Holocene centennial to millennial shifts in North-Atlantic storminess and ocean dynamics

• Published in: Scientific Reports
• Main Authors: Goslin, Jérôme, Fruergaard, Mikkel, Sander, Lasse, Gałka, Mariusz, Menviel, Laurie, Monkenbusch, Johannes, Thibault, Nicolas, Clemmensen, Lars B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: https://curis.ku.dk/portal/da/publications/holocene-centennial-to-millennial-shifts-in-northatlantic-storminess-and-ocean-dynamics(56b9fd29-1722-4380-b254-ded695d58edf).html; https://doi.org/10.1038/s41598-018-29949-8; https://curis.ku.dk/ws/files/208718415/Holocene_centennial_to_millennial_shifts_in_North_Atlantic_storminess_and_ocean_dynamics.pdf

The forcing mechanisms responsible for centennial to millennial variability of mid-latitude storminess are still poorly understood. On decadal scales, the present-day geographic variability of North-Atlantic storminess responds to latitudinal shifts of the North-Atlantic westerly wind-belt under the prime control of the North-Atlantic Oscillation (NAO). An equivalent mechanism operating at centennial to millennial time scales during the Holocene is still to be ascertained, especially owing to the lack of high-resolution and continuous records of past-storminess extending far enough in time. Here we present a reconstruction of past storminess activity based on a high-resolution record of wind-blown sand retrieved from a near-coastal wetland. Our record extends back to ca. 10,000 B.P. and allows to continuously document fluctuations in the frequency of Holocene storm-force winds at our study-site at a mean high temporal resolution of 40 years. Large similarities between our record and palaeo-oceanographic records of Holocene climate changes in the North-Atlantic suggest that our past-storminess record reproduces a signal of significance for the North-Eastern Atlantic realm. We find that Holocene North-Atlantic storminess is dominated by robust millennial (≈2,500-year) to centennial (≈400 and 200-year) periodicities. These changes in storminess were accompanied by changes in the precipitation regimes over northern Europe, evidencing large-scale shifts in the latitudinal positions of the Atlantic westerlies akin to present-day NAO patterns. We propose that these shifts originate from changes in the position and extent of the Azores high-pressure system and Polar vortex, as supported by climate model simulations. Finally, we demonstrate that enhanced zonal storminess activity over the North-Atlantic was the driver of centennial-scale changes in North-Atlantic oceanic circulation, while ocean dynamics most likely influenced back the atmospheric circulation at millennial time-scales. This may vouch for the instrumental role played by North-Atlantic storminess in triggering abrupt climate change at centennial scales during the Holocene.