Die Biosphäre im 21. Jahrhundert - ein System zwischen menschlicher Nutzung und Klimawandel Ursula Heyder heyder@pik-potsdam.de Potsdam Institut für Klimafolgenforschung
Erdsystemstabilität Kipp-Elemente im Erdsystem Lenton et al. 2008
Ernährungssicherheit Human appropriation of net primary production (HANPP), Haberl et al. (2007)
Biodiversität / Naturschutz IUCN, 2008 Emre Turak
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?
Belastungen der Biosphäre Erforschung von Biosphäre im globalen Wandel
Biosphäre unter Druck Landnutzung Stickstoffeinsatz Bevölkerungswachstum Energieverbrauch Biosphäre Klimawandel
Exponentielles Wachstum Physical limits Carrying Capacity 1 2 4 8 16 32 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
Tragfähigkeit der Erde? Technologische Entwicklung Erhöhung landwirtschaftl. Effizienz Klimawandel Bodendegradation Abbau nichterneuerbarer Aquifere Schadstoffe
Menschlicher Einfluss auf Ökosysteme Continent Area Undisturbed Partially disturbed Human dominated [km 2 ] [%] [%] [%] Europe 5.759.321 15,6 19,6 64,9 Asia 53.311.557 42,2 29,1 28,7 Africa 33.985.316 48,9 35,8 15,4 N-America 26.179.907 56,3 18,8 24,9 S-Amerika 20.120.346 62,5 22,5 15,1 Australasia 9.487.262 62,3 25,8 12,0 Antarctica 13.208.983 100,0 0,0 0,0 World total (a) 134.904.471 27,0 36,7 36,3 (a) Excluding rock/ice/barren land Welt im Wandel: Erhaltung und nachhaltige Nutzung der Biosphäre / WBGU / Jahresgutachten 1999.- Berlin; Heidelberg: Springer, 2000, S.20
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
CO2-Emissionen steigen immer schneller Raupach et al. 2007
Niederschlags-Projektionen IPCC, 2008
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)
It is very likely that hot extremes, heat waves and heavy precipitation events will continue to become more frequent. (IPCC 2007, WG1)
Veränderte Feuer-Regimes
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).
The impacts of climate change can be strongly modified by non-climate factors. (IPCC 2007, WG 2)
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
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
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?
Methoden der Klimafolgenforschung Experimente in kontrollierter Umgebung Beobachtungen / Paläostudien / Gradienten in Umweltbedingungen Modelle
Skalen der Klimafolgenforschung Level of Detail Physiology Community Species Continent Region Global Spatial resolution / Generality
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
Labor-Experimente: Photosynthese Lolium perenne L. (Sasaki et al. 2001) Photosynthese hängt von Temperatur und CO2 ab
FACE Free Air CO2-Enrichment Intakte Ökosysteme Mikroklima wird nicht beeinflusst Pflanzen können während ihres ganzen Lebenszyklus untersucht werden
FACE-Ergebnisse Hickler et al. 2008, Norby et al. 2005, 550 ppmv CO2
Biodiversitäts-Experimente in Wiesen Zeitliche Ökosystemstabilität 1996-2005, Tilman et al., 2006
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 http://www.b2science.org/
Biosphere 2
Paläostudien: historische Ökosystemveränderungen Ende Eiszeit 11500 J. Pollendiagramm
Lebensraumfragmentierung erschwert Wanderung von Arten
Klima-Gradienten Holridge Diagram of Biogeography (1947)
Beobachtungen von Klimafolgen Verschiebung der Baum-/Waldgrenze Wanderung von Arten Verhaltensänderungen z.b. Parmesan et al. 2006
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.
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
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
Modelling process Scientific Question Information about the system / Understanding key processes Definition of system boundaries Conceptual model Detailed predictive Modelling Model Validation
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
Positive Rückkopplung: Zersetzung Temperatur beschleunigt CO2
Vegetation / climate feedbacks in the boreal zone Conceptual Model Temperature limited system + - Warming Carbon fixed + Vegetation Cover + + + Transpiration + Absorption of solar radiation - + Clouds
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
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
Predicted vegetation zone shifts IPCC, 2007
Hadley centre climate model projections and a constant, preindustrial CO2 concentration Response of terrestrial ecosystems to CO2 and climate change Cramer et al. 2001 Changing CO 2 and constant, preindustrial climate Changes in both, climate and CO 2
Example: Amazonia (LPJ) n = 1.731.060 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)
rel. changes in crop & pasture yield UKMO-HadCM3 Constant CO2-100 -50-10 10 50 >100 to to to to to -50-10 10 50 100 % (1992-2001 vs. 2022-2031) Dynamic CO2 UKMO-HadCM3 Crop UKMO-HadCM3 Crop UKMO-HadCM3 ECHAM5/MPI Pasture ECHAM5/MPI ECHAM5/MPI ECHAM5/MPI Pasture Popp (2008), in prep.
Bioenergy Beringer (2009, in prep)
Landnutzungsmodellierung (MAgPIE) Lotze-Campen et al. (2008)
Integrated Assessment Tools
Smith et al. 2008