Publications by authors named "Tripti Bhattacharya"

3 Publications

  • Page 1 of 1

Past climates inform our future.

Science 2020 11;370(6517)

Department of Oceanography, Texas A&M University, College Station, TX, USA.

As the world warms, there is a profound need to improve projections of climate change. Although the latest Earth system models offer an unprecedented number of features, fundamental uncertainties continue to cloud our view of the future. Past climates provide the only opportunity to observe how the Earth system responds to high carbon dioxide, underlining a fundamental role for paleoclimatology in constraining future climate change. Here, we review the relevancy of paleoclimate information for climate prediction and discuss the prospects for emerging methodologies to further insights gained from past climates. Advances in proxy methods and interpretations pave the way for the use of past climates for model evaluation-a practice that we argue should be widely adopted.
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http://dx.doi.org/10.1126/science.aay3701DOI Listing
November 2020

Glacial changes in tropical climate amplified by the Indian Ocean.

Sci Adv 2018 Dec 12;4(12):eaat9658. Epub 2018 Dec 12.

National Center for Atmospheric Research, Climate and Global Dynamics Laboratory, 1850 Table Mesa Drive, Boulder, CO 80305, USA.

The mechanisms driving glacial-interglacial changes in the climate of the Indo-Pacific warm pool are poorly understood. Here, we address this question by combining paleoclimate proxies with model simulations of the Last Glacial Maximum climate. We find evidence of two mechanisms explaining key patterns of ocean cooling and rainfall change interpreted from proxy data. Exposure of the Sahul shelf excites a positive ocean-atmosphere feedback involving a stronger surface temperature gradient along the equatorial Indian Ocean and a weaker Walker circulation-a response explaining the drier/wetter dipole across the basin. Northern Hemisphere cooling by ice sheet albedo drives a monsoonal retreat across Africa and the Arabian Peninsula-a response that triggers a weakening of the Indian monsoon via cooling of the Arabian Sea and associated reductions in moisture supply. These results demonstrate the importance of air-sea interactions in the Indian Ocean, amplifying externally forced climate changes over a large part of the tropics.
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http://dx.doi.org/10.1126/sciadv.aat9658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6291310PMC
December 2018

Cultural implications of late Holocene climate change in the Cuenca Oriental, Mexico.

Proc Natl Acad Sci U S A 2015 Feb 26;112(6):1693-8. Epub 2015 Jan 26.

Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94550.

There is currently no consensus on the importance of climate change in Mesoamerican prehistory. Some invoke drought as a causal factor in major cultural transitions, including the abandonment of many sites at 900 CE, while others conclude that cultural factors were more important. This lack of agreement reflects the fact that the history of climate change in many regions of Mesoamerica is poorly understood. We present paleolimnological evidence suggesting that climate change was important in the abandonment of Cantona between 900 CE and 1050 CE. At its peak, Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants. The site is located in the Cuenca Oriental, a semiarid basin east of Mexico City. We developed a subcentennial reconstruction of regional climate from a nearby maar lake, Aljojuca. The modern climatology of the region suggests that sediments record changes in summer monsoonal precipitation. Elemental geochemistry (X-ray fluorescence) and δ(18)O from authigenic calcite indicate a centennial-scale arid interval between 500 CE and 1150 CE, overlaid on a long-term drying trend. Comparison of this record to Cantona's chronology suggests that both the city's peak population and its abandonment occurred during this arid period. The human response to climate change most likely resulted from the interplay of environmental and political factors. During earlier periods of Cantona's history, increasing aridity and political unrest may have actually increased the city's importance. However, by 1050 CE, this extended arid period, possibly combined with regional political change, contributed to the city's abandonment.
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http://dx.doi.org/10.1073/pnas.1405653112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4330754PMC
February 2015