Reconstruction of the variability of the southwest monsoon during the past 3 ka, from the continental margin of the southeastern Arabian Sea

Chauhan, O.S.; Vogelsang, E.; Basavaiah, N.; Kader, U. Syed Abdul

doi:10.1002/jqs.1359

Cited by 55 publications

(47 citation statements)

References 64 publications

(120 reference statements)

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“…Recent foraminifer-based records of Govil and Naidu [2011] and Chauhan et al [2010] suggests increased monsoon variability after ca. 3,500 and 2,200 years BP respectively whereas a speleothem record from NE India [Adkins et al, 2011;Breitenbach, 2010] shows increased monsoon variance in the last $2,000 years.…”

Section: Monsoon Variability In the Core Monsoon Zonementioning

confidence: 99%

Holocene aridification of India

Ponton

Giosan

Eglinton

et al. 2012

Geophysical Research Letters

210

196

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Spanning a latitudinal range typical for deserts, the Indian peninsula is fertile instead and sustains over a billion people through monsoonal rains. Despite the strong link between climate and society, our knowledge of the long‐term monsoon variability is incomplete over the Indian subcontinent. Here we reconstruct the Holocene paleoclimate in the core monsoon zone (CMZ) of the Indian peninsula using a sediment core recovered offshore from the mouth of Godavari River. Carbon isotopes of sedimentary leaf waxes provide an integrated and regionally extensive record of the flora in the CMZ and document a gradual increase in aridity‐adapted vegetation from ∼4,000 until 1,700 years ago followed by the persistence of aridity‐adapted plants after that. The oxygen isotopic composition of planktonic foraminiferGlobigerinoides ruberdetects unprecedented high salinity events in the Bay of Bengal over the last 3,000 years, and especially after 1,700 years ago, which suggest that the CMZ aridification intensified in the late Holocene through a series of sub‐millennial dry episodes. Cultural changes occurred across the Indian subcontinent as the climate became more arid after ∼4,000 years. Sedentary agriculture took hold in the drying central and south India, while the urban Harappan civilization collapsed in the already arid Indus basin. The establishment of a more variable hydroclimate over the last ca. 1,700 years may have led to the rapid proliferation of water‐conservation technology in south India.

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Section: Monsoon Variability In the Core Monsoon Zonementioning

confidence: 99%

Holocene aridification of India

Ponton

Giosan

Eglinton

et al. 2012

Geophysical Research Letters

210

196

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“…In the eastern Arabian Sea, small annual mean SST variability (less than 1 0 C) reconstructed on G. ruber contrasts with the increased seasonality indicated by coeval temperature record on G. bulloides over the past -4,000 years [Anand et al, 2008], lending further support to the idea that 6'0O., excursions primarily reflect changes in monsoon variability. Recent foraminifer-based records of Govil and Naidu [2011] and Chauhan et a. [2010] suggests increased monsoon variability after ca.…”

Section: L03704 L03704mentioning

confidence: 99%

Aridification of the Indian subcontinent during the Holocene : implications for landscape evolution, sedimentation, carbon cycle, and human civilizations

Ponton¹

2012

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The Indian monsoon affects the livelihood of over one billion people. Despite the importance of climate to society, knowledge of long-term monsoon variability is limited. This thesis provides Holocene records of monsoon variability, using sediment cores from river-dominated margins of the Bay of Bengal (off the Godavari River) and the Arabian Sea (off the Indus River). Carbon isotopes of terrestrial plant leaf waxes (6 13 Cwax) preserved in sediment provide integrated and regionally extensive records of flora for both sites. For the Godavari River basin the 61 3 Cwax record shows a gradual increase in aridity-adapted vegetation from ~4,000 until 1,700 years ago followed by the persistence of aridity-adapted plants to the present. The oxygen isotopic composition of planktonic foraminifera from this site indicates drought-prone conditions began as early as -3,000 years BP. The aridity record also allowed examination of relationships between hydroclimate and terrestrial carbon discharge to the ocean. Comparison of radiocarbon measurements of sedimentary plant waxes with planktonic foraminifera reveal increasing age offsets starting -4,000 yrs BP, suggesting that increased aridity slows carbon cycling and/or transport rates. At the second site, a seismic survey of the Indus River subaqueous delta describes the morphology and Holocene sedimentation of the Pakistani shelf and identified suitable coring locations for paleoclimate reconstructions. The 6 3 Cwax record shows a stable arid climate over the dry regions of the Indus plain and a terrestrial biome dominated by C 4 vegetation for the last 6,000 years. As the climate became more arid 4,000 years, sedentary agriculture took hold in central and south India while the urban Harappan civilization collapsed in the already arid Indus basin. This thesis integrates marine and continental records to create regionally extensive paleoenvironmental reconstructions that have implications for landscape evolution, sedimentation, the terrestrial organic carbon cycle, and prehistoric human civilizations in the Indian subcontinent. 3 4A mi Tito y mi Sense, por haberme despertado el interes por la Ciencia. 5Creo muy poco en lo que veo. Y de lo que me cuentan... nada.-Juan Siyago 6 Acknowledgements I am indebted to my Advisors for their unconditional support and generosity with their ideas and their time. Thank you for keeping me afloat when the seas were rough and I had started to drown. I learned that persistence is key and Science is humbling. Through this journey Liviu's tenacity and strong guidance, and Tim's enthusiasm and optimistic outlook delivered me safely to shore.I will like to thank my committee members and Chair for their invaluable contributions to improve this thesis, but most importantly for their continuous support, concern and encouragement through out these years. Delia, for always being my advocate and offering your experience to suggest alternative solutions. Valier, I have learned immensely from you in the lab and our discussions have always been frui...

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“…Hence, this time bracket is probably showing the generally cold and arid climate of the Little Ice Age (LIA) after which the southwest monsoon got intensified. The relatively high rainfall during the MWP and low rainfall during the LIA are also documented in other palaeomonsoon records from the region (Agnihotri et al 2002;Tiwari et al 2005;Chauhan et al 2010a ; Fig. 6).…”

Section: The 1000 Cal Years Bp To the Present Periodmentioning

confidence: 69%

“…6). Chauhan et al (2010a) documented arid periods around 450-650, 1000 and 2200-1800 cal. years BP Bryson and Swain (1981) documented scanty rainfall around 2000 cal.…”

Section: The~3100-2500 Cal Years Bp Periodmentioning

confidence: 97%

“…The pollen sequences from the respective sites have also offered insights into the changing floristic patterns and the coeval climatic episodes. Besides pollen, other proxies like foraminifera (Nagender Nath et al 2012;Bassinot et al 2011;Banakar et al 2010;Khare et al 2008), foraminiferal isotopic and elemental data (Saraswat et al 2013), rock magnetic properties (Anil Kumar et al 2005;Thamban et al 2007), oxygen isotopes (Prabhu et al 2004), nitrogen isotopes (d 15 N; Agnihotri et al 2008), geochemical parameters (Chauhan et al 2010a), biomarkers (Kurian et al 2009), and clay mineral data (Chauhan et al 2010a) of marine sediments have also been employed in reconstructing the palaeoclimate of the region. However, most of these do not provide much information on the important climatic events of the Holocene.…”

Section: Introductionmentioning

confidence: 99%

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Vegetational and climatic variations during the past 3100 years in southern India: evidence from pollen, magnetic susceptibility and particle size data

Bhattacharyya¹,

Sandeep

Misra

et al. 2015

Environ Earth Sci

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Vegetational history vis a vis climate change during the past 3100 cal. years BP was deciphered from pollen data supplemented with magnetic susceptibility and particle size data for a 2.5 m long sediment core from Pookot Lake, Kerala, southern India. Pollen data suggest a mixed assemblage of upland tropical elements and wetland mangrove taxa. The presence of trace amounts of pollen grains of montane taxa like Betula, Pinus and Alnus points to their long distance dispersal. Pollen grains of Ixora, Syzygium, Symplocos, Moraceae and Arecaceae that represent tropical vegetation were also recovered, indicating modern vegetation in and around Pookot Lake. Mangrove elements are mostly represented by species of Rhizophora and Ceriops decandra along with other taxa. High-rainfall periods are characterised by high sand % and low clay % and vice versa. The pollen data correspond well with magnetic susceptibility and particle size data. The data obtained suggest three broad phases of climate, with minor oscillations, during the past 3100 cal. years BP: (1) wet climate during 3100-2500 cal. years BP; (2) dry climate spanning a long period that ended around 1000 cal. years BP; (3) amelioration in climate after 1000 cal. years BP, reflected in the presence of luxuriant vegetation and high magnetic susceptibility values.

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Reconstruction of the variability of the southwest monsoon during the past 3 ka, from the continental margin of the southeastern Arabian Sea

Cited by 55 publications

References 64 publications

Holocene aridification of India

Holocene aridification of India

Aridification of the Indian subcontinent during the Holocene : implications for landscape evolution, sedimentation, carbon cycle, and human civilizations

Vegetational and climatic variations during the past 3100 years in southern India: evidence from pollen, magnetic susceptibility and particle size data

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