Objectif
A timely theme in Earth Sciences is the quantification of chemical weathering and fluxes to the oceans, and their role in defining seawater chemistry and atmospheric CO2 levels. Until recently, most studies have assumed that weathering rates and river fluxes are essentially at a steady state and that present day rates are typical of the past. Where rate changes have occurred, they are largely thought to have been gradual – e.g. in response to mountain uplift. However, recent work has suggested that weathering rates and river fluxes show rapid changes on timescales of ~1000 years; resulting from accelerated weathering of fresh fine-grained glacial deposits exposed during deglaciation. The same is true of new erupted lava and volcanic ash, which weathers much faster when newly erupted. Volcanic islands have already been recognised as important contributors to terrestrial weathering rates and the transport of dissolved elements to the oceans. Volcanism can vary from small, high-frequency eruptions that are part of the climatic 'steady-state'; to large, rare eruptions that either produce widely dispersed ash or great volumes of lava. Several processes allow this newly erupted material to weather quickly in the initial years after deposition. This introduces, in the case of the large eruptions, a new sink for atmospheric carbon dioxide by providing elements necessary for calcite shell formation to the oceans. The subsequent 'biological pump' depletes the ocean in CO2, which in turn reacts with the atmosphere to cool the planet. This process could potentially act as 'tipping point', pushing the Earth's climate from an inter-glacial to a glacial regime. This project seeks to quantify the early, elevated weathering of two types of volcanic rock using a combination of laboratory experiments and field observations. We will then use this data to model the potential impact of this phenomena using a state-of-the-art global climate model.
Champ scientifique
Thème(s)
Appel à propositions
FP7-PEOPLE-2009-IEF
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Régime de financement
MC-IEF - Intra-European Fellowships (IEF)Coordinateur
101 Reykjavik
Islande