Abstract: We present a 650-year Antarctic ice core record of concentration and isotopic ratios ((13)C and (18)O) of atmospheric carbon monoxide. Concentrations decreased by ~25% (14 ppbv) from mid-1300s to the 1600s, then recovered completely by the late 1800s. (13)C and (18)O decreased by about 2 and 4 respectively from mid-1300s to the 1600s, then increase by about 2.5 and 4 by the late 1800s. These observations and isotope mass balance model results imply that large variations in the degree of biomass burning in the Southern Hemisphere occurred during the last 650 years, with a decrease by about 50% in the 1600s, an increase of about 100% by the late 1800s, and another decrease by about 70% from the late 1800s to present day.

Abstract: Anisotropy in the Earth's upper mantle is a signature of past and present deformation. Here we present a new data set of 50,000 uniformly processed SKS shear wave splitting measurements that probe upper mantle anisotropy beneath seismic stations in the frequency band 0.020.1 Hz. The data set consists of measurements obtained at 2000 seismic stations from 2000 events. We identify several stations characterized by an apparent absence of shear wave splitting (so-called null stations). Station-averaged measurements are obtained by stacking shear wave splitting error surfaces. The stacked data set shows excellent agreement with a compilation of previous SKS measurements. The average amount of splitting beneath seismic stations (after error surface stacking) is 0.8 s, slightly lower than that found previously by vectorial averaging of non-null measurement splitting parameters. The data set disagrees, however, with an azimuthally anisotropic surface wave tomography model (DKP2005), suggesting that caution should be exercised when using such models for geodynamic interpretation, especially in continental regions. Studying our data set in detail, we find evidence that flow in the asthenosphere exerts partial control over SKS splitting in orogenic regions globally. In the active orogenic environment of the western USA, where we have the densest coverage, our data suggest that shallow asthenospheric flow is guided by a wall of thick lithosphere to the east.

Abstract: Telemetry methods and remote sensing now make it possible to record the spatial usage of wide-ranging marine animals and the biophysical characteristics of their pelagic habitats. Furthermore, recent statistical advances mean that such data can be used to test ecological hypotheses and estimate species distributions. Black-browed Albatrosses Thalassarche melanophrys are highly mobile marine predators with a circumpolar breeding and foraging distribution in the Southern Hemisphere. Although they remain relatively abundant, increased fisheries bycatch has led to their listing as endangered by conservation bodies. We satellite-tracked 163 breeding Black-browed Albatrosses and eight closely related Campbell Albatrosses T. impavida from nine colonies. We then quantified habitat usage, and modeled population-level spatial distribution at spatiotemporal scales .50 km and 1 month, as a function of habitat accessibility, habitat preference, and intraspecific competition, using mixed-effects generalized additive models (GAMM). During incubation, birds foraged over a wider area than in the post-brood chick-rearing period, when they are more time constrained. Throughout breeding, the order of habitat preference of Black-browed Albatrosses was for neritic (0500 m), shelf-break and upper shelf-slope (5001000 m), and then oceanic (.1000 m) waters. Black-browed Albatrosses also preferred areas with steeper (.38) bathymetric relief and, in addition, during incubation, warmer sea surface temperatures (peak preference ;168C). Although this suggests specialization in neritic habitats, incubation-stage Black- browed Albatrosses from South Georgia also foraged extensively in oceanic waters, preferring areas with high eddy kinetic energy (.250 cm2/s2), especially the Brazil-Malvinas Confluence, a region of intense mesoscale turbulence. During chick-rearing, this species had a more southerly distribution, and following the seasonal retreat of sea ice, birds from some populations utilized neritic polar waters. Campbell Albatrosses showed similar bathymetric preferences but also preferred positive sea level anomalies. Black-browed Albatross foraging areas were partially spatially segregated with respect to colony and region, with birds preferring locations distant from neighboring colonies, presumably in order to reduce competition between parapatric conspecifics. At the global scale, the greatest concentrations of breeding Black-browed Albatrosses are in southern South American neritic, shelf-break, and shelf-slope waters. These regions also hold large fisheries and should therefore be a priority for introduction of bycatch mitigation measures.