Kauri Tree‐Ring Stable Isotopes Reveal a Centennial Climate Downturn Following the Antarctic Cold Reversal in New Zealand. Issue 2 (24th January 2021) - Pauly, M.
Abstract: The dynamics of the Late Glacial have been demonstrated by numerous records from the Northern Hemisphere and far fewer from the Southern Hemisphere (SH). SH paleoclimate records reveal a general warming trend, interrupted by a deglaciation pause Antarctic Cold Reversal (ACR; ∼14, 700–13, 000 cal BP). Here, we present decadal tree‐ring stable isotope chronologies (δ 18 O, δ 13 C) from New Zealand (NZ) subfossil kauri trees ( n = 6) covering the post‐ACR millennium from 13, 020 to 11, 850 cal BP. We find a distinct, simultaneous downturn (∼12, 625–12, 375 cal BP) in all tree‐ring proxies paralleling regional tree growth declines, suggesting a widespread climate deterioration. This downturn was characterized by sustained high precipitation, low temperatures, and high relative humidity in NZ with incoming weather fronts from the South Ocean. Despite these promising results, questions remain about what drove the Kauri Downturn and how the hydroclimatic conditions were altered during this time period. Key Points: Dual isotope (δ 18 Ocel, δ 13 Ccel ) tree‐ring stable isotope chronologies (KAU‐ISO) were developed from New Zealand kauri trees, covering 13, 020–11, 850 cal BP A simultaneous downturn in all tree‐ring proxies was established covering 250 years (Kauri Downturn = KD) The records presented provide new high‐resolution evidence of hydroclimate conditions in NZ at the end of the Late Glacial