Age determination and color reflectance of ODP Hole 165-1002D

Attempts to place Palaeolithic finds within a precise climatic framework are complicated by both uncertainty over the radiocarbon calibration beyond about 21,500 14C years bp (Reimer et al., 2004) and the absence of a master calendar chronology for climate events from reference archives such as Greenland ice cores or speleothems (Svensson et al., 2006, doi:10.1016/j.quascirev.2006.08.003). Here we present an alternative approach, in which 14C dates of interest are mapped directly onto the palaeoclimate record of the Cariaco Basin by means of its 14C series (Hughen et al., 2004, doi:10.1126/science.1090300), circumventing calendar age model and correlation uncertainties, and placing dated events in the millennial-scale climate context of the last glacial period. This is applied to different sets of dates from levels with Mousterian artefacts, presumably produced by late Neanderthals, from Gorham's Cave in Gibraltar: first, generally accepted estimates of about 32,000 14C years bp for the uppermost Mousterian levels (Pettitt and Bailey, 2000; Bronk Ramsey et al., 2002, doi:10.1111/1475-4754.00040); second, a possible extended Middle Palaeolithic occupation until about 28,000 14C years bp (Finlayson et al., 2006, doi:10.1038/nature05195); and third, more contentious evidence for persistence until about 24,000 14C years bp (Finlayson et al., 2006, doi:10.1038/nature05195). This study shows that the three sets translate to different scenarios on the role of climate in Neanderthal extinction. The first two correspond to intervals of general climatic instability between stadials and interstadials that characterized most of the Middle Pleniglacial and are not coeval with Heinrich Events. In contrast, if accepted, the youngest date indicates that late Neanderthals may have persisted up to the onset of a major environmental shift, which included an expansion in global ice volume and an increased latitudinal temperature gradient. More generally, our radiocarbon climatostratigraphic approach can be applied to any 'snapshot' date from discontinuous records in a variety of deposits and can become a powerful tool in evaluating the climatic signature of critical intervals in Late Pleistocene human evolution.

High resolution color reflectance and hematite and goethite record of ODP Hole 184-1143A in the South China Sea

Precipitation has a larger variability than temperature in tropical monsoon regions, thus it is an important climate variable. However, reconstructions of long-term rainfall histories are scarce because of the lack of reliable proxies. Here we document that iron oxide minerals, specifically the ratio of hematite to goethite (Hm/Gt), is a reasonable precipitation proxy. Using diffuse reflectance spectrophotometry, we measured samples from Ocean Drilling Program (ODP) 1143 drilling site (9°21.72'N, 113°17.11'E, 2777 m water depth) for hematite and goethite, whose formation processes are favored by opposing climate conditions. In order to determine the content of hematite and goethite we produced a set of calibration samples by removing the iron oxides to generate the natural matrix to which hematite and goethite in known percentages were added. From these calibration samples we developed a transfer function for determining hematite and goethite concentration from a sample's spectral reflectance. Applying this method to ODP 1143 sediments (top 34 m of a 510 m core with sampling interval of 10 cm) we were able to reconstruct a continuous precipitation history for SE Asia of the past 600 kyr using the Hm/Gt ratio as a proxy of the precipitation variability of Asian monsoon. The reliability of this Hm/Gt proxy is corroborated by its consistency with the stalagmite delta18O data from South China. Comparing long-term Hm/Gt records with the surface temperature gradient of equatorial Pacific Ocean, we found that monsoon precipitation and El Niño are correlated for the last 600 kyr. The development of El Niño-like conditions decreased SE Asia precipitation, whereas precipitation increases in response to La Niña intensification

Iberian Margin 420 kyr geochemical and color variations record

Here we report 420 kyr long records of sediment geochemical and color variations from the southwestern Iberian Margin. We synchronized the Iberian Margin sediment record to Antarctic ice cores and speleothem records on millennial time scales and investigated the phase responses relative to orbital forcing of multiple proxy records available from these cores. Iberian Margin sediments contain strong precession power. Sediment "redness" (a* and 570-560 nm) and the ratio of long-chain alcohols to n-alkanes (C26OH/(C26OH + C29)) are highly coherent and in-phase with precession. Redder layers and more oxidizing conditions (low alcohol ratio) occur near precession minima (summer insolation maxima). We suggest these proxies respond rapidly to low-latitude insolation forcing by wind-driven processes (e.g., dust transport, upwelling, precipitation). Most Iberian Margin sediment parameters lag obliquity maxima by 7-8 ka, indicating a consistent linear response to insolation forcing at obliquity frequencies driven mainly by high-latitude processes. Although the lengths of the time series are short (420 ka) for detecting 100 kyr eccentricity cycles, the phase relationships support those obtained by Shackleton []. Antarctic temperature and the Iberian Margin alcohol ratios (C26OH/(C26OH + C29)) lead eccentricity maxima by 6 kyr, with lower ratios (increased oxygenation) occurring at eccentricity maxima. CO2, CH4, and Iberian SST are nearly in phase with eccentricity, and minimum ice volume (as inferred from Pacific d18Oseawater) lags eccentricity maxima by 10 kyr. The phase relationships derived in this study continue to support a potential role of the Earth's carbon cycle in contributing to the 100 kyr cycle.

Shipborne ocean color remote sensing

In this paper, modernized shipborne procedures are presented to collect and process above-water radiometry for remote sensing applications. A setup of five radiometers and a bidirectional camera system, which provides panoramic sea surface and sky images, is proposed for the collection of high-resolution radiometric quantities. Images from the camera system can be used to determine sky state and potential glint, whitecaps, or foam contamination. A peak in the observed remote sensing reflectance RRS spectra between 750-780 nm was typically found in spectra with relatively high surface reflected glint (SRG), which suggests this waveband could be a useful SRG indicator. Simplified steps for computing uncertainties in SRG corrected RRS are proposed and discussed. The potential of utilizing "unweighted multimodel averaging," which is the average of four or more common SRG correction models, is examined to determine the best approximation RRS. This best approximation RRS provides an estimate of RRS based on various SRG correction models established using radiative transfer simulations and field investigations. Applying the average RRS provides a measure of the inherent uncertainties or biases that result from a user subjectively choosing any one SRG correction model. Comparisons between inherent and apparent optical property derived observations were used to assess the robustness of the SRG multimodel averaging ap- proach. Correlations among the standard SRG models were completed to determine the degree of association or similarities between the SRG models. Results suggest that the choice of glint models strongly affects derived RRS values and can also influence the blue to green band ratios used for modeling biogeochemical parameters such as for chlorophyll a. The objective here is to present a uniform and traceable methodology for determining ship- borne RRS measurements and its associated errors due to glint correction and to ensure the direct comparability of these measurements in future investigations. We encourage the ocean color community to publish radiometric field measurements with matching and complete metadata in open access repositories.

World Atmospheric Temperature Isotherms (January), 1884 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Karte der Januar-Isotherme. It is part of a two map set: [Karten der Isothermen, von Alexander Supan]. It was published by Ed. Holzel in 1884. Scale [ca. 1:110,000,000]. Map in German. The image inside the map neatline is georeferenced to the surface of the earth and fit to a non-standard 'Mercator' projection with the central meridian at 17.666 degrees west. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, selected cities, shoreline features, and more. Isotherms are shown at 2 degree intervals for January. This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

World Atmospheric Temperature Isotherms (July), 1884 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Karte der Juli-Isothermen. It is part of a two map set: [Karten der Isothermen, von Alexander Supan]. It was published by Ed. Holzel in 1884. Scale [ca. 1:110,000,000]. Map in German. The image inside the map neatline is georeferenced to the surface of the earth and fit to a non-standard 'Mercator' projection with the central meridian at 17.666 degrees west. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, selected cities, shoreline features, and more. Isotherms are shown at 2 degree intervals for July. This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

Geochemistry, minerals, color, rare earth elements and d18O at DSDP Hole 92-504B

Investigations of borehole waters sampled in Hole 504B during Leg 92 revealed changes in major-ion composition similar to changes observed previously (during Leg 83). The uniformity of chloride concentrations with increasing depth suggests efficient downhole mixing processes along density gradients caused by large temperature gradients. Chemical and mineralogical studies of suspended drilling mud (bentonite) suggest that this material has undergone substantial alteration and that CaSO4 (anhydrite/gypsum) has precipitated in the deeper parts of the hole. Rare earth element studies suggest contributions of both the bentonites and the basalts to the REE distributions. Studies of the isotopic composition (87Sr/86Sr) of dissolved strontium indicate a strong contribution of basaltic nonradiogenic strontium, although differences between the Leg 83 and Leg 92 data indicate an influence of bentonite during Leg 92. The oxygen isotope composition of the water does not change appreciably downhole. This uniformity can be understood in terms of high water-rock ratios and suggests that the chemical changes observed are due either to alteration processes involving bentonites and basaltic material from the walls of the hole or to exchange with formation fluids from the surrounding basement, which may have altered in composition at relatively high water-rock ratios.

Isotope characterization and estimated temperature of formation of calcite veins in ODP Sites 124-768 and 124-770 (Table 1)

Secondary carbonate minerals were recovered within the basalts at both ODP Sites 768 and 770 in the Sulu and Celebes seas. Petrographic and X-ray diffraction analyses indicate that the carbonates are calcites. Other alteration products recognized in the thin sections are smectites, iron oxides, and gypsum. The 13C values of carbonates from both sites range from 1.6 per mil to 2.3 per mil, which are indicative of inorganic carbonate formation with no contributions from 13C-depleted sources such as oxidized organic carbon or methane. The oxygen isotopes at Site 770 range from 30.8 per mil to 31.6 per mil, which indicates a pervasive circulation of cold seawater (9° to 12°C) during alteration of the Celebes Sea basalts. In contrast, carbonates associated with Site 768 basalts have less positive d18O values (21.0 per mil to 27.3 per mil). A lighter 18O isotopic signature indicates the formation of secondary calcite at either higher temperatures or in a system closed to seawater. The rapidly deposited pyroclastic flows at Site 768 would have limited water access to the crust very soon after its formation, which leads us to speculate that the carbonates in the Sulu Sea basalts were formed by isotopically modified fluids resulting from basalt alteration in a closed system.

Influence of incubation temperature on hatchling phenotype in reptiles

Incubation temperature influences hatchling phenotypes such as sex, size, shape, color, behavior, and locomotor performance in many reptiles, and there is growing concern that global warming might adversely affect reptile populations by altering frequencies of hatchling phenotypes. Here I overview a recent theoretical model used to predict hatchling sex of reptiles with temperature-dependent sex determination. This model predicts that sex ratios will be fairly robust to moderate global warming as long as eggs experience substantial daily cyclic fluctuations in incubation temperatures so that embryos are exposed to temperatures that inhibit embryonic development for part of the day. I also review studies that examine the influence of incubation temperature on posthatch locomotion performance and growth because these are the traits that are likely to have the greatest effect on hatchling fitness. The majority of these studies used artificial constant-temperature incubation, but some have addressed fluctuating incubation temperature regimes. Although the number of studies is small, it appears that fluctuating temperatures may enhance hatchling locomotor performance. This finding should not be surprising, given that the majority of natural reptile nests are relatively shallow and therefore experience daily fluctuations in incubation temperature.