven energy flows and protecting remaining natural carbon sinks must be treated as central pillars of effective climate policy. Integrating high‑resolution biosphere modeling, stronger land‑use governance and nature‑positive investments offers a pathway to reduce risk and recover safe operating space for people and planet. The map of functional biosphere integrity produced by this study provides a diagnostic tool—and a warning—about how closely human prosperity is bound to the health of the living planet.
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