| Summary: | A global climate component we faintly understand is the Southern Westerly Winds (SWW). Long-term SWW trends play a major role in determining Southern South American precipitation and fire regimes, deep-sea CO2 ventilation, Antarctic sea-ice extent, along with energy and moisture transfer between high and low latitudes. SWW behavior is determined by large-scale pressure gradients related to orbital configuration and Earth system circulation patterns. However, on millennial to centennial time scales, key coupled Southern Ocean-atmosphere dynamics are currently blurred by contrasting interpretations regarding SWW evolution during the early Holocene, that ultimately influence how we interpret subsequent periods. Here I present the first continuous diatom record from Southwestern Patagonia (SWP) that spans the entire Holocene, with the intention of contesting contingent hypothesis regarding SWW evolution since the glacial-interglacial transition. The most salient diatom assemblages from Lago Cipreses (51°S) suggest changes in lake freezing and lake mixing regimes, i.e., long and moderate freeze-over seasons occur at times of increased small fragilarioid and Aulacoseira abundance, respectively, and turbulent and stratified early-ice off periods occur at times of increased Aulacoseira and Non-small fragilarioid benthos abundance, respectively. The results I obtained show the recurrence of environmental conditions reflected in the evolution of the diatom assemblages. In sum with the results of a previously published elemental analysis, pollen, and charcoal record from the same lake, I infer conspicuous warm/dry conditions between ~9-7.4 ka, ~6.1-5.2 ka, and ~3.8-3.1 ka (ka=calibrated kiloyears before 1950 CE), interpreted as weak SWW influence over SWP, and prominent cold/wet conditions between ~14.2–12 ka and ~3.1–0 ka, interpreted as strong SWW influence over SWP. Enhanced hydroclimatic variability is noted to have developed A global climate component we faintly understand is the Southern Westerly Winds (SWW). ...
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