Age determination, carbon geochemistry and palynology of section AC003

Sedimentary records from California's Northern Channel Islands and the adjacent Santa Barbara Basin (SBB) indicate intense regional biomass burning (wildfire) at the Ållerød-Younger Dryas boundary (~13.0-12.9 ka) (All age ranges in this paper are expressed in thousands of calendar years before present [ka]. Radiocarbon ages will be identified and clearly marked "14C years".). Multiproxy records in SBB Ocean Drilling Project (ODP) Site 893 indicate that these wildfires coincided with the onset of regional cooling and an abrupt vegetational shift from closed montane forest to more open habitats. Abrupt ecosystem disruption is evident on the Northern Channel Islands at the Ållerød-Younger Dryas boundary with the onset of biomass burning and resulting mass sediment wasting of the landscape. These wildfires coincide with the extinction of Mammuthus exilis [pygmy mammoth]. The earliest evidence for human presence on these islands at 13.1-12.9 ka (~11,000-10,900 14C years) is followed by an apparent 600-800 year gap in the archaeological record, which is followed by indications of a larger-scale colonization after 12.2 ka. Although a number of processes could have contributed to a post 18 ka decline in M. exilis populations (e.g., reduction of habitat due to sea-level rise and human exploitation of limited insular populations), we argue that the ultimate demise of M. exilis was more likely a result of continental scale ecosystem disruption that registered across North America at the onset of the Younger Dryas cooling episode, contemporaneous with the extinction of other megafaunal taxa. Evidence for ecosystem disruption at 13-12.9 ka on these offshore islands is consistent with the Younger Dryas boundary cosmic impact hypothesis [Firestone et al., 2007, doi:10.1073/pnas.0706977104].

Aerosol total mass concentration and optical depth during IPY 2007-2008 at Maitri and Larsemann Hills Station

The properties of background aerosols and their dependence on meteorological, geographical and human influence are examined using measured spectral aerosol optical depth (AOD), total mass concentration (Mt) and derived number size distribution (NSD) over two distinct coastal locations of Antarctica; Maitri (70°S, 12°E, 123 m m.s.l.) and Larsemann Hills (LH; 69°S, 77°E, 48 m m.s.l.) during southern hemispheric summer of 2007-2008 as a part of the 27th Indian Scientific Expedition to Antarctica (ISEA) during International Polar Year (IPY). Our investigations showed comparable values for the mean columnar AOD at 500 nm over Maitri (0.034±0.005) and LH (0.032±0.006) indicating good spatial homogeneity in the columnar aerosol properties over the coastal Antarctica. Estimation of Angstrom exponent a showed accumulation mode dominance at Maitri (alpha ~1.2±0.3) and coarse mode dominance at LH (0.7±0.2). On the other hand, mass concentration (M(T)) of ambient aerosols showed relatively high values (~8.25±2.87 µg/m**3) at Maitri in comparison to LH (6.03±1.33 µg/m**3).

Planktonic foraminifera distribution during the mid-Piacenzian warm period in the North Atlantic

The mid-Piacenzian (MP) warm period (3.264-3.025 Ma) has been identified as the most recent time in geologic history during which mean global surface temperatures were considerably warmer than today for a sustained period. This interval has therefore been proposed as a potential (albeit imperfect) analog for future climate change and as such, has received much scientific attention over the past two decades. Central to this research effort is the Pliocene Research, Interpretation, and Synoptic Mapping (PRISM) project, an iterative paleoenvironmental reconstruction of the MP focused on increasing our understanding of warm-period climate forcings, dynamics, and feedbacks by providing three-dimensional data sets for general circulation models. A mainstay of the PRISM project has been the development of a global sea surface temperature (SST) data set based primarily upon quantitative analyses of planktic foraminifer assemblages, supplemented with geochemical SST estimates wherever possible. In order to improve spatial coverage of the PRISM faunal data set in the low and mid-latitude North Atlantic, this study provides a description of the MP planktic foraminifer assemblage from five Ocean Drilling Program sites (951, 958, 1006, 1062, and 1063) in the subtropical gyre, a region critical to Atlantic Ocean circulation and tropical heat advection. Assemblages from each core provide evidence for a temperature- and circulation-driven 5-10° northward displacement of MP faunal provinces, as well as regional shifts in planktic foraminifer populations linked to species ecology and interactions. General biogeographic trends also indicate that, relative to modern conditions, gyre circulation was stronger (particularly the Gulf Stream, North Atlantic Current, and North Equatorial Current) and meridionally broader. A comparison of mid-Piacenzian and modern North Atlantic planktic foraminifer assemblages suggests that low latitude western boundary currents were less than 1 °C warmer while eastern boundary currents were ~1-2 °C warmer, supporting the hypothesis of enhanced northward heat advection along western boundary currents and warming of high latitude Northeast Atlantic source regions for the Canary Current. These findings are consistent with a model of reduced meridional SST gradients, with little-to-no low latitude warming, and more vigorous ocean circulation. Results therefore support the theory that enhanced meridional overturn circulation and associated northward heat advection made an important contribution, in conjunction with elevated atmospheric CO2 concentrations, to the 2-3 °C global surface temperature increase (relative to today) and strong polar amplification of SST warmth during the MP warm period.

Bathymetry grids and maps of Mozambique Ridge compiled from cruises 64PE305, 64PE306, SO-87, SO-182, SO-183, ME-33/2, ME-63/1 bathymetry

Based on data from R.V. Pelagia, R.V. Sonne and R.V. Meteor multibeam sonar surveys, a high resolution bathymetry was generated for the Mozambique Ridge. The mapping area is divided into five sheets, one overview and four sub-sheets. The boundaries are (west/east/south/north): Sheet 1: 28°30' E/37°00' E/36°20' S/24°50' S; Sheet 2: 32°45' E/36°45' E/28°20' S/25°20' S; Sheet 3: 31°30' E/36°45' E/30°20' S/28°10' S; Sheet 4: 30°30' E/36°30' E/33°15' S/30°15' S; Sheet 5: 28°30' E/36°10' E/36°20' S/33°10' S. Each sheet was generated twice: one from swath sonar bathymetry only, the other one is completed with depths from ETOPO2 predicted bathymetry. Basic outcome of the investigation are Digital Terrain Models (DTM), one for each sheet with 0.05 arcmin (~91 meter) grid spacing and one for the entire area (sheet 1) with 0.1 arcmin grid spacing. The DTM's were utilized for contouring and generating maps. The grid formats are NetCDF (Network Common Data Form) and ASCII (ESRI ArcGIS exchange format). The Maps are formatted as jpg-images and as small sized PNG (Portable Network Graphics) preview images. The provided maps have a paper size of DIN A0 (1189 x 841 mm).