Ashok Kumar Singhvi Prof. Ashok Kumar Singhvi Planetary and Geosciences Division Physical Research Laboratory India If you would like to interview this scientist, please contact Leah Christen. > biographical information > abstract > paper

Biographical Information:

Ashok Kumar Singhvi is a nuclear physicist turned paleoclimatologist. His principal expertise is in luminescence dating of sediments, paleoclimates and paleoseismology/tectonics, and radiation effects in minerals. He has contributed to the development of luminescence dating and his methodologies have been widely used. He has applied this dating method extensively to a variety of sedimentary archives in India and elsewhere. He initiated the application of luminescence to drylands.

He led and participated in major programs on the sedimentary records from the Thar, Arabia, W. Sahara, Kalahari, Namibia and Mexico. His work brought out new concepts on “response time” of landforms and the “windows of opportunity” for creating a sedimentary record. This has major implications for the climate–landform relationship. He led two successful, UNESCO-sponsored International Geological Correlation Programmes on drylands and past monsoons.

He is a member of the science program committee of the UNESCO-IUGS initiative for the International Year of Planet Earth. He is also a member of the PAGES Scientific Steering Committee. Singhvi is a fellow of the Indian National Science Academy and the Third World Academy of Sciences, associate editor of Quaternary Research and member of the editorial board of Quaternary Science Reviews. He received the Farouk El-Baz Desert Research Award from the Geological Society of America in 2004, and the National Mineral Award in India in 2003.

Abstract:

Monsoon and Man in the Indian Subcontinent

In respect of its human dimensions, the Indian monsoon is perhaps the single most articulate weather system that determines the lives and the well being of a large proportion of humanity. The monsoon system in the region depends on a variety of parameters, ranging from solar variability to ENSO events to land-ocean temperature contrasts. Statistically valid correlation with up to 10 global parameters is seen. In an anticipated global warming scenario, two important aspects for the Indian context are, (i) the spatial variability and, (ii) the timing of rainfall events within a season. Both of these have a direct bearing on the aspects of food security and human migrations. Considerable effort has been made in understanding monsoon systematics, in part through rigorous and empirical modeling efforts. Analysis of rainfall trends from the instrumental records so far does not show significant deviation from the mean.

Considerable effort has also been made to reconstruct the paleo-record using a varied set of proxies that range from tree rings to desert sands, and using cores from tanks to deep ocean cores. Inferences from different sedimentary records of the Holocene have shown occasional discordance. For the more recent millennium, the records are even more confusing. For example, marine G. bulloides data have been used to suggest recent enhancement of the monsoon winds correlating to rising temperatures. Contrastingly, the instrumental data of the past century does not show any such trend. Rainfall reconstruction from man-made tanks also supports this inference. Tree-ring data from the Himalayas show an overall cooling trend in the same period. Similarly, the medieval warming and arid phase preceding it have been placed differently in different reconstructions. Archeological and historical records provide additional documentation of the monsoon. In this presentation, a synthesis of the current understanding of paleo-records along with an evaluation of the proxies and their chronometry will be presented.

Paper:

This paper will be released during the meeting.