Description du projet
Décryptage des transitions climatiques soudaines dans les carottes de glace du Groenland
Les carottes de glace polaire comptent parmi les archives naturelles les plus importantes fournissant des informations sur les transitions climatiques soudaines. Les mécanismes climatiques sous‑jacents n’ont pas encore été entièrement déchiffrés, notamment les processus à l’origine des changements soudains, mais les techniques de fusion conventionnelles à résolution centimétrique peinent à fournir l’analyse temporelle fine requise du fait de l’amincissement continu des couches de glace. La technologie de spectrométrie de masse à plasma induit par couplage inductif par ablation au laser (LA-ICP-MS) permet une analyse microdestructive des impuretés des carottes de glace à une résolution de l’ordre du micron. Le projet MICRO-CLIMATE, financé par l’UE, connecte pour la première fois deux installations de LA-ICP-MS pionnières des universités du Maine et de Venise. Le projet permettra de réaliser des analyses à haut débit et à haute précision pour (i) identifier l’empreinte de la matrice de glace et limiter la préservation du signal, et (ii) déchiffrer la chronologie des changements dans les indicateurs marins, terrestres et atmosphériques.
Objectif
Understanding natural climate dynamics is fundamental to anticipate, avoid, and assess mitigation potential for abrupt climate change, one of the grand challenges to global sustainability. As one of the most important natural archives, polar ice cores have led to the discovery of past abrupt climate transitions, such as the abrupt onset of stadial-interstadial warming in Greenland, happening as fast as just a few decades. The underlying processes remain to be fully deciphered, especially whether oceanic or atmospheric changes initiate abrupt changes, or if they act simultaneously. To study the sequence of events requires fine temporal detail, which conventional cm-resolution melting techniques cannot provide due to continuous thinning of ice layers. Laser-Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS) is a key technology in this respect, offering micro-destructive ice core impurity analysis at micron scale-resolution. At this high resolution, however, it is pivotal to avoid misinterpretation by taking into account interaction of impurities with the ice crystal matrix. MICRO-CLIMATE brings together, for the first time, two state-of-the-art LA-ICP-MS setups (at the Universities of Maine and Venice) to realize what one partner could not achieve alone: high-throughput AND high detail analysis for constraining signal preservation. In Venice, imaging the 2D impurity distribution detects the imprint of the ice matrix. In Maine, impurity profiles over meter-long ice core rods are investigated to decipher the timing of changes in marine, terrestrial and atmospheric proxies, before, during and after abrupt transitions. By this means a high-resolution fingerprint of the abrupt change is unfolded – which climate components change first, which follow? Ultimately, the project will advance our understanding of how to interpret ice core geochemistry at high-resolution and produce a refined LA-ICPMS application that can be employed in upcoming ice core projects.
Champ scientifique
Mots‑clés
Programme(s)
Régime de financement
MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinateur
30123 Venezia
Italie