Papers by Camille Contoux
Arctic sea ice simulation in the PlioMIP ensemble
Climate of the Past, 2016
Earth and Planetary Science Letters, 2015
Editor: J. Lynch-Stieglitz Keywords: Greenland ice sheet Pliocene paleoclimate modelling ice shee... more Editor: J. Lynch-Stieglitz Keywords: Greenland ice sheet Pliocene paleoclimate modelling ice sheet modelling
Climate Dynamics, 2015
component of vertical moisture advection, resulting in enhanced mid-Pliocene EASM precipitation c... more component of vertical moisture advection, resulting in enhanced mid-Pliocene EASM precipitation compared to PI in both simulations. Moist static energy diagnosis identifies the combined effect of enhanced zonal thermal contrast and column-integrated meridional stationary eddy velocity v * and its convergence ∂v * ∂y as the physical mechanisms that sustain the enhancement of mid-Pliocene EASM precipitation in both simulations compared to the PI experiments. This takes place through a strengthening of the EASM circulation and moisture transport into the EASM domain associated with an increase in local moisture convergence in the mid-Pliocene in both simulations. Moisture budget analysis also reveals that the larger area-averaged mid-Pliocene EASM precipitation increase in the CGCM compared to its AGCM component is mainly caused by the dynamical component contributing more to the vertical moisture advection in the CGCM (i.e. IPSL-CM5A) compared to its AGCM (LMDZ5). The large simulated differences in the spatial pattern of the mid-Pliocene EASM precipitation between the two simulations result from the combined effect of enhanced meridional thermal contrast over the EASM domain and increased v * convergence over South China in the CGCM simulation compared to the AGCM simulation.
Climate of the Past Discussions, 2013
Based on the simulations with fifteen climate models in the Pliocene Model Intercomparison Projec... more Based on the simulations with fifteen climate models in the Pliocene Model Intercomparison Project (PlioMIP), the regional climate of East Asia (focusing on China) during the mid-Pliocene is investigated in this study. Compared to the pre-industrial, the multi-model ensemble mean (MMM) of all models shows the East Asian summer 5 wind (EASW) largely strengthens in monsoon China, and the East Asian winter wind (EAWW) strengthens in south monsoon China but slightly weakens in north monsoon China in mid-Pliocene. The MMM of all models also illustrates a warmer and wetter mid-Pliocene climate in China. The simulated weakened mid-Pliocene EAWW in north monsoon China and intensified EASW in monsoon China agree well with geological re-10 constructions. However, the model-model discrepancy in simulating mid-Pliocene East Asian monsoon climate, in particular EAWW, should be further addressed in the future work of PlioMIP.
Climate of the Past Discussions, 2015
Eight general circulation models have simulated the mid-Pliocene Warm Period (mPWP, 3.264 to 3.02... more Eight general circulation models have simulated the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Ma) as part of the Pliocene Modelling Intercomparison Project (PlioMIP). Here, we analyse and compare their simulation of Arctic sea ice for both the pre-industrial and the mid-Pliocene. Mid-Pliocene sea ice thickness and extent 5 is reduced and displays greater variability within the ensemble compared to the preindustrial. This variability is highest in the summer months, when the model spread in the mid-Pliocene is more than three times larger than the rest of the year. Correlations between mid-Pliocene Arctic temperatures and sea ice extents are almost twice as strong as the equivalent correlations for the pre-industrial simulations. It is suggested 10 that the weaker relationship between pre-industrial Arctic sea ice and temperatures is likely due to the tuning of climate models to achieve an optimal pre-industrial sea ice cover, which may also affect future predictions of Arctic sea ice. Model tuning for the pre-industrial does not appear to be best suited for simulating the different climate state of the mid-Pliocene. This highlights the importance of evaluating climate models 15 through simulation of past climates, and the urgent need for more proxy evidence of sea ice during the Pliocene.
Erratum to: Drivers and mechanisms for enhanced summer monsoon precipitation over East Asia during the mid-Pliocene in the IPSL-CM5A
Climate Dynamics, 2015
The mid-Pliocene Warm Period (mPWP, ca. 3.3 -3 Ma) is the last geological period showing a warmer... more The mid-Pliocene Warm Period (mPWP, ca. 3.3 -3 Ma) is the last geological period showing a warmer climate than the preindustrial during a sustained period of time, much longer than interglacial periods of the last million years. Moreover, mPWP position of the continents and atmospheric pCO2 are very close to present-day, both conditions making the mPWP a relevant analogue for future global warming. For these reasons, the mPWP has been the focus of Pliocene Modelling Intercomparison Project (PlioMIP), which associates data analysis and modelling. We use the IPSLCM5 Earth System model and its atmospheric component alone (LMDZ), to simulate the climate of the mPWP. Boundary conditions such as sea surface temperatures (SSTs), topography, ice sheet extent and vegetation are the ones used within the PlioMIP framework. On a global scale we show the impact of different boundary conditions with LMDZ, and of a global coupling on the simulated climate. Results from the Earth System model are a...
Using results from the PlioMIP ensemble to investigate the Greenland Ice Sheet during the warm Pliocene
Climate of the Past Discussions, 2014
Middle Miocene Hominoids dispersion and radiation: impact of climate and vegetation changes in Europe
ABSTRACT The middle Miocene is a time of important climatic changes, and a crucial period for ape... more ABSTRACT The middle Miocene is a time of important climatic changes, and a crucial period for ape's evolution. The Middle Miocene Climatic Optimum (MMCO), that occurred approximately 17 to 15 Ma, was one of the last global warming event of the Cenozoic. This period also corresponds to the first dispersion of apes from Africa to Europe, which was made possible by tectonic and environmental changes, in particular the expansion of hominoids habitat: (sub-)tropical forest. Following the MMCO, an abrupt global cooling occurred that coincides with an important radiation of European hominoids. The most common view is that the widening of hominoids habitat during the MMCO was the main factor of their dispersion from Africa to Europe. Moreover, the major climatic change that followed induced an opening of the environment because of cooler and dryer conditions, which should have lead to a fragmentation of hominoids' habitat. This imply that hominoids evolved separately in refuges during the end of the Miocene, so the radiation observed in the fossil record of European Miocene apes is interpreted as a divergent evolution in a fragmented habitat. However, no study has yet demonstrated this evolutionary scenario. Our aim is to study the environmental changes during the middle Miocene, in particular climate and vegetation changes, and to link them with these two major events of hominoids' evolution. Using climate and vegetation models, we investigate the role of environmental variation in hominoids' evolution during the middle Miocene, in particular between 17 and 14 Ma. We perform two climatic experiments (16Ma and 14Ma) with the atmospheric general circulation model LMDZ. The results of these experiments will then be used to force the dynamic vegetation model CARAIB. This should help us to simulate hominoids' habitat for the two time period chosen, and to discuss the role of important climate change for Miocene apes evolution.
The last development of sustainable warm climate occurred during the Mid-Pliocene [3.3-3.0 Ma] pe... more The last development of sustainable warm climate occurred during the Mid-Pliocene [3.3-3.0 Ma] period which is a world tectonically similar to our present day world. Despite some climatic modulations, this time period may be considered as a long (300 Ka) warm period with global annual temperature higher by 2or 3 • C than pre-industrial. We choose the opportunity of the comparison exercises CMIP5 and PMIP3 (PLIOMIP) to compare Mid Pliocene equilibrium climate simulations obtained with IPSL, OAGCM with PLIOMIP boundary conditions and RCP4.5 future scenario using the same model.
Megalake Chad (MLC) occurrences are widely documented for the mid-Holocene period but also for th... more Megalake Chad (MLC) occurrences are widely documented for the mid-Holocene period but also for the Mio-Pliocene (Schuster et al., 2009). From 7 to 3 Ma, analysis of sedimentary deposits of the Djurab desert region show desertic to full-lacustrine facies, suggesting an alternance of dry to wet climates (Schuster, 2002, Schuster et al., 2009, lacustrine conditions being associated to fauna dispersal and early hominid presence (e.g. Brunet et al., 1995Brunet et al., , 2002. Some studies (e.g. Braconnot and Marti, 2003) suggest a control of precession on monsoon. Using late Pliocene climate simulations and different orbital configurations, can we constrain variations of the Megalake and reach the water volume of 350 000 km 2 proposed by several authors (Ghienne et al., 2002; Leblanc et al., 2006)? Can we propose a timing for the MLC occurrences?
From Toumai to Lucy: climate and orographic forcing on Environment and Early Human
Modelling the mid-Pliocene Warm Period climate with the IPSL coupled model and its atmospheric component LMDZ5A
Scientific Reports, 2013
The mid-Piacenzian climate represents the most geologically recent interval of long-term average ... more The mid-Piacenzian climate represents the most geologically recent interval of long-term average warmth relative to the last million years, and shares similarities with the climate projected for the end of the 21 st century. As such, it represents a natural experiment from which we can gain insight into potential climate change impacts, enabling more informed policy decisions for mitigation and adaptation. Here, we present the first systematic comparison of Pliocene sea surface temperature (SST) between an ensemble of eight climate model simulations produced as part of PlioMIP (Pliocene Model Intercomparison Project) with the PRISM (Pliocene Research, Interpretation and Synoptic Mapping) Project mean annual SST field. Our results highlight key regional and dynamic situations where there is discord between the palaeoenvironmental reconstruction and the climate model simulations. These differences have led to improved strategies for both experimental design and temporal refinement of the palaeoenvironmental reconstruction.
Nature Climate Change, 2013
Comparing simulations of key warm periods in Earth history with contemporaneous geological proxy ... more Comparing simulations of key warm periods in Earth history with contemporaneous geological proxy data is a useful approach for evaluating the ability of climate models to simulate warm, high-CO 2 climates that are unprecedented in the more recent past 1-3 . Here we use a global data set of confidence-assessed, proxy-based temperature estimates and biome reconstructions to assess the ability of eight models to simulate warm terrestrial climates of the Pliocene epoch. The Late Pliocene, 3.6-2.6 million years ago, is an accessible geological interval to understand climate processes of a warmer world 4 . We show that model-predicted surface air temperatures reveal a substantial cold bias in the Northern Hemisphere. Particularly strong data-model mismatches in mean annual temperatures (up to 18 • C) exist in northern Russia. Our model sensitivity tests identify insufficient temporal constraints hampering the accurate configuration of model boundary conditions as an important factor impacting on datamodel discrepancies. We conclude that to allow a more robust evaluation of the ability of present climate models to predict warm climates, future Pliocene data-model comparison studies should focus on orbitally defined time slices 5 .
Geochemistry, Geophysics, Geosystems, 2014
1] As compared to the late Pleistocene, Alkenone-based sea surface temperature (SST) in the Bengu... more 1] As compared to the late Pleistocene, Alkenone-based sea surface temperature (SST) in the Benguela region revealed relatively warm and stable SST recorded between 3.5 and 2.0 Ma, and coincide with a period of increasing biological productivity as revealed by increasing deposition of biogenic opal. We assess how the hydrological patterns recorded in SST proxies are embedded in the geological record by performing a proxy-proxy comparison. We used Laser-Ablation Inductively Coupled Plasma-Mass Spectrometry to measure the Mg/Ca on the planktonic foraminifera species Globigerina bulloides, allowing in situ measurements of Mg/Ca on individual foraminiferal tests. Mg/Ca-derived temperatures provide much colder temperatures than alkenone-derived SST by up to 10 C. We build a scenario involving contrasting sensitivities of paleothermometers upon the annual cycle, namely alkenones preferentially capturing SST when the surface ocean is warmer than the mean-annual average SST, and G. bulloides capturing SST when upwelling intensifies. Multichamber analysis also suggests that G. bulloides migrates below the sea surface while calcifying its last chambers prior to gametogenesis, allowing the extraction of both surface and subsurface temperature from Mg/Ca measured on different chambers. The range of temperatures recorded between our multiple SST proxies is supported by the range of temperatures simulated with a general circulation model when different seasons, different water depth and different orbital configurations occurring during the late Pliocene are considered. A greater seasonal cycle in SST during the Pliocene can account for alkenone and Mg/Ca-derived temperature contrast, pointing to a radically different mode of upwelling activity in the Benguela region compared to today.
Climate of the Past, 2013
Climate of the Past, 2013
In the Pliocene Model Intercomparison Project (PlioMIP), eight state-of-the-art coupled climate m... more In the Pliocene Model Intercomparison Project (PlioMIP), eight state-of-the-art coupled climate models have simulated the mid-Pliocene warm period (mPWP, 3.264 to 3.025 Ma). Here, we compare the Atlantic Meridional Overturning Circulation (AMOC), northward ocean heat transport and ocean stratification simulated with these models.
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Papers by Camille Contoux