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Elemental concentrations and stable oxygen and carbon isotope ratios are reported for five mammillary calcite specimens collected from the groundwater-filled fissures Devils Hole and Devils Hole II in the southern Amargosa Desert, south-western Nevada. Previous studies of these specimens yielded oxygen and carbon isotope chronologies of paleoclimatic and paleo hydrologic conditions over an approximately 500,000-year time period as defined by uranium series dates (Winograd and others, 1992, 2006; Landwehr and others, 1997, 2011). The elemental concentration measurements reveal additional chronologies in the mammillary calcite. The specimens were sampled by milling contiguous 0.050-inch-thick layers (1.27 millimeters)...
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During recent decades, lake levels in the Yukon Flats region of interior Alaska have fluctuated dramatically. However, prior to recorded observations, no data are available to indicate if similar or more extreme variations occurred during past centuries and millennia. This study explores the history of Yukon Flats lake origins and lake levels for the past approximately 5,500 years from sediment analyses guided by previous work on permafrost extent, thermokarst, and modern isotope hydrology. Sediments dated by 210Pb and AMS radiocarbon indicate stable chronologies following initial lake initiation. Subsequent lithology is autochthonous, and oxygen isotope ratios of endogenic carbonate reflect lake level change at...
Understanding and modeling precipitation isotope (δ18O and δD) patterns for large regions of the globe requires quantifying processes governing continental-scale climatology and hydrology. In this study, we have evaluated the extent to which inclusion of monthly moisture source temperature and moisture source locations in the Rayleigh distillation model aid in reproducing the relationships between monthly time series of precipitation isotope (δ18O) values and temperature across the contiguous United States. The steepest isotope-temperature slopes (0.5‰–0.6‰ δ18O/°C) and greatest δ18O value correlations with temperature (r2 = 0.5–0.8), derived from 5 continuous years of the data from the United States...
The growth of carbonate formations in caves (speleothems) is sensitive to changes in environmental conditions at the surface (temperature, precipitation and vegetation) and can provide useful paleoclimatic and paleoenvironmental information. We use 73 230Th dates from speleothems collected from a cave in southwestern Oregon (USA) to constrain speleothem growth for the past 380 000 years. Most speleothem growth occurred during interglacial periods, whereas little growth occurred during glacial intervals. To evaluate potential environmental controls on speleothem growth we use two new modeling approaches: i) a one-dimensional thermal advection–diffusion model to estimate cave temperatures during the last glacial cycle,...
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This dataset collects sea surface temperature data generated through alkenone analysis of late Pliocene sediments collected from cores and field localities by USGS PRISM project members. Alkenone analysis of sample material was performed by Timothy Herbert at Brown University.
Summer monsoonal rains (the southwest monsoon) are an important source of moisture for parts of the southwestern United States and northern Mexico. Improved documentation of the variability in the southwest monsoon is needed because changes in the amount and seasonal distribution of precipitation in this semiarid region of North America influence overall water supply and fire severity. Comparison of abundance variations in the planktic foraminifer Globigerinoides sacculifer in marine cores from the western and northern Gulf of Mexico with terrestrial proxy records of precipitation (tree-ring width and packrat-midden occurrences) from the southwestern United States indicate that G. sacculifer abundance is a proxy...
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The present study investigates the environmental significance of the oxygen isotopic composition of several modern land snail species collected along two north-to-south transects in Alaska and Scandinavia at latitudes between 60 and 70 °N. We tested the hypothesis that land snail shell δ18O values primarily track precipitation δ18O. The results show that shell δ18O values from Scandinavia were ~5.1‰ enriched in 18O with respect to snails from Alaska, equivalent to differences in precipitation δ18O values between the two regions. Within the Alaskan transect, shell δ18O values increased with observed increasing air temperature and precipitation δ18O, whereas shell δ18O values from Scandinavia did not correlate to...
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The isotopic values of fossil snail shells can be important archives of past climate. Here we present the first carbon (δ13C) and oxygen (δ18O) isotope values of radiocarbon-dated and live-collected snails in interior Alaska to explore changes in vegetation and humidity through the late glacial period (14-11.7 ka). Snail shell δ13C values were relatively consistent through the late glacial. However, late glacial shell δ13C values are 2.8‰ higher than modern shells. This offset is best explained by changes in the δ13C values of plants consumed by snails. Snail shell δ18O values varied through the late glacial, which can be partially explained by changes in relative humidity (RH). RH during the snail growing period...
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These files provide global coverage data describing boundary conditions for various aspects of the physical world representing several chosen times in Earth's history to be used as input data for climate modeling experiments. The raster data sets are provided in NetCDF format which is standard for climate modelling.
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Model experiments that attempt to simulate climates of the past serve to identify both similarities and differences between two climate states and, when compared with simulations run by other models and with geological data, to identify model-specific biases. Uncertainties associated with both the data and the models must be considered in such an exercise. The most recent period of sustained global warmth similar to what is projected for the near future occurred about 3.3–3.0 million years ago, during the Pliocene epoch. Here, we present Pliocene sea surface temperature data, newly characterized in terms of level of confidence.
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Sixty packrat middens were collected in Canyonlands and Grand Canyon National Parks, and these series include sites north of areas that produced previous detailed series from the Colorado Plateau. The exceptionally long time series obtained from each of three sites (>48,000 C-14 yr BP to present) include some of the oldest middens yet discovered. Most middens contain a typical late-Wisconsinan glaciation mixture of mesic and xeric taxa, evidence that plant species responded to climate change by range adjustments of elevational distribution based oil individual criteria, Differences in elevational range from today for trees and shrubs ranged from no apparent change to as much as 1200 m difference. The oldest middens...
The Colorado River has historically been an abundant source of supply for water users in the United States and Mexico. With growth of demands on this water supply, the time of historical abundance has ended. The previous five years of drought remain manifested in low reservoir levels. The Secretary of the Interior is beginning preparation of first-ever shortage criteria for the reservoir system. These conditions demonstrate the need for a strong scientific foundation in understanding climatic and hydrologic conditions that influence Colorado River water supplies. We know that droughts will inevitably occur in the future – a future made more uncertain by the impacts of climate change and increased hydrologic variability....
map background search result map search result map 50,000 years of vegetation and climate history on the Colorado Plateau, Utah and Arizona, USA PRISM late Pliocene (Piacenzian) alkenone - derived SST data Data release for Lake levels in a discontinuous permafrost landscape: Late Holocene variations inferred from sediment oxygen isotopes, Yukon Flats, Alaska Revised PRISM3 Pliocene Sea Surface Temperature Estimates Elemental Concentrations and Carbon and Oxygen Isotope Ratios in Mammillary Calcite from Devils Hole and Devils Hole II, Nevada, USA Data release for Oxygen isotopes of land snail shells in high latitude regions Data release for Late glacial-Younger Dryas climate in interior Alaska as inferred from the isotope values of land snail shells Pliocene Model Intercomparison Project Phase 3 (PlioMIP3) Data Distribution Elemental Concentrations and Carbon and Oxygen Isotope Ratios in Mammillary Calcite from Devils Hole and Devils Hole II, Nevada, USA Data release for Lake levels in a discontinuous permafrost landscape: Late Holocene variations inferred from sediment oxygen isotopes, Yukon Flats, Alaska 50,000 years of vegetation and climate history on the Colorado Plateau, Utah and Arizona, USA Data release for Late glacial-Younger Dryas climate in interior Alaska as inferred from the isotope values of land snail shells Data release for Oxygen isotopes of land snail shells in high latitude regions PRISM late Pliocene (Piacenzian) alkenone - derived SST data Revised PRISM3 Pliocene Sea Surface Temperature Estimates Pliocene Model Intercomparison Project Phase 3 (PlioMIP3) Data Distribution