Climate and hydrographic variability in the Indo-Pacific Warm Pool over the past 26,000 years.

摘要

The Indo-Pacific Warm Pool is currently the warmest region of the modern ocean, with annual average sea surface temperatures upwards of 28°C. As such, it is the largest single source of heat and moisture to the atmosphere. Climate modeling efforts and paleoceanographic reconstructions have shown that the hydrology of the IPWP responds to climate changes in the high latitudes on centennial to multi-millennial timescales (e.g. Stott et al., 2002 Zhang and Delworth, 2005 Partin et al., 2007). Here I use three sediment cores from the Makassar Strait, Indonesia, to assess changes in ocean temperature and salinity over the past 26,000 years. Temperature and salinity were reconstructed from the Mg/Ca ratios and delta18O measurements from planktonic and benthic foraminifera. Reconstructions show that sea surface temperatures were about 3oC cooler during the last glacial maximum, and reached a peak in the early Holocene, about 10,000 years ago. The delta18 Osw record, which generally indicates salinity, shows a strong correspondence to insolation and the position of the Intertropical Convergence Zone. A cooling and freshening trend occurs from 10,000 to 2,000 years before present. Over the past 2,000 years, a high resolution analysis shows pronounced changes in sea surface temperature in concert with variations in Northern Hemisphere air temperature. Reconstructed sea surface salinity shows a strong covariance with the temperature, and also the position of the Intertropical Convergence Zone, indicating that the position of the Intertropical Convergence is an important control on precipitation in this region on centennial to multi-millennial timescales.