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Common Boundaries

Johan Rockstrφm
Director, Stockholm Environment Institute

Human pressure on the planet is reaching a saturation point which, if exceeded, may undermine social and economic development. This is new, as are its effects on our global commons — the stratospheric ozone layer, the climate system, the biosphere, the hydrosphere, and the cryosphere — verified through empirical observations over the past 20 years or so. These manifestations include, the rapid depletion of the ozone layer, a continued exponential rate of biodiversity loss, degradation of air quality, land and freshwater, aerosol loading and chemical pollution at regional scales, climate change, and unsustainable appropriation of such finite natural resources as oil and phosphorus. The impacts are starting to manifest themselves in ways that affect economies around the world.

The scale of human influence is so large that we may have entered a new geological epoch, the Anthropocene, where humanity constitutes a geological planetary force. We may therefore be pushing ourselves out of our current epoch, the Holocene, the last 10,000 years of inter-glacial, which has provided extraordinarily stable environmental conditions, enabling world development as we know it.

The driving forces behind this globalization of environmental challenges starts in the mid 1950s. Up until this point, the relative impact from humanity on the global commons was low — the environmental impacts from almost 200 years of industrialization remained, until then, largely limited to local and regional impacts on water, land, air. After mid-century the human enterprise changes pace. The industrial metabolism goes to scale, and we start seeing an exponential increase in social wellbeing, GDP growth, population numbers, health improvements and human impacts on the environment. So, this is the point when global environmental change manifests itself on essentially all parameters that matter for human wellbeing: from habitat loss to climate change.

Three additional and interacting factors accentuate the challenge. The first is the growth of population and affluence: we are largely committed to grow from the current 7 billion to 9 billion people by 2050, in a world that is rapidly urbanizing and becoming more affluent (the majority of the world population, which remains poor, has so far claimed only a limited fraction of the global commons, while having a right to a share of them). Secondly, science increasingly indicates the risk of abrupt and irreversible changes, when systems — from local ecosystems to the climate — are pushed across tipping points. This can lead to catastrophic shifts in conditions for nations and regions, potentially triggered by changes in global commons, such as increasing greenhouse gases in the atmosphere, triggering a destabilization of the Greenland ice sheet. The third is the growing evidence of our social and economic dependence on ecosystem services for human wellbeing, from such local functions as fertile soils to global ones like a stable Arctic.

We need to rethink human development in this new Anthropocene epoch. We urgently need to bend the curves of negative global environmental change in order to navigate within a safe operating space in the Earth system. Global commons must be governed as an integral part of national and regional development.

The concept of planetary boundaries provides a framework in this context. It identifies environmental processes that determine the stability of components of the Earth system — and proposes sustainable boundaries for the key variables that determine change for each process, set in order to try to avoid tipping points that may cause abrupt and deleterious regional and global disruption. Nine such planetary boundary processes have been proposed. These include the three global commons where there is evidence of large scale thresholds — climate change, depletion of the ozone layer, and ocean acidification — and processes that provide regulatory functions that determine the resilience of major biomes — and ultimately the Earth system — land use change, freshwater use, the rate of biodiversity loss, and human interference with the global nitrogen and phosphorus cycles. The final two are chemical pollution and aerosol loading. Safe boundaries have been quantified for the first seven and were chosen at the lower — more risk averse — end of the uncertainty range articulated by science, as a way of applying a precautionary principle: for climate change, for example, it was placed at 350 ppm CO2 (parts per million), when science indicates the risk of crossing tipping points in the range of 350 – 550 ppm CO2.

Together these nine planetary boundaries provide a safe operating space for humanity. The first analysis indicates that we have transgressed the safe space for three of them — climate change, rate of biodiversity loss and extracting nitrogen from the atmosphere. This places us in a slippery and risky danger zone where we cannot exclude hitting tipping points: the accelerated melting of ice in the Arctic may be one early warning of such a non-linear dynamic.

Governance of the global commons is required to achieve sustainable development and thus human wellbeing. We can no longer focus solely on national priorities for economic development and environmental protection. The influence all nations have on the global commons — at a point of growing environmental saturation — generates worldwide feedbacks that influence local economies. Nor can we focus on climate change alone. We most now simultaneously address sustainability at the planetary scale for all the key environmental processes linked to the stability of the Earth’s biophysical systems.

The planetary boundary concept may be useful in supporting the governance of our global commons. We need to recognize the social implications of living within safe boundaries, and all the boundaries have to add up, within safe levels, at the global scale. Thus no nation or region can appropriate a larger share of the global commons without both transparently reporting this to all other nations, and agreeing on mechanisms to ensure that the aggregate use of planetary space remains within safe boundaries. Staying within the safe operating space in the Anthropocene, in a world with growing populations and affluence, will require distributing the planetary space among nations. This is, to say the least, a challenging but necessary task, which, when we succeed, will benefit humanity as a whole for generations.

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