The Planetary Boundaries framework claims that for humanity to remain within a “safe operating space”, land use for crops should be limited to 15% of Earth's ice-free land. This presentation examines the rationale behind this claim and then offers a counterargument that global limits on land use would likely create more problems than solutions, and that, rather than a globally defined limit on land use, improved multi-scale land management strategies might better benefit both humanity and non-human nature.
The main rationale for limiting human alteration of the Earth system is that “crossing certain biophysical thresholds could have disastrous consequences for humanity”. It is unclear, however, how a 15% limit on land use for crops was derived. About 12% of Earth's land is now used to grow crops and an additional 26% or so is used for pastures and other grazing lands. These uses have been sustained for millennia in many regions. One likely rationale is that human use of land might be considered inherently detrimental to the biosphere. If the biosphere sustains humanity, limiting land use would be beneficial. Yet agriculture supplies the overwhelming majority of human sustenance; the unaltered biosphere very little. Even modest pressures on land availability for food production, such as biofuel demands, can drive up food prices with clear negative impacts on food security in developing regions. In short, there is scant evidence for benefits to humanity by limiting land use, though negative impacts are clear.
Land used for agriculture does negatively impact non-human species. There is no social good derived from this, and many good reasons to reverse this. It is possible to maintain agricultural productivity while recovering biodiversity, but this will require major concerted efforts around the world, tailored to widely differing conditions. Robust and adaptive governance systems that include strong stakeholder participation can guide and enforce efficient use of land while protecting and restoring essential habitat. To be effective, such governance must be in place wherever suitable land exists, as the global marketplace now rapidly converts any local and regional failures in land governance into opportunities to clear land for commodities, such as the rapid conversion of tropical forests into oil palm plantations in Indonesia. Human use of land is decided by a complex web of cross-scale stakeholder relations and institutional arrangements that defies top-down global solutions. Multifunctional land management strategies at local, regional and national scales are the real Planetary Opportunities to sustain the ecological heritage of our planet while advancing the state of humanity in the Anthropocene.