Seven out of eight. Sounds like a decent grade, right? Wrong. It should be a wake-up call. Seven of the eight “planetary boundaries” redefined in 2023 have been crossed! We’re pushing our planet past its limits, jeopardizing the very systems that sustain us.
One of those critical boundaries is the “functional integrity of the biosphere.” Think of it as the ability of the plant world to harness enough energy through photosynthesis to keep everything in balance. But our actions are throwing this delicate clockwork out of whack. The big question is: just how much?
Published in One Earth, a study from the Potsdam Institute for Climate Impact Research (PIK) provides some alarming answers, and puts numbers on how close to the edge we are.
Map of the two merged indicators: the functional integrity of the biosphere is one of the eight planetary boundaries. Each zone has been assigned a status: “safe zone” (green), “zone at increasing risk” (yellow/orange) or “high risk zone” (red/purple).
© Stenzel, Fabian et al. One Earth, Volume 8, Issue 8, 101393
Biomass Mismanagement: Wood and Harvests
Food, raw materials, and carbon storage – our society relies heavily on the biosphere. “Civilization has a crucial need to use the biosphere,” says Fabian Stenzel, the study’s lead author.
Quantifying the pressure we exert on the biosphere becomes all the more important, regionally and over time, in order to identify overloads.
Researchers developed two key indicators to track how we’re impacting the biosphere:
- The proportion of natural productivity diverted by humanity for its own uses (harvests, timber).
- How agriculture and impervious surfaces reduce photosynthetic activity.
They also assessed the risk of ecosystem destabilization, considering vegetation structure and the flow of water, carbon, and nitrogen.
The Impact of Land Use Change
Using a global biosphere model, the study offers a detailed look at each year since 1600, factoring in climate change and human land use.
The research team calculated, mapped, and compared the two indicators of functional integrity of the biosphere, compared them with other measures from the literature for which “critical thresholds” are known.
Each zone was assigned a status: “safe zone”, “zone at increasing risk” or “high risk zone”.
Industrialization’s Devastation
The calculations reveal a worrying trend since 1600. In 1900, 37% of the global land area exceeded the locally defined “safe zone” or was in the “high risk” zone.
Now? A staggering 60% is beyond the safe zone, and 38% is in high-risk territory.
The 20th century saw industrialization take its toll. Land use severely impacted the Earth system, even “well before global warming.” Europe, Asia, and North America experienced significant shifts in vegetation cover, mainly due to agriculture.
A Warning to Governments
For Professor Johan Rockström, director of PIK and the mastermind behind the planetary boundaries concept, this world map is a “major scientific advance” and an important impulse for the future development of international climate policy:
Governments need to see the connection between biomass, natural carbon sinks, and climate change mitigation. Biosphere protection combined with strong climate action is paramount.
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