Filters: Tags: paleoclimate (X) > partyWithName: U.S. Geological Survey - ScienceBase (X)
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The late Pleistocene was a climatically dynamic period, with abrupt shifts between cool-wet and warm-dry conditions. Increased effective precipitation supported large pluvial lakes and long-lived spring ecosystems in valleys and basins throughout the western and southwestern U.S., but the source and seasonality of the precipitation are debated. Here we present stable carbon and oxygen isotope data from tooth enamel of late Pleistocene herbivores recovered from paleowetland deposits at Tule Spring Fossil Beds National Monument in the Las Vegas Valley of southern Nevada, as well as modern herbivores from the surrounding area, to investigate whether winter or summer precipitation was responsible for driving the wet...
PRISM3D uses multiple proxies to develop February and August synoptic reconstructions of the surface ocean. Planktonic foraminiferal assemblages were translated to February and August surface temperatures via factor analytic transfer function and the modern analog technique. Mg/Ca and alkenone paleothermometry were incorporated as supplementary data for the first time in a PRISM reconstruction. Individual time series were calibrated to age using a combination of magnetobioisostratigraphy, and warm peaks within the PRISM interval were averaged.These warm peak averages for February and August form the basic data used to produce contour maps of mid-Pliocene SST. Wherever other proxy data were available, they were plotted...
In the past century, eruptions of Steamboat Geyser in Yellowstone’s Norris Geyser Basin were mainly clustered in three episodes: between 1961 and 1969, between 1982 and 1984, and in a sequence of eruptions that began in 2018 (Reed et al., 2021) and resulted in extensive damage to, and mortality of the surrounding trees. To characterize tree response to geyser activity over time, and the response of geyser activity to climate variability, aerial and ground imagery were analyzed to document changes in tree coverage around the geyser since 1954. Twenty samples of silicified tree remnants were collected from near the geyser vent for radiocarbon (14C) dating to determine if trees grew during periods when the geyser was...
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)...
Categories: Data;
Tags: Amargosa Valley,
Climatology,
Death Valley National Park,
Devils Hole,
GGGSC,
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...
Categories: Data;
Tags: Alaska,
Holocene,
Land Use Change,
USGS Science Data Catalog (SDC),
Yukon Flats,
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.
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...
Categories: Data;
Tags: Alaska,
Climatology,
Scandinavia,
USGS Science Data Catalog (SDC),
calibration,
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...
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.
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.
Categories: Data;
Types: Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Arctic Ocean,
Atlantic Ocean,
Climatology,
Ecology,
Marine Geology,
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