Safe Operating Space For Humanity - HEB

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  • מבוסס על מאמר שהתפרסם ב - Nature
  • האנושות התפתחה בתקופה רגועה מבחינה אקלימית , שאיפשרה את צמיחת הציויליזציה
  • אבל במאה השנים האחרונות אנחנו מתערבים באופן בוטה במערכות האקולוגיות הגלובליות ומאיימים להוציא את המערכות משווי משקל ולעבור את יכולת האיזון הטבעית שלהן
  • דוגמא : פעילות אנושית נמרצת יכולה להעביר את המערכת ממצב יציב רצוי , למצב יציב אחר , אך שאינו רצוי
  • מציעים פרדיגמה חדשה
  • בגלל שלמערכות רבות קיים סף פעולה בטוח , שאינו לינארי , אנחנו דומים לאדם על סף תהום . איפשהו , אנחנו לא בדיוק יודעים איפה , נמצא הסף , שאם נעבור אותו נעבור ממצב יציב אחד רצוי , למצב אחר פחות רצוי . אבל בלי אפשרות לחזור
  • נמצאו 9 תחומים ( משום מה בטבלה יש 10...) תחומים מסומנים באדום נחצו

Transcript

  • 1. דר ' שחר דולב – 2010 חלק מהזכויות שמורות מסמך זה מוגן ברישיון של Creative Commons ייחוס-שימוש לא מסחרי, שיתוף זהה, 2.5, ישראל העמותה הישראלית לכלכלה בת - קיימא
  • 2. 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
  • 3. Humanity’s period of grace – the last 10000 years Aborigines arrive in Australia Beginning of agriculture Great European civilisations: Greek, Roman Source: GRIP ice core data (Greenland) and S. Oppenheimer, ”Out of Eden”, 2004 First migration of fully modern humans out of Africa Migrations of fully modern humans from South Asia to Europe
  • 4. Humanity in the Anthropocene Steffen, W., et al. 2004 Kaufman, Darrell S., et al. 2009. Recent Warming Reverses Long-Term Arctic Cooling. Science , September 4, 2009
  • 5. 1 2
    • overfishing, coastal
    • eutrophication
    • phosphorous accum-
    • ulation in soil and mud
    • fire prevention
    3 state shift
    • disease,
    • hurricane
    • flooding, warming,
    • overexploitation
    • of predators
    • good rains, continu-
    • ous heavy grazing
    coral dominance clear water grassland 4 algal dominance turbid water shrub-bushland Valuable Ecosystem Services Loss of ecosystem services (Desirable) (Undesirable)
  • 6. אך היציבות של המערכת הגלובלית
  • 7. אינה מובטחת לנו עוד
  • 8. From: ” Limits to growth” ” Carrying capacity” ” Guardrails” ” Tipping Elements” To: ” Planetary Boundaries”
  • 9. 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
  • 10. שני סוגים שונים של גבולות פעולה בטוחים מעבר רציף , אין גבול ברור ערך סף עם גבול ברור ( גם אם לא ידוע )
  • 11.  
  • 12. How to set a planetary boundary
    • Should constitute an unacceptable human-induced global environmental change.
    • The position of a planetary boundary is a function of the degree of risk the global community is willing to take, and/or for how long a boundary can be transgressed before a threshold is crossed.
    • The position is furthermore a function of the social and ecological resilience of the impacted societies (e.g., the ability of coastal communities to cope with sea level rise later this century if a climate change boundary is transgressed for too long).
    • Boundaries are identified for processes where the time needed to trigger an abrupt or irreversible change is within an “ethical time horizon” - a timeframe (i) short enough to influence today’s decisions while long enough to provide the basis for sustainability over many generations to come, and (ii) within which decisions taken can influence whether or not the estimated threshold is crossed.
  • 13. How to set PB criteria
    • A variable that is universally applicable for the sub-systems linked to the same boundary
    • Can function as a robust indicator of process change
    • Available and reliable data.
    • “… we have taken a pragmatic approach, sometimes choosing a parameter of ultimate ecological impact (e.g., rate of extinction of species for biodiversity loss), a proxy indicator (e.g., aragonite saturation state for ocean acidification), or a human driving force variable (e.g., P load in the oceans)”.
  • 14.  
  • 15. Climate Change Ocean acidification Ozone depletion Global Freshwater Use Rate of Biodiversity Loss Biogeochemical loading: Global N & P Cycles Atmospheric Aerosol Loading Land System Change Chemical Pollution Planetary Boundaries
  • 16. Climate Change < 350 ppm CO 2 < 1W m 2 (350 – 500 ppm CO 2 ; 1-1.5 W m 2 ) Ocean acidification Aragonite saturation ratio > 80 % above pre-industrial levels (> 80% - > 70 %) Ozone depletion < 5 % of Pre-Industrial 290 DU (5 - 10%) Global Freshwater Use <4000 km 3 /yr (4000 – 6000 km 3 /yr) Rate of Biodiversity Loss < 10 E/MSY (< 10 - < 1000 E/MSY) Biogeochemical loading: Global N & P Cycles Limit industrial fixation of N 2 to 35 Tg N yr -1 (25 % of natural fixation) (25%-35%) P < 10× natural weathering inflow to Oceans (10× – 100×) Atmospheric Aerosol Loading To be determined Land System Change ≤ 15 % of land under crops (15-20%) Chemical Pollution Plastics, Endocrine Desruptors, Nuclear Waste Emitted globally To be determined Planetary Boundaries
  • 17. Nitrogen flow Agricultural land use Ocean acidity Freshwater consumption Phosphorus flow Climate Change Atmospheric aerosol load Chemical pollution Ozone depletion Biodiversity loss ? ? 50-60 70-80 Latest data 90-00 Pre- Ind. ? ? ? ?
  • 18. מסקנות
    • לפעילות האנושית השפעה בקנה מידה גלובאלי
    • מציעים את ' גבולות הפעולה ' כמודל להכוונת מדיניות
    • ישנן ' נקודות מפנה ' רבות ( אי - ליניאריות )
    • קיימים פערי מידע גדולים
    • המידע הקיים מספיק כדי לקבוע מדיניות בנושאים החשובים
    • יש לפעול כעת !
  • 19. Rate of Biodiversity Loss Avoid 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 Earth’s 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
  • 20. Global Freshwater Use Avoid 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 km 3 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 < 4000 km 3 yr -1
  • 21. Climate Change what is required to avoid the crossing of critical thresholds that separate qualitatively different climate system states
    • We suggest boundary values of 350 ppm CO 2 and 1 W m -2 above pre-industrial level
  • 22. Ozone depletion Avoiding 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
  • 23. Atmospheric Aerosol Loading Avoid 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 Earth’s radiative balance
    • May have substantial implications on hydrological cycle and, e.g., Asian monsoon circulation
    • Fine particle (PM 2.5 ) air pollution
    • Processes and mechanisms behind these correlations remain to be fully explained
  • 24. Ocean acidification Challenge to marine biodiversity and ability of oceans to function as sink of CO 2
    • 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 ( Ω arag = 3.44 to a current value of 2.9)
    • 2×CO 2  Ω 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 > 80 % pre-industrial Ω arag = 2.75
  • 25. Chemical Pollution Steer 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
  • 26. Land System Change Avoid 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
  • 27. 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 N 2 from the atmosphere into reactive forms than all of the Earth’s 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 N 2 from the atmosphere
  • 28. 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 (> 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
  • 29. 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
  • 30.
    • 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
  • 31.
    • 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.