Past Ocean Dynamics - Jörg Lippold
At times of overwhelming scientific evidence that human activities are the primary cause of global climate warming understanding the mechanisms of the climate system is of highest importance. In order to better predict future changes and to potentially develop adaptation and mitigation strategies we turn towards the past.
Our goal is to assessing past evolution and feedback reactions of the global climate system under varying boundary conditions.
The geological past offers a wide array of natural experiments during which the climate changed. These changes sometimes occurred abruptly, thereby allowing deciphering the triggers and feedback mechanisms on various time scales - from the huge climatic revolutions between glacial and interglacials shaping the face of the earth, to more subtle and relatively attenuated variations during the time period of human cultural evolution.
Our research groups aims for defining paleoclimate parameters by generating and interpreting new data. This includes method development and reconstructing key parameters of the biogeochemical cycles like redox-conditions, airborne dust, circulation, ages, weathering and provenance by analyzing elemental and isotopic compositions. The main focus of our research is set on the Oceans.
Covering the majority of Earth’s surface the Oceans strongly influence climate and represent fundamental resources to much of our planet’s population. The Oceans also sequester a huge amount of carbon dioxide, therefore lowering the effects of anthropogenic emissions today.
Understanding the Ocean’s dynamic of the past, today and of the future is therefore essential.
The last glacial/interglacial cycle (i.e., approximately the last 130,000 years) comprises a wide array of different boundary conditions under which ocean circulation changed profoundly. Hence, it provides an ideal natural laboratory for identifying the triggers and feedback mechanisms responsible for climate change on different time scales.
While modern ocean condition parameters can be measured directly from vessels, by moorings, submarine cables and even independently operating floaters the reconstruction of past water mass kinetics seems to be an inconceivable task at first glance. Our reconstruction of paleo-information depends on proxy data recovered from deep-sea sediment cores. Based on measurements of isotopic compositions (e.g. U-series) down to ultra-low concentrations we reconstruct the past deep ocean hydrography during key periods of climate history. Supported by models we transfer the ocean-wide patterns of these proxy data into quantitative estimates of past circulation strength.