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ICE&LASERS Report Summary

Project ID: 291062
Funded under: FP7-IDEAS-ERC
Country: France

Final Report Summary - ICE&LASERS (Innovative Concepts for Extracting climate and atmospheric composition records from polar ice cores using new LASER Sensors)

ICE&LASERS proposed to make a breakthrough in two challenges of paleoclimate science:

(1) To extend the Antarctic ice core records to 1.5 million years ago – in order to understand the unexplained climate shift from 40,000-year periodicities to 100,000-year ones which took place about 1 million years ago - by building an innovative probe making its own way into the Antarctic ice sheet within a single field season. The probe would include a built-in laser spectrometer in order to measure in situ the depth profile of H2O isotopes in ice as well as greenhouse gas concentration in trapped gases, down to bedrock.

(2) To combine revolutionary detectors with new extraction techniques for measuring with unsurpassed accuracy and resolution the concentrations of CH4, CO2 and CO (a tracer related to the CH4 cycle), and the isotopic ratios of CO2 and CO in polar ice. This work would provide more insight into possible natural feedbacks under a warming future.

ICE&LASERS tackled both scientific challenges, thanks to an analytical revolution for measuring trace gases and their stable isotopes: Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS), patented by one of the four CNRS research units involved in the project. The project uniquely combined the know-how of laser physicists together with experienced ice core scientists and engineers, making it a truly interdisciplinary project.

At completion, ICE&LASERS has fully succeeded in solving many complex technological tasks related with the innovative probe. The built-in laser spectrometer has been designed, built and it demonstrated its unique performances while being immersed in an Antarctic borehole at -54°C. Its diameter has been astonishingly reduced to only 50 mm. The overall probe design was completed from scratch. The construction was successful and the probe was deployed and tested for the first time at Concordia Station in Antarctica during the field season 2016/2017. Another test season took place in 2017/2018 at the same place. Most of the technological solutions were validated. However the team faced problems with the casing required to render the top 100 m of snow layers leak-tight. Therefore a new way of getting leak-tightness will be tested at Concordia Station in 2018/2019 (thus after project completion). If successful, the probe will be deployed for measuring the target signals in the ice sheet during the field season 2019/2020, at a site located about 40 km away from Concordia Station.

Although not originally planned at project start, we also deployed the instrument for the first time into the deep ocean to measure dissolved methane in water using a custom-made interface, with success. This led to a remarkable side valorization of the overall project. Through two additional fundings (including an ERC Proof of Concept grant), we could (1) patent the interface, (2) negociate a licencing with a foreign company, (3) apply the new device over a gas-hydrate degassing zone off Svalbard with very important physical findings, (4) apply it to characterize dissolved methane in Lake Kivu in Rwanda, (5) apply the concept for a new project currently submitted to the ERC, through the 2018 Consolidator call for proposals.

The second challenge of ICE&LASERS has also seen big progress. Reference curves for the past evolution of CH4 have been achieved. We also discovered - thanks to the unique technological setup constructed with ICE&LASERS - the existency of stratigraphic inversion at decimetric scale inside ice cores drilled at very low accumulation sites. Aside from the discovery of large and seasonal in-situ artefacts in Greenland ice, a reference record of the carbon monoxide evolution in the atmosphere was also obtained from Antarctic ice cores. The first OF-CEAS laser spectrometer based on quantum-cascade diode laser has been built for the investigation of CO2 isotopes. However a dead-end problem of saturation of absorption bands precluded us to go further in this endeavour.

Reported by

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
France
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