High-resolution analyses of an early Holocene climate event may imply decreased solar forcing as an important climate trigger

Abstract

Early Holocene lacustrine, tree-ring, ice-core, and marine records reveal that the Northern Hemisphere underwent a short cooling event at 10 300 calendar yr B.P. (9100 ¹⁴C yr B.P.). The records were compared on a common high-resolution time scale and show that the event lasted less than 200 yr, with a cooling peak of 50 yr, and the event coincides with a distinct Holocene thermohaline disturbance recognized in the North Atlantic Ocean. In spite of well- known freshwater forcings at the time of the event, the negligible difference between the modeled Δ¹⁴C record, based on the GISP2 (Greenland Ice Sheet Project 2) ¹⁰Be data, and the measured values, does not allow for detectable Δ¹⁴C changes related to global ocean ventilation. We can, however, show that the onset of the cooling coincides with the onset of one of the largest Holocene ¹⁰Be flux peaks. This finding may imply that the climate system is more sensitive to solar-related changes than previously thought and that such changes may be an important underlying mechanism for sub-Milankovitch climate variability.