Dr. Michael Deininger

Average annual daily precipitation on Earth for the period from 1979 to 2015 CE. Graphics: Michael Deininger, Johannes Gutenberg University Mainz.

The entrance of Molara cave, Sicily, where the Holocene stalagmite MO-1 was sampled.

FR-18, a candle-shaped stalagmite, from Frasassi cave, Italy, that began to grow 18,000 years ago. Photo credits: Andrea Borsato

My research is focused on atmospheric dynamics and its interactions with the climate system, particularly with the ocean circulation, on seasonal to geologic time scales. Earth’s climate system is the promoter to balance the meridional temperature gradients between the tropical and polar regions. To achieve this the different components of the climate system, the atmospheric and ocean circulation, transport energy towards the poles. The atmospheric circulation is furthermore responsible for the distribution of water that results in the heterogeneous pattern of precipitation – and temperature – over the continents and oceans. Therefore, the variability of the atmospheric circulation and its drivers are crucial parameters of Earth’s climate system.

To resolve past changes of the atmospheric circulation and to unveil the underlying mechanisms and forcing I primarily work with speleothems. Speleothems are inorganic carbonate deposits growing in caves. Speleothems form from cave waters, and their proxies allow to recover information on climatological, hydrological and environmental variations from above the cave that in turn allow to infer changes of the atmospheric circulation – and of Earth’s climate system.

My primary focus is to investigate Holocene (the last 10,000 years) and late Quaternary (the last 600,000 years) climate and environmental dynamics in Europe by using state-of-the-art statistical methods (PC-PCA method) and by generating precisely dated high-resolution speleothem proxy time series. These analyses include also investigations if Holocene climate dynamics co-varied with cultural developments in Europe during the Holocene.
Furthermore, another aspect of this work includes inter-hemispheric analysis of climate and environmental variations in Europe and South America in the late Quaternary and its synchronicity, to unveil the underlying causes and mechanism. Another important aspect of my work at the moment is to search for old speleothems that grew during the Pliocene, which is the latest time period on Earth when the atmospheric CO2 concentration was 400 ppm. Hence, such speleothems would provide fundamental insights into how the atmospheric circulation response to high atmospheric CO2 concentrations – and may give a look into the future development of the atmospheric circulation.