DOI: 10.25921/n033-6p34
title: NOAA/WDS Paleoclimatology - Aqaba, Eilat - Northern Gulf of Aqaba Modern and Fossil Coral d18O and Sr/Ca Data

description: The last interglacial period (about 125,000 years ago) is thought to have been at least as warm as the present climate. Owing to changes in the Earth's orbit around the Sun, it is thought that insolation in the Northern Hemisphere varied more strongly than today on seasonal timescales, which would have led to corresponding changes in the seasonal temperature cycle. Here we present seasonally resolved proxy records using corals from the northernmost Red Sea, which record climate during the last interglacial period, the late Holocene epoch and the present. We find an increased seasonality in the temperature recorded in the last interglacial coral. Today, climate in the northern Red Sea is sensitive to the North Atlantic Oscillation, a climate oscillation that strongly influences winter temperatures and precipitation in the North Atlantic region.  From our coral records and simulations with a coupled atmosphere-ocean circulation model, we conclude that a tendency towards the high-index state of the North Atlantic Oscillation during the last interglacial period, which is consistent with European proxy records, contributed to the larger amplitude of the seasonal cycle in the Middle East.
description: Northern Gulf of Aqaba bimonthly coral oxygen isotope and Sr/Ca data of modern and fossil Porites colonies from the northernmost Red Sea. Modern Corals: EILAT-15B (1988-1995 yr AD), AQ2 (1991-1996 yr AD), EILAT-1 (1988-1993 yr AD). Fossil Corals: AQB-10-B (98 years around 2910 cal. yr BP), AQB-3-A (44 years around 121.9 kyr ago). Two modern corals from Eilat/Israel (EILAT-15B, EILAT-1), and one modern coral (AQ2), one fossil late Holocene coral (AQB-10-B) and one fossil last interglacial coral from Aqaba/Jordan. Microsampling, d18O analyses, age model construction, and interpolation to a bimonthly resolution were performed as recently described for a modern coral from the northernmost Red Sea (Felis et al., Paleoceanography, 2000). The microdrill bit diameter was adapted to a coral’s mean growth rate as estimated from X-radiographs in order to obtain at least six samples per year on average by continuous spot-sampling. The strong seasonal cycle in d18O was used to count annual layers in the corals. This age model is supported by the consistent pattern of annual density-band pairs. The chronologies were constructed by designating the maximum d18O value in a given year equal to mid-February (consistent with the climatological minimum in SST) and assuming a constant extension rate between the Februarys of each year. Therefore we interpolated linearly between these fixed points for further age assignments. The values obtained were interpolated linearly to create six equally spaced values per year, providing a bimonthly resolution (January-February, March-April, May-June, etc.). The age model error of the coral chronologies is in the order of 2-3 months for any given year. For a fossil coral the internal chronology starts at the base (oldest part) of a colony. For Sr/Ca analyses, inductively coupled plasma mass spectrometry was used. More information can be found in the original reference (Felis et al., Nature, 2004).