Reconstructing Monsoon and Climate Variability from Naimona'nyi Ice Cores, Southwest Himalayas

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

This project funds the recovery of two ice cores to bedrock from the Naimona'nyi ice field (30o 27.06N; 81o 19.94' E, 6100 meters above sea level) in the western Tibetan Himalayas and to produce a long, high resolution multi-proxy climate history, including monsoonal variability, for this data-sparse region. The Naimona'nyi ice field is in a distinctly different climate regime from the four previous ice cores recovered from the Tibetan Plateau (TP). This ice field receives nearly equal amounts of summer and winter snowfall. Summer precipitation arrives from the Arabian Sea via the summer monsoon circulation while winter precipitation arrives from more continental sources via winter westerly cyclogenesis. Thus, integration of the Naimona'nyi climate and precipitation histories with contemporaneous records from Dasuopu Glacier, dominated by monsoonal precipitation, will yield more robust and better resolved records of winter snowfall variability and Arabian sea surface temperatures (SSTs) and thus of monsoonal variability that affects highly populated areas of southern Asia. This project has four key scientific goals: (1) to reconstruct high resolution records of temperature, aridity and atmospheric circulation patterns using isotopes of oxygen and deuterium, major ionic chemistry, and insoluble dust measurements; (2) to integrate these records with other paleoclimate histories from the Himalayas to reconstruct the variability of both summer monsoon snowfall and winter precipitation from westerly cyclogenic storms with annual to decadal resolution required to discern abrupt climate changes; (3) to produce a regional fire history; and (4) to determine if older (pre-Holocene) glacial stage ice exists in the dryer western Himalayas. The fifty-eight glaciers on Naimona'nyi once covered an area ten times greater than today, suggesting that the climate in the western Himalayas was once much wetter. The anticipated records from this research, along with other millennial-scale records from both high and low latitudes, will help establish the timing of the onset of low latitude glaciation that is currently hypothesized to be precession driven and asynchronous. Today, evidence is accumulating for an ongoing strong warming throughout the tropics. During the last twenty-four years, the volume of China's 46,298 glaciers has decreased five percent, equivalent to a loss of more than 3,000 km of ice. There has been a notable acceleration in retreat rates since 1990. The ice core records anticipated from Naimona'nyi, coupled with contemporary observations in the region, will further the climate science community's understanding of the climatic factors controlling the recent loss of mass from these ice fields in the western Himalaya. The project presents a strong international collaborative effort between the Institute for Tibetan Plateau Research (ITPR) of the Chinese Academy of Sciences (CAS) and the Ohio State University Byrd Polar Research Center (OSU-BPRC) in scientific research and cultural exchange.