NOAA/WDS Paleoclimatology - Atlantic and Pacific 800 KYr Benthic d18O Stacks

Benthic d18O is often used as a stratigraphic tool to place marine records on a common age model and as a proxy for the timing of ice volume/sea level change. However, Skinner and Shackleton (2005) found that the timing of benthic d18O change at the last termination differed by 3900 years between one Atlantic site and one Pacific site. These results suggest that benthic d18O change may not always accurately record the timing of deglaciation. We compare benthic d18O records from 20 Atlantic sites and 14 Pacific sites to evaluate systematic differences in the timing of terminations in benthic d18O. Analysis of sedimentation rates derived from the alignment of benthic d18O suggests a statistically significant Atlantic lead over Pacific benthic d18O change during the last six terminations. We estimate an average Pacific benthic d18O lag of 1600 years for Terminations 1-5, slightly larger than the delay expected from ocean mixing rates given that most glacial meltwater probably enters the North Atlantic. We additionally find evidence of ~4000-year Pacific d18O lags at approximately 128 ka and 330 ka, suggesting that stratigraphic correlation of d18O has the potential to generate age model errors of several thousand years during terminations. A simple model demonstrates that these lags can be generated by diachronous temperature changes and do not require slower circulation rates. Most importantly, diachronous benthic d18O responses must be taken into account when comparing Atlantic and Pacific benthic d18O records or when using benthic d18O records as a proxy for the timing of ice volume change.