Calcium carbonate global LGM Burial rate data

Global databases of calcium carbonate concentrations and mass accumulation rates in Holocene and last glacial maximum sediments were used to estimate the deep-sea sedimentary calcium carbonate burial rate during these two time intervals. Sparse calcite mass accumulation rate data were extrapolated across regions of varying calcium carbonate concentration using a gridded map of calcium carbonate concentrations and the assumption that accumulation of noncarbonate material is uncorrelated with calcite concentration within some geographical region. Mean noncarbonate accumulation rates were estimated within each of nine regions, determined by the distribution and nature of the accumulation rate data. For core-top sediments the regions of reasonable data coverage encompass 67% of the high-calcite (>75%) sediments globally, and within these regions we estimate an accumulation rate of 55.9 ± 3.6 x 10**11 mol/yr. The same regions cover 48% of glacial high-CaCO3 sediments (the smaller fraction is due to a shift of calcite deposition to the poorly sampled South Pacific) and total 44.1 ± 6.0 x 10**11 mol/yr. Projecting both estimates to 100 % coverage yields accumulation estimates of 8.3 x 10**12 mol/yr today and 9.2 x 10**12 mol/yr during glacial time. This is little better than a guess given the incomplete data coverage, but it suggests that glacial deep sea calcite burial rate was probably not considerably faster than today in spite of a presumed decrease in shallow water burial during glacial time.

Database of the GLAMAP project

A uniform chronology for foraminifera-based sea surface temperature records has been established in more than 120 sediment cores obtained from the equatorial and eastern Atlantic up to the Arctic Ocean. The chronostratigraphy of the last 30,000 years is mainly based on published d18O records and 14C ages from accelerator mass spectrometry, converted into calendar-year ages. The high-precision age control provides the database necessary for the uniform reconstruction of the climate interval of the Last Glacial Maximum within the GLAMAP-2000 project.

Glacial North Atlantic: Sea surface conditions reconstructed by GLAMAP 2000

The response of the tropical ocean to global climate change and the extent of sea ice in the glacial nordic seas belong to the great controversies in paleoclimatology. Our new reconstruction of peak glacial sea surface temperatures (SSTs) in the Atlantic is based on census counts of planktic foraminifera, using the Maximum Similarity Technique Version 28 (SIMMAX-28) modern analog technique with 947 modern analog samples and 119 well-dated sediment cores. Our study compares two slightly different scenarios of the Last Glacial Maximum (LGM), the Environmental Processes of the Ice Age: Land, Oceans, Glaciers (EPILOG), and Glacial Atlantic Ocean Mapping (GLAMAP 2000) time slices. The comparison shows that the maximum LGM cooling in the Southern Hemisphere slightly preceeded that in the north. In both time slices sea ice was restricted to the north western margin of the nordic seas during glacial northern summer, while the central and eastern parts were ice-free. During northern glacial winter, sea ice advanced to the south of Iceland and Faeroe. In the central northern North Atlantic an anticyclonic gyre formed between 45° and 60°N, with a cool water mass centered west of Ireland, where glacial cooling reached a maximum of >12°C. In the subtropical ocean gyres the new reconstruction supports the glacial-to-interglacial stability of SST as shown by CLIMAP Project Members (CLIMAP) [1981]. The zonal belt of minimum SST seasonality between 2° and 6°N suggests that the LGM caloric equator occupied the same latitude as today. In contrast to the CLIMAP reconstruction, the glacial cooling of the tropical east Atlantic upwelling belt reached up to 6°-8°C during Northern Hemisphere summer. Differences between these SIMMAX-based and published U37[k]- and Mg/Ca-based equatorial SST records are ascribed to strong SST seasonalities and SST signals that were produced by different planktic species groups during different seasons.

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Stomach content records for pelagic fish (herring, mackerel, blue whiting, albacore and bluefin tuna) in the northeast Atlantic

Fish stomach content records extracted from the DAPSTOM 4.5 database (held at the UK Centre for Environment, Fisheries and Aquaculture Science - CEFAS). Data collated as part of the EU Euro-Basin project and specifically concerning herring (Clupea harengus), mackerel (Scomber scombrus), blue whiting (Micromesistius poutassou), albacore (Thunnus alalunga) and bluefin tuna (Thunnus thynnus). The data set consist of 20720 records - collected throughout the northeast Atlantic, between 1906 and 2011 - mostly during routine fisheries monitoring research cruises.

Age models and stable isotopes of sediment cores from the northern seas

Oxygen and carbon isotope measurements were carried out on tests of planktic foraminifers N. pachyderma (sin.) from eight sediment cores taken from the eastern Arctic Ocean, the Fram Strait, and the lceland Sea, in order to reconstruct Arctic Ocean and Norwegian-Greenland Sea circulation patterns and ice covers during the last 130,000 years. In addition, the influence of ice, temperature and salinity effects on the isotopic signal was quantified. Isotope measurements on foraminifers from sediment surface samples were used to elucidate the ecology of N. pachyderma (sin.). Changes in the oxygen and carbon isotope composition of N. pachyderma (sin.) from sediment surface samples document the horizontal and vertical changes of water mass boundaries controlled by water temperature and salinity, because N. pachyderma (sin.) shows drastic changes in depth habitats, depending on the water mass properties. It was able to be shown that in the investigated areas a regional and spatial apparent increase of the ice effect occurred. This happened especially during the termination I by direct advection of meltwaters from nearby continents or during the termination and in interglacials by supply of isotopically light water from rivers. A northwardly proceeding overprint of the 'global' ice effect, increasing from the Norwegian-Greenland Sea to the Arctic Ocean, was not able to be demonstrated. By means of a model the influence of temperature and salinity on the global ice volume signal during the last 130,000 years was recorded. In combination with the results of this study, the model was the basis for a reconstruction of the paleoceanographic development of the Arctic Ocean and the Norwegian-Greenland Sea during this time interval. The conception of a relatively thick and permanent sea ice cover in the Nordic Seas during glacial times should be replaced by the model of a seasonally and regionally highly variable ice cover. Only during isotope stage 5e may there have been a local deep water formation in the Fram Strait.

Downwelling spectral irradiance as measured in different depths, remote sensing reflectance and phytoplankton pigment concentration during POLARSTERN cruises ANT-XXIV/1, ANT-XXIV/4, ANT-XXVI/4 and Maria S. Merian cruise MSM18/3

The composition and abundance of algal pigments provide information on phytoplankton community characteristics such as photoacclimation, overall biomass and taxonomic composition. In particular, pigments play a major role in photoprotection and in the light-driven part of photosynthesis. Most phytoplankton pigments can be measured by high-performance liquid chromatography (HPLC) techniques applied to filtered water samples. This method, as well as other laboratory analyses, is time consuming and therefore limits the number of samples that can be processed in a given time. In order to receive information on phytoplankton pigment composition with a higher temporal and spatial resolution, we have developed a method to assess pigment concentrations from continuous optical measurements. The method applies an empirical orthogonal function (EOF) analysis to remote-sensing reflectance data derived from ship-based hyperspectral underwater radiometry and from multispectral satellite data (using the Medium Resolution Imaging Spectrometer - MERIS - Polymer product developed by Steinmetz et al., 2011, doi:10.1364/OE.19.009783) measured in the Atlantic Ocean. Subsequently we developed multiple linear regression models with measured (collocated) pigment concentrations as the response variable and EOF loadings as predictor variables. The model results show that surface concentrations of a suite of pigments and pigment groups can be well predicted from the ship-based reflectance measurements, even when only a multispectral resolution is chosen (i.e., eight bands, similar to those used by MERIS). Based on the MERIS reflectance data, concentrations of total and monovinyl chlorophyll a and the groups of photoprotective and photosynthetic carotenoids can be predicted with high quality. As a demonstration of the utility of the approach, the fitted model based on satellite reflectance data as input was applied to 1 month of MERIS Polymer data to predict the concentration of those pigment groups for the whole eastern tropical Atlantic area. Bootstrapping explorations of cross-validation error indicate that the method can produce reliable predictions with relatively small data sets (e.g., < 50 collocated values of reflectance and pigment concentration). The method allows for the derivation of time series from continuous reflectance data of various pigment groups at various regions, which can be used to study variability and change of phytoplankton composition and photophysiology.

Reconstructions of eolian dust accumulation in northwest African margin sediments

Reconstructions of eolian dust accumulation in northwest African margin sediments provide important continuous records of past changes in atmospheric circulation and aridity in the region. Existing records indicate dramatic changes in North African dust emissions over the last 20 ka, but the limited spatial extent of these records and the lack of high-resolution flux data do not allow us to determine whether changes in dust deposition occurred with similar timing, magnitude and abruptness throughout northwest Africa. Here we present new records from a meridional transect of cores stretching from 31°N to 19°N along the northwest African margin. By combining grain size endmember modeling with 230Th-normalized fluxes for the first time, we are able to document spatial and temporal changes in dust deposition under the North African dust plume throughout the last 20 ka. Our results provide quantitative estimates of the magnitude of dust flux changes associated with Heinrich Stadial 1, the Younger Dryas, and the African Humid Period (AHP; ~11.7-5 ka), offering robust targets for model-based estimates of the climatic and biogeochemical impacts of past changes in North African dust emissions. Our data suggest that dust fluxes between 8 and 6 ka were a factor of ~5 lower than average fluxes during the last 2 ka. Using a simple model to estimate the effects of bioturbation on dust input signals, we find that our data are consistent with abrupt, synchronous changes in dust fluxes in all cores at the beginning and end of the AHP. The mean ages of these transitions are 11.8±0.2 ka (1Sigma) and 4.9±0.2 ka, respectively.