Late‐Pleistocene precipitation δ 18 O interpolated across the global landmass

Global water cycles, ecosystem assemblages, and weathering rates were impacted by the ∼4°C of global warming that took place over the course of the last glacial termination. Fossil groundwaters can be useful indicators of late‐Pleistocene precipitation isotope compositions, which, in turn, can help to test hypotheses about the drivers and impacts of glacial‐interglacial climate changes. Here, a global catalog of 126 fossil groundwater records is used to interpolate late‐Pleistocene precipitation δ 18 O across the global landmass. The interpolated data show that extratropical late‐Pleistocene terrestrial precipitation was near uniformly depleted in 18 O relative to the late Holocene. By contrast, tropical δ 18 O responses to deglacial warming diverged; late‐Pleistocene δ 18 O was higher‐than‐modern across India and South China but lower‐than‐modern throughout much of northern and southern Africa. Groundwaters that recharged beneath large northern hemisphere ice sheets have different Holocene‐Pleistocene δ 18 O relationships than paleowaters that recharged subaerially, potentially aiding reconstructions of englacial transport in paleo ice sheets. Global terrestrial late‐Pleistocene precipitation δ 18 O maps may help to determine 3‐D groundwater age distributions, constrain Pleistocene mammal movements, and better understand glacial climate dynamics.