Leaf physiognomy records the Miocene intensification of the South Asia Monsoon

Bhatia, Harshita; Srivastava, Gaurav; Spicer, Robert A.; Farnsworth, Alexander; Spicer, Teresa E.V.; Mehrotra, RC; Paudayal, Khum N.; Valdes, Paul J.

doi:10.1016/j.gloplacha.2020.103365

Cited by 25 publications

(5 citation statements)

References 93 publications

(151 reference statements)

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“…The HM itself has little impacts on the development of the SASM in the western region. The enhanced precipitation at 13 Ma inferred from leaf fossil in the eastern HM is suggested to attribute to the rise of the HM (Bhatia et al, 2021). This monsoon-HM linkage cannot be replicated by our experiments.…”

Section: Application To Monsoonal Reconstructionscontrasting

confidence: 66%

South Asian summer monsoon enhanced by the uplift of Iranian Plateau in Middle Miocene

Zuo

Sun

Zhao

et al. 2022

Preprint

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Abstract. The South Asian summer monsoon (SASM) remarkably strengthened during the Middle Miocene (16–11 Ma), coincident with the rapid uplifts of the Iranian Plateau (IP) and the Himalaya (HM). Although the development of the SASM has long been linked to the topographic changes in the Tibetan Plateau (TP) region, the effects of the HM and IP uplift are still vigorously debated, and the underlying mechanisms remain unclear. Based on Middle Miocene paleogeography, we employ the fully coupled earth system model CESM to perform a set of topographic sensitivity experiments with altered altitudes of the IP and the HM. Our simulations reproduce the strengthening of the SASM in northwestern India and over the Arabian Sea, largely attributing to the thermal effect of the IP uplift. The elevated IP insulates the warm and moist airs from the westerlies in the south of the IP and produces a low-level cyclonic circulation around the IP, which leads to the convergence of the warm and moist air in the northwestern India and triggers positive feedback between the moist convection and the large-scale monsoon circulation, further enhancing the monsoonal precipitation. Whereas the HM uplift produces orographic precipitation without favorable circulation adjustment for the SASM. We thus interpret the intensification of the Middle Miocene SASM in the western part of the South Asia as a response to the IP uplift while the subtle SASM change in eastern India reflects the effects of the HM uplift.

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Section: Application To Monsoonal Reconstructionscontrasting

confidence: 66%

South Asian summer monsoon enhanced by the uplift of Iranian Plateau in Middle Miocene

Zuo

Sun

Zhao

et al. 2022

Preprint

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“…Note that T w msl values ( Table 1 ) for the Lutetian are similar to those for the Oligocene, which is seemingly counterintuitive in the context of secular climate change inferred from deep-sea isotopes ( 32 ). This is because T w msl is dependent on evaporative processes, and summer vapor pressure deficit at the closest sea level reference sites in northern India derived from the Climate Leaf Analysis Multivariate Program (CLAMP) ( 46 ) was higher in the Eocene (the air was drier) than in the Oligocene. The drier Eocene conditions will have induced more evaporative cooling and reduced the T w msl for the Eocene to near those of the Oligocene.…”

Section: Resultsmentioning

confidence: 99%

The rise and demise of the Paleogene Central Tibetan Valley

et al. 2022

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Reconstructing the Paleogene topography and climate of central Tibet informs understanding of collisional tectonic mechanisms and their links to climate and biodiversity. Radiometric dates of volcanic/sedimentary rocks and paleotemperatures based on clumped isotopes within ancient soil carbonate nodules from the Lunpola Basin, part of an east-west trending band of basins in central Tibet and now at 4.7 km, suggest that the basin rose from <2.0 km at 50 to 38 million years (Ma) to >4.0 km by 29 Ma. The height change is quantified using the rates at which wet-bulb temperatures ( T w ) decline at land surfaces as those surface rise. In this case, T w fell from ~8°C at ~38 Ma to ~1°C at 29 Ma, suggesting at least ~2.0 km of surface uplift in ~10 Ma under warm Eocene to Oligocene conditions. These results confirm that a Paleogene Central Tibetan Valley transformed to a plateau before the Neogene.

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“…A similar reconstruction based on fossil leaves suggested the existence of a tropical evergreen forest and a warm humid climate at low elevations in the Eastern Himalaya during the Plio-Pleistocene (Khan et al, 2011). Other recent leaf fossil-based studies in the eastern Himalaya (Bhatia et al, 2021;Hazra et al, 2020) reported a slightly warmer, wetter, and more humid Neogene climate in the region, although Khan et al (2019) found that overall, the regional climate has been remained unchanged over the last 15 million years. In terms of glaciation history, it is a matter of consensus that East Asia was generally less glaciated compared to North America and Europe (Shi & Yao, 2002), with most of the glaciers being localized in the Himalaya and the Tibetan Plateau.…”

Section: Range Dynamics Under Past Climate Changementioning

confidence: 91%

“…A similar reconstruction based on fossil leaves suggested the existence of a tropical evergreen forest and a warm humid climate at low elevations in the Eastern Himalaya during the Plio‐Pleistocene (Khan et al., 2011 ). Other recent leaf fossil‐based studies in the eastern Himalaya (Bhatia et al., 2021 ; Hazra et al., 2020 ) reported a slightly warmer, wetter, and more humid Neogene climate in the region, although Khan et al. ( 2019 ) found that overall, the regional climate has been remained unchanged over the last 15 million years.…”

Section: Impact Of Climate Change On Plant Distributionmentioning

confidence: 97%