A Holocene North Atlantic SST record and regional climate variability

By combined use of 210Pb dates, identification of Icelandic tephras of known age, and wiggle matching of 14C radiocarbon dates, exceptional accurate chronologies have been established for two cores (P1003MC and SC) raised from the same location on the Norwegian continental margin and that span the last 8 ka. They are located directly under the core of the eastern branch of Atlantic water entering the Nordic Seas. Comparing oxygen isotope measurements on the planktonic foraminiferal species Neogloboquadrina pachyderma (dex) with nearby instrumental time series, suggest that this parameter at this site primarily reflects summer temperature conditions of near surface (c. 50 m) waters. We argue that this proxy, to some degree, reflects North Atlantic sea surface temperature variability through the Holocene. A detailed correlations of the oxygen isotope record with solar proxies for the last 1 ka was not apparent for the whole 8 ka record. However, a statistically significant (>95%) spectral peak at c. 83 yr may represent the so-called Gleissberg solar cycle. A relative high correlation (r = 0.53) between 14C productivity and the ocean near surface temperature proxy was obtained on 800–1500 year band filtered data, the latter lagging 180 year after the solar proxy. Multi-channel Singular-Spectrum Analyses carried out on the P1003 time series, the oxygen isotope record from the Renland Ice Core from Eastern Greenland, and on the Torneträsk tree-ring record from central Scandinavia, reveals a significant common frequency at 280 year. The expression of this frequency in the different records shows variability in phase relationship and strength over time and does not appear to have any similarity to any known modes of climate variability in the area. In order to predict future climate change in the region it is of utmost importance to develop a better understanding of the mechanisms behind multi-decadal and multi-centennial scale climate variability.

► Accurate chronology for a record (last 8 ka) from the SE Nordic Seas established.
► Training planktic foraminiferal oxygen isotopes to instrumental temperature time series.
► Significant N. Atlantic frequency at 280 yrs in surface temperature variability identified.
► Anomaly at c. 5200 BC reflecting melt water discharge from the Laurentide ice sheet?