Paläoklima und Statistik


Aktuelle Projekte

  • Influence of large-scale climate variability on upwelling regimes off the Namibian coast: implications for past and future climates (funded by the German Ministry of Research within the coordinated project GENUS II 'Geochemistry and Ecology of the Namibian up-welling system', 2012-2014)
  • Climate Signals in Coastal Deposits (CLISCODE, funded within the Helmholtz Climate Initiative REKLIM 'Regional Climate Change', 2011-2015)
  • Precipitation in the past millennia in Europe -Extension back to Roman times (PRIME-II, funded by the DFG/ INTERDYNAMIK, 2012-2014)
  • Neue statistische Verfahren für amplitudenoptimierte Paläoklimarekonstruktionen aus zeitlich hochaufgelösten verrauschten Proxydaten (funded by the DFG, start October 2011)
  • The future climate of the Hamburg region under the assumption of a global temperature increase of two Kelvin (Hamburg 2K, funded by the federal government within the cluster of excellence CLISAP "Integrated Climate System Analysis and Prediction", 2010-2012)
  • Plußsee long-term data acquisition and analysis (PLUSDATA, funded by the federal government within the cluster of excellence CLISAP "Integrated Climate System Analysis and Prediction", 2009-2012)
  • Advanced modeling tool for scenarios of the Baltic Sea ECOsystem to SUPPORT decision making (ECOSUPPORT, funded by the EU-BMBF, 2009-2011)

Abgeschlossene Projekte

  • Precipitation in the past millennium in Europe (PRIME, funded by the DFG/ INTERDYNAMIK, 2010-2011)
  • European Climate of the last millennium (MILLENNIUM European Climate, funded by the EU, 2006-2011)
  • Regional climate modelling in southern South America for the Holocene and the 21st century (REGCLIMOSS, funded by the DFG, 2008-2009)
  • Relationships between Baltic Sea level variations and periods of rapid climate change in the Holocene as analogues for future changes (SINCOS-2, funded by the DFG, 2007-2009)
  • Frenquency and intensity of heavy precipitations in Mediterranean Spain within a modified climate (FIRME, funded by the CICYT, Spain)
  • Regional Atmospheric Models in the Simulation of Hydric Extremes (RAMSHES, funded by the CICYT, Spain)
  • An integrated research attempt on the unique Alpine instrumental and proxy data potential (<a href="">ALP-IMP</a>, funded by the BMBF/DEKLIM)
  • Transient simulation of the MIDdle HOLocene with a coupled atmosphere-ocean general circulation model (<a href="">MIDHOL</a>, funded by the BMBF/DEKLIM)
  • Climate Change at the end of the Eemian warm period (<a href="">EEM</a>, funded by the BMBF/DEKLIM)
  • Sinking coasts -Climate related sea-level variations in the Baltic Sea in the last few thousand years (<a href="">SINCOS</a>, funded by the DFG)
  • Simulations, Observations and Palaeodata -climate variability over the last 500 years (<a href="">SOAP</a>, funded by the EU)
  • Coral climate history of the subtropical North Atlantic - High resolution proxy records from Bermuda (<a href= "">CORCLIM</a>, funded by the BMBF/DEKLIM)
  • Reconstructing the European climate for the instrumental period by means of Data Assimilation through Upscaling and Nudging (<a href="">DATUN</a>, funded by the BMBF/DEKLIM)
  • Integrated Baltic Sea Environmental Study (<a href="">IBSEN</a>, funded by the BMBF/DEKLIM)
  • Natural climate variability in historical times (<a href="">KIHZ</a>, funded by the HGF)

Projects Details

Precipitation in the past millennia in Europe -Extension back to Roman times (PRIME-II, funded by the DFG/ INTERDYNAMIC)

PRIME-II will study the climate and the hydrological cycle in Europe and the Mediterranean area over the last 2,000 years, by combining information from low and high resolution terrestrial and marine proxy data. We will apply novel sophisticated statistical methods (Bayesian Hierarchical Modeling) and high-resolution climate modeling to reconstruct spatial fields of temperature and precipitation with associated uncertainties. Emphasis will be placed on the estimations of the amplitudes of natural climate variations at different temporal and spatial scales, ranging from regional to continental, and on the estimation of the influence of large-scale temperatures and external forcings on the European/Mediterranean hydrological regimes. We will also focus on the climate transitions between natural warm and cold / wet and dry periods from present back to Roman times and study the potential implications for past societies. The influence of external forcing factors such as orbital, solar and land use changes on the hydrological cycle will be disentangled by conducting a series of regional climate simulations with different forcing configurations for specific periods. These will also be used as a test bed to check the robustness of the statistical methods applied to reconstruct temperature and precipitation.

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The future climate of the Hamburg region under the assumption of a global temperature increase of two Kelvin (Hamburg 2K, funded by the federal government within the cluster of excellence CLISAP "Integrated Climate System Analysis and Prediction")

The European Union considers a limit of 2 degree increases of global mean annual temperature relative to the pre-industrial level a desirable target to avoid disruptive climate change. This target has also been adopted in the Copenhagen Accord in December 2009. This projects aims to estimate plausible climatic scenarios for the Hamburg region provided that the global mean annual temperature rise can be limited to 2 degrees within the 21st century. The project makes use of simulations with global climate models driven by scenarios of global greenhouse emissions that fulfil these target. The global simulations will be then downscaled at much higher spatial resolution using dynamical and statistical-dynamical downscaling techniques. The generated data set will comprise plausible regional climate scenarios covering the 21st century for the region around Hamburg with a spatial resolution of 2 km and time resolution of a few. Uncertainties originated in the use of different climate models will be considered when possible. These data sets will be used to estimate climate impacts for this region. In this project some of these impacts will be addressed, for instance changes in the North Sea circulation, extreme events and storm surges, but the data set will be available for a much wider range of future applications.

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Precipitation in the past millennium in Europe (PRIME, funded by the DFG/ INTERDYNAMIC)

Simulations of the effect of increasing anthropogenic climate forcing on future precipitation changes still display a large degree of uncertainty due to the lack of agreement among different climate models. This is especially true regarding possible changes in regional to continental hydrological extreme events at daily to seasonal timescales. To reduce these uncertainties, climate models will be tested by comparing simulations covering the past millennium with newly developed hydrologic reconstructions. Sophisticated statistical methods will be applied that assimilate both proxy (documentary, marine and terrestrial) and instrumental data to estimate the probability distribution of all parameters and the climate field through time on a regular spatial grid. The output will include an estimate of the full covariance structure of the hydrologic reconstructions, as well as diagnostic measures that indicate the utility of the different proxy time series for successful reconstruction. Thus, we aim at ascertaining whether global and regional climate simulations are consistent with new proxy-derived hydrological reconstructions, focusing on the spatial patterns of mean precipitation and on the frequency of extremes with associated uncertainties. Over the last millennium the external climate forcing has also undergone variations that may impinge their fingerprints on past hydrological changes, which can be compared to that simulated by climate models. Furthermore, the physical mechanisms leading to slow changes in mean European precipitation and in the frequency of extremes will be jointly analysed in the simulations and using reconstructions of the past large-scale atmospheric circulation. Thereby the fingerprint of the external forcing on the past hydrological changes can be identified in a more robust way. The expected outcome is an evaluation of the model skill in simulating future precipitation changes at continental and regional scale, identification of their deficiencies, and the detection of externally driven precipitation changes, reducing uncertainty for future climate predictions at seasonal and continental scale.

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Plußsee long-term data acquisition and analysis (PLUSDATA)

This project investigates the impact of interannual climatic variation and climate trend on plankton from Plußsee (North Germany), its diversity, occurrence, relative distribution and seasonal pattern. The projected anthropogenic climate change will likely not occur simply as a general rise of temperatures, but different trends in summer and winter, changes in wind strength, and surface net solar radiation are expected. We will identify the plankton signatures of climate variability and possibly long-term climate change through an exhaustive statistical analysis of climate data and this data set. Changes in plankton species diversity and their relative distribution can be due to differences in the degree of synchronous versus asynchronous responses to altering climate conditions. We will investigate whether differences in response can be detected between more r-strategic and more k-strategic plankton organisms and which effect this may have on the species diversity. Sensitive phases which could have an impact on the dynamic of the plankton succession at other times of the year will be investigated. Special attention will be paid to key-stone species, their appearance and disappearance and shifts in their relative abundance from year to year, and potential impacts on the food web structure and function, and biogeochemical dynamics in the lake.

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Advanced modeling tool for scenarios of the Baltic Sea ECOsystem to SUPPORT decision making (ECOSUPPORT)

This project addresses the urgent need for policy-relevant information on the combined future impacts of climate change and industrial & agricultural practices in the Baltic Sea (BS) catchment on the BS ecosystem.
The main aim is to provide a multi-model system tool to support decision makers. The tool is based upon scenarios from an existing state-of-the-art coupled atmosphere-ice-ocean-land surface model for the BS catchment area, marine physical-biogeochemical models of differing complexity, a food web model, statistical fish population models, economic calculations, and new data detailing climate effects on marine biota.

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Regional climate modelling in southern South America for the Holocene and the 21st century (REGCLIMOSS)

To support the estimations of future climate changes, climate models have to be tested in climates different from the present, comparing their output with proxy indicators of past climate. This project will analyse the possible causes and regional patterns of climate anomalies in southern South America by means of climate simulations with a high-resolution regional climate model for different periods of the Holocene and the 21st century. Proxy-based reconstruction of lake levels in south-eastern Patagonia indicate lower lake levels in the mid-Holocene (7000-4500 years ago) than during pre-industrial times, i.e. 1500-1850.
The regional simulations will address the role of precipitation and evaporation on lake levels, the moisture sources and the influence of external climate forcings, such as orbital parameters, solar variability and past and future impacts of atmospheric greenhouse gas concentrations. The project will also consider the relationships between the large-scale atmospheric circulation and local climate anomalies for past and future climates. Downscaling models between large-scale circulation and local hydrological variables will be calibrated using data from the instrumental period and from the regional climate simulations. This will allow to ascertain the stability of these statistical relationships and to apply them to longer transient simulations with a coarse resolution global climate model.

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Relationships between Baltic Sea level variations and periods of rapid climate change in the Holocene as analogues for future changes (CLIMLEVEL-2, funded by the DFG)

Variations of Baltic Sea level caused by rapid climate change within the last 8000 years will be estimated from joint analysis of long instrumental series, proxy data and simulations with global climate models. The overall goal is to find analogues for rapid sea-level changes in the past record that can be used to estimate changes in the next centuries.
1) The output of global climate simulations with the global climate model ECHO-G for the Holocene will be regionalized with standard statistical downscaling methods, which relate meteorological forcing (wind, temperature, rainfall) and sea-level variations yielding – together with the simulated steric sea-level variations- estimations of the past and future variations of sea-level for each individual sea-level gauge. These statistical models have been already designed and validated in the project SINCOS (Hünicke and Zorita, 2006). The simulations would allow identifying periods in the past where the climate forcing may have produced sea-level changes as rapid as those expected in this century.
2) The estimations of past climate-related sea-level changes will be validated by the analysis of tree-ring data from living oaks along the southern coast of the Baltic Sea. After calibration with the well-known climate during the recent century, the climatic signal can be expected to be also retrievable from the long-term oak chronology along the southern coast of the Baltic Sea composed of several absolutely dated as well as some floating parts over the last 8.000 years. Statistical models may be designed that describe the indirect relationship proxy data - climate forcing – sea level in a similar manner as meteorological data and sea-level data (project SINCOS). The statistical models can be then applied to the long time series of climatic proxy data, such as tree-ring series, to obtain a second and independent estimation of the climate-related sea-level variability. Particular attention will be posed on decadal cold periods in the past millennium, the Late Maunder Minimum around 1700 and specially the Dalton Minimum around 1800. In the latter period a direct analysis of climate change and instrumental sea-level change may be possible for a number of gauges. The analysis of tree-ring data will be performed and the results put at our disposal by a contract for scientific services (‘Werkvertrag’).

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European Climate of the last millennium (MILLENNIUM European Climate, funded by the EU)

Millennium will answer one of the most critical questions in climate research: does the magnitude and rate of 20th Century climate change exceed the natural variability of European climate over the last millennium? Existing climate reconstructions rely on inadequate data and uncerestimate variability. Improved GCM parameterization requires more accurate reconstructions and integrated modelling.We will supply high-resolution chronologies that capture the magnitude and rate of change and the magnitude and frequency of extreme events over the last 1000 years. Our multi-disciplinary team will use innovative and developing technologies to extract quantitative palaeoclimate information from documentary and natural archives, including trees, lakes, mires and ice cores. A multi-proxy approach provides seasonal palaeoclimate signals with quantified precision. Advances in dating allow us, for the first time, to place terrestrial and marine proxy records on the same timescale, allowing lead and lag relationships in ocean-atmosphere forcing to be captured. Annually banded seashells will be cross-dated like tree rings, and tephra-rich sediments used to construct a marine chronology independent of 14C dating. This can be used to reconstruct changes in ventilation linked directly to the strength of North Atlantic circulation.Millennial reconstructions of European climate, at a range of scales, will define whether recent climate change is unusual in the context of past variability. Millennium proxy-based reconstructions will be fused with a hierarchy of models, run over both millennium and century time scales using a purpose-built PC cluster and the huge resources of the distributed computing network. Integrated hind- and forecast modelling, (using HadCM3) will allow us to test whether current empirically reconstructed climate records based on regression methods underestimate climate sensitivity or if current GCM simulations give overestimates.

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