How Defining Planetary Boundaries Can Transform Our Approach to Growth

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5-1-2011 How Defining Planetary Boundaries Can Transform Our Approach to Growth

W. L. Steffen

Johan Rockström

Robert Costanza Portland State University

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Citation Details Steffen, W., Rockström, J., & Costanza, R. (2011). How Defining Planetary Boundaries Can Transform Our Approach to Growth. Solutions: For A Sustainable & Desirable Future, 2(3), 59-65.

This Article is brought to you for free and open access. It has been accepted for inclusion in Institute for Sustainable Solutions Publications and Presentations by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. Feature How Defining Planetary Boundaries Can Transform Our Approach to Growth

by Will Steffen, Johan Rockström, and Robert Costanza

Rockström et al. Nature (2009) and Ida Kubiszewski/Solutions The globe represents the proposed safe operating space for the nine planetary systems. The wedges represent an estimate of the current position for each variable. The boundaries in three systems (rate of biodiversity loss, climate change, and human interference with the nitrogen cycle) have already been exceeded.

In Brief Our planet’s ability to provide an accommodating environment for humanity is being challenged by our own activities. The environment—our life-support system—is changing rapidly from the stable Holocene state of the last 12,000 years, during which we developed agriculture, villages, cities, and contemporary civilizations, to an unknown future state of significantly different conditions. One way to address this challenge is to determine “safe boundaries” based on fundamental characteristics of our planet and to operate within them. By “boundary,” we mean a specific point related to a global-scale environmental process beyond which humanity should not go. Identifying our planet’s intrinsic, non- negotiable limits is not easy, but here we specify nine areas that are most in need of well-defined planetary boundaries, and we explain the steps needed to begin defining and living within them.

www.thesolutionsjournal.org | May-June 2011 | Solutions | 59 Author Note: This article is based on move to someplace else. As human that certain preconditions must be set the papers “A safe operating space for population has grown, these short- that acknowledge and respect those humanity,”1 published in Nature, and term solutions are no longer viable. boundaries. “Planetary boundaries: Exploring the Furthermore, the impacts of our pres- This new situation is captured in safe operating space for humanity,”2 ence were not usually felt beyond our the concept of the Anthropocene, a published in Ecology and Society. See immediate surroundings. This is also newly defined geological era beginning these papers for a complete description of no longer the case. The global envi- around the 1800s, with the Industrial the planetary boundaries. Here, we pres- ronment has provided an especially Revolution. The term was introduced ent the underlying concepts and suggest and popularized by Nobel Laureate ways to limit continued growth of the Paul Crutzen,5 who felt the recent influ- material economy on a finite planet. Key Concepts ence of human activity on the Earth was significant enough as to constitute The Challenge the naming of a new epoch. The past • In the last 200 years, humanity has Over the past half century, we transitioned into a new geological 12,000 years or so is a period defined by have become adept at dealing with era—termed the Anthropocene— geologists as the Holocene, an epoch environmental problems on a local which is defined by an accelerating in which global average temperature departure from the stable environ- and global scale. The worst excesses mental conditions of the past 12,000 has been remarkably stable and during of the Industrial Revolution have, in years into a new, unknown state of which time agriculture developed, fol- many cases, been ameliorated. Rivers, Earth. lowed by the appearance of ever larger such as the Thames in London, have settlements and the development of been cleaned up and the air quality • In order to maintain a global environ- complex civilizations in Africa, Asia, ment that is conducive for human in major cities, such as Los Angeles, development and well-being, we South and Central America, and the is better. Synthetic pesticides once must define and respect planetary Mediterranean region. sprayed on our crops, such as DDT, boundaries that delineate a “safe Since the Industrial Revolution, operating space” for humanity. We have been banned in most developed must return to the long-term stable the human enterprise has expanded so countries, and lead has been removed global environment that nurtured rapidly that we are now overwhelm- from petroleum-based fuels. These human development. ing the capacity of the Earth system to impressive successes have been absorb our wastes and to sustainably celebrated, perhaps most notably in • The nine areas that are most in need provide the services we require. In of planetary boundaries are climate Bjorn Lomborg’s book The Skeptical change, biodiversity loss, excess the period since the Second World Environmentalist.3 nitrogen and phosphorus production, War, the acceleration of development However, to say we have done stratospheric ozone depletion, ocean has become particularly dramatic. acidification, global consumption of enough globally would be false on two freshwater, change in land use for Humanity is fundamentally chang- counts. First, while these problems have agriculture, air pollution, and chemi- ing the Earth’s physical climate,6 been addressed in many European and cal pollution. overwhelming its capacity to provide North American nations, over three- ecosystem services, homogenizing its • We estimate that humanity has 7 quarters of the world’s people do not live already transgressed three of biological diversity, and substantially in developed countries. For them, many these boundaries: climate change, modifying the global cycles of key of the local and regional environmental biodiversity loss, and phosphorus elements like nitrogen, carbon, and problems still exist and, in many cases, production. phosphorus.8 We are indeed passing are worsening. Second, the environ- through the exit door of the Holocene • Several steps can be taken to estab- ment—our life-support system—is lish and enforce these boundaries, and into the unknown world of the under increasing threat from a wide and they are suggested here. Anthropocene. range of human pressures, many of So what is the solution to this them emanating from consumption in dilemma? Humanity needs to change the wealthy countries. The deterioration accommodating environment over course, but in what direction and of the global environment puts even the past 12,000 years for humanity what principles should guide the more pressure on the poorest countries to develop and thrive.4 But the world journey? The problem has been to limit growth, even as they struggle to population is no longer small, spread recognized for several decades, and bring their populations out of poverty. out, and technologically limited. many attempts have been undertaken This is an entirely new situation for Does our planet have boundaries to define or inform solutions—limits humanity. In the past when we fouled regarding the amount of growth it to growth,9 safe minimum stan- our local environment, we could can absorb? We believe it does and dards,10 the precautionary approach,11

60 | Solutions | May-June 2011 | www.thesolutionsjournal.org Conceptual Diagram of Boundary, reshold, and Zone of Uncertainty

Planetary Planetary boundary boundary Dangerous T hreshold level

Safe Zone of operating uncertainty Zone of space uncertainty Response variable (e.g., extent of land ice) ) carbon sequestration (e.g., Mt yr- Terrestrial Control variable (e.g., ppm CO2 ) Land-use change (e.g., % terrestrial ecosystems under cropland)

12 and tolerable windows, for example. Table 1: Categories of Boundaries These provide an excellent knowl- SLOW PROCESSES WITHOUT BOUNDARY CHARACTER PROCESSES WITH GLOBAL edge base from which to work toward KNOWN GLOBAL SCALE SCALE THRESHOLDS a more sustainable future. SCALE OF PROCESS THRESHOLDS

The Concept of Planetary SYSTEMIC PROCESSES Boundaries AT PLANETARY SCALE How do we begin to identify what aspects of our planet need boundaries and what those boundaries are? The 1,2 concept of planetary boundaries, AGGREGATED PROCESSES while building on earlier efforts, takes FROM LOCAL/REGIONAL SCALE a rather different approach. It does not focus so directly on the human enterprise, as do most of these earlier approaches, but rather emphasizes the Earth as a complex system. Here we identify nine areas that are most in need of set planetary boundaries: climate change; biodiversity loss; excess nitrogen and phosphorus production, Rockström et al. Ecology & Society (2009) and Richard Morin/Solutions Our initial analysis yielded nine planetary boundaries for Earth-system processes, such as for climate which pollutes our soils and waters; change, which undoubtedly features threshold/abrupt change behavior, and for others, such as Table 2: Planetary Boundaries stratospheric ozone depletion; ocean biodiversity loss, which are slow processes that erode resilience over time. acidification; global consumption of Earth-System Process Parameters Proposed Current Pre-industrial freshwater; change in land use for agri- Boundary Status Value culture; air pollution; and chemical toClimate approach Change dangerous(i) orAtmospheric potentially carbon A second350 example387 is biodiversity280 dioxide concentration pollution (table 1). catastrophic thresholds(parts in perour million own by volume)loss, which does occur naturally and What do we mean by “boundary”? life-support system. (ii) Change in radiative would continue1 to some1.5 degree with0 - forcing This refers to a specific point related Climate change, biodiversity(watts per meter squared)out human interference. However, to a global-scale environmental pro- loss, and phosphorus and nitrogen the rate of animal extinction has Rate of Biodiversity Extinction Rate 10 >100 0.1-1 cess beyond which humanity should productionLoss are just three(number areas of species in per skyrocketed in the postindustrial age. not go. The position of the boundary which boundaries canmillion be determined species per year) Compared with fossil records, today is a normative judgment, informed by and measured, and we will use these the rate of extinction per species is Nitrogen Cycle (part Amount of N2 removed from 35 121 0 of a boundary with the the atmosphere for human science but largely based on human asphosphorus examples. cycle) use (million of tonnes per year)100–1,000 times more than what perceptions of risk. This doesn’t mean Human-provoked climate change could be considered natural. Human Phosphorus Cycle Quality of P f lowing into 11 8.5-9.5 -1 that any change in the Earth system is(part no longerof a boundary disputed. theScientists oceans (million can of tonnesactivities are to blame: urban and is dangerous. Our planet can undergo measurewith the nitrogen climate cycle) changeper year) by studying agricultural development, sprawl, abrupt changes naturally. An example theStratospheric levels of OzoneCO2 in ourConcentration atmosphere. of ozone increases276 in wildfires283 that destroy290 hab- is the sudden switch in North Atlantic OurDepletion proposed climate( Dobsonboundary unit) is itat, introduction of new species into ocean circulation when a critical level that human changes to atmospheric environments, and the exploitation of of freshwater input is reached. But COOcean should Acidiﬁcation not drive itsGlobal concentra mean saturation- land for 2.75human consumption—such2.90 3.44 2 state of aragonite in these thresholds and abrupt changes tion beyond 350 partssurface per million sea water by as the destruction of the rainforests. are intrinsic features of the Earth volume, and that radiative forcing— We believe another 30 percent of Global Freshwater Use Consumption of freshwater 4,000 2,600 415 system and cannot be eliminated or the change in the energyby humans balance (km 3 per year) wildlife will come under the threat modified by human actions, such as at the Earth’s surface—should not of extinction this century if change is the development of new technolo- exceedChange 1in wattLand Use per squarePercentage meter of above global landnot made.15 The dangers11.7 of biodiversityLow cover converted to gies. We have to learn to live with preindustrial levels. Transgressingcropland loss go beyond nostalgia for certain thresholds and respect them. An these boundaries could lead to the animals: entire ecosystems rely on Atmospheric aerosol Overall particulate concentration abrupt change is a hardwired feature meltingloading of ice sheets, risingin the atmosphere, sea level, on a certain threatenedTo be determined species. of the Earth system independent of abrupt shifts in forestregional and agricul basis - Setting a planetary boundary for human existence, while violation of a turalChemical land, Pollution and increasingFor example, intensity amount emittedbiodiversity is difficult because there to, or concentration of boundary is a subjective judgment by and frequency of extremepersistent events organic like pollutants, is so little known about the way in humanity about how close we wish floods, wildfires, and heatplastics, waves. endocrine disrupters,which species are interwoven and how heavy metals, and nuclear To be determined waste in, the global environment or the effects on the ecosystem andwww.thesolutionsjournal.org | May-June 2011 | Solutions | 61 functioning of Earth system thereof they connect to the broader environ- the concept of planetary boundaries atmospheric circulation globally and ment. However, we propose beginning presents huge challenges for global ultimately affect water resources in by using the extinction rate as a governance and institutions. East Asia through changes in rainfall. flawed but acceptable indicator. Our Even small changes can have a suggested planetary boundary is that Critical Features of the synergistic effect when linked to other of ten times the background rate of Planetary Boundaries Concept small changes. For example, conver- extinction. More research may change Several features of the planetary sion of forest to cropland, increased this boundary. boundaries conceptual framework use of nitrogen and phosphorus In our third example, we propose are critical to understanding how the fertilizers, and increased extraction that no more than 11 million approach works. of freshwater for irrigation could all tonnes of phosphorous should First, planetary boundaries are act together to reduce biodiversity be allowed to flow into the ocean explicitly designed for the global more than if each of these variables each year—which is ten times the scale and are aimed at keeping the acted independently. Many changes natural background state. Excessive Earth within safe ranges that existed feed back into each other. The pro- production of phosphorus, along prior to the Industrial Revolution. cesses involving ocean acidity and with nitrogen, is a by-product of Although some Earth-system pro- atmospheric CO2 concentration are our agricultural system. Excessive cesses, such as ocean acidification, are an example of a reinforcing feedback phosphorous and nitrogen produc- intrinsically global in scale, others loop. An increase in ocean acidity tion pollutes waterways and coastal become global only when they aggre- reduces the strength of the “biological areas and adds harmful gases to the gate from much smaller scales. pump” that removes carbon from the atmosphere. Current levels already In no way does this mean that local atmosphere, which in turn increases exceed critical thresholds for many or regional environmental issues, the atmospheric CO2 concentration, estuaries and freshwater sites, and which have largely been the focus of which increases the physical uptake so further research may reduce the policy and management for decades, of CO2 by the ocean, which further current phosphorus and nitrogen have become less important. Efforts to increases acidity, and so on. boundaries. reduce pollution and limit and reverse Finally, the planetary boundaries We propose that a boundary be ecosystem degradation at local and approach doesn’t say anything explicit set for each of the nine areas and that regional scales continue to be very about resource use, affluence, or it be respected globally, in order for important and in fact have become human population size. These are part humans to continue along a healthy, even more important because of their of the trade-offs that allow humanity productive path for an indefinite larger-scale implications. However, to continue to pursue increased well- amount of time (table 2). It is impor- we must now also focus on the global being. The boundaries simply define tant to acknowledge that we don’t scale explicitly—in addition to and the regions of global environment know precisely where the threshold not at the expense of the many envi- space that, if human activities push the might lie along the control variable ronmental issues we still need to solve Earth system into that space, would (i.e., a variable—sometimes a human at smaller scales. A global solution to lead to unacceptably deleterious conse- intervention—that can influence the sustainability challenge is thus a quences for humanity as a whole. whether or not a threshold is crossed) prerequisite for living sustainably at Because the planetary boundaries or how much change in a slow local and regional scales. approach says nothing about the process will undermine resilience at Second, there is much interaction distribution of affluence and technolo- larger scales. Thus, we need to define among the planet’s features that lies at gies among the human population, a zone within which we are reason- the heart of the planetary boundaries a “fortress world,” in which there are ably sure the threshold lies or beyond approach. This is not at all surprising huge differences in the distribution of which we are reasonably sure that a given that the Earth behaves as a wealth, and a much more egalitarian significant degree of resilience will single, complex system at the global world, with more equitable socioeco- be lost. scale, but it does complicate the nomic systems, could equally well Staying within the “planetary formulation and implementation of satisfy the boundary conditions. These playing field” does not assure that planetary boundaries. There are cas- two socioeconomic states, however, humanity will thrive, or even cading impacts, in which transgressing would deliver vastly different outcomes survive, but straying outside the one boundary can have implications for human well-being. Thus, remaining playing field will make it very dif- for other boundaries. For example, within the planetary boundaries is a ficult for humanity to thrive under converting the Amazon rainforest to a necessary—but not sufficient—condi- any circumstances. Implementing grassland or savanna could influence tion for a bright future for humanity.

62 | Solutions | May-June 2011 | www.thesolutionsjournal.org Conceptual Diagram of Boundary, reshold, and Zone of Uncertainty

Planetary Planetary boundary boundary Dangerous T hreshold level

Table 1: Categories of Boundaries

SLOW PROCESSES WITHOUT BOUNDARY CHARACTER PROCESSES WITH GLOBAL KNOWN GLOBAL SCALE SCALE THRESHOLDS SCALE OF PROCESS THRESHOLDS

SYSTEMIC PROCESSES AT PLANETARY SCALE

AGGREGATED PROCESSES FROM LOCAL/REGIONAL SCALE

Table 2: Planetary Boundaries

Earth-System Process Parameters Proposed Current Pre-industrial Boundary Status Value

Climate Change (i) Atmospheric carbon 350 387 280 dioxide concentration (parts per million by volume) (ii) Change in radiative 1 1.5 0 forcing (watts per meter squared)

Rate of Biodiversity Extinction Rate 10 >100 0.1-1 Loss (number of species per million species per year)

Nitrogen Cycle (part Amount of N2 removed from 35 121 0 of a boundary with the the atmosphere for human phosphorus cycle) use (million of tonnes per year)

Phosphorus Cycle Quality of P f lowing into 11 8.5-9.5 -1 (part of a boundary the oceans (million of tonnes with the nitrogen cycle) per year)

Stratospheric Ozone Concentration of ozone 276 283 290 Depletion (Dobson unit)

Ocean Acidiﬁcation Global mean saturation 2.75 2.90 3.44 state of aragonite in surface sea water

Global Freshwater Use Consumption of freshwater 4,000 2,600 415 by humans (km3 per year)

Change in Land Use Percentage of global land 15 11.7 Low cover converted to cropland

Atmospheric aerosol Overall particulate concentration loading in the atmosphere, on a To be determined regional basis

Rockström et al. Nature (2009) and Richard Morin/Solutions We have assigned a control variable (or parameter) to each of the Earth-system processes and, in addition, have taken a first guess—some better substantiated than others—at a planetary boundary for each. To see how humanity is faring with respect to the boundaries, we have listed the current and preindustrial values of the control variable along with the proposed boundary.

www.thesolutionsjournal.org | May-June 2011 | Solutions | 63 Conceptual Diagram of Boundary, reshold, and Zone of Uncertainty

Planetary Planetary boundary boundary Dangerous T hreshold level

Rockström et al. Ecology & Society (2009) and Richard Morin/Solutions The left panel shows a boundary for a process that has a well-defined threshold, leading to an abrupt change if that threshold is crossed. The right panel shows a boundary for a “slow” process that does not have a threshold but is important for maintaining resilience at regional or global scales. In each case there is a zone of uncertainty as to where the threshold lies or where an unacceptable erosion of resilience occurs. Table 1: Categories of Boundaries

The Implications for within a zone of uncertainty, some • SLOWCapacity PROCESSES to assimilate new WITHOUT information. BOUNDARY CHARACTER PROCESSES WITH GLOBAL Governance much larger than others. Although In KNOWNaddition to GLOBAL reducing theSCALE zone of SCALE THRESHOLDS AsSCALE a practical OF solution PROCESS for living further scientific research will uncertaintyTHRESHOLDS for some boundaries, sustainably in the modern era, the reduce these uncertainties in scientific research will continue planetary boundaries approach raises many cases, they will never be to uncover more insights into the important questions and opportuni- completely eliminated. In a dynamics of the Earth system itself. SYSTEMIC PROCESSES ties for governance and institutions, poisonous political environment, This could lead to the need for evenAT to PLANETARY the point of challenging SCALE the uncertainties can be exploited as additional planetary boundaries concept of national sovereignty. We reasons for inaction, but scientists or the reformulation of existing have identified four specific chal- must be able to address uncertainty ones. The increasing flow of lenges for governance:13 without being attacked. A global new scientific information will governance system will need undoubtedly put pressure on any • Early-warning systems. The nature to live with a certain level of institutional framework to keep up ofAGGREGATED Earth-system dynamics—the PROCESSES uncertainty, emphasizing the with the pace of new knowledge. A nonlinearities, tipping elements, need for a precautionary approach case in point is in the debate over FROM LOCAL/REGIONAL thresholds/abrupt changes— when determining the position of how much greenhouse gas can be SCALE strongly suggests that humanity boundaries. released without disastrous effects. needs a system to warn us • Multilevel governance. Interacting After a long time trying to convince when we are approaching such with the traditional institutions the international community that potentially catastrophic points. that currently exist at national, the climate change boundary should

Indeed, the planetary boundaries subnational, and local levels will be 450 ppm CO2, a growing number approach is based directly on be necessary, and probably will of scientists are suggesting that a

this feature of the Earth system. be complex and challenging to 350 ppm CO2 boundary would be An early-warning system is a implement. Creating effective more appropriate. prerequisite for being able to multilevel governance systems will recognize and steer away from be especially important for those Ultimately, there will need to be an such thresholds. planetary boundaries that are based institution (or institutions) operating, • Dealing with uncertainties. Each of on aggregates of many local and with authority, above the level of the planetary boundaries is placed regional actions. individual countries to ensure that the

64 | Solutions | May-June 2011 | www.thesolutionsjournal.org Table 2: Planetary Boundaries