Planetary Boundaries

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Planetary Boundaries
Exploring the Safe Operating Space for Humanity
Prof. Johan Rockström Stockholm Resilience Centre
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A biosphere shaped by humanity
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Humanity in the Anthropocene
Steffen, W., et al. 2004
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Humanitys period of grace the last 10000
years
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Critical transitions or regime shifts
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Valuable Ecosystem Services Loss of
ecosystem services (Desirable)
(Undesirable)
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coral dominance clear water grassland
algal dominance turbid water shrub-bushla
nd
state shift
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• overfishing, coastal
• eutrophication
• phosphorous accum-
• ulation in soil and mud
• fire prevention

• disease,
• hurricane
• flooding, warming,
• overexploitation
• of predators
• good rains, continu-
• ous heavy grazing

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The Resilience of the Earth System
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Our precarious predicament
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Planetary Boundaries Exploring the safe
operating space for humanity in the Anthropocene
(Nature, 461 472 475, Sept 24 - 2009)
Johan Rockström, Will Steffen, Kevin Noone, Åsa
Persson, F. Stuart Chapin, Eric F. Lambin,
Timothy M. Lenton, Marten Scheffer, Carl Folke,
Hans Joachim Schellnhuber, Björn Nykvist, Cynthia
A. de Wit, Terry Hughes, Sander van der Leeuw,
Henning Rodhe, Sverker Sörlin, Peter K. Snyder,
Robert Costanza, Uno Svedin, Malin Falkenmark,
Louise Karlberg, Robert W. Corell, Victoria J.
Fabry, James Hansen, Brian Walker, Diana
Liverman, Katherine Richardson, Paul Crutzen,
Jonathan A. Foley
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PB concept rests on three branches of Scientific
inquiry

• Earth System and sustainability science
  (Understanding Earth System processes ICSU,
  IGBP, ESSP, IPCC, MEA, evolution of
  sustainability science)
• Scale of human action in relation to the capacity
  of the planet to sustain it (Kenneth Boulding
  Spaceship Earth, Herman Daly, Club of Rome,
  Ecological Economics reserach agenda, Ecological
  Footprint...)
• Shocks and Abrupt change in Social-Ecological
  systems from local to global scales
• (Resilience, GAIA, tipping elements,
  guardrails...)

Planetary Boundaries concept
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From Limits to growth Carrying
capacity Guardrails Tipping Elements To
Planetary Boundaries
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Two different types ofplanetary boundary
processes
2. No known global threshold effect
1. Critical continental to global threshold
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Climate Change
Ozone depletion
Atmospheric Aerosol Loading
Biogeochemical loading Global N P Cycles
Planetary Boundaries
Ocean acidification
Rate of Biodiversity Loss
Global Freshwater Use
Land System Change
Chemical Pollution
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Climate Change lt 350 ppm CO2 lt 1W m2 (350 500
ppm CO2 1-1.5 W m2)
Ozone depletion lt 5 of Pre-Industrial 290 DU (5
- 10)
Biogeochemical loading Global N P Cycles
Limit industrial fixation of N2 to 35 Tg N
yr-1(25 of natural fixation) (25-35) P lt 10
natural weathering inflow to Oceans (10 100)
Atmospheric Aerosol Loading To be determined
Planetary Boundaries
Ocean acidification Aragonite saturation ratio gt
80 above pre-industrial levels (gt 80 - gt 70 )
Global Freshwater Use lt4000 km3/yr (4000 6000
km3/yr)
Rate of Biodiversity Loss lt 10 E/MSY (lt 10 - lt
1000 E/MSY)
Land System Change 15 of land under
crops (15-20)
Chemical Pollution Plastics, Endocrine
Desruptors, Nuclear Waste Emitted globally To be
determined
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Rate of Biodiversity LossAvoid large scale
irreversible loss of functional diversity and
ecological resilience

• The current and projected rate of biodiversity
  loss constitutes the sixth major extinction event
  in the history of life on Earth the first to be
  driven by human activities on the planet
• Local and regional biodiversity changes can have
  pervasive effects on Earth System functioning
• Biodiversity plays a key role for functional
  diversity and thereby ecosystem resilience
• Humans have increased the rate of species
  extinction by 100-1,000 times the background
  rates that were typical over Earths history
• Average global extinction rate projected to
  increase another 10-fold, to 1,000-10,000 E/MSY
  during the current century
• Suggesting a safe planetary boundary (here placed
  at 10 E/MSY) of an extinction rate within an
  order of magnitude of the natural background rate

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Global Freshwater UseAvoid water induced
environmental change at regional scale

• Humans now alter global runoff flows, through
  withdrawals of blue water, and changes in green
  water flows, affecting water partitioning and
  moisture feedback
• Physical water scarcity when withdrawals exceed
  5000 6000 km3 yr-1
• Final availability of runoff determined by
  consumptive use of green and blue water flows
• Consumptive use of blue water an aggregate
  control variable with boundary set at lt 4000 km3
  yr-1

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Climate Changewhat is required to avoid the
crossing of critical thresholds that separate
qualitatively different climate system states

• We suggest boundary values of 350 ppm CO2 and 1 W
  m-2 above pre-industrial level

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Planetary Inter-connections
Peter Snyder et al. 2004
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Climate Change
Ozone depletion
?
Phosphorus flow
Latest data
Atmospheric aerosol load
?
?
90-00
?
Nitrogen flow
Ocean acidity
70-80
?
50-60
Biodiversity loss
Freshwater consumption
?
Pre- Ind.
Chemical pollution
Agricultural land use
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Conclusions

• In the Anthropocene Humanity is, for the first
  time, influencing hard-wired processes at the
  Earth System scale
• We define the Holocene as the desired stable
  state providing necessary environmental
  pre-conditions for human development
• We need a new approach to global sustainability
  and development. Scientific insights from
  research on resilience and complex systems, and
  Earth System Science, on the risks of human
  induced tipping points in a multitude of Earth
  system processes and sub-systems
• We propose that a Planetary Boundary framework
  may provide one step towards this necessary
  redefinition

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• The Planetary Boundaries analysis presented in
  Nature is a proof-of-concept analysis, with
  many of the proposed boundaries being first best
  guesses. Many uncertainties remain, and will
  continue to remain.
• What we suggest is a challenge to the Earth
  System Science community to advance further
  research on Earth system interactions and
  non-linear dynamics
• Large Knowledge gaps remain
• Understanding of threshold dynamics
• Boundary interactions and feedbacks
• Spatial variability and patchiness may require
  global and regional boundaries
• Allowed overshoot time unclear

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• No doubt, a Planetary Boundaries approach to
  sustainable development would have profound
  implications for governance and policy across
  scales. Large scientific challenges to address
  the human dimensions and governance implications
  of development within Planetary Boundaries
• Despite uncertainties on allowed overshoot before
  large discontinuities, we have enough evidence to
  act now. Time is running out on several of the
  Planetary Boundaries, and the momentum of driving
  forces tremendous. This is a first attempt to
  define the safe space for human development,
  which may prove critical in turbulent times
  ahead.

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Ozone depletionAvoiding the risk of large
impacts for humans and ecosystem from thinning of
extra-polar ozone layer

• Antarctic ozone depletion a classic example of an
  unexpected crossing of a threshold
• Our framing on extra-polar ozone layer depletion
• Identifying a threshold remains uncertain
• a less than 5 decrease in column ozone levels
  for any particular latitude

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Atmospheric Aerosol LoadingAvoid major influence
on climate system and human health at regional to
global scales

• Human activities have doubled the global
  concentration of most aerosols since the
  pre-industrial era
• Influence on the Earths radiative balance
• May have substantial implications on hydrological
  cycle and, e.g., Asian monsoon circulation
• Fine particle (PM2.5) air pollution
• Processes and mechanisms behind these
  correlations remain to be fully explained

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Ocean acidificationChallenge to marine
biodiversity and ability of oceans to function as
sink of CO2

• 0.1 pH units decline, 30 H increase, 100 x
  faster than pre-industrial
• Rising pH ? dissolution of Calcium Carbonate
  (Aragonite) shells of marine organisms (corals
  and other marine life)
• Globally surface aragonite saturation state is
  declining (?arag 3.44 to a current value of
  2.9)
• 2CO2 ? ?arag 2.29
• Global average above unity, still Southern Ocean
  and Arctic ocean projected to become corrosive to
  aragonite by 2030-2060
• Deleterious effects on marine organisms start
  well above Aragonite unity.
• Proposed boundar gt 80 pre-industrial ?arag
  2.75

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Chemical PollutionSteer away from irreversible
impacts on living organisms

• Global, ubiquitous impact on the physiological
  development and demography of humans and other
  organisms with ultimate impacts on ecosystem
  functioning and structure
• By acting as a slow variable that affects other
  planetary boundaries (e.g., rate of biodiversity
  loss)
• 2 complementary approaches amounts of persistent
  pollutants with global distribution (e.g.,
  mercury) Effects of chemical pollution on living
  organisms
• Difficult to find an appropriate aggregate
  control variable. Close interactions with Aerosol
  loading may require sub-boundaries based on
  sub-impacts/categories of chemicals

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Land System ChangeAvoid unsustainable land
system change predominantly from intensive
agricultural use

• Contributes to global environmental change with
  the risk of undermining human well-being and long
  term sustainability
• Threat to biodiversity and undermining of
  regulatory capacity of ecosystems
• Complex global aggregate where the spatial
  distribution and intensity of land system change
  is critically important
• Concentrate agricultural land use to most
  productive land.
• No more than 15 of the global ice-free land
  surface should be converted to cropland

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Biogeochemical flows Human interference with
global N cycle

• Local to regional scale interference with N and P
  flows has pushed aquatic and marine systems
  across thresholds generating abrupt non-linear
  change
• Human modification of the nitrogen cycle is now
  profound (converting more N2 from the atmosphere
  into reactive forms than all of the Earths
  terrestrial processes combined)
• N and P slow variables eroding resilience of
  important sub-systems of the Earth system
• First guess of boundary level return to 25 of
  the current human fixation of N2 from the
  atmosphere

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Biogeochemical flows Human interference with
global P cycle

• The crossing of a critical threshold of P inflow
  to the oceans could explain global-scale ocean
  anoxic events (OAE), and past mass extinctions of
  marine life
• A boundary level should be set that (with current
  knowledge) allows humanity to safely steer away
  from the risk of triggering an OAE even over
  longer time horizons (gt 1,000 yrs)
• May require that anthropogenic P inflow to the
  ocean is not allowed to exceed a human induced
  level of 10 times the natural background rate of
  1 Mt P yr-1. This is higher than the proposed
  trigger rate of past OAEs
• There are very large uncertainties in these
  analyses, due to the complex interactions between
  oxic-anoxic states
• bi-stable oxic and anoxic conditions believed to
  be induced by positive feedbacks between anoxia,
  phosphorus recycling from sediments and marine
  productivity
• Past OAEs could have been induced by P inflow to
  the oceans exceeding 20 of the natural
  background weathering rate
• The increase of reactive P to the oceans from
  human activities has been estimated (year 2000)
  at 9 Mt yr-1
• 10-fold increase of P inflow to the oceans (i.e.,
  slightly higher than the current level), if
  sustained for 1,000 years, would raise the anoxic
  fraction to critical levels
• Current estimates of available phosphate rock
  reserves (up to 20 Gt of P) suggest that such an
  input could not be sustained for more than 1000
  years.