Overview

The Indian Monsoon, a subsystem of the Asian Monsoon, is one of the best examples of coupling between solid Earth and atmospheric processes. Climate and vegetation are known to be interlinked on multiple timescales, but the specific impact of monsoon precipitation on sub-tropical vegetation is poorly constrained. A recent study demonstrate that the shift from C3- to C4-dominated biomes occurred during the late Pliocene in response of the seasonal summer monsoon precipitation in Australia [1], which is much later than reported from Asia, Africa, and the Americas. Records from the Indian Monsoon region indicates precipitation and vegetation linkages during the late Miocene [2] and during glacial-interglacial intervals of the late Pleistocene [3]. Our ongoing work at International Ocean Discovery Programme (IODP) Expedition sites indicate Indian Summer Monsoon variability with the ice-volume increase linked to the intensification of Northern Hemisphere Glaciation (iNHG) in the Pliocene, as well as long term evolution since 10 Ma at. However, these records have yet to be coupled with vegetation and fire history. This project will apply multi-proxy micropalaeontological and geochemical methods to reconstruct vegetation, aridity, wildfire, and seasonality of monsoon runoff on a variety of time scales (500 yr – sub-millennial, 2 kyr – sub-orbital or 100 kyr – sub-tectonic), depending on the candidate’s interest, from the core Indian Monsoon region of the Bay of Bengal and Andaman Sea. These records will address key questions: What is the response of vegetation to changing monsoon precipitation and vice a versa at (sub) millennial, (sub) orbital and longer timescales? Was the aridity of the Indian subcontinent temporally linked with Indian monsoon evolution? Is there a link between wildfire occurrence, monsoon intensity and vegetation type? How are Indian Summer Monsoon vegetation dynamics is linked to the other Asian and global Monsoon regions? The new records from this project will be compared with published terrestrial records to identify the nature of the linkage between the Indian, Asian and global monsoons.

This project will primarily utilise newly drilled continuous sedimentary successions from the Bay of Bengal and Andaman Sea (IODP Expedition 353, Sites U1445/46 and U1447/48).

The student will reconstruct past environmental change focusing on the following parameters:

  • vegetation history using fossil pollens and spores
  • macro and micro-charcoal abundances

There is a strong possibility to include reconstruction of seasonal rainfall using coupled trace elements and oxygen isotope in planktic foraminifera and/or organic geochemical proxies.

Figure 1:  The IODP Sites (U1445/46 and U1447/48) in the Bay of Bengal and Andaman Sea. New records from this project will compare records from Indian and East Asian Monsoon regions.

Methodology

The deep-sea mud samples will be extracted for macrocharcoal (>180 mm) and finer fraction for pollens, microcharcoal and spores in the fully equipped laboratories at The Open University using acid digestion techniques, and will be examined and classified using transmitted light microscopy (supervisor Dr Mander). Regional taxonomic identification of pollens will allow us to infer changes in vegetation on land in comparison with existing monsoon runoff variation data (supervisor Dr Bhagwat). Detailed charcoal work will be carried out to reconstruct fire history (in collaboration with Dr Belcher at the University of Exeter). Additionally, geochemical work to reconstruct seasonal monsoon temperature and precipitation for the targeted intervals will be investigated using coupled trace elements and oxygen isotope composition of individual planktic foraminifera (Dr Anand) and additionally organic geochemical proxies will be used to determine trends in the vegetation type (with supervisor Dr Littler at the University of Exeter ).

Training and Skills

The student will have the opportunity to gain experience in a wide variety of laboratory techniques including deep-sea sample processing, palynology (pollen identification) and geochemical techniques provided at the state of the art facilities at The Open University and University of Exeter. The student will interact with Dr Belcher’s group at the University of Exeter on charcoal work. Additionally, there is a strong possibility to explore geochemical techniques such as individual planktic foraminifera oxygen isotope and trace element measurements (in collaboration with Dr Hathorne) and organic geochemical proxies (Dr Littler at the University of Exeter), if interested. Finally the monsoon intensity record will be placed in context with global vegetation and climate records.

Specific skills that will be acquired during this project:

  • Conducting research on deep-sea sediments from Indian margin and Andaman Sea sites (IODP Expedition 353) and working with a transdisciplinary international team
  • Palynology and geochemical analyses
  • Data handling and interpretation from a wide variety of sources
  • Scientific communication through writing, poster and oral presentations to academic and non-academic audiences
  • Online teaching opportunities via the Open University Virtual Learning Environment are also available, including teaching on the new Massive Open Online Courses (MOOCs).

Timeline

Year 1: Obtain training in sample processing of core material for palynology (taxonomy) and geochemical proxies. Process samples to generate a low resolution vegetation and fire change record.

Year 2: Present preliminary data at the UK-IODP meeting. Generate vegetation and aridity and seasonal precipitation variability records from two sites on a variety of time scales.

Year 3–3.5: Finish remaining analytical work, data analyses, and present results at an international conference and write up thesis and manuscripts.

Partners and collaboration (including CASE)

This project will benefit from international collaborations and networking opportunities with IODP 353 expedition scientists. In particular there will be collaboration with Dr. Belcher (University of Exeter) on charcoal, Ed Hathorne (GEOMAR, Germany) on individual foraminifera geochemistry, and Marie-Curie fellow Dr. Charuta Kulkarni at the Open University working on Holocene Indian pollens and charcoal. Additionally, collaboration with shore-based scientists working on the long term evolution of vegetation and climate is likely. In addition, there will be collaborative opportunity across CENTA.

Further Details

Students should have an understanding of Earth System with enthusiasm for learning and applying multi-proxy palynological tools. Experience of palaeoclimate research is desirable. The student will join a well-established team researching on palaeoclimate proxies at the Open University and the University of Exeter.

Please contact Pallavi Anand (pallavi.anand@open.ac.uk) for further information.

Applications must include: