Gases in ice cores
Bubble enclosures in polar ice cores represent the only direct archive of the paleoatmosphere. The investigation of this gas archive by careful extraction and high precision analysis allows to reconstruct atmospheric trace gas concentrations over the last approximately 500,000 years. In connection with other ice core proxy information this enables to study the biogeochemical cycles connected to these gases and to reconstruct the climate/greenhouse gas relationship over the last five glacial/Interglacial cycles.
The glaciology department at AWI specializes on the study of the isotopic composition of greenhouse gases. This allows to infer details about temporal changes in the source composition of these atmospheric constituents. Special emphasis lies on the reconstruction of the global carbon cycle and the climate forcing potential of various greenhouse gases as carbon dioxide, methane and nitrous oxide. To this end novel mass spectrometric techniques (isotope ratio monitoring gas chromatography/mass spectrometry (irm GCMS)) and quantitative gas extraction protocols are established to allow for high-precision isotopic measurements on the minute gas samples extracted from ice core samples.
Gas extraction from ice cores for methane isotopic studies.
Interpretation of CO2 and CH4 records and their isotopic signature is aided by biogeochemical modeling at AWI using the new global Box model of the Isotopic Carbon cYCLE (BICYCLE) as well as complex climate models. Uisng Bicycle it was possible to provide for the first time a transient scenario to quantitatively explain glacial/interglacial changes in atmospheric CO2.
The gas studies are performed in close collaboration with other European groups concentrating on the reconstruction of CO2 and CH4 concentration records in the EPICA ice cores.
Projects
- Carbon and hydrogen isotopic composition of methane in the paleoatmospheric archive of polar ice cores - This project is intended to reveal the contribution of different methane sources to changes of the atmospheric methane concentration during climate variations.
- Isotopic investigation of the global carbon cycle. A new sublimation and GCMS technique has been recently established allowing for high precision carbon isotopic analysis on very small ice core samples. This work has been performed within the Young scientist Research group on Earth climate System reconstructions from Polar Ice Cores (RESPIC) within the German climate research program DEKLIM funded by the German Ministry of Education and Research. Also the carbon cycle model BICYCLE has been developed with RESPIC. These studies are now continued within the AWI group NEW KEYS within the research program MARCOPOLI.
