Ocean Circulation and Climate Dynamics
Paleoproxies: Key to the Past
The evolution of climate and oceanography during earth’s history is studied by means of „natural climate archives“ (e.g., sediment cores, corals) from oceanographic key regions. The temporal varibility of certain environmental parameters such as water temperature, marine productivity, or global ice volume is reconstructed using a spectrum of established proxies. The understanding of the involved processes, proxy calibration and the development of novel proxies is therefore essential for paleo-oceanography.
Modern reconstructions make use of a variety of chemical, physical, sedimentological, and biological proxies that are able to describe the environmental parameters not only qualitatively but also quantitatively – an important prerequisite for the successful modeling of past climate conditions. It is for example possible to reconstruct paleo-water temperatures with an accuracy of less than ± 1°C.
The currently most important paleo-information carrier are microfossils and their organic remains preserved in the oceanic sedimentary archives. The exact knowledge of their ecology, the preservation potential of their biogenic remains as well as the processes involved in the signal generation are essential for assessing the reliability and applicability of a proxy. However, it becomes evident that the use of a single proxy is often not sufficient to quantify the temporal variations of a climate-related parameter with a viable accuracy. Only the application of various proxies that are based on diverse processes – the „multi-proxy“ approach – enables the optimization of paleoreconstructions.