11 Millenial-scale Correlation Between Ice-core and Marine Sediment Records

Friday, 25 July 2003
8:00 AM - 12:00 PM

MILLENNIAL TO DECADAL SCALE CHANGES IN SE PACIFIC CLIMATE AND AAIW OVER THE LAST 75 KYR

Paper number: 11-10
Program: SYMPOSIA
Time: 11:10 AM – 11:30 AM

Authors

Abstract

The amount and type of intermediate water formed in the Southern Hemisphere affects climate both directly through heat transport/transfer, and indirectly through its influence on the physical and chemical properties of the upper ocean and equatorial thermocline. Globally, the meridional transport of heat associated with intermediate water formation is equivalent to that associated with deep waters. Oceanographic records spanning the last few decades from the Indian and Pacific link suggest that changes in heat and freshwater budgets in the southern hemisphere intermediate water source regions are transmitted to lower latitudes via intermediate depth ventilation. Computer simulations aimed at understanding the origin of the observed changes in Southern Hemisphere intermediate waters point toward the importance of the Southern Westerlies. Yet, the paucity of longer-term records of Southern Hemisphere intermediate water and westerly wind variability hinder the assessment of this ocean-atmospheric link inferred by models.

Here we present centennially (~100 yr) resolved planktonic and benthic foraminiferal isotopic time series from the Chilean slope ODP Site 1233—located beneath the northernmost reaches of Southern Westerlies at a water depth intersecting lower AAIW. Our benthic foraminiferal (Cibicidoides wuellerstorfi) d13C and d18O records monitor the physical and chemical properties of AAIW close to its source in the SE Pacific, while our planktonic isotopic records monitor the surface ocean climate and current systems west Chile. The coupling between abrupt changes in South Pacific intermediate water ventilation and high latitude surface ocean climate is examined over the last 75 kyr. We compare the timing of the SE Pacific intermediate and surface ocean changes to tropical pacific records to assess the role of tropical-extratropical ocean-atmospheric teleconnections in abrupt climate changes globally.