Alfred Wegner Institute

Bremerhaven, Germany

Alfred Wegner Institute

Bremerhaven, Germany
SEARCH FILTERS
Time filter
Source Type

Salt L.A.,Netherlands Institute for Sea Research | Salt L.A.,French National Center for Scientific Research | Van Heuven S.M.A.C.,University of Groningen | Van Heuven S.M.A.C.,Alfred Wegner Institute | And 4 more authors.
Biogeosciences | Year: 2015

Observations along the southwestern Atlantic WOCE A17 line made during the Dutch GEOTRACES-NL programme (2010-2011) were compared with historical data from 1994 to quantify the changes in the anthropogenic component of the total pool of dissolved inorganic carbon (ΔCant). Application of the extended multi-linear regression (eMLR) method shows that the ΔCant from 1994 to 2011 has largely remained confined to the upper 1000 dbar. The greatest changes occur in the upper 200 dbar in the Subantarctic Zone (SAZ), where a maximum increase of 37 μmol kg-1 is found. South Atlantic Central Water (SACW) experienced the highest rate of increase in Cant, at 0.99 ± 0.14 μmol kg-1 yr-1, resulting in a maximum rate of decrease in pH of 0.0016 yr-1. The highest rates of acidification relative to ΔCant, however, were found in Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW). The low buffering capacity of SAMW and AAIW combined with their relatively high rates of Cant, increase of 0.53 ± 0.11 and 0.36 ± 0.06 μmol kg-1 yr-1, respectively, has lead to rapid acidification in the SAZ, and will continue to do so whilst simultaneously reducing the chemical buffering capacity of this significant CO2 sink ©Author(s) 2015. CC Attribution 3.0 License..


Christl M.,ETH Zurich | Lachner J.,ETH Zurich | Vockenhuber C.,ETH Zurich | Lechtenfeld O.,Alfred Wegner Institute | And 3 more authors.
Geochimica et Cosmochimica Acta | Year: 2012

In this study the first two oceanic depth profiles of 236U sampled in the western equatorial Atlantic Ocean are presented. The measured 236U/ 238U ratios decrease from about 10 -9 at the surface down to about 10 -10. Even the lowest ratios measured below 4000m depth are more than three orders of magnitude above the estimated natural 236U/ 238U level for the pre-anthropogenic ocean. This clearly indicates that anthropogenic 236U already has reached the deep Atlantic Ocean. Three different conceptual models are applied to identify the relevant processes capable of transporting significant amounts of 236U from the surface into the deep ocean. While the vertical transport of particulate U is excluded as a significant source, box model calculations suggest that North Atlantic Deep Water production with some minor contribution of 236U from nuclear reprocessing as the most likely source for 236U in the deep western equatorial Atlantic Ocean. Our results show that 236U has a large potential as a new, conservative, and transient tracer in Oceanography. © 2011 Elsevier Ltd.


Dishon G.,Haifa University | Fisch J.,University of Miami | Horn I.,Leibniz University of Hanover | Kaczmarek K.,Alfred Wegner Institute | And 5 more authors.
Biogeosciences | Year: 2015

Coral reefs occupy only ∼ 0.1 percent of the ocean's habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced a significant global decline due to a variety of causes, one of the major causes being widespread coral bleaching events. During bleaching, the coral expels its symbiotic algae, thereby losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) to demonstrate a distinct biologically induced decline of boron (B) isotopic composition (δ11B) as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published δ11B data and our recorded vital effect of coral bleaching on the δ11B signal, we also describe at least two possible coral bleaching events since the Last Glacial Maximum. The implementation of this bleaching proxy holds the potential of identifying occurrences of coral bleaching throughout the geological record. A deeper temporal view of coral bleaching will enable scientists to determine if it occurred in the past during times of environmental change and what outcome it may have had on coral population structure. Understanding the frequency of bleaching events is also critical for determining the relationship between natural and anthropogenic causes of these events. © 2015 Author(s).


Muller-Michaelis A.,Alfred Wegner Institute | Uenzelmann-Neben G.,Alfred Wegner Institute | Stein R.,Alfred Wegner Institute
Marine Geology | Year: 2013

The Eirik Drift lies on the continental slope south of Greenland, where it has been formed under the influence of Northern Component Water (NCW). NCW flow is an essential part of the global Thermohaline Circulation (THC), which is closely connected to the world's climate. Changes in pathways and intensity of NCW flow bear information about modifications of the North Atlantic THC in a changing climate. There is some disagreement about when deep-current controlled sedimentation at the Eirik Drift started. While the onset of drift building was previously dated as early Pliocene or late Miocene in age we suggest that the effect of large-scale current deposition had been initiated by at least 19-17. Ma based on the seismostratigraphic analysis of sedimentary structures identified in a set of high-resolution seismic reflection data. This assumption of an early Miocene onset of NCW flow is supported by regional evidence regarding the breaching of the Greenland-Scotland Ridge, which is documented in several erosional unconformities within the North Atlantic. After the onset of deep-current controlled sedimentation at the Eirik Drift, two major changes in the deep-current system are revealed during the Miocene: At the mid- to late Miocene boundary (12-10 Ma) and at 7.5 Ma. © 2013 Elsevier B.V.


In order to better explain to children and laypeople the complex mechanisms related to global warming and the Antarctic Ice Sheet, researchers have partnered with game developers to create a new game that illustrates the way that the Antarctic Ice Sheet will be affected by anthropogenic climate change, according to an email sent to CleanTechnica. The new interactive game — the Ice Flows Game — was officially launched only a few days ago at the SCAR (Scientific Committee for Antarctic Research) Open Science Conference in Kuala Lumpur. The email provides more: “The game is built on a simple representation of how ice flows in Antarctica and how it responds to changes in the environment — through changes in snowfall and ocean temperature. It allows players to impose climatic changes to control the extent of the ice sheet to guide penguins to fish; if they get it wrong, the penguin may meet its doom in the jaws of a leopard seal. The aim is to promote understanding of the complexity of the ice sheet system by enabling the player to carry out their own ice sheet model experiments, much like the scientists working on the research. The game has a number of levels representing how different parts of the Antarctic will respond to climate change.” The game was actually developed as part of a research project on the Filchner Ice Shelf system in Antarctica. This utilized field measurements — with numerical modeling of ice flow, ocean currents, and the atmosphere — in order to better understand future predictions. The game itself was developed by Anne Le Brocq of the University of Exeter, in partnership with the game developers Inhouse Visuals and Questionable Quality as well as with the British Antarctic Survey, the leader of the wider research project. Researchers from “the UK Met Office, National Oceanography Centre, University College London, the University of Oxford, and the Alfred Wegner Institute in Germany” also took part. Funding came from the Natural Environment Research Council. The aforementioned Dr Anne Le Brocq, a Senior Lecturer in Physical Geography at the University of Exeter, commented: “The response of the Antarctic Ice Sheet to a changing climate is very complex and, as a result, is difficult to communicate in a clear and understandable way. The use of a game helps not only to visualize the system, but also to provide an immersive environment for the player to fully understand the behaviour of the ice sheet and how it responds to changes in the environment. Hopefully it’s fun to play too!” Out of all the actions that are needed to even attempt to address climate change, I admit that the development of a children’s game wasn’t at the front of my mind. Perhaps it’ll have some value, though — whether someone is exposed to something at a young age or not seems to have a lot to do with what they find to be believable.   Drive an electric car? Complete one of our short surveys for our next electric car report.   Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.  

Loading Alfred Wegner Institute collaborators
Loading Alfred Wegner Institute collaborators