Quantifying molecular oxygen isotope variations during a Heinrich stadial

C. Reutenauer (1) , A. Landais (2, 3) , T Blunier (1) , C Bréant (2) , M Kageyama (2, 4) , M.-N Woillez (2) , C Risi (5) , V Mariotti (2) , P Braconnot (2, 6)

1 Centre for Ice and Climate [Copenhagen]
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 GLACCIOS - Glaces et Continents, Climats et Isotopes Stables
4 CLIM - Modélisation du climat
5 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
6 MERMAID - Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics

δ 18 O of atmospheric oxygen (δ 18 O atm) undergoes millennial-scale variations during the last glacial period, and systematically increases during Heinrich stadials (HSs). Changes in δ 18 O atm combine variations in biospheric and water cycle processes. The identification of the main driver of the millennial variability in δ 18 O atm is thus not straightforward. Here, we quantify the response of δ 18 O atm to such millennial events using a freshwater hosing simulation performed under glacial boundary conditions. Our global approach takes into account the latest estimates of isotope frac-tionation factor for respiratory and photosynthetic processes and make use of atmospheric water isotope and vegetation changes. Our modeling approach allows to reproduce the main observed features of a HS in terms of climatic conditions , vegetation distribution and δ 18 O of precipitation. We use it to decipher the relative importance of the different processes behind the observed changes in δ 18 O atm. The results highlight the dominant role of hydrology on δ 18 O atm and confirm that δ 18 O atm can be seen as a global integrator of hydrological changes over vegetated areas.

Domaines: Climatologie

C. Reutenauer, A. Landais, T Blunier, C Bréant, M Kageyama, et al.. Quantifying molecular oxygen isotope variations during a Heinrich stadial. Climate of the Past, 2015, 11 (11), pp.1527-1551. ⟨10.5194/cp-11-1527-2015⟩. ⟨hal-01259465⟩