Die Biosphäre im 21. Jahrhundert - ein System zwischen menschlicher Nutzung und Klimawandel

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1 Die Biosphäre im 21. Jahrhundert - ein System zwischen menschlicher Nutzung und Klimawandel Ursula Heyder heyder@pik-potsdam.de Potsdam Institut für Klimafolgenforschung

2 Erdsystemstabilität Kipp-Elemente im Erdsystem Lenton et al. 2008

3 Ernährungssicherheit Human appropriation of net primary production (HANPP), Haberl et al. (2007)

4 Biodiversität / Naturschutz IUCN, 2008 Emre Turak

5 Schlüsselfragen Verständnis Wie reagiert die Biosphäre auf schnelle Klimaänderungen? Welche Rolle spielen andere menschliche Einflüsse? Prioritäten Welche Biosphäre wollen wir? Management Wie können Ökosysteme geschützt oder gesteuert werden, um gesetzte Ziele zu erreichen?

6 Belastungen der Biosphäre Erforschung von Biosphäre im globalen Wandel

7 Biosphäre unter Druck Landnutzung Stickstoffeinsatz Bevölkerungswachstum Energieverbrauch Biosphäre Klimawandel

8 Exponentielles Wachstum Physical limits Carrying Capacity The carrying capacity is the population size of a species that an environment can sustain in the long term, given the food, habitat, water and other necessities available in the environment

9 Tragfähigkeit der Erde? Technologische Entwicklung Erhöhung landwirtschaftl. Effizienz Klimawandel Bodendegradation Abbau nichterneuerbarer Aquifere Schadstoffe

10 Menschlicher Einfluss auf Ökosysteme Continent Area Undisturbed Partially disturbed Human dominated [km 2 ] [%] [%] [%] Europe ,6 19,6 64,9 Asia ,2 29,1 28,7 Africa ,9 35,8 15,4 N-America ,3 18,8 24,9 S-Amerika ,5 22,5 15,1 Australasia ,3 25,8 12,0 Antarctica ,0 0,0 0,0 World total (a) ,0 36,7 36,3 (a) Excluding rock/ice/barren land Welt im Wandel: Erhaltung und nachhaltige Nutzung der Biosphäre / WBGU / Jahresgutachten Berlin; Heidelberg: Springer, 2000, S.20

11 Globale Szenarien zum Klimawandel Substantial changes in structure and functioning of terrestrial ecosystems are very likely to occur with a global warming of more than 2 to 3 C above pre-industrial levels (high confidence). IPCC 2007, WG2

12 CO2-Emissionen steigen immer schneller Raupach et al. 2007

13 Niederschlags-Projektionen IPCC, 2008

14 Spiegel Online, 2005 More intense and longer droughts have been observed over wider areas since the 1970s, particularly in the tropics and subtropics. (IPCC 2007, WG1)

15 It is very likely that hot extremes, heat waves and heavy precipitation events will continue to become more frequent. (IPCC 2007, WG1)

16 Veränderte Feuer-Regimes

17 IPCC 2007 (WG2), beobachtete Klimafolgen More evidence from a wider range of species and communities in terrestrial ecosystems and substantial new evidence in marine and freshwater systems show that recent warming is strongly affecting natural biological systems (very high confidence).

18 The impacts of climate change can be strongly modified by non-climate factors. (IPCC 2007, WG 2)

19 During the course of this century the resilience of many ecosystems (their ability to adapt naturally) is likely to be exceeded by an unprecedented combination of change in climate, associated disturbances (e.g., flooding, drought, wildfire, insects, ocean acidification) and in other global IPCC, 2007 change drivers (especially land-use change, pollution and over-exploitation of resources), if greenhouse gas emissions and other changes continue at or above current rates (high confidence). IPCC, 2007

20 Systemstabilität Unstable Disturbances shift the system to a different type, which may take very long to recover e.g. coral reefs Resistant Ability to absorb disturbances e.g. many forest ecosystems (within limits!) Resilient Ability to recover after disturbances without change of the whole system e.g. Fire dominated ecosystems Field of attraction

21 Menschlicher Einfluss und menschliche Ansprüche an die Biosphäre werden im 21. Jhdt zunehmen: Nahrung, Bioenergie, Raum Klimawandel verstärkt die Probleme in vielen Regionen und belastet natürliche Ökosysteme zusätzlich Können Ökosysteme sich anpassen? Welche Regionen sind am stärksten gefährdet?

22 Methoden der Klimafolgenforschung Experimente in kontrollierter Umgebung Beobachtungen / Paläostudien / Gradienten in Umweltbedingungen Modelle

23 Skalen der Klimafolgenforschung Level of Detail Physiology Community Species Continent Region Global Spatial resolution / Generality

24 SRES CO2 equivalents Photosynthesis Plant Photosynthesis Carbondioxide + Water + Light Glucose + Oxygen Leaf stomata open to let Carbondioxide into the leaf, but the plant loses water at the same time Carbondioxide concentrations will at least double until 2100 Enhanced plant growth especially in dry areas

25 Labor-Experimente: Photosynthese Lolium perenne L. (Sasaki et al. 2001) Photosynthese hängt von Temperatur und CO2 ab

26 FACE Free Air CO2-Enrichment Intakte Ökosysteme Mikroklima wird nicht beeinflusst Pflanzen können während ihres ganzen Lebenszyklus untersucht werden

27 FACE-Ergebnisse Hickler et al. 2008, Norby et al. 2005, 550 ppmv CO2

28 Biodiversitäts-Experimente in Wiesen Zeitliche Ökosystemstabilität , Tilman et al., 2006

29 Biosphere 2 Very large controlled environment artificial world where eight humans lived for two years, sealed off from Earth, in a privately funded self-sufficiency experiment in the early 1990s. The structure contains recreations of Earth's savanna, desert, ocean and tropical rainforest wilderness. Ocean with coral reef Today used for global warming experiments

30 Biosphere 2

31 Paläostudien: historische Ökosystemveränderungen Ende Eiszeit J. Pollendiagramm

32 Lebensraumfragmentierung erschwert Wanderung von Arten

33 Klima-Gradienten Holridge Diagram of Biogeography (1947)

34 Beobachtungen von Klimafolgen Verschiebung der Baum-/Waldgrenze Wanderung von Arten Verhaltensänderungen z.b. Parmesan et al. 2006

35 Modellierung Ein Modell ist eine vereinfachte Beschreibung der Realität. Wissenschaftliche Modelle versuchen, die wesentlichen Parameter eines Phänomens zu erfassen und zur Vorhersage des Systems zu nutzen.

36 We do not believe that available data and theories will ever permit accurate predictions of what will happen to the world over the coming century. But we do believe that current knowledge permits us to rule out a range of futures as unrealistic Meadows et al. 2004, Limits to Growth: The 30-Year Update

37 Modellierung Extrapolation to unobserved conditions Deeper Understanding of processes, complex systems, nonlinear system behaviour Provides a mechanism to test a set of complex hypotheses Mind Games : What would happen, if? Trying out many different management scenarios Trying out extreme conditions Reducing Uncertainty in ecosystem responses Large scale / global impact assessment possible

38 Modelling process Scientific Question Information about the system / Understanding key processes Definition of system boundaries Conceptual model Detailed predictive Modelling Model Validation

39 Some definitions Model: generalised and simplified description of reality, Abstraction of reality Variable: changes value during a model run Parameter: constant value throughout a model run, but may change between runs State of a model: values of all model variables at one point in time Simulation: development of model state over time

40 Positive Rückkopplung: Zersetzung Temperatur beschleunigt CO2

41 Vegetation / climate feedbacks in the boreal zone Conceptual Model Temperature limited system + - Warming Carbon fixed + Vegetation Cover Transpiration + Absorption of solar radiation - + Clouds

42 Dynamic Global Vegetation Models combine biogeography, biogeochemistry, plant physiology, dynamic vegetation and crop models First global models, which are able to simulate ecosystems away from equilibrium important under high rates of climate change! Plants are represented as plant functional types (PFTs) instead of species Examples: IBIS, ORCHIDEE, TRIFFID, LPJmL/LPJ-GUESS

43 LPJmL LPJ with managed lands Input data: CO 2, Climate, Soil, land use Potential natural vegetation Irrigated + nonirrigated pasture Irrigated + non-irrigated croplands Bondeau et al. 2007, Modelling the role of agriculture for the 20 th century global terrestrial carbon balance

44 Predicted vegetation zone shifts IPCC, 2007

45 Hadley centre climate model projections and a constant, preindustrial CO2 concentration Response of terrestrial ecosystems to CO2 and climate change Cramer et al Changing CO 2 and constant, preindustrial climate Changes in both, climate and CO 2

46 Example: Amazonia (LPJ) n = tree cover Precipitation [mm/a] Sankaran et al. 2005, African Savannas Mean annual precipitation explains ~ 50% of tree cover variance (in LPJ) precipitation threshold depends on CO2- concentration Critical precipitation threshold 600 mm / year 500 mm / year (elevated CO2)

47 rel. changes in crop & pasture yield UKMO-HadCM3 Constant CO >100 to to to to to % ( vs ) Dynamic CO2 UKMO-HadCM3 Crop UKMO-HadCM3 Crop UKMO-HadCM3 ECHAM5/MPI Pasture ECHAM5/MPI ECHAM5/MPI ECHAM5/MPI Pasture Popp (2008), in prep.

48 Bioenergy Beringer (2009, in prep)

49 Landnutzungsmodellierung (MAgPIE) Lotze-Campen et al. (2008)

50 Integrated Assessment Tools

51 Smith et al. 2008