Quaternary Climate Change over the Indian Subcontinent

Neloy Khare, Neloy Khare

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000391763
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Geology & Earth Sciences

Quaternary studies provide the essential context for evaluation of what is happening with the earth's climate today, and to clarify our vulnerability to hazardous natural processes. This book covers scientific aspects of past and present climatic changes of the quaternary period focused on the Indian subcontinent via response of modern environmental conditions on climate proxies, reconstruction of paleoclimate, paleomonsoon, glacial geology, climate variabilities using dendrochronology, cave deposits including quaternary tectonics and climate change over the Himalayan region. It consists of data generated from different landforms including lakes, caves, rivers, swamps, pits, and trenches using different proxies.

Aimed at researchers, graduate students, professionals in geology, geography and environmental sciences, micropaleontology, and Quaternary climate change, this book:

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• Studies Quaternary climate using various proxies in varied environments on the Indian sub-continent

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• Covers pertinent historical and environmental archives to understand the current climate scenario

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• Discusses the impact of climate change on biotic and abiotic components

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• Includes thorough review of paleoclimate change studies

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• Devotes significant space to glacial geology and all glacial climate proxies

1 Late Quaternary Climatic History of the Indian Subcontinent

A Review of the Data Sources on the Land and the Sea

S. Rajan

National Centre for Polar and Ocean Research (Formerly)

CONTENTS

Introduction: Background

Quaternary Climate System

Late Quaternary Climate of India

Multimillennial Scale Variability of the Indian Summer Monsoon

Millennial-Scale Variability of the Indian Summer Monsoon

Centennial to Multidecadal-Scale Variability of the Indian Summer Monsoon

Decadal-to-Interannual Scale Variability of the Indian Summer Monsoon

Summary

Acknowledgments

References

Introduction: Background

Natural climate change at all temporal scales, with or without human interference, represents one of the most fundamental issues of scientific and social concern today. With the perceived influence of climate change on all forms of ecosystem stresses including extreme natural events, there has been a subtle but definite transformation in the ongoing studies on climate change, from why it happens to how it has changed in the past and how it will change in the future. At first instance, this might sound paradoxical considering that the earth’s climate system especially at the centennial to the millennial scale (10²–10³ years) tends to be abrupt and rapid and hence difficult to predict. Furthermore, these changes do not follow a simple pattern and their impacts vary from region to region making it difficult to find analogs of a certain period in the geological record. In addition, these abrupt changes are superimposed upon the more cyclic multimillennial (10⁴–10⁵-year) responses of the earth system to variations in the orbital parameters or to the still longer time scales (>10⁶ years) related to plate tectonics.

Despite the challenges that complicate the picture of a changing climate through time, documentation of past climate remains an important element of earth system studies. A rationale for these studies stems from the observation that the processes related to the interactions among the ocean, atmosphere, geosphere, and the cryosphere, which drive/modulate the climate changes, tend to be cyclic. Therefore, it is only logical that with increased and better documentation of past climates, such cyclic recurrences and the driving forces behind them can be better understood and the climate models predicting future climates can be evaluated and fine-tuned where necessary. Increased knowledge is also the best way to improve the effectiveness of our response and, maybe, even to increase our ability to adapt to a changing climate.

This chapter is an attempt to present the late Quaternary climatic history of the Indian subcontinent through a review of some of the recently published studies carried out utilizing proxy data from the terrestrial and offshore areas as well as model simulations. The emphasis is on the last ~100 kyr (=100,000 years) spanning the Holocene and the last glaciation for which relatively detailed information is available. The choice of the late Quaternary timeframe was dictated by three considerations: (1) Late Quaternary climate during much of the last glacial period has been documented to be highly unstable marked by abrupt and rapid quasi-periodic shifts in temperature that occurred on decadal time scales and lasted for a few centuries (described further, below). (2) Correlative multi-proxy records of such climatic perturbations at temporal resolutions ranging from decadal-to-centennial and beyond are available from the offshore and terrestrial environments of the Indian sub-continent. (3) At a shorter interannual scale, instrument and proxy records as well as model results indicate marked variability in Indian summer monsoon (ISM) precipitation over the past 1–2 millennia (e.g. Berkelhammer et al., 2010; Feng and Hu, 2008; Goswami et al., 2006; Sinha et al., 2007). The forcing functions behind these precipitation variations remain topics of academic debate and call for careful consideration to understand the full spectrum of monsoon behavior on all time scales.

There have been many review papers of late on the paleoclimate studies in India focused on both terrestrial and marine realms. One of the early reviews of the Asian and Indian paleomonsoon variability at different time scales, from tectonic to centennial, has been by Clemens (2006). Singhvi and Kale (2010) published a comprehensive status report on the paleoclimate of India and adjacent regions as a part of the IGBP-WCRP-SCOPE-Report series, detailing the key issues in climate change studies and some of the salient results from marine and terrestrial proxy records. Tiwari et al. (2009, 2011) provided reviews on the spatial and temporal variability in multiproxy paleomonsoon records from the Indian region during the past 30 kyr and since the last glacial maximum (LGM) respectively. Gupta et al. (2012) described the paleoceanographic studies carried out by Indian scientists in the Arabian Sea and the Bay of Bengal sectors of the Indian Ocean between 2006 and 2012. Some of the other notable reviews of the Quaternary monsoon history of India based on terrestrial and/or marine proxy records from the Indian subcontinent and the adjoining seas are by Saraswat et al. (2014), Achyuthan et al. (2016), and Ramesh et al. (2017). Most recently, Krishnan et al. (2020) have brought out an edited volume providing an assessment of the Indian climate system and its short-term variability based on observational data and analyses, as a report of the Ministry of Earth Sciences, Government of India. The present chapter is an update to these reviews with consideration of all recent contributions published up to June 2020.

Quaternary Climate System

The Quaternary period encompassing the last ~2.6 million years of earth history has essentially been one of frigidity with the climate being cold enough over 90% of the timespan to support major ice sheets (Holmgren and Karlen, 1998). Proxy records of late Quaternary climate derived from deep-sea sediments and Antarctic ice cores show a repeating pattern of glacial (cold and arid)/interglacial (warm and humid) cycles characterized by a 100-kyr periodicity, with global temperature differences between the cycles averaging 9°C–12°C (Petit et al., 1999; Shackleton, 2000). Such transitions between the glacial and the interglacial conditions have been suggested to have been paced by cyclical variations in the summer insolation at high latitudes in the northern hemisphere. Three major cycles of earth’s orbital variability around the sun (“Milankovitch cycles”) recur over time associated with eccentricity (100-kyr cycles), obliquity (41-kyr cycle), and precession (23-kyr cycle; e.g. Hays et al., 1976; Imbrie and Imbrie, 1979; Sharaf and Boudnikova, 1967). The insolation variability is also strongly modulated by such global boundary conditions as atmospheric CO₂, sea level, ice-sheet extent, and sea surface temperature (Labeyrie et al., 2003).

Despite a consensus on the role of orbital-scale forcing on earth’s climate, the mechanism(s) by which these changes in insolation pace the timing of the climate cyclicity remain matters of debate. There is also an element of uncertainty with regard to which of the two orbital elements – obliquity and precession – paced the dominant 100 kyr glacial–interglacial cycles of the Quaternary, considering that the 100 kyr eccentricity band is small in the insolation spectrum (e.g. Feng and Bailer-Jones, 2015; Imbrie et al., 1989, 1993). Furthermore, the extent to which the feedbacks from processes internal to the climate system such as, for example, from the continental ice sheet and other climate components, including the atmospheric concentration of water vapor, CO₂, and other gases, as well as the atmospheric concentration of volcanic dust and variations in the cloud cover impact the external orbital forcing is also not well known (Labeyrie et al., 2003; Shackleton, 2000).

Superimposed on the orbital-scale variations are centennial to millennial-scale events marked by large, abrupt, and rapid alternations between stadial (cold) and interstadial (warm) conditions in time scales of a decade or so and which persist over hundreds to one thousand years ago or longer. First recognized in the Greenland ice cores from within the ~30–80 kyr BP interval (Baldini et al., 2015; Bond et al., 1993; Dansgaard et al., 1984; Oeschger et al., 1984), correlative evidences of such abrupt climate perturbations referred to as “Dansgaard–Oeschger cycles or D–O cycles” have been documented from several parts of the world, from the Greenland ice cores to the marine and terrestrial sedimentary records as well as from the Antarctic peninsula (e.g. Behl and Kennett, 1996; Bender et al., 1994; Blunier et al., 1998; Charles et al., 1996; Clark and Bartlein, 1995; Cowley, 1992; Curry and Oppo, 1997; Deplazes et al., 2013; EPICA Community Members, 2006; Genty et al., 2003; Greenland Ice-core Project (GRIP) Members, 1993; Kanner et al., 2012; Keigwin et al., 1994; Kennett and Ingram, 1995; Leduc et al., 2007; Leuschner and Sirocko, 2000; Mayewski et al., 1996; Oeschger et al., 1984; Oppo and Lehman, 1995; Porter and Ann, 1995; Schmidt and Hertzberg, 2011; Schulz et al., 1998; Stocker et al., 1992; Street-Perrot and Perrot, 1990; Wang et al., 2001; also Rajan and Khare, 2002, for an overview). Similar millennial-scale changes probably occurred during previous ice ages as well (Franco et al., 2012; Thouveny et al., 1994; Voelker, 2002).

The synchronous global signature of these abrupt climate changes has been suggested to be indicative of the potential for a global response related to an initial forcing linked to the instabilities of the Northern Hemisphere ice sheets and consequent variations in freshwater flux to the North Atlantic, or feedback related to Atlantic thermohaline circulation, the effects in both cases being transmitted and amplified elsewhere by way of oceans and/or atmosphere (e.g. Alley, 1995; Broecker, 1994, 1995; Rahmstorf, 2002). Other hypotheses for the origin of these millennial-scale cycles involve rhythmic solar forcing (Bond et al., 2001) or internal oscillations of the coupled ocean-atmosphere system (e.g. Alley et al., 2001).

Nested within the millennial-scale climate cycles are abrupt submillennial to decadal events, during which the climate has been documented to change from one state to another. High-resolution observational records from terrestrial, marine, and ice cores and model simulations, show that paleoclimate trends over the late Quaternary and especially during the Holocene period have been punctuated by significant fluctuations at century to multidecadal time scales (Steffensen et al., 2008). These fluctuations are mostly marked from the LGM (21 ± 2 calendar ka BP) to the present day. At least some of these climatic fluctuations have been proposed to be the result of melt-water-driven changes in the Atlantic meridional overturning circulation – the large-scale oceanic overturning circulation that transports heat from the South Atlantic to the North Atlantic high latitudes. For example, in some regions of Europe, monthly temperatures increased by >15°C over a century during the Bølling–Allerød (B–A) warming event (14,700–12,900 BP) and cooled by >10°C ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Foreword
• Preface
• Acknowledgments
• Editors
• Contributors
• Chapter 1 Late Quaternary Climatic History of the Indian Subcontinent: A Review of the Data Sources on the Land and the Sea
• Chapter 2 The Climatic and Anthropogenic Influences on Himalayan Glacial and Non-Glacial Lakes: A Review
• Chapter 3 Holocene to Present Monsoon Variability in Peninsular India as Reflected in Lake and Marine Sediment Records: A Review
• Chapter 4 Speleothems, Monsoon, and Holocene–Quaternary Climate: A Review from the Indian Subcontinent
• Chapter 5 A 45 ka Record of Productivity in the Western Bay of Bengal: Implications on the Indian Monsoon and Atlantic Climate
• Chapter 6 The Interplay of Mid to Late Holocene Tectonism and Northeast Monsoon on the Landscape Evolution: Palar River Basin, Southern Peninsular India
• Chapter 7 Importance of the Geochemistry of Northern Indian Ocean Sediments for Assessing the Quaternary Climate Change and Future Directions
• Chapter 8 Pollen Analysis and Paleoenvironmental Studies of Archeological Deposits from the Konkan Coast of India
• Chapter 9 Revisiting Late Quaternary Sea Levels along the Indian Sub-Continent with a Novel Approach in the Face of Climate Change
• Chapter 10 Evaluation of Recent and Paleo-Tsunami Deposits over Indian Subcontinents through Multiproxy Clues
• Chapter 11 Ostracod Diversity from Continental Slope Sediments of Gulf of Mannar, India: Bathymetry and Ecological Variations
• Chapter 12 Ecological Assessment of Recent Benthic Ostracoda, Off Kurusadai Island, Gulf of Mannar, India
• Chapter 13 A Study on Benthic Foraminifera, Texture, and Sediment Geochemistry along the Depositional Environment of Palk Strait, East Coast of India
• Chapter 14 Quaternary Faunal Records from Upper Reaches of Sina Basin: A Case Study of Math Pimpri – An Early Historic Site
• Glossary
• Index