MILLENNIAL SCALE OSCILLATIONS IN PALEOCEANOGRAPHIC RECORDS FROM ATLANTIC CANADA

Large scale oscillations on centennial through millennial time scales have recently been detected in Holocene paleoclimatic and paleoceanographic records from the North Atlantic region. While the causes of these oscillations are not well constrained, it appears critical to document the inherent variability of the Holocene climate system in view of global warming. Contrary to glacial intervals, the boundary conditions of the Holocene climate system were similar as those of the present day climate. Understanding the inherent variability of the Holocene climate system might unable us to explain the changes we observe presently and also to anticipate how climate might behave in the future.

Wavelet analysis was used to identify oscillation periods in sea surface temperature and salinity reconstructions. The reconstructions were based on palynological records (dinoflagellate cyst) from LaHave Basin on the Scotian Shelf (Atlantic Canada). The wavelet method allows the representation of signal on the time-frequency domain. In the LaHave record, millennial scale oscillations have been recognized and localized in time. Periods of about 900 and 1500 years are clearly present in our four data sets. The 1500-years period probably corresponds to the Dansgaard-Oeschger interstadials. Two others periods of about 2200 and 4100 years were also identified.