Scientists are getting ready to drill for an ice core holding the oldest ice on planet. They want to reach 1,5 million year old ice with traces of past climate changes.
Text: Maja Sojtaric
Current record for oldest ice core in the world is 800.000 years old. The core from East Antarctica’s plateau, is over three kilometers long, and contains snowfall and trapped air from the past. It took a total of eight years to drill during Antarctic summer seasons.
To break this record and delve deeper into climate history, scientists need to be inventive. New, groundbreaking instrumentation needs to be developed to make it possible to reveal climate secrets frozen deep in the Antarctic ice.
An ideal place to test and proof the performance of such an instrument is the Arctic Ocean and this was done during a recent CAGE-cruise.
Melting through kilometres of ice
Ice cores are spectacular records of past climate change because they contain traces of climate gases, such as methane. Most spectrometers that perform these measurements are bulky and usually installed in laboratories. A team in Grenoble has now developed a compact laser spectrometer and gas extraction system, which, linked together, can do very fast and precise measurements.
The instrument will be mounted on a pioneering type of coring equipment, capable of reaching truy ancient ice.
“We are miniaturising the lab to bring it down the ice sheet and measure in-situ while coring”, explains engineer Jack Triest.
He is one of the members of the SUBGLACIOR project, which is being developed at the Laboratoire Glaciologie et Géophysique de l’Environnement (LGGE) and National Center for Scientific Research (CNRS) in Grenoble, France.
Instead of conventional drilling, SUBGLACIOR aims to melt its way through several kilometres of the Antarctic ice sheet. While under way it will be measuring methane concentrations and isotope ratios in the melted water. These climate signatures will be measured using the embedded laser spectrometer specially developed by Roberto Grilli at the Laboratoire Interdisciplinaire de Physique.
Same principle in the Arctic Ocean
Separation of water to gas follows the same principle in ocean water as it does in ice cores. Triest and Grilli joined therefore a CAGE-cruise in late October 2015 to a key area of known methane release off the coast of the Svalbard archipelago in the Arctic Ocean.
”We wanted to proof the quality of our measurements in a challenging environment. The hypothesis was that the instrument would have much better response time and repeatability than other commercially available instruments. That was very much confirmed. The instrument performed very well and we got excellent high resolution data as a result of the fast response time”.
Response time is important to exactly determine the amplitude and location of the release of the methane leaks from the ocean floor. It turns out that the technology developed for the purpose of ice core dating, can also help answer very current scientific questions from the deep ocean. Not only did the Arctic Ocean test help proof the quality of the instrumentation to be used in the Antarctic ice, it also provided scientist with some new data from the Arctic methane seeps.
The results from the Arctic Ocean campaign will be published early this year. “Exciting developments”, say Directeur de Recherché at CNRS Jerome Chappelaz and the director of CAGE Jürgen Mienert.
FACT SHEET: SUBGLACIOR
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an innovative probe that will provide the information needed to qualify potential sites on the Antarctic ice sheet that could include ice that is over a million years old and still in good stratigraphic order.
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aims to perforate the ice sheet down to the bedrock in a single season. It will conduct continuous and in-situ measurements of the isotopic composition of the melted water and the methane concentration in gases trapped in the ice.
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3,2 million EURO project funded by, among others, European Research Council, and The French National Research Agency.
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Lead by Dr. Jerome Chappelaz.