Planetary Boundaries

The pioneering Limits to growth study published in the early 1970’s was harshly attacked by its neoliberal critics at the time of its release and many years afterwards. 40 years later however, accumulated data has proven the model’s worst scenario prediction most closely matches realworld data. Human population has reached a level that is now consistently taxing the planets life support systems. Now as then, this is not the message which growth-minded economists want to hear. The business-as-usual approach of the past 3 decades means that our civilization has continued to consume vast amounts of virgin resources, while our linear manufacturing processes produces equally vast amounts of pollution.

In Sept 24, 2009, a group of 29 Earth Systems Scientists led by Johan Rockstrom of the Stockholm Resilience Centre published an article in Nature entitled: “A safe operating space for humanity“. This article, which summarized years of work built upon the pioneering “Limits to Growth” study of many decades earlier and attempted to define, for the first time ever, safe operating boundaries of human activity for a number of critical environmental areas.


Figure 2: The Nine Planetary Boundaries – click on each for more information (Source: Rockstrom et. al, 2009)

The boundaries are interlinked and the authors suggest we have already overstepped three of them:

  1. atmospheric carbon dioxide concentration
  2. biodiversity loss
  3. the nitrogen cycle

and we are close to the boundaries of a further three:

  1. land use,
  2. fresh water use
  3. ocean acidification

In 2015, the group released an update to their original 2009 study.

The planet’s response to major changes is nonlinear. For example, as atmospheric carbon dioxide levels increase glaciers react in a relatively limited way for a long time before reaching a threshold, then they can melt rapidly. The same holds true with Methane Clarates or permafrost which are kept from outgassing due to  conditions of temperature and pressure which are quickly deteriorating.  The exact position of a threshold is extremely difficult, if not impossible, to pinpoint and is based upon the best available evidence. “We have put this boundary at the lower edge of the uncertainty level around this threshold,” says Rockström.

While the Nature feature concludes, “The evidence so far suggests that, as long as thresholds are not crossed, humanity has the freedom to pursue long-term social and economic development”, the longer paper in Ecology and Society, upon which the Nature paper is based, is far bleaker which concludes that “Incremental change can lead to the unexpected crossing of thresholds that drive the Earth system, or significant sub-systems, abruptly into states deleterious or even catastrophic to human well-being.”

The authors write:

These boundaries define the safe operating space for humanity with respect to the Earth system and are associated with the planet’s biophysical subsystems or processes. Although Earth’s complex systems sometimes respond smoothly to changing pressures, it seems that this will prove to be the exception rather than the rule. Many subsystems of Earth react in a nonlinear, often abrupt, way, and are particularly sensitive around threshold levels of certain key variables.

If these thresholds are crossed, then important subsystems, such as a monsoon system, could shift into a new state, often with deleterious or potentially even disastrous consequences for humans. Most of these thresholds can be defined by a critical value for one or more control variables, such as carbon dioxide concentration. Not all processes or subsystems on Earth have well-defined thresholds, although human actions that undermine the resilience of such processes or subsystems — for example, land and water degradation — can increase the risk that thresholds will also be crossed in other processes, such as the climate system. We have tried to identify the Earth-system processes and associated thresholds which, if crossed, could generate unacceptable environmental change. We have found nine such processes for which we believe it is necessary to define planetary boundaries.

Figure 3: Personal impacts of planetary boundaries: click on the Play button in the graphic to explore


Figure 4: First draft figures of planetary boundaries (Source: Rockstrom et. al)

Earth System Trends  and Planetary Boundaries

When we look at the trends, Of the past 100,000 years, it has only been in the last 10,000, an age called the holocene, when the earth gave rise to ideal conditions for human beings to flourish. Ironically, our very success in this period has increased our numbers from a few million to 7 billion and approaching 9 billion in 2050. We are following the trajectory of a classic adaptive cycle in resilience / complexity theory and approaching the destruction stage.

Figure 5: The last 100,000 years and the 10,000 years of stability called the Holocene

Since 1950, many major earth system processes have begun to follow a hockey stick or exponential increase. The graphs below from Rockstrom’s presentation all indicate exponential resource depletion, waste & pollution creation as well as earth system stressors – a confluence of factors which can lead to tipping points and runaway effects that force us into completely new and uncharted system regime.

 Figure 6: Planetary Boundaries: specific boundary graphs (Source: Rockstrom et. al)

Rockstrom and other scientists created the framework of Planetary Boundaries as a simple and effective way to demonstrate how cumulative human activity bringing nature to unstable states where tipping points may lead us to new, uncharted regimes. The diagrams below show the trajectories of the 9 planetary boundaries from 1950 to the present day.



Figure 7a: Start – Preindustrial time

Figure 7b: 1950s

Figure 7c: 1960s

Figure 7d: 1990s

Figure 7e: late 2000

Scientific Debate on the Planetary Limits

Boundaries of this global nature is bound to generate debate and controversy – especially when working in an area as loaded as climate change and natural resources. Healthy scientific debate is now beginning as scientists try to grapple with exactly what these boundaries are. One such critic is Dr. Simon L. Lewis, a researcher at the School of Geography, Faculty of Environment, University of Leeds.

In a brief column in the May 23, 2012 edition of Nature, Lewis argues:

 Simon L. Lewis

Victor Galaz, one of Rockstrom’s Planetary Boundaries collaborators replied in a brief  comment in the June 14, 2012 edition of Nature:

Other criticism

  • Setting boundaries for policymakers can allow potentially indefinite slow degradation, argues William Schlesinger from the Cary Institute of Ecosystem Studies in New York.
  • Phosphorus Cap of 11 – William Schlesinger says the cap on phosphorus is too lenient, saying “If we cross a threshold for phosphorus that leads to deep-oceanic anoxia, we risk a truly dire situation.”
  • The land-use boundary- less than 15 percent of the global ice-free land surface should be converted to cropland – Stephen Bass from the International Institute for Environment and Development in London suggests a limit on soil degradation or soil loss would be a more useful boundary because there is a big difference between intensive and more sustainable farming techniques. But Rockström et al. argue that land-use change can trigger rapid continental- scale changes. For example, IGBP chair Carlos Nobre and colleagues believe there is strong evidence that as more of the Amazon rainforest is turned over to cultivation and grazing, eventually a threshold will be crossed that transforms the basin to semi-arid savannah. This would likely have consequences for the Earth’s climate system. So, perhaps soil degradation should be an additional boundary.
  • Climate boundary at 350 parts per million CO2 – arguably the most contentious. Myles Allen from the University of Oxford argued in Nature, and at a recent IGBP/Royal Swedish Academy of Sciences Stockholm symposium, that this boundary misses the point. CO 2 should be viewed as a non-renewable resource. To avoid dangerous climate change we should stop emitting carbon to the atmosphere once we reach one trillion tonnes. Michael Raupach from the Global Carbon Project points out on page 24 that, if this is the limit, we have just passed
  • peak CO2.
  • Annual freshwater consumption boundary of 4000 cubic kilometres – could be too high
  • Biodiversity extinction rate of 10 species / million – more consensus is needed on extinction rates
  • Chemical pollution boundary may prove impossible to figure out – there are up to 100,000 chemicals on the global market

While researchers have been critical of the detail, the boundaries concept has had a positive reception, particularly regarding consequences for policy. If the planetary-boundaries concept proves sound – further analysis from a larger community is required – it throws down the gauntlet to policymakers. The paper suggests in no uncertain terms that governance systems are inadequate to address the scale of the problem, not just at a planetary level, but also at regional and local scales. This is why the planetary boundaries concept may prove so attractive: governments prefer dealing with boundaries than uncertainties.

(Source: International Geosphere Biosphere Programme)

Scientific Paper claims there are no Tipping Points

We conclude that the terrestrial biosphere is likely to respond heterogeneously in time and space to drivers, which implies that the pattern of change in any global aggregate ecosystem attribute will be relatively rate constant and cumulative, rather than exhibiting any identifiable tipping points at timescales shorter than geological time periods. From this, we infer that characterizing global biotic change with single global aggregates is misleading or inapt and that identifying critical points along a continuum of forcing might not be feasible.

- Brooks et. al

A Feb 2013 paper from professor Barry W. Brooks claims that there is no such thing as a global tipping point. The paper, Does the terrestrial biosphere have planetary tipping points?  reaches the conclusion that there is no grounding for the concept of global tipping points. Already, many climate denial websites have cited the paper as “debunking the concept of planetary boundaries and tipping points”.

From Brooks perspective, the only way such a massive shift could occur is if ecosystems around the world respond to human forcings in essentially identical ways. There would need to be “strong connections between continents that allow for rapid diffusion of impacts across the planet.” says Brooks but he further adds that this kind of connection is unlikely to exist because geological formations such as oceans and mountain ranges separate ecosystems from each other.

The researchers looked at four major drivers of terrestrial ecosystem change:

  1. climate change,
  2. land-use change,
  3. habitat fragmentation
  4. biodiversity loss

and concluded that truly global nonlinear responses won’t happen. Instead, global-scale transitions are likely to be smooth. Brooks arguments are not based on any new quantitative research but is, instead  a survey of existing research with a proposal for testable hypothesis to test the claim of global tipping points.

To many serious researchers involved in the field, however, Brooks arguments fall flat. A number of leading researchers of global tipping points and state shifts have read the paper and their initial reaction is that the  paper is one which may help to more clearly define the terminology and use of tipping point nomenclature within nonlinear systems theory, but it doesn’t alter the basic reality of the ecocidal trajectory human civilization is on.

Professor Tim Lenton, an expert in tipping points does not see much evidence of global tipping points but doesn’t rule them out yet either.  Citing  the melting permafrost tipping point as an example, Lenton agrees with the paper in that he doesn’t see how state change in Canada might be synchronized to a state change in Siberia. Instead, Lenton thinks it’s more likely that different parts of the Arctic are going to reach the thawing threshold at the same time just because they’re getting to the same kind of temperature. To Lenton, it is a technicality and a rather moot point whether multiple systems are tipping as one, or if a number of unconnected systems are individually tipping simultaneously; the results are disastrous regardless.

U.C. professor Tony Barnosky, author of an important paper published in Nature in 2012 entitled Approaching a state shift in Earth’s biosphere says “If there is plausibility to one of these tipping points, which I think there is, then it’s an even more urgent matter to act to slow all of these individual stressors down, because the outcomes could be more surprising and more disruptive to society, and happen faster than we have time to react…. I’d much rather err on the side of precaution then ignore the possibility of tipping points and then be unpleasantly surprised when they happen.”

One possible scenario that Lenton and James Hansen can envision is an Arctic Ocean with an ice-free summer may trigger large scale melting of permafrost.  Hansen doesn’t see how Greenland could survive if the Artic Ocean begins a cycle of ice free summers. Melting permafrost will be accompanied by significant methane outgassing which in turn increases temperatures in a positive feedback cycle which will accelerate melting further. In this way, different ecosystems can actually interact to trigger large scale localized change in each other in a global domino effect. The one thing they all share is a warming ocean of air.

 Bankrupting Nature – Denying our Planetary Boundaries

The Club of Room released an important book in 2012 entitled Bankrupting Nature. Authored by Johan Rockstrom of the Stockholm Resilience Centre and lead author of the concept of planetary boundaries and Swedish politician and environmental activist Anders Wijkman, this powerful book shows us that humanity is in deep denial about the magnitude of the global environmental challenges facing the world. Despite growing scientific consensus on major environmental threats as well as resource depletion, societies are largely continuing with business as usual, at best attempting to tinker at the margins of the problems.

Anders Wijkam and Johan Rockstrom on how we have disturbed the energy balance of the planet

Bankrupting Nature is a book which lays out a blue-print for a radically changed economic system that links economics with ecology, arguing that this is the only way to generate growth in the future.

“The challenges of sustainability cannot be met by simply tinkering with the current economic system”, say the authors. The authors take a fairly upbeat view on possible short-term measures to stem the overuse of resources – such as reforms on land use and the development of renewables – but say that this is not enough to solve long-term resource depletion.

We need a circular economy that decouples wealth and welfare from resource consumption, and assigns a value to natural capital, so the depreciation of the earth’s resources and the loss of biodiversity are taken into account in national budgets.

Such an economic model should lead to a reform of the tax system: raising taxes on resource use and reducing those on labour. It should be based on business models where revenue is earned through performance and high-quality service – extending product-life – while also creating more work opportunities. A key element of a circular economy is to design industrial systems that recycle and reuse materials wherever possible and phase-out fossil fuels. A pre-condition would be to introduce mandatory reporting by major companies, in particular bank and financial institutions, on how their activities affect the environment, in particular the risks associated with high-carbon investments.

The scientific evidence is overwhelming that, without taking measures like these, human pressure on the planet poses major risks for the future prosperity of society as we know it, say the authors. We have already overstepped the ‘planetary boundaries’, thus destabilising the earth’s ‘operating system’, as evidenced by the recent spate of extreme weather events.

A recent review of the book in Nature says “Bankrupting Nature deserves our attention…. The book’s arguments are familiar but rarely have they been gathered together in one place to clarify the links between politics, economics and ecology”.

(Source: Anders Wijkman)

The 12 principle messages from Bankrupting Nature are:


Oxfam Paper confirms Mythology of Development vs Environment: If we Uplift the Poor, we will NOT Cross Planetary Boundaries

It is the stick with which the greens are beaten daily: if we spend money on protecting the environment, the poor will starve, or freeze to death, or will go without shoes and education. Most of those making this argument do so disingenuously: they support the conservative or libertarian politics that keep the poor in their place and ensure that the 1% harvest the lion’s share of the world’s resources.

Journalists writing for the corporate press, with views somewhere to the right of Vlad the Impaler and no prior record of concern for the poor, suddenly become their doughty champions when the interests of the proprietorial class are threatened. If tar sands cannot be extracted in Canada, they maintain, subsistence farmers in Africa will starve. If Tesco’s profits are threatened, children will die of malaria. When it is done cleverly, promoting the interests of corporations and the ultra-rich under the guise of concern for the poor is an effective public relations strategy.

- George Monbiot

Since the establishment of planetary boundaries, right wing groups and Libertarians have predictably argued against them, making the false claim  that they cannot support environmentalism because it would mean hampering social development.  A Feb 2012 Oxfam paper  proposes a new model called the doughnut model of development which refutes these claims as it incorporates the planetary boundaries model within a framework for social development that stays within their ecological limits.  Some examples of some of the findings from the paper are:

  • Providing enough food for the 13% of the world’s people who suffer from hunger means raising world supplies by just 1%.
  • Providing electricity to the 19% of people who currently have none would raise global carbon emissions by just 1%
  • Bringing everyone above the global absolute poverty line ($1.25 a day) would need just 0.2% of global income

The report further points out:

  • half the world’s carbon emissions are produced by just 11% of its people
  • 50% of the world’s people produce just 11% of its emissions
  • Animal feed used in the EU alone, which accounts for just 7% of the world’s people, uses up 33% of the planet’s sustainable nitrogen budget
  • Excessive resource use by the world’s richest 10% of consumers crowds out much-needed resource use by billions of other people
  • It is not the needs of the poor that threaten the biosphere, but the demands of the rich
  • crossing any of the nine planetary boundaries can severely undermine human development, first and foremost for women and men living in poverty
  • social justice is impossible without far greater global equity in the use of natural resources, with the greatest reductions coming from the world’s richest consumers

Politically, the easy way to tackle poverty is to try to raise the living standards of the poor while doing nothing to curb the consumption of the rich. This is the strategy almost all governments follow. However, it is a formula for environmental disaster, which only spreads poverty and deprivation.

Pushing the Boundaries: The Earth System in the Anthropocene

The following diagrams are excerpted from the report Pushing the Boundaries: The Earth System in the Anthropocene  for the Schumacher Institute for Sustainable Systems, Spring 2012 authored by Steven Robert Harris.

This report uses the recently developed concept of planetary boundaries to frame an overview of the current status of the Earth system as revealed by a number of large-scale scientific studies carried out over the last decade. Findings from the studies converge on a common conclusion: that human activities are now the dominant force driving major planetary developments such as climate change, ocean acidification and biodiversity depletion – and that these changes offer serious challenges to further human development. It seems that the whole Earth system has irrevocably entered the Anthropocene, a new geological epoch characterised by large-scale human impacts on the Earth system. Although there is widespread agreement that the Anthropocene began around 1800 with the advent of the thermo-industrial revolution, some researchers argue that humans became the main drivers of global climate change as early as 8-10,000 years ago, with the rise of agriculture. Wherever we place the beginning of the Anthropocene, historical studies across multiple disciplines now strongly suggest that since the last Ice Age most, if not all human cultures have developed at considerable cost to their supporting ecosystems, both locally and globally. The challenge for the current generation is to use our newly gained and rapidly improving scientific understanding of the functioning and dynamics of the Earth system – and humanity’s place within that system – to guide future human development along more equitable and ecologically sustainable pathways.