A speleothem precipitation record from Alabama spanning the last 12 thousand years: links between Northern Hemisphere high-latitude cooling and Southeastern US hydroclimate

Abstract

I present a new stalagmite δ18O record, named War Eagle 1, collected from War Eagle Cave in Northern Alabama that spans the interval between 12,222 years to 320 years before present (BP), thus offering a paleoclimate record of Holocene climate variability from the interior southeast United States (SEUS). I interpret this record to reflect an amount effect on interannual timescales and the relative contribution of summer relative to winter precipitation amount to the annual amount and isotopic budget. I find a close connection between hydroclimate variability in the SEUS, North Atlantic temperature variability and Caribbean hydroclimate. A consistent picture emerged whereby winter precipitation in the SEUS increases during events of high latitude cooling triggered by slowdown of North Atlantic deep-water formation, such as during the Younger Dryas and 8.2 ka cold events. In contrast, I find evidence suggesting that both summer and winter precipitation in the SEUS decrease across the transition from the ‘Holocene Climate Optimum’ to the ‘Neoglacial’, which is generally attributed to external orbital forcing.