EGU21-7993
https://doi.org/10.5194/egusphere-egu21-7993
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Peat-based record from southern Patagonia shows centennial-scale variability since 4.2 ka

Julie Loisel and Kristen Sarna
Julie Loisel and Kristen Sarna
  • Texas A&M University, Geography, United States of America (julieloisel@tamu.edu)

Here we present a 4200-year-old high-resolution peat core reconstruction from southern Patagonia. Our detailed carbon isotope (δ13C) record and testate amoeba-inferred water table depth reconstruction point to a progressive wetting of the peatland surface from 4200 to 1500 cal. yr BP, followed by a dry event at 1200-800 cal. yr BP and drier conditions since then. Superimposed on this trend are centennial-scale dips in δ13C values and water table depths that we associate with warm/dry spells. We interpret these shifts, which are akin to positive phases of the Southern Annual Mode (SAM), as reflecting century-scale changes in the Southern Westerly Wind belt during the late Holocene. Other records from southern South America and Tasmania have revealed synchronous changes in local vegetation and fire activity, strengthening our hypothesis. We know that millennial-scale shifts in the Westerly winds influence ocean upwelling in the Southern Ocean, with effects on global atmospheric carbon dioxide (CO2) concentrations. Our study, along with a few others, may help elucidate whether centennial-scale SAM-like shifts could also modulate the global carbon cycle via CO2 degassing from the deep ocean. This is important because instrumental and reanalysis records indicate strengthening and poleward contraction indicate a positive phase of the SAM since the late twentieth century.

How to cite: Loisel, J. and Sarna, K.: Peat-based record from southern Patagonia shows centennial-scale variability since 4.2 ka, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7993, https://doi.org/10.5194/egusphere-egu21-7993, 2021.

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