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Transgressing Planetary Boundaries
Are humans shifting the entire Earth system?
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| The diagram shows the nine planetary boundaries. Source: Steffen et al. (2015), Design: Globaia |
Four out of nine Planetary Boundaries (PB), beyond which humanity runs the risk of major environmental crisis, have to date been transgressed. These include: genetic diversity, climate change, biogeochemical flows and land-system change. That is the message of a large group of scientists, lead by Will Steffen, who recently published their improved estimation in the journal Science.
The concept planetary boundaries was first used in the original paper from 2009, in which Rockström et al. identified nine different natural processes that are critical for the stability of the Earth system. In that paper they also estimated boundaries, parameters of change, within which humanity would like to stay to ensure long term progress and survival.
By transgressing four out of nine boundaries humanity is now on the verge of shifting the entire Earth system, from a friend with predictable and temperate climate full of diversity to a foe with unpredictable and warmer climate with less diversity. For example, large marine ecosystems could change dramatically due to ocean acidification and eutrophication, higher temperatures could threaten agricultural productivity and human health, and continued loss of biodiversity could mean faster spread of diseases and pests.
Steffen explains that once we have passed a threshold it becomes increasingly difficult to turn back or even slow down changes in the Earth system. In other words, it could potentially have catastrophic consequences. The authors have named two of the nine PBs "core" since they are fundamental to the integrity of the Earth system. These two include climate change and biosphere integrity, and we have basically passed both of those two boundaries.
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