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Topography and bathymetry of the Maritime Continent. (a) Present day. Light blue areas are the shallow Sunda and Sahul shelves that are emerged during periods of low‐sea level (Voris, 2001). (b) With an emerged Sunda shelf. Arrows delineate the main passages of the South China Sea (SCS) and Indonesian Throughflow (ITF).
Source publication
Drastic paleogeography changes in the Indonesian archipelago over the Plio‐Pleistocene, either in response to sea level oscillations or vertical land motion, enabled the periodic emergence of the Sunda shelf. When emerged, this wide continental platform in the heart of the Maritime Continent may have modified regional and global climate systems. We...
Citations
... Anticipated shifts in rainfall-driving factors due to climate change are expected to impact rainfall characteristics in the IMC, both spatially and temporally, leading to initial observations of nonstationary rainfall. Furthermore, the IMC stands as one of the largest and most infuential centers of atmospheric convection globally [18,19], playing a pivotal role in the equatorial region's climate system [20]. Changes in rainfall patterns within the IMC can serve as indicators of shifts in climate variability, such as those linked to ENSO. ...
The investigation into changing rainfall patterns in the Indonesian Maritime Continent (IMC) involved testing for trends, step changes, and variance nonstationarity using the Mann–Kendall, Pettitt, and White tests, respectively. The analysis covered data from 106 meteorological stations over the period from 1981 to 2021, with all tests conducted at annual time scales to understand the evolving precipitation dynamics in the region. According to the findings of this study, the average annual rainfall in IMC is nonstationary. Rainfall has increased dramatically by 12.72 mm with a significant shift point in 1994. However, this characteristic is likely to vary if the analysis period is extended, reduced, or conducted in different time frames. The spatial analysis indicates that 35.8% of meteorological stations observed a notable increase in rainfall, while 28.3% experienced a significant shift, and 16% displayed considerable variation. Consequently, the study only partially identified the nonstationary nature of rainfall in the IMC. Moreover, the research highlights a substantial rise in rainfall in the central to eastern IMC region, whereas the central to western region predominantly shows a decrease. This nonstationary test helps avoid errors in climatic conditions and analytical methods, presenting recommendations for hydrological projects. Consequently, employing this nonstationary test helps prevent inaccuracies in understanding climatic conditions and analytical techniques, thereby offering valuable suggestions for hydrological projects.
... Geographically, the Java Sea region is located in the southern of the Sunda Shelf [1,2]. The region is bounded by the Karimata Strait -South China Sea to the northwest and the Flores Sea-Makassar Strait to the east. ...
The optimization of small pelagic fisheries in the Java Sea could be enhanced by providing oceanographic information for analysis and determining potential fishing grounds. This study aims to investigate shelf oceanographic factors influencing small pelagic fisheries using multidatasets of sea surface temperature and surface salinity CROCO ocean model output (2010 – 2020), distribution of light-fishing vessel position of VIIRS satellite, and small pelagic fish catches landing data (round scads Decapterus spp. and the spotted sardinella Amblygaster sirm) at Pekalongan Fishing Port, Central Java. The results showed that the peak of fishing season for the spotted sardinella occurs during northwest monsoon, in which the eastward monsoon current and Sunda shelf throughflow brings fresher (±32.4 psu) and warmer (±28.5 oC) water into the Java Sea. In contrast, the peak of fishing season for round scads. is associated with saltier (>33.0 psu) and cooler (<28.5 °C) water supplied by the westward monsoon current and Makassar ITF during the southeast monsoon. Alternating intensification of monsoonal current along the northern Java and the southern Kalimantan coast during different monsoon periods is associated with a higher abundance of neritic and oceanic small pelagic fishes, respectively.
... Existing models indicate that shelf exposure should be the largest influence on regional atmospheric circulation, although they diverge regarding the relative influence of the different shelf regions and the influence of changing vegetation. Sarr et al. (2019b) found that, secondary to land exposure, vegetated surface properties modulate the radiative effect and turbulent heat flux. Expanded C 4 grasslands produced weaker evaporation rates, lower latent heat release, and less surface cooling than a C 3 rainforest, leading toward less precipitation in the Sunda Shelf region (Sarr et al., 2019b). ...
... Sarr et al. (2019b) found that, secondary to land exposure, vegetated surface properties modulate the radiative effect and turbulent heat flux. Expanded C 4 grasslands produced weaker evaporation rates, lower latent heat release, and less surface cooling than a C 3 rainforest, leading toward less precipitation in the Sunda Shelf region (Sarr et al., 2019b). DiNezio et al. (2016) prescribed widespread C 4 grasses to represent the vegetation of the Sunda and Sahul shelves, and found vegetation was not a first-order influence on the atmospheric responses to shelf exposure. ...
Recent research has found that the subsiding Sunda Shelf (Southeast Asia) was permanently exposed prior to ca. 400 ka with initial submersion-exposure cyclicity, associated with interglacial-glacial sea-level cycles, beginning between 400 and 240 ka. We analyzed the impact submersion-exposure cycles on regional environment and climate through a 640 k.y. leaf-wax carbon isotope (δ13Cwax) reconstruction at Andaman Sea Site U1448, representing relative changes in C3/C4 plant abundances. Prior to ca. 250 ka, the Sunda region was inhabited by a stable C3 (forest) biome, after which submersion-exposure cycles initiated with the deglacial sea-level rise at ca. 250 ka. During subsequent glacial-age sea-level drops, the newly exposed shelf was rapidly colonized by C4 grasses, followed by slow transitions back to C3 forests, representing a tenfold increase in the variability of C3/C4 vegetation in the Sunda region. The C3/C4 regime shift since 250 ka is coherent across the Southeast (SE) Asia peninsula and Sunda Shelf and is coincident with a shift in the east-west sea-surface temperature gradient in the equatorial Pacific Ocean. We hypothesize that the expansion of C4 grasslands promoted and sustained drier glacial-age climates over SE Asia via a feedback mechanism that contributed to weakening the ascending branch of the east-west atmospheric circulation in the equatorial Pacific region known as the Walker Circulation. Our results indicate that the Sunda Shelf region has a larger influence on Walker Circulation than is seen in current paleoclimate simulations.
... During cooler periods, the decreased capacity in holding moisture, and the weakened atmospheric convection over the warm pool in response to increased land area and albedo could have caused an overall LGM drying over the maritime continent (DiNezio and Tierney, 2013;DiNezio et al., 2016). The continental interior drying might be strengthened by increased transport distance of moisture from the coastal regions (Heaney, 1991;Yamanaka et al., 2018) and the negative feedback between grassland expansion and moisture recycling (Cannon et al., 2009;Sarr et al., 2019). Moreover, this drying was probably more pronounced in the dry seasons, i.e., enhanced seasonality of precipitation rather than a drastic reduction in annual precipitation (Dubois et al., 2014). ...
... This proposition invites to go beyond the current study and comprehensively investigate the joint evolution of the entire ecological and physical -climatic and physiographic-environments. Physiographic changes in SE Asia triggered a chain of modifications that impacted the behavior of H. erectus, including the regional climate and its feedback relationships with the vegetation cover 49 , and ultimately on the foodchain on which hunter-gatherers relied 50 . In order to more thoroughly address the impact of this changes on habitat suitability, species distribution modeling would be a natural avenue to more precisely reconstruct the evolution of early humans 47,51 . ...
... This proposition invites to go beyond the current study and comprehensively investigate the joint evolution of the entire ecological and physical -climatic and physiographic-environments. Physiographic changes in SE Asia triggered a chain of modifications that impacted the behavior of H. erectus, including the regional climate and its feedback relationships with the vegetation cover 49 , and ultimately on the foodchain on which hunter-gatherers relied 50 . In order to more thoroughly address the impact of this changes on habitat suitability, species distribution modeling would be a natural avenue to more precisely reconstruct the evolution of early humans 47,51 . ...
The migration of Homo erectus in Southeast Asia during Early Pleistocene is cardinal to our comprehension of the evolution of the genus Homo. However, the limited consideration of the rapidly changing physical environment, together with controversial datings of hominin bearing sites, make it challenging to secure the robust timeline needed to unveil the behavior of early humans. Here, we reappraise the first appearance datum of Javanese H. erectus by adding the most reliable age constraints based on cosmogenic nuclides 10Be and 26Al produced in situ to a compilation of earlier estimates. We find that H. erectus reached Java and dwelled at Sangiran, Java, ca. 1.8 Ma. Using this age as a baseline, we develop a probabilistic approach to reconstruct their dispersal routes, coupling ecological movement simulations to landscape evolution models forced by reconstructed geodynamic and climatic histories. We demonstrate that the hospitable terra firma conditions of Sundaland facilitated the prior dispersal of hominins to the edge of Java, where they conversely could not settle until the Javanese archipelago emerged from the sea and connected to Sundaland. The dispersal of H. erectus across Sundaland occurred over at least tens to hundreds kyr, a time scale over which changes in their physical environment, whether climatic or physiographic, may have become primary forcings on their behavior. Our comprehensive reconstruction method to unravel the peopling timeline of SE Asia provides a novel framework to evaluate the evolution of early humans.
... On the one hand, sea-level ascents and descents induced by climate variation have resulted in periodical transgression-regression of the shelf (Hanebuth et al., 2000;Morley et al., 2021). On the other hand, the large-scale flooding and exposure of the Sunda Shelf have caused climate change at various scales by affecting oceanic circulation, moisture transport, silicate-carbonate weathering, photosynthetic carbon fixation, etc. (Abrams et al., 2018;DiNezio & Tierney, 2013;Sarr et al., 2019). ...
Plain Language Summary
The organic carbon (OC) formed by the photosynthesis of marine and terrestrial organisms consumes atmospheric CO2 (pCO2). Its long‐term burial in marine environments, especially on continental shelves, could influence the global carbon cycle and induce climate change. However, precisely assessing how much OC has been buried on shelves and quantifying how it affected climate change in the geological past is challenging. This is mainly due to the difficulty of obtaining complete spatial‐temporal records buried deeply on shelves and the complexity of climate feedbacks involving OC burial. To fill this gap to a certain extent, we calculated the middle Miocene OC burial of the Sunda Shelf, the world's largest tropical shelf, using 367 drilling sites and evaluated its impact on the profound carbon perturbation and climate transition of this period. We found that more OC was buried during the greenhouse period, but a faster burial rate occurred after polar cooling. The accelerated OC burial on the Sunda Shelf would cause an additional 34.77–69.16 ppm pCO2 sequestration, accounting for at least one‐sixth of the global pCO2 reduction of the middle Miocene. Efficient OC burial on the shelf was promoted by drainage system progradation and vegetation expansion arose along with sea level drop.
... (Westerhold et al., 2020;Zachos et al., 2008) and sea levels (Miller et al., 2005). Geology and Pleistocene eustasy interacted in Sundaland (Husson et al., 2020;Sarr et al., 2019;Sathiamurthy & Voris, 2006;Voris, 2000;Woodruff, 2010). During Pleistocene glacial periods, sea level dropped between −60 and −120 m and created connections between Sundaland's islands (Figure 1e,f). ...
Aim
Sea-level changes have long been put forward to explain the colonization of Southeast Asian islands by freshwater aquatic organisms. We examined the relative impact of Sundaland geology since the Oligocene and of Pleistocene Eustatic Fluctuations on the mitochondrial lineage diversification of a species-rich subfamily of freshwater fishes widely distributed in Southeast Asia. We specifically tested if the expansion of exposed lands and increased island connectivity during Pleistocene low sea levels (the paleoriver hypothesis) induced bursts of diversification.
Location
Sundaland.
Taxon
Rasborinae (Actinopterygii, Cypriniformes, Danionidae).
Methods
We aggregated 1,017 cytochrome oxidase I sequences and 79 mitogenomes to delineate Molecular Operational Taxonomic Units (MOTUs) and further reconstruct a time-calibrated phylogeny of Rasborinae. Ancestral area estimations were conducted using both island and paleoriver partitioning to examine the impact of island connectivity during Pleistocene sea-level changes on dispersal. Temporal trends of diversification are explored through statistical selection of best-fit models.
Results
The origin of Sundaland mitochondrial lineages is dated at c. 33 Ma and four major clades are identified, which diversified between c. 31 and 22 Ma. The Island of Borneo and North Sunda paleoriver are identified as the source of Sundaland Rasborinae. Geographical patterns of lineage divergence indicate that most divergence events occurred within islands and diversification under constant birth rate models are the most likely for all clades.
Conclusions
The geographical and historical context of diversification of mitochondrial lineages in Rasborinae provides little support for the paleoriver hypothesis. The onset of isolation of Borneo from mainland Asia triggered the initial diversification of the group (c. 31–22 Ma). The late colonization of Java and Sumatra occurred through several independent dispersal events, poorly explained by Pleistocene sea-level changes and frequently followed by in situ diversification.
... In short, despite competition for moisture among neighboring islands (e.g., Qian, 2007), the presence of a large number of islands in the MC provides a more conducive environment for increased precipitation in the MC islands. Our results are consistent with Sarr et al. (2019), who in a paleoclimate study showed that the Sunda shelf induced an increase in seasonal rainfall cycle over itself, with higher precipitation rates during the transitional rainy season. The shelf's response is characterized by the seasonal enhancement of moisture convergence and continental precipitation driven by the land surface's thermal properties. ...
... The shelf's response is characterized by the seasonal enhancement of moisture convergence and continental precipitation driven by the land surface's thermal properties. Sarr et al. (2019), however, did not estimate the effect of the Sunda shelf on neighboring islands. ...
The land‐sea contrast in the Maritime Continent (MC) has been found to influence the Madden–Julian Oscillation (MJO). However, the specific contribution from individual islands to the precipitation over the surrounding islands during MJO propagation is not well known. We found that when an island is removed in the presence of lower‐tropospheric westerlies, precipitation increases over islands that are located to its east due to the strengthening of the westerlies. Frictional convergence of the stronger westerlies, aided by Coriolis, leads to an increase in vertical advection of moisture and precipitation over an island located to the east. On the other hand, the reduced heating over the removed island reduces the westerlies and precipitation to the west of the removed island and is consistent with the response of large‐scale circulation to tropical heating. During background easterlies prior to MJO arrival, a systematic decrease in precipitation was found in the surrounding islands to the west side of the removed island. But, on the eastern side of the removed island, no systematic change in precipitation was found. The results imply that changes in large‐scale circulation in response to convection (or a lack thereof) over a removed island may significantly influence precipitation in the neighboring islands. Therefore, biases in model precipitation over an island in the MC may arise from bias in precipitation over a neighboring island. Moreover, the presence of different island chains in the MC has led to a more conducive environment for more overall precipitation over the islands in the MC.
... Jet position and AMOC have been improved, together with the sea-ice cover. IPSL-CM5A2 also benefits from higher parallelization (namely MPI-OpenMP in the atmosphere), which improves the model scalability and allows the model to reach ∼ 100 yr d −1 simulated on the JOLIOT-CURIE French supercomputer (Sarr et al., 2019;. We nonetheless first provide a validation of the model on modern climatic conditions for the Asian monsoon regions. ...
... Ce schéma a été modifié dans la version "nouvelle physique" du modèle LMDz6 , alors que les modèles précédents utilisaient le schéma de Tiedke [Tiedtke, 1989]. [Sarr et al., 2019] ...
Les moussons régissent le climat d’une large partie de l’Asie depuis le subcontinent indien jusqu’à l’est de la Chine actuellement. Leur mise en place et leur évolution restent cependant débattues et sont régulièrement réévaluées grâce à l’acquisition de nouveaux indicateurs climatiques. Des données récentes suggèrent que le régime de mousson en Asie fonctionnait déjà il y a environ 40 Ma, à l’Éocène supérieur, dans un contexte climatique globalement plus chaud et dans une configuration paléogéographique très différente d’aujourd’hui. Le but de cette thèse est d’étudier les conditions d’une mise en place des moussons asiatiques au cours de la période 42-33 Ma, englobant la fin de l’Éocène et la transition climatique majeure de l’Éocène-Oligocène. Nous balayons les différents champs d’incertitudes persistantes pour cette époque (paléogéographie, pCO2, niveau marin) et les différentes sources de variabilité climatique (le forçage orbital essentiellement). Nous utilisons le modèle de système- Terre IPSL-CM5A2, récemment adapté à l’étude des paléoclimats. En utilisant une première paléogéographie tardi-Éocène et une pCO2 de 1120 ppm, nous montrons dans un premier temps que le modèle simule des précipitations extrêmement saisonnières en Asie, sans pour autant présenter la circulation atmosphérique caractéristique des moussons. La sensibilité du climat et du couvert végétal tardi-Éocène aux paramètres orbitaux est ensuite évaluée à travers différents tests de sensibilité. Nous démontrons que les variations orbitales ont pu être un forçage majeur de variabilité climatique et biologique en Asie. Les configurations favorisant des gradients thermiques inter-hémisphériques importants (via des obliquités fortes et/ou des précessions induisant des étés boréaux chauds), en provoquant une migration accrue des masses d’air équatoriales humides sur le continent, génèrent des climats saisonnièrement très humides en été sur le sud-est asiatique. Plus globalement, le couvert végétal semble également très sensible aux variations orbitales dans les subtropiques et aux hautes latitudes. Ces résultats ouvrent de nouvelles pistes de réflexion sur de possibles relations entre forçage orbital, climat et ouverture de corridors de dispersion des faunes asiatiques vers l’Europe et l’Amérique (phénomènes nommés Grande Coupure). Enfin, nous comparons les circulations atmosphériques générées par des reconstructions paléogéographiques alternatives de la région asiatique. Elles testent par exemple différentes altitudes du plateau tibétain et différentes morphologies de la phase initiale de collision entre l’Inde et l’Asie, ces deux aspects étant encore extrêmement débattus. Pour finir, ces résultats sont mis en perspective en les comparant à des simulations climatiques à ∼34, ∼20 et ∼10 Ma. Le climat simulé en Asie apparaît finalement très peu sensible aux changements locaux de la paléogéographie indo-tibétaine. À l’inverse, nous notons l’apparition progressive des champs de pressions et des vents caractéristiques des moussons à mesure que le retrait de la mer Paratéthys et de la fermeture de l’océan Néotéthys permet l’exondation de la péninsule arabique et de l’Asie centrale, augmentant ainsi fortement la continentalité de la région. Nous suggérons ainsi que les gradients thermiques induits par la continentalité asiatique sur une échelle de temps géologique, ou par des paramètres orbitaux favorables sur une échelle de temps de quelques milliers d’années constituent les forçages dominants du régime des moussons en Asie.
