Oxygen and carbon isotopic compositions of foraminifers at DSDP Hole 72-517

Oxygen and carbon isotope analyses were performed on monospecific or mixed-species samples of benthic foraminifers, as well as on the planktonic species Globigerinoides ruber from a 24-m hydraulic piston core raised on the western flank of the Rio Grande Rise, at DSDP Site 517 (30°56.81'S and 38°02.47'W, water depth 2963 m) in the southwestern Atlantic. This site is presently located in the core of North Atlantic Deep Water (NADW). This is the first long isotopic record of Quaternary benthic foraminifers; it displays at least 30 isotopic stages, 25 of them readily correlated with the standard sequence of Pacific Core V28-239. The depths of both the Bruhnes/Matuyama boundary and the Jaramillo Event based on oxygen isotope stratigraphy agree well with paleomagnetic results. Quaternary faunal data from this part of the Atlantic are dated through isotopic stratigraphy and partially contradict data previously published by Williams and Ledbetter (1979). There was a substantial increase in the size of the earth's major ice sheets culminating at Stage 22 and corresponding to a l per mil progressive increase of d18O maximal values. Further, ice volume-induced isotopic changes were not identical for different glacial cycles. Oxygen and carbon isotope analyses of benthic foraminifers show that during Pleistocene glacial episodes, NADW was cooler than today and that Mediterranean outflow might still have contributed to the NADW sources. The comparison of coiling ratio changes of Globorotalia truncatulinoides with planktonic and benthic oxygen isotope records shows that there might have been southward excursions of the Brazil Current during the Pleistocene, perhaps related to Antarctic surface water surges. The question of the location of NADW sources during glacial maxima remains open.

Fig. S1. Loci of possible event locations based on differential ts - tp arrival times at the single functioning geophone

Geological storage of CO2 that has been captured at large, point source emitters represents a key potential method for reduction of anthropogenic greenhouse gas emissions. However, this technology will only be viable if it can be guaranteed that injected CO2 will remain trapped in the subsurface for thousands of years or more. A signi?cant issue for storage security is the geomechanical response of the reservoir. Concerns have been raised that geomechanical deformation induced by CO2 injection will create or reactivate fracture networks in the sealing caprocks, providing a pathway for CO2 leakage. In this paper, we examine three large-scale sites where CO2 is injected at rates of ab. 1 megatonne/y or more: Sleipner, Weyburn, and In Salah. We compare and contrast the observed geomechanical behavior of each site, with particular focus on the risks to storage security posed by geomechanical deformation. At Sleipner, the large, high-permeability storage aquifer has experienced little pore pressure increase over 15 y of injection, implying little possibility of geomechanical deformation. At Weyburn, 45 y of oil production has depleted pore pressures before increases associated with CO2 injection. The long history of the ?eld has led to complicated, sometimes nonintuitive geomechanical deformation. At In Salah, injection into the water leg of a gas reservoir has increased pore pressures, leading to uplift and substantial microseismic activity. The differences in the geomechanical responses of these sites emphasize the need for systematic geomechanical appraisal before injection in any potential storage site.

Sea surface temperature reconstruction based on alkenones of sediment core M35003-4

Evidence for abrupt climate changes on millennial and shorter timescales is widespread in marine and terrestrial climate records (Dansgard et al., 1993, doi:10.1038/364218a0; Bond et al., 1993, doi:10.1038/365143a0; Charles et al., 1996, doi:10.1016/0012-821X(96)00083-0, Bard et al., 1997, doi:10.1038/385707a0). Rapid reorganization of ocean circulation is considered to exert some control over these changes (Broecker et al., 1985, doi:10.1038/315021a0), as are shifts in the concentrations of atmospheric greenhouse gases (Broecker, 1994, doi:10.1038/372421a0). The response of the climate system to these two influences is fundamentally different: slowing of thermohaline overturn in the North Atlantic Ocean is expected to decrease northward heat transport by the ocean and to induce warming of the tropical Atlantic (Crowley, 1992, doi:10.1029/92PA01058; Manabe and Stouffer, 1997, doi:10.1029/96PA03932), whereas atmospheric greenhouse forcing should cause roughly synchronous global temperature changes (Manabe et al., 1991, doi:10.1175/1520-0442(1991)004<0785:TROACO>2.0.CO;2). So these two mechanisms of climate change should be distinguishable by the timing of surface-water temperature variations relative to changes in deep-water circulation. Here we present a high-temporal-resolution record of sea surface temperatures from the western tropical North Atlantic Ocean which spans the past 29,000 years, derived from measurements of temperature-sensitive alkenone unsaturation in sedimentary organic matter. We find significant warming is documented for Heinrich event H1 (16,900-15,400 calendar years bp) and the Younger Dryas event (12,900-11,600 cal. yr bp), which were periods of intense cooling in the northern North Atlantic. Temperature changes in the tropical and high-latitude North Atlantic are out of phase, suggesting that the thermohaline circulation was the important trigger for these rapid climate changes.

Radiocarbon dating and alkenone-based proxies of sediment core GeoB7702-3

In this study we utilize two organic geochemical proxies, the Uk'37 index and TEX86, to examine past sea surface temperatures (SST) from a site located near the Nile River Delta in the eastern Mediterranean (EM) Sea. The Uk'37 and TEX86 records generally are in agreement and indicate SST ranges of 14°C-26°C and 14°C-28°C, respectively, during the last 27 cal ka. During the Holocene, TEX86-based SST estimates are usually higher than Uk'37-based SST estimates, which is likely due to seasonal differences between the timing of the haptophyte and crenarchaeota blooms in the EM and is related to the onset of the modern flow regime of the Nile River. Both records show that SST varied on centennial to millennial timescales in response to global climate events, i.e., cooling during the Last Glacial Maximum (LGM), Heinrich event 1 (H1), and the Younger Dryas (YD) and warming during the Bølling-Allerød and in the early Holocene during deposition of sapropel S1. The H1 cooling was particularly severe and is marked by a drop in SST of ~4.5°C in comparison to pre-H1 SST, with temperatures >1°C cooler than during the LGM. In contrast to high-latitude and western Mediterranean records, which indicate both an abrupt onset and termination of the YD event, the transition from the YD to the Holocene was much more gradual in the EM.

Spring snowmelt and midwinter thaw and refreeze north of 60°N based on Seawinds QuikScat 2000-2009

The scatterometer SeaWinds on QuikSCAT provided regular measurements at Ku-band from 1999 to 2009. Although it was designed for ocean applications, it has been frequently used for the assessment of seasonal snowmelt patterns aside from other terrestrial applications such as ice cap monitoring, phenology and urban mapping. This paper discusses general data characteristics of SeaWinds and reviews relevant change detection algorithms. Depending on the complexity of the method, parameters such as long-term noise and multiple event analyses were incorporated. Temporal averaging is a commonly accepted preprocessing step with consideration of diurnal, multi-day or seasonal averages.

An individual based model spatial distribution, production and biomass for Calanus finmarchicus in the Norwegian Sea

The copepod Calanus finmarchicus is the dominant species of the meso-zooplankton in the Norwegian Sea, and constitutes an important link between the phytoplankton and the higher trophic levels in the Norwegian Sea food chain. An individualbased model for C. finmarchicus, based on super-individuals and evolving traits for behaviour, stages, etc., is two-way coupled to the NORWegian ECOlogical Model system (NORWECOM). One year of modelled C. finmarchicus spatial distribution, production and biomass are found to represent observations reasonably well. High C. finmarchicus abundance is found along the Norwegian shelf-break in the early summer, while the overwintering population is found along the slope and in the deeper Norwegian Sea basins. The timing of the spring bloom is generally later than in the observations. Annual Norwegian Sea production is found to be 29 million tonnes of carbon and a production to biomass (P/B) ratio of 4.3 emerges. Sensitivity tests show that the modelling system is robust to initial values of behavioural traits and with regards to the number of super-individuals simulated given that this is above about 50,000 individuals. Experiments with the model system indicate that it provides a valuable tool for studies of ecosystem responses to causative forces such as prey density or overwintering population size. For example, introducing C. finmarchicus food limitations reduces the stock dramatically, but on the other hand, a reduced stock may rebuild in one year under normal conditions. The NetCDF file contains model grid coordinates and bottom topography.

Global planktonic foraminifera seasonality

Shell fluxes of planktonic Foraminifera species vary intra-annually in a pattern that appears to follow the seasonal cycle. However, the variation in the timing and prominence of seasonal flux maxima in space and among species remains poorly constrained. Thus, although changing seasonality may result in a flux-weighted temperature offset of more than 5° C within a species, this effect is often ignored in the interpretation of Foraminifera-based paleoceanographic records. To address this issue we present an analysis of the intra-annual pattern of shell flux variability in 37 globally distributed time series. The existence of a seasonal component in flux variability was objectively characterised using periodic regression. This analysis yielded estimates of the number, timing and prominence of seasonal flux maxima. Over 80% of the flux series across all species showed a statistically significant periodic component, indicating that a considerable part of the intra-annual flux variability is predictable. Temperature appears to be a powerful predictor of flux seasonality, but its effect differs among species. Three different modes of seasonality are distinguishable. Tropical and subtropical species (Globigerinoides ruber (white and pink varieties), Neogloboquadrina dutertrei, Globigerinoides sacculifer, Orbulina universa, Globigerinella siphonifera, Pulleniatina obliquiloculata, Globorotalia menardii, Globoturborotalita rubescens, Globoturborotalita tenella and Globigerinoides conglobatus) appear to have a less predictable flux pattern, with random peak timing in warm waters. In colder waters, seasonality is more prevalent: peak fluxes occur shortly after summer temperature maxima and peak prominence increases. This tendency is stronger in species with a narrower temperature range, implying that warm-adapted species find it increasingly difficult to reproduce outside their optimum temperature range and that, with decreasing mean temperature, their flux is progressively more focussed in the warm season. The second group includes the temperate to cold-water species Globigerina bulloides, Globigerinita glutinata, Turborotalita quinqueloba, Neogloboquadrina incompta, Neogloboquadrina pachyderma, Globorotalia scitula, Globigerinella calida, Globigerina falconensis, Globorotalia theyeri and Globigerinita uvula. These species show a highly predictable seasonal pattern, with one to two peaks a year, which occur earlier in warmer waters. Peak prominence in this group is independent of temperature. The earlier-when-warmer pattern in this group is related to the timing of productivity maxima. Finally, the deep-dwelling Globorotalia truncatulinoides and Globorotalia inflata show a regular and pronounced peak in winter and spring. The remarkably low flux outside the main pulse may indicate a long reproductive cycle of these species. Overall, our analysis indicates that the seasonality of planktonic Foraminifera shell flux is predictable and reveals the existence of distinct modes of phenology among species. We evaluate the effect of changing seasonality on paleoceanographic reconstructions and find that, irrespective of the seasonality mode, the actual magnitude of environmental change will be underestimated. The observed constraints on flux seasonality can serve as the basis for predictive modelling of flux pattern. As long as the diversity of species seasonality is accounted for in such models, the results can be used to improve reconstructions of the magnitude of environmental change in paleoceanographic records.

Immobilisation dose rates and photogrammetry based mass calculations for southern elephant seals during expedition JUB2010

Immobilization and anaesthesia of adult male southern elephant seals (Mirounga leonina) is potentially risky for animals and scientists. A tiletamine/zolazepam injection is considered the most appropriate drug combination for field application in this species. Since appropriate dosages are difficult to assess due to uncertainties in weight estimation, we used photogrammetry-derived weight estimates to ensure precise post hoc calculations of dosages. We report on 15 intramuscular tiletamine/zolazepam immobilizations of post-moult males of the upper weight class at King George Island/Isla 25 de Mayo, in April 2010. Initial injections were made using blowpipe syringes. Mean tiletamine/zolazepam combined dosages of 0.71 mg/kg (SD ± 0.16) ranged between 0.46 and 1.01 mg/kg. In four cases, ketamine was added in dosages between 0.96 and 2.61 mg/kg. Mean induction period was 23 min (± 15), and the mean duration of the procedures from first injection to release of the animals required 96 min (± 51). Four seals exhibited periods of apnoea, and one case of an extended, repetitive, and potentially critical apnoea (> 25 and 8 min) required intervention in order to successfully re-initiate spontaneous respiration. All procedures resulted in proper immobilizations allowing for the deployment of the satellite tags on the seals' heads. The fact that even substantial deviations between the initial weight estimates and the photogrammetry-derived weight estimates had no apparent effect on the course of the immobilization underlines the drugs' wide safety margin in this species.

(Table 1) Organic geochemistry of ODP Hole 134-832B and Site 134-833

Ocean Drilling Program (ODP) Leg 134 was located in the central part of the New Hebrides Island Arc, in the Southwest Pacific. Here the d'Entrecasteaux Zone of ridges, the North d'Entrecasteaux Ridge and South d'Entrecasteaux Chain, is colliding with the arc. The region has a Neogene history of subduction polarity reversal, ridge-arc collision, and back-arc spreading. The reasons for drilling in this region included the following: (1) to determine the differences in the style and time scale of deformation associated with the two ridge-like features (a fairly continuous ridge and an irregularly topographic seamount chain) that are colliding with the central New Hebrides Island Arc; (2) to document the evolution of the magmatic arc in relation to the collision process and possible Neogene reversal of subduction; and (3) to understand the process of dewatering of a small accretionary wedge associated with ridge collision and subduction. Seven sites were occupied during the leg, five (Sites 827-831) were located in the d'Entrecasteaux Zone where collision is active. Three sites (Sites 827, 828, and 829) were located where the North d'Entrecasteaux Ridge is colliding, whereas two sites (Sites 830 and 831) were located in the South d'Entrecasteaux Chain collision zone. Sites 828 (on North d'Entrecasteaux Ridge) and 831 (on Bougainville Guyot) were located on the Pacific Plate, whereas all other sites were located on a microplate of the North Fiji Basin. Two sites (Sites 832 and 831) were located in the intra-arc North Aoba Basin. Results of Leg 134 drilling showed that forearc deformation associated with the North d'Entrecasteaux Ridge and South d'Entrecasteaux Chain collision is distinct and different. The d'Entrecasteaux Zone is an Eocene subduction/obduction complex with a distinct submerged island arc. Collision and subduction of the North d'Entrecasteaux Ridge results in off scraping of ridge material and plating of the forearc with thrust sheets (flakes) as well as distinct forearc uplift. Some offscraped sedimentary rocks and surficial volcanic basement rocks of the North d'Entrecasteaux Ridge are being underplated to the New Hebrides Island forearc. In contrast, the South d'Entrecasteaux Chain is a serrated feature resulting in intermittent collision and subduction of seamounts. The collision of the Bougainville Guyot has indented the forearc and appears to be causing shortening through thrust faulting. In addition, we found that the Quaternary relative convergence rate between the New Hebrides Island Arc at the latitude of Espiritu Santo Island is as high as 14 to 16 cm/yr. The northward migration rate of the d'Entrecasteaux Zone was found the be ~2 to 4 cm/yr based on the newly determined Quaternary relative convergence rate. Using these rates we established the timing of initial d'Entrecasteaux Zone collision with the arc at ~3 Ma at the latitude of Epi Island and fixed the impact of the North d'Entrecasteaux Ridge upon Espiritu Santo Island at early Pleistocene (between 1.89 and 1.58 Ma). Dewatering is occurring in the North d'Entrecasteaux Ridge accretionary wedge, and the wedge is dryer than other previously studied accretionary wedges, such as Barbados. This could be the result of less sediment being subducted at the New Hebrides compared to the Barbados.

Metal content of nodules at Sea Scope stations based upon different analysis methods

Information on possible resource value of sea floor manganese nodule deposits in the eastern north Pacific has been obtained by a study of records and collections of the 1972 Sea Scope Expedition.

Multi-sensor global compilation of mid-Holocene sea surface temperatures, based on Mg/Ca and alkenone palaeothermometry and reconstructions obtained using planktonic foraminifera and organic-walled dinoflagellate cyst

We present and examine a multi-sensor global compilation of mid-Holocene (MH) sea surface temperatures (SST), based on Mg/Ca and alkenone palaeothermometry and reconstructions obtained using planktonic foraminifera and organic-walled dinoflagellate cyst census counts. We assess the uncertainties originating from using different methodologies and evaluate the potential of MH SST reconstructions as a benchmark for climate-model simulations. The comparison between different analytical approaches (time frame, baseline climate) shows the choice of time window for the MH has a negligible effect on the reconstructed SST pattern, but the choice of baseline climate affects both the magnitude and spatial pattern of the reconstructed SSTs. Comparison of the SST reconstructions made using different sensors shows significant discrepancies at a regional scale, with uncertainties often exceeding the reconstructed SST anomaly. Apparent patterns in SST may largely be a reflection of the use of different sensors in different regions. Overall, the uncertainties associated with the SST reconstructions are generally larger than the MH anomalies. Thus, the SST data currently available cannot serve as a target for benchmarking model simulations.

Age tie points and geochemistry of sediment cores from the Antarctic continental margin

Few high-latitude terrestrial records document the timing and nature of the Cenozoic "Greenhouse" to "Icehouse" transition. Here we exploit the bulk geochemistry of marine siliciclastic sediments from drill cores on Antarctica's continental margin to extract a unique semiquantitative temperature and precipitation record for Eocene to mid-Miocene (~54-13 Ma). Alkaline elements are strongly enriched in the detrital mineral fraction in fine-grained siliciclastic marine sediments and only occur as trace metals in the biogenic fraction. Hence, terrestrial climofunctions similar to the chemical index of alteration (CIA) can be applied to the alkaline major element geochemistry of marine sediments on continental margins in order to reconstruct changes in precipitation and temperature. We validate this approach by comparison with published paleotemperature and precipitation records derived from fossil wood, leaves, and pollen and find remarkable agreement, despite uncertainties in the calibrations of the different proxies. A long-term cooling on the order of >=8°C is observed between the Early Eocene Climatic Optimum (~54-52 Ma) and the middle Miocene (~15-13 Ma) with the onset of transient cooling episodes in the middle Eocene at ~46-45 Ma. High-latitude stratigraphic records currently exhibit insufficient temporal resolution to reconstruct continental aridity and inferred ice-sheet development during the middle to late Eocene (~45-37 Ma). However, we find an abrupt aridification of East Antarctica near the Eocene-Oligocene transition (~34 Ma), which suggests that ice coverage influenced high-latitude atmospheric circulation patterns through albedo effects from the earliest Oligocene onward.