Continuous 500,000-Year Climate Record from Vein Calcite in Devils Hole, Nevada

Winograd, Isaac; Coplen, Tyler; Landwehr, Jurate; Riggs, Alan; Ludwig, Kenneth; Szabo, Barney; Kolesar, Peter; Revesz, Kinga

The authors analyzed a 36-centimeter core of vein calcite taken from Devils Hole in Death Valley National Park for oxygen isotope composition, and then obtained uranium series measurements using mass spectrometry. The vein calcite deposit precipitated continuously from calcite-supersaturated ground water over the past 500,000 years, providing a record of the paleoclimate during the mid-to-late Pleistocene, and enabling the authors to determine accurately the timing and duration of the major climate shifts spanning several glacial cycles. They use this information to comment on the validity of two theoretical approaches used to explain the onset and recurrence of the ice ages: the Milankovitch hypothesis and nonlinear dynamical simulations of Pleistocene climates. The authors compare the paleoclimatic record from their Devils Hole core with two other well-established isotope records (Vostok, Antarctica ice core and SPECMAP, the marine oxygen-18 standard). They conclude that the paleoclimatic record indicated by the Devils Hole core is inconsistent with the Milankovitch hypothesis which links the ice ages to changes in the amount of sunlight absorbed by the Earth due to periodic variations in the shape of Earth's orbit and the tilt of its axis. Instead, the core's record suggests that climate shifts were aperiodic; probably governed by complex interactions among many factors including ocean currents, ocean productivity, sea-surface temperatures, jet streams, cloud cover, and atmospheric concentrations of dust, greenhouse gases, and water vapor.

Continuous 500,000-Year Climate Record from Vein Calcite in Devils Hole, Nevada

Series