Another advantage of the method: the air extracted from the ice samples is not lost during the measurement in the laser spectrometer, instead it can be used for further analyzes afterwards. This technique ensures one hundred percent extraction efficiency. Individual samples are collected at centimeter resolution by freezing the air at -258☌ during the continuous sublimation process. Using the sublimation technique developed in Bern, an ice core sample can be slowly transformed from the top to the bottom from the solid to gaseous state. Thanks to this pioneering work, says Hubertus Fischer, it will be possible to take greenhouse gas measurements with the necessary precision and temporal resolution in such old ice. At the University of Bern, in turn, the new sublimation extraction system was devised and built that makes it possible to obtain such small air samples continuously and without contamination from an ice core. We are proud that this makes it possible to study the valuable ice cores," says Emmenegger. "Achieving this high precision in such small samples was hardly imaginable for a long time. The team led by Lukas Emmenegger, head of Empa's "Air Pollutants/Environmental Technology" department, developed a new laser spectrometer that can measure greenhouse gases on a sample of just 1.5 milliliters of air. The Bern Group worked closely with Empa researchers on the technical development for this. The new method has just been published in the journal Atmospheric Measurement Techniques. Perfect recycling of precious ice samples
REMO RECOVER SOFTWARE KEY ARCHIVE
Ice cores are an extremely important climate archive because only they contain the air of the past to directly measure past greenhouse gas concentrations. "These are important prerequisites," explains Hubertus Fischer, "for obtaining high-precision, high-resolution records from the oldest ice in Beyond EPICA." In the 1.5 million year old ice, 15,000 to 20,000 years of climate history are compressed into just one meter of ice core, which places completely new demands on ice core analyzes. The ice sample needed for this is with a thickness of just one centimeter very small, yet the highest accuracy is possible in the measurement. The team led by Hubertus Fischer, professor of experimental climate physics and member of the Oeschger Center for Climate Change Research has succeeded, in collaboration with Empa, in developing a new technique to jointly measure the greenhouse gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) as well as the carbon isotope composition of CO2. The University of Bern plays a crucial role in the development of the new analysis technologies. Only then will the complex analysis of the oldest ice in this core follow, which new methods are currently being developed for. If everything goes as planned, this should be the case in 2025. A depth of around 2700 meters must be reached in the Antarctic ice sheet and an ice core recovered.
The project objective is to look back 1.5 million years into the past and obtain data on the development of temperature, the composition of the atmosphere and the carbon cycle. The drilling reached a depth of 808 meters. The Beyond EPICA - Oldest Ice project, a European consortium that includes the University of Bern, completed its second field season at the end of January. The search for the oldest ice on earth has taken an important step forward.
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