MADRID, 18 (EUROPA PRESS)
A new study has mapped the planetary boundary of the “functional integrity of the biosphere” in spatial detail and over centuries.
This study reveals that 60% of the global land surface is already outside the locally defined safety zone, and 38% is even in the high-risk zone.
The study was led by the Potsdam Institute for Climate Impact Research (PIK) in collaboration with BOKU University Vienna and published in the journal One Earth.
The functional integrity of the biosphere refers to the plant world's ability to co-regulate the state of the Earth system. This requires that the plant world be able to obtain sufficient energy through photosynthesis to maintain the flows of carbon, water, and nitrogen that support ecosystems and their numerous interconnected processes, despite current massive human intervention.
Along with biodiversity loss and climate change, functional integrity forms the core of the Planetary Boundaries analytical framework for a safe operating space for humanity.
"There is a tremendous need for civilization to utilize the biosphere for food, raw materials, and, in the future, also for climate protection," said Fabian Stenzel, lead author of the study and a member of the PIK research group, Safe Terrestrial Operational Space, in a statement.
«After all, human demand for biomass continues to grow, and growing fast-growing grasses or trees to produce bioenergy with carbon capture and storage is seen by many as an important strategy to support climate stabilization.
"Therefore, it becomes even more important to quantify the pressure we are already exerting on the biosphere, differentiated by region and over time, to identify overloads. Our research is paving the way for this.
The study is based on the latest update of the Planetary Boundaries framework, published in 2023.
"The framework now clearly places energy flows from photosynthesis in global vegetation at the heart of the processes that co-regulate planetary stability," explains Wolfgang Lucht, head of the Department of Earth System Analysis at PIK and coordinator of the study.
STRESS ON NATURE
"These energy flows drive all life, but humans are now diverting a significant portion of them to their own ends, disrupting nature's dynamic processes."
The stress this causes to the Earth system can be measured by the proportion of natural biomass productivity that humanity channels into its own uses (through harvested crops, residues, and wood), but also by the reduction in photosynthetic activity caused by cultivation and soil sealing.
The study added to this measure a second powerful indicator of biosphere integrity: an ecosystem destabilization risk indicator that records complex structural changes in vegetation and in the biosphere's water, carbon, and nitrogen balances.
EVOLUTION SINCE 1600
Based on the LPJmL global biosphere model, which simulates daily fluxes of water, carbon, and nitrogen at a resolution of half a degree of longitude/latitude, the study provides a detailed inventory for each year since 1600, based on changes in climate and human land use.
The research team not only calculated, mapped, and compared the two indicators of biosphere functional integrity, but also evaluated them through mathematical comparison with other measures in the literature for which "critical thresholds" are known.
This resulted in each area being assigned a status based on local ecosystem change tolerance limits: Safe Operating Space, Increasing Risk Zone, or High Risk Zone.
The model's calculations show that worrying developments began as early as 1600 in the mid-latitudes. By 1900, the proportion of the global land area where ecosystem changes exceeded the locally defined safe zone, or were even in the high-risk zone, was 37% and 14%, respectively, compared to 60% and 38% today.
Industrialization was beginning to take its toll; land use affected the state of the Earth system long before global warming. Currently, this biosphere boundary has been crossed across almost the entire Earth's surface—primarily in Europe, Asia, and North America—which has experienced significant vegetation cover conversion, primarily due to agriculture.
"This first global map showing the breach of the limit of the biosphere's functional integrity, representing both human appropriation of biomass and ecological disruption, represents a major scientific breakthrough, as it provides a better overall understanding of planetary boundaries," says Johan Rockström, director of the PIK and one of the study's co-authors.
"It also provides an important impetus for further development of international climate policy, as it highlights the link between biomass and natural carbon sinks and how they can contribute to mitigating climate change. Governments must address this as a single, fundamental issue: the comprehensive protection of the biosphere coupled with decisive climate action."
