Jeudi 3
Sessions générales
Session de posters
› 14:50 - 14:55 (05min)
Thermal history of the Western Pacific Warm Pool as an indicator of global temperature
Kazuyo Tachikawa  1@  , Laurence Vidal  2  , Corinne Sonzogni  3  
1 : Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement  (CEREGE)  -  Site web
Aix-Marseille Univ, CEREGE, UMR 6635, 13545 Aix en Provence cedex 4, France, CNRS, CEREGE, UMR 6635, 13545 Aix en Provence cedex 4, France, IRD, CEREGE, UMR 161, 13545 Aix en Provence cedex 4, France, Collège de France, CEREGE, 13545 Aix en Provence cedex 4, France
Europôle de l'Arbois, BP 80, 13545 Aix-en-Provence Cedex 04, France -  France
2 : Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement  (CEREGE)  -  Site web
Aix-Marseille Univ, CEREGE, UMR 6635, 13545 Aix en Provence cedex 4, France, CNRS, CEREGE, UMR 6635, 13545 Aix en Provence cedex 4, France, IRD, CEREGE, UMR 161, 13545 Aix en Provence cedex 4, France, Collège de France, CEREGE, 13545 Aix en Provence cedex 4, France
Europôle de l'Arbois, BP 80, 13545 Aix-en-Provence Cedex 04, France -  France
3 : Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement  (CEREGE)  -  Site web
Aix-Marseille Univ, CEREGE, UMR 6635, 13545 Aix en Provence cedex 4, France, CNRS, CEREGE, UMR 6635, 13545 Aix en Provence cedex 4, France, IRD, CEREGE, UMR 161, 13545 Aix en Provence cedex 4, France, Collège de France, CEREGE, 13545 Aix en Provence cedex 4, France
Europôle de l'Arbois, BP 80, 13545 Aix-en-Provence Cedex 04, France -  France

Climate modelling studies suggest that Sea Surface Temperature (SST) in the tropical ocean is tightly correlated with global surface temperature under different climate background, leading to the hypothesis that tropical ocean could provide reference temperature variability in response to past radiative forcing. The Western Pacific Warm Pool (WPWP) is ideal to examine this hypothesis because of its SST mainly determined thermodynamically. However, highly resolved paleo-SST records have been limited in marginal seas where local effects might mask the global signal. Here we present the reconstruction of the last 400 kyr SST based on planktonic foraminiferal Mg/Ca thermometer from a marine sediment collected in the north of the New Guinea Island, the centre of the present WPWP. Striking similarity and synchronism between the WPWP SST, the benthic foraminiferal δ18O of the same core, and the atmospheric CO2 record from Antarctic ice cores indicate that the WPWP SST record primarily reflects a global signal for the whole studied period. Local effects on the SST change were identified to be minor and associated with seasonal production of the planktonic foraminifer. Estimation of the global mean temperature inferred from the SST record is compared with the past greenhouse gas and ice sheet albedo forcing. This allows quantifying a climate sensitivity of 2.6±0.1ºC for doubled atmospheric CO2, which closely agrees with the most plausible value of 3ºC. Focusing on glacial periods gives a lower sensitivity whereas interglacial periods yield a higher sensitivity, in particular the penultimate interglacial period indicates further warming. This is observational evidence that climate sensitivity could be dependant on climate background, and additional feedbacks may exist in warm mean states.

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