The ISM is a central feature of the Earth’s climate system that directly impacts over 1 billion people. Little is known about its log-term variability at human timescales, however, because few high-resolution terrestrial records of Holocene ISM rainfall are available from key centers of action. This work will develop four such records in order to (i) place modern ISM variability into a historical context, (ii) test hypotheses for the climate mechanisms controlling the ISM and (iii) provide data for validation of global climate models. By combining proxies that are sensitive to local and synoptic precipitation we will investigate ISM variability at multiple spatial and temporal scales, thereby providing new insight into how this system responds to abrupt and long-term changes in climate boundary conditions. Ultimately, our objective is to provide a paleoclimate context for ISM variability and empirical inputs for climate models that will allow for better predictions of future changes. Such information is essential for mitigating and/or adapting to ISM rainfall variability under global warming.



In collaboration with colleagues from the Institute of Tibetan Plateau Research -Chinese Academy of Sciences, we are investigating Indian summer monsoon (ISM) variability during the Holocene with decadally resolved sediment records from four alpine lakes on the southeastern Tibetan Plateau. This research builds on our previous NSF-supported work in the Nyainqentanglha Mountains, which are a major center of action in the ISM system and a primary gateway for moisture entering the Tibetan Plateau. With this work, we will reconstruct local ISM variability with physical sedimentology and geochemistry and synoptic variability with hydrogen isotope measurements on terrestrial leaf waxes. The results will be synthesized with paleoclimate records from the Tibetan Plateau and surrounding region, as well as with records from key regions in the global climate system to address central questions about Holocene ISM variability.


Ph.D. Position Available: The PSL is currently seeking applicants that wish to pursue a Ph.D. paleoclimatology in the Department of Earth Sciences at IUPUI. The student will work on NSF funded research related to Holocene Indian summer monsoon variability as recorded in a series of lake sediment archives from the Tibetan Plateau. The research will include extensive fieldwork in addition to a variety of laboratory and analytical activities. Familiarity with sediment cores, physical sedimentology and isotope geochemistry is desired, but not essential. Those with, or close to completing, a M.Sc. are particularly encouraged to apply. Interested candidates should send their C.V. and transcripts (copies are fine) as a single PDF file directly to Dr. Broxton Bird (bwbird@iupui.ediu). Please contact Dr. Bird with any questions about the position


This research is funded by the United States National Science Foundation award EAR-1023547 and the Chinese National Natural Science Foundation award 41150110153.

 

Figure 1 Map of the Tibetan Plateau and surrounding area.  The target region for this proposal is boxed in red. The thick dashed lines demarcate the region of Tibet influenced by the ISM with the Himalaya to the south and the Tanggula Mtns. to the north. ISM Moisture is derived from the Bay of Bengal and delivered and deliverd to the Tibetan Plateau via the Brahmaputra River Valley and the Nyainqentanglha Mountains.

Reconstructing Holocene Indian summer monsoon variability with decadally-resolved Tibetan lake sediments

Tibet