16,000-year hydroclimate reconstruction from Lake Von, Aotearoa New Zealand indicates Pacific-wide synchrony in Southern Hemisphere westerly wind variability

Abstract

The intensity and latitudinal position of the Southern Hemisphere westerly winds (SWW) influence precipitation patterns across the mid to high latitudes of the Southern Hemisphere, including across southern Te Waipounamu/South Island, Aotearoa New Zealand. Te Waipounamu/South Island is located along the modern northern margin of the strongest SWW, but there are no continuous high-resolution records of westerly wind variability and hydroclimate that extend back to the end of glaciation from this region. Here, we present a multi-millennial to multi-centennial reconstruction of hydroclimate and westerly wind intensity for southern Aotearoa New Zealand using a sediment core from Lake Von in Central Otago that spans the last ∼16,000 years. Higher lake levels and an expanded lake extent are caused by cooler and wetter climate conditions under more intense westerly wind flow. Conversely, a reduction in westerly wind intensity results in a warmer and drier climate, lower lake levels and migration of the shoreline towards the lake depocenter. There are seven episodes of low lake level between 11100 and 3500 cal yr BP that occur within two broad intervals between 11100 and 8300 cal yr BP and 6000–3500 cal yr BP. There are three periods of relatively high lake level between 12500 and 11200 cal yr BP, 8300 - 6000 cal yr BP, and 3500 cal yr BP to present. Multi-millennial to multi-centennial fluctuations in hydroclimate and westerly wind intensity at Lake Von are replicated by records across the Pacific Basin in southern South America showing synchronous hemisphere-wide shifts in westerly wind intensity through time.