Paleomonsoon precipitation deduced from a sediment core from the equatorial Indian Ocean

Manish Tiwari, R. Ramesh, B. L K Somayajulu, A.J. Timothy Jull, G. S. Burr

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Rapid shifts in past climate recorded in polar ice sheets have elicited various explanations relating to either thermohaline circulation changes by ice-rafting or natural greenhouse gas concentrations modulated by climatic conditions in the tropics. To compare the tropical paleoclimate record with the polar record, one must choose sediment cores from highly productive ocean regions. Necessarily, such regions reflect the wind records in the tropics, because high productivity is associated with upwelling driven by winds. Comparing tropical precipitation records with high-latitude records is, however, a more difficult task because sediments recording paleoprecipitation usually have low sedimentation rates, and offer coarser resolution relative to polar ice cores. Here, we present δ18O data of three planktonic species of Foraminifera (a proxy for precipitation) from such a sediment core, spanning the past 35 ka for the equatorial Indian Ocean, which falls under the southwest monsoon (SWM) realm. Results show that minimum SWM precipitation occurred at the Last Glacial Maximum, with a subsequent increase at Termination IA. During the Holocene, SWM precipitation intensified uniformly up to the core top (∼2.2 ka B.P.), as revealed by generally decreasing δ18O values. Variations in precipitation are consistent with climate changes recorded in polar ice sheets. Although the different resolutions of the two records preclude a rigorous comparison, abrupt cooling/warming events appear to be accompanied by sudden reduction/enhancement in (SWM) rainfall. Thus, mechanisms with time scales much shorter than a millennium, such as natural greenhouse warming (e.g., CH4 concentration), controlled by emissions from the tropics, could have played a major role in high-latitude climate change.

Original languageEnglish (US)
Pages (from-to)23-30
Number of pages8
JournalGeo-Marine Letters
Volume26
Issue number1
DOIs
StatePublished - Mar 2006

Fingerprint

Tropics
sediment core
Ice
Sediments
Precipitation (meteorology)
monsoon
Climate change
ice sheet
Greenhouses
warming
Sedimentation
Greenhouse gases
ice rafting
Rain
climate change
thermohaline circulation
Productivity
Cooling
ice core
Last Glacial Maximum

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Oceanography
  • Geotechnical Engineering and Engineering Geology
  • Environmental Science (miscellaneous)

Cite this

Paleomonsoon precipitation deduced from a sediment core from the equatorial Indian Ocean. / Tiwari, Manish; Ramesh, R.; Somayajulu, B. L K; Jull, A.J. Timothy; Burr, G. S.

In: Geo-Marine Letters, Vol. 26, No. 1, 03.2006, p. 23-30.

Research output: Contribution to journalArticle

Tiwari, Manish ; Ramesh, R. ; Somayajulu, B. L K ; Jull, A.J. Timothy ; Burr, G. S. / Paleomonsoon precipitation deduced from a sediment core from the equatorial Indian Ocean. In: Geo-Marine Letters. 2006 ; Vol. 26, No. 1. pp. 23-30.
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