Evidence from driftwood records for century-to-millennial scale variations of the high latitude atmospheric circulation during the Holocene

Different Holocene sea-ice drift patterns in the Arctic Ocean have been hypothesized by Dyke et al. from radiometric analyses of driftwood collected in the Canadian Arctic Archipelago. A dynamic-thermodynamic sea-ice model is used to simulate the modes of Arctic Ocean ice circulation for different atmospheric forcings, and hence determine the atmospheric circulations which may have accounted for the inferred ice drift patterns. The model is forced with the monthly mean wind stresses from 1968 (a year with very large ice export) and 1984 (very low ice export), two years with drastically different winter sea level pressure patterns and with different phases of the NAO index. The simulations show that for the 1968 wind stresses, a weak Beaufort Gyre with a broad Transpolar Drift Stream (TDS) shifted to the east are produced, leading to a large ice export from the Arctic. Similarly, the 1984 wind stresses lead to an expanded Beaufort Gyre with a weak TDS shifted to the west and a low ice export. These results correspond to the patterns inferred by Dyke et al. Based on the simulations, the driftwood record suggests that for centuries to millennia during the Holocene, the high latitude average atmospheric circulation may have resembled that of 1968, 1984 and today's climatology, with abrupt changes from one state to the other