Historical climate variation in the Maldives, Indian Ocean, based on proxy data from Scleractinian coral skeletons

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The goal of the proposed study is to reconstruct historical climate variability m the Maldives by analyzing the skeletons of massive corals with regard to growth rate and geochemical composition such as oxygen and carbon isotopes and trace elements of strontium and calcium. It is planned to sample at least 5 corals on Rasdhoo Atoll by drilling cores out of massive coral colonies such as Porites sp. and to reconstruct sea surface temperature variation over the last 100-200 years (1800-2000 AD) along the cores. In addition, carbon isotopes might provide information about illumination, nutrients, and anthropogenic CO2 emission in time. The data will help to better understand climate development in the northwestern Indian Ocean, which is strongly influenced by the monsoon and the El-Nino Southern Oscillation (ENSO). Knowledge of the development of these systems is of great socio-economic value because extreme deviations from the normal monsoon or ENSO climate variation may cause flooding, draughts, and even regional economic crises. The data will also allow to identify historical bleaching events in corals, that are caused by high temperatures, and possible cyclicity in these events might allow prediction of future bleachings. In addition, fossil corals from reef cores will be analyzed in order to obtain Holocene and possibly late Pleistocene climate proxy data.