Das Projekt "High-End cLimate Impacts and eXtremes (HELIX-RD3) - WP10: Risk Management of Tipping Points" wird vom Umweltbundesamt gefördert und von Potsdam-Institut für Klimafolgenforschung e.V. durchgeführt. With the target of limiting global warming to 2°C increasingly difficult to achieve, policymakers, businesses and other decision-makers need to plan to adapt to changes in climate under higher levels of global warming. This requires coherent information on the future climate conditions, and the consequences of different adaptation actions. International negotiations on limiting global warming also require clear information on the consequences of different levels of climate change. While a vast array of projections, scenarios and estimates of future climate change and its impacts already exists, much is conflicting, unclear, of unknown levels of certainty and difficult to use to inform decisions. HELIX addresses this by providing a clear, coherent, internally-consistent view of a manageable number of 'future worlds' under higher levels of global warming reached under a range of circumstances, supported by advice on which aspects are more certain and which less certain. This will be delivered through groundbreaking scientific research across a range of physical, natural and social science disciplines, in close engagement with experienced users of climate change information in order to ensure appropriate focus, clarity and utility. Since international climate policy often frames climate change in terms of levels of global warming relative to pre-industrial state, our research will focus on addressing the questions 'What do 4°C and 6°C worlds look like compared to 2°C?' and 'What are the consequences of different adaptation choices?' Our core product will a set of eight coherent global scenarios of the natural and human world at these levels of warming achieved at different rates and with different pathways of adaptation by society. A second product will provide more detailed information in three focus regions; Europe, East Africa and the north-eastern Indian sub-continent. This will all be supported by a comprehensive analysis of confidence and uncertainty. PIK participates in WP10 'Risk Management of Tipping Points', exploring impacts of passing key climate tipping points, including potential feedback onto the wider economy and identifying tipping point adaptation options and limits to adaptation.
Das Projekt "Fire - climate feedback in the Earth System" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Meteorologie durchgeführt. Fires are an integral Earth System process, which is controlled by climate and at the same time impacts climate in multiple ways. As such fires form a feedback mechanism in the Earth System, which might amplify or dampen climate change. At present this feedback is not well understood nor is it represented in current generation Earth System models used to study climate change. The proposed research project aims to quantify the fire-climate feedback by incorporating the integral role of fires into an Earth System Model (ESM). Together with improved observational based process understanding the project will analyze how fires have developed throughout Earth history and how single fire driven processes contribute to the overall fire climate impact. A mechanistic terrestrial biosphere fire model will be implemented into the ESM and fire mediated climate relevant processes will be coupled between the different ESM compartments, including the atmosphere, ocean and cryosphere. This cross-disciplinary research project will foster the understanding of past climate change and will hopefully allow a better assessment of human induced future climate change by further constraining the climate sensitivity of the Earth system.
Das Projekt "Sub project: What ends an Interglacial? Feedbacks between tropical rainfall, Atlantic climate and ice sheets during the Last Interglacial (EndLIG)" wird vom Umweltbundesamt gefördert und von Universität Bremen, Fachbereich 5 Geowissenschaften, Fachgebiet Geosystem Modellierung durchgeführt. When and how the present interglacial will end remains an open question. With a relatively wellknown climate, the Last Interglacial (LIG) and following glacial inception can shed some light on the climate mechanisms leading to the establishment of a new ice age. Two key questions arise from the chain of climate events known to end the LIG: (1) Did the interglacial North Atlantic warmth, prolonged by an active thermohaline circulation (THC), favor or delay the growth of northern ice sheets? (2) Did reorganizations in South American moisture contribute to prolong the North Atlantic warmth by maintaining a salty North Atlantic and active THC at the end of the LIG, as suggested by tropical moisture feedbacks observed during glacial times? To address these questions, we propose here to combine new paleoclimate reconstructions with climate model experiments. First, we will reconstruct the detailed evolution of the South American rainbelt during the last glacial inception, by applying complementary proxies on a transect of marine sediment cores. Second, we will assess the impact of tropical hydrologic changes on tropical Atlantic sea surface salinities (SSS) and the Atlantic THC, by comparing tropical Atlantic SSS and deep-water properties with model sensitivity experiments where we will vary the tropical freshwater forcing. Finally, we will perform a transient climate/ice-sheet model run for the last glacial inception, and a sensitivity study, in which different ocean heat fluxes will be imposed to investigate the effect of prolonged North Atlantic warmth on ice sheet growth.
Das Projekt "Models and observations to test climate feedbacks" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Meteorologie durchgeführt. The project will assess the ability of state-of-the-art European models used to project future climates to reproduce a climate different from today through comparisons with benchmark palaeoenvironrnental data sets. We will analyse mean climate, interannual to multi-decadal climate vability, and the relationship between them. The European models include dynamic representations of the atmosphere, ocean, sea-ice and land-surface, and interactions among these components. The project will use different configurations of the coupled models to study feedbacks between ocean circulation, vegetation and the atmosphere. We focus on 6000 years before present (6 ka) and 21 ka, which represent different states of the climate system and the ocean circulation. In addition to using global syntheses of palaoenvironmental data to evaluate the simulated mean climate, we will use high-resolution terrestrial and marine records to evaluate the simulated changes in high-frequency variability.
Das Projekt "Teilprojekt 1, (Modul B)" wird vom Umweltbundesamt gefördert und von Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung - Institut AWI - Forschungsstelle Potsdam durchgeführt. Im Projekt FAST-O3 wird ein großes Defizit bisher existierender genereller Zirkulationsmodelle mit gekoppeltem Ozean (AOGCMs), wie sie für die Vorhersagen der IPCC-Studien oder zeitaufwändige Ensemble-Läufe genutzt werden, behoben: Aus Rechenzeitgründen enthalten diese Modelle keine interaktive Ozonschicht und sind nicht in der Lage, das antarktische Ozonloch und dessen Rückkopplung auf das Klima zu simulieren. Wir werden ein semi-empirisches, sehr schnelles stratosphärisches Chemie- und Transportschema entwickeln, welches es erlauben wird, eine interaktive Ozonschicht in existierende AOGCMs einzubinden. Dies wird zu einer erheblichen Verbesserung des Vorhersage-Skills des Gesamtsystems führen, da Prozesse in der Ozonschicht bedeutende Rückkopplungseffekte auf das gesamte Klimasystem haben. Ein bereits vorhandener und am AWI entwickelter Prototyp namens SWIFT, der bereits für polare Regionen geeignet ist, wird für extrapolare Regionen und für den Einsatz als Modul in einem generellen Zirkulationsmodell oder die Kopplung zu so einem Modell erweitert und weiterentwickelt. Dies umfasst: 1. Weiterentwicklung des Modells und Einbau globaler Ozonchemie, 2. Einbau eines schnellen Advektionsschemas auf Basis des ATLAS-Modells, 3. Kopplung zum EMAC-Modell und Ensemble-Läufe, 4. Validation gegen volle Chemie-Läufe, 5. Einbindung in das MiKlip Modellsystem.
Das Projekt "How is the evolution of stratospheric ozone affected by climate change, and how strong is the feedback? (SHARP-OFC)" wird vom Umweltbundesamt gefördert und von Universität Bremen, Institut für Umweltphysik durchgeführt. One major goal of this project is to analyse updated observational trace gas data together with stateof- the art models (CTMs and CCMs) in order to obtain a better understanding of the interaction between ozone and climate change and the underlying dynamical and chemical processes. The extended satellite, balloon and aircraft observations combined with improved model calculations (CTM and CCM) are used to further reduce the uncertainties in the bromine budget, in particular the contribution from VSLS (very short lived substances) and to further elucidate on the role of iodine in the stratosphere. Furthermore detailed studies on the long-term evolution (trends and variability) of observed stratospheric trace gases with foci on profiles of O3, NO2 and aerosols retrieved from SCIAMACHY are proposed. Future evolution of stratospheric ozone will be investigated using updated EMAC CCM model runs, some of them in combination with an interactive atmosphere-ocean feedback. In addition to issues on the climate feedback on future ozone, particular emphasis will be given to the increasing role of N2O and GHG emissions.
Das Projekt "Teilprojekt 2: Modellierung des Permafrostkohlenstoffs mithilfe des Modells CLIMBER-2" wird vom Umweltbundesamt gefördert und von Potsdam-Institut für Klimafolgenforschung e.V. durchgeführt. The overarching goal of the project is to understand and quantify mechanisms and feedbacks of the terrestrial carbon cycle and climate during glacial cycles. 1. Harmonization of vegetation dynamics models across ESMs: The goal is to evaluate and to harmonize the dynamic vegetation model components for the transient deglaciation simulations. How well changes in vegetation cover simulated by the models are staying against observations recorded in pollen archives? 2. Simulation of changes in permafrost carbon: It is known that total amount of carbon in living terrestrial biomass during glacial time was substantially reduced and hence opposed glacial CO2 drawdown. The role of soil carbon is not well understood but it is likely that a large amount of carbon during glacial time was accumulated in the permafrost and beneath the ice sheets. Here we want to study the role of these extremely slow carbon pools during glacial cycle. 3. Simulation of changes in weathering fluxes: The third scientific goal of the proposed project is to test the hypothesis that the altered matter fluxes from chemical erosion during large-scale glaciations significantly altered alkalinity and P fluxes since glacial times. To understand the variation of these fluxes, it is necessary to quantify chemical erosion from the areas where glacial extent variations impact chemical erosion: the area below the ice sheets, the fresh glacial sediment, and the exposed shelf. The main tasks for the postdoc are (1) to develop a model for permafrost carbon storage within CLIMBER-2 and (2) quantification of the terrestrial mechanisms in transient simulation through the complete glacial cycle. A particular focus is on analysis of the development of permafrost carbon during glacial inception and deglaciation. The main scientific challenge to be met by the Postdoc is to disentangle roles of terrestrial and marine biogeochemical mechanisms in period of abrupt climate and CO2 changes to be done jointly with WP 2.1. Successful fulfilment of all these tasks requires experienced and competent researcher to be employed. This 50%-postdoc position is complementary to the 50%-postdoc position requested for PIK in PalMod 2.1.
Das Projekt "Teilprojekt 7: Transiente glaziale Simulationen mithilfe des Modells CLIMBER-2 mit einem verbesserten 3-D-Ozean-Kohlenstoffkreislauf" wird vom Umweltbundesamt gefördert und von Potsdam-Institut für Klimafolgenforschung e.V. durchgeführt. This project aims at a more detailed understanding of the marine carbon cycle during glacial-interglacial changes. The ultimate goal is to explain the marine contributions to the observed glacial low atmospheric CO2 of about 190 ppmv measured in ice cores and its rise over time towards its pre-industrial value of 278 ppmv and to understand its forcing of and feedback to natural climate change during the last deglaciation. The main task of the PostDoc is to implement existing marine carbon cycle components into the new CLIMBER-2 version with the 3-D ocean and update the model by including additional processes and tracers, such as Fe and Si concentrations and hypothesis on some new processes. Further major improvements of CLIMBER (performed in PalMod WP 2.2) will include the addition of permafrost and peat pools in terrestrial carbon cycle. The PostDoc is intended to spend 50% of his/her time on PalMOd 2.1 (marine carbon cycle) and 50% on PalMod 2.2 (terrestrial carbon cycle).
Das Projekt "Sub project: Cyclic ice sheet collapses, meltwater events and proxies for a reduction of bottom water circulation along the West Antarctic Peninsula margin" wird vom Umweltbundesamt gefördert und von Universität Bremen, Zentrum für marine Umweltwissenschaften durchgeführt. The melting of continental ice sheets during deglaciations provides freshwater to the oceans that affect the global sea level and the strength of the thermohaline circulation (THC). This is well documented in the Northern Hemisphere but less understood for the Southern Ocean. Recent climate models indicate that sea ice reduction, meltwater and deepwater formation in Antarctica is equally important for the meridional overturning circulation. Cores from drifts along the West Antarctic Peninsula offer the chance to study more than eighty deglaciation cycles with ice sheet collapses. During those collapses intriguing occurrences of iron diagenesis in conjunction with well-preserved diatom plume deposits suggest episodes of anaerobic sediment conditions and reduced bottom water dynamics. We propose to use U/Th as additional evidence for the suggested anoxic conditions. 34S-isotopes and diffusion reaction models will constrain the duration and vertical extend of anaerobic episodes in the sediment column. Those episodes documented from Sites of active Antarctic bottom water formation likely represent the peak in meltwater production and at the same time the onset of increased THC, initiating a gradual Antarctic cooling that preludes the next glaciation. Better constrains on Antarctic bottom water circulation will ultimately improve our understanding of South-North climate feedbacks.
Das Projekt "Simulation and understanding of the major transitions in Quaternary climate dynamics (Q-DYNAMICS)" wird vom Umweltbundesamt gefördert und von Potsdam-Institut für Klimafolgenforschung e.V. durchgeführt. Understanding climate variability during the past 3 million years remains a scientific challenge. Paleoclimate records provide rich information about Quaternary climate cycles and reveal several pronounced changes in the regimes of climate variability. The mechanisms of these transitions are still not properly understood. Although a number of hypotheses have been proposed, testing of these hypotheses is hampered by the lack of an appropriate modeling tool. We propose to study the nature of these regime changes with a new Earth system model of intermediate complexity, which will be developed based on the existent and comprehensively tested model CLIMBER-2. Although the new model will have higher spatial resolution than CLIMBER-2, it will be still be computationally efficient to enable us to perform experiments at million-year time scales. Using an ensemble of model realizations obtained by a perturbed physics approach, we will perform a set of transient experiments to test existing hypotheses concerning the mechanisms of the Pliocene-Pleistocene Transition (ca. 2.7 Ma), Mid-Pliocene Revolution (between 1.2 and 0.8 Ma) and Mid-Brunhes Event (ca. 430 ka). The final goal is to reproduce these transitions using orbital forcing as the only prescribed forcing while atmospheric composition, evolution of terrestrial sediment layer and aeloian dust transport and deposition will be simulated by the model. With this we expect to make a substantial progress in understanding the non-linear dynamics of the principal components of the Earth system, such as ice sheets, ocean circulation and carbon cycle, as well as the role of various climate feedbacks. We will also assess a possibility of using the available plaeoclimate information about climate variability over the past 3 million years to provide better constraints on Earth system sensitivity and stability to external forcings and internal perturbations.
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