Description du projet
Des scientifiques trouvent un nouveau moyen de suivre le cycle du carbone
Le cycle mondial du carbone, dans lequel le carbone est échangé entre des réservoirs situés dans l’atmosphère, les océans et la terre, joue un rôle en matière de climat. Les océans peuvent absorber une énorme quantité de CO2, et les organismes marins sont essentiels à ce processus via la pompe à carbone biologique (BCP). En surface, les photosynthétiseurs tels que le phytoplancton transforment le CO2 dissous en carbone organique. La majeure partie de ce dernier est reconvertie en CO2 par la respiration des animaux, des plantes et des bactéries, et retourne dans l’atmosphère sur de courtes périodes. Lorsque les plantes et les animaux meurent, ils en emmènent avec eux une petite fraction dans les profondeurs, qui se libère lentement par décomposition. La BCP joue un rôle essentiel dans les processus climatiques, mais elle encore est mal comprise. Le projet SCrIPT, financé par l’UE, développe un indicateur permettant d’évaluer les changements de la BCP au fil du temps, passé comme à venir.
Objectif
The overall concept of this proposal is to investigate the main biogeochemical processes modulating spatial and temporal changes in marine export productivity, and assess their role in regulating atmospheric carbon dioxide (CO2) concentrations, both under present conditions and in the geological past. The exchange of CO2 between the atmosphere and ocean interior mediated by the oceanic ecosystem is a pivotal mechanism modulating the global carbon cycle, and thus, a substantial driver of the Earth’s climatic evolution.
The overarching objective of this research proposal is to develop a novel proxy to trace changes in the global strength of the marine biological carbon pump (BCP) based on stable Chromium (Cr) isotopes. Despite its significance for the global carbon cycle, the BCP is still poorly constrained. This project will explore a tracer that has recently been developed to investigate the rise of atmospheric oxygen in the early history of the Earth and develop it thoroughly through a comprehensive, multidisciplinary calibration program and apply it to the much more subtle redox variations associated with organic matter remineralization in the ocean. The proposed approach includes phytoplankton culture experiments, water-column investigations and sedimentary analysis and will aim at elucidating the mechanisms governing the reduction of Cr and its associated isotopic fractionation. The proxy will subsequently be used to reconstruct export production variability in the past and assess its role in modulating glacial/interglacial climate oscillations. These past changes tended to be much slower than the current, anthropogenic change. Nonetheless, they can help to appraise sensitivities and point toward potentially dominant mechanisms of change. The observations gathered within the framework of this research program will enable refining the evolution of the marine carbon cycle and the rapidly declining buffering capacity of the ocean.
Champ scientifique
- humanitieshistory and archaeologyhistory
- natural scienceschemical sciencesinorganic chemistrytransition metals
- social scienceseconomics and businesseconomicsproduction economicsproductivity
- natural sciencesbiological sciencesecologyecosystems
- natural sciencesearth and related environmental sciencesatmospheric sciencesclimatologyclimatic changes
Mots‑clés
Programme(s)
Régime de financement
ERC-COG - Consolidator GrantInstitution d’accueil
1015 LAUSANNE
Suisse