Evaluation of Eemian and Holocene Climate Variability: Synthesis of marine archives with climate modelling (HolEem)

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The major objective of the project is to investigate the spatio-temporal pattern of temperature changes during the Eemian and Holocene as derived from integrations with a comprehensive global climate model and marine surface ocean temperature records on a global scale. We will explore the worldwide distribution of existing, reedited, and newly collected marine paleotemperature data and compare it with results from transient experiments with a state-of-theart general circulation model used in the assessment of future climate change. The paleodata collection and the modelling efforts will aim to investigate the regionally very different temporal climate patterns during the middle to late Holocene (the last 6,000 years) and the Eemian (125,000 years before present). Special emphasis is placed on the last 2-3 thousand years, striving to complement a study of the last millennium. With advanced statistical analysis of spatial and temporal variability in the paleodata records and in the model results, natural climate variability modes and their amplitude will be identified in the data and compared with the climate variability tracked down in the model experiments. The extension of the Latest Holocene climate simulations into the next centuries, using scenarios for future greenhouse gas emission, can help to assess 4 future climatic change influenced by natural and anthropogenic “forcing”. The statistical analyses will extract climate phenomena from different proxy time series (Alkenones and Mg/Ca) and elaborate common variability and teleconnections for the last two interglacial periods. The aim is to unravel the influence of internal variability and natural forcing factors, like e.g. parameters of the Earth's orbit, on climate variability and regional heterogeneity in climate trends. The variations in the large-scale ocean circulation and feedback mechanisms between thermohaline circulation changes and low-frequency variations of climate will be investigated.