The research group, currently consisting of Svante Björck, Karl Ljung and Dan Hammarlund, has retrieved cores of lake sediments and peat along a north-south transect of Atlantic islands and adjacent land areas: Greenland, Iceland, Faroes, Azores, Tristan da Cunha, Isla de los Estados, and the Antarctic Peninsula. Based on detailed analyses of geochemistry, mineral magnetism and pollen content, hitherto unknown details of Atlantic climate dynamics have been resolved. Extensive radiocarbon dating and rapid sedimentation rates in the terrestrial deposits allow a much higher temporal resolution of the data than provided by marine sediment cores.
-- Our records reflect details of the climatic evolution in the Atlantic region since the end of the last Ice Age to the present day. We would have liked to compare our results to similar data sets from other parts of the South Atlantic, but no other records provide the same degree of resolution, says Professor Björck. After the end of the last Glacial both Hemispheres became warmer as a result of melting ice sheets, but during the last 9000 years we can identify a persistent "seesaw" pattern. When the South Atlantic was warm it was cold in the North Atlantic and vice verse.
-- This is most certainly related to large-scale ocean circulation in the Atlantic Ocean. The main current system - "the Great Ocean Conveyor" - is driven by sinking of dense, relatively cold and salty water in the northern North Atlantic. This results in southward-flowing deep-water that is replaced by warm surface water brought to high northern latitudes from the tropics and ultimately from the South Atlantic, says Svante Björck, and continues:
-- The deep-water formation in the north is dependent on cooling of surface water with a high salt content. If sufficiently large amounts of fresh water are supplied to the North Atlantic, such as from melting ice-sheets or major increases in precipitation, the deep-water formation, and hence the transport of warm surface water from the south, may cease or at least decrease substantially. This is known to have happened repeatedly during the present Interglacial (the warm period since the last Ice Age). Minor disturbances have taken place in recent time, such as the Great Salt Anomaly in the 1970s, which seriously affected the cod population around the Faroe Islands. Our results from Nightingale Island in the Tristan da Cunha island group, between South Africa and Argentina, for the first time give evidence of warming of the South Atlantic associated with cooling in the north. This is a major breakthrough in palaeoclimate research.
In agreement with most other climate researchers, the Lund group is not concerned about a complete shut-down of the Gulf Stream as envisioned in the apocalyptic film "The day after tomorrow". However, future warming induced by anthropogenic greenhouse-gas emissions may influence the system.
-- We don't know with certainty what will happen. Some attempts at measuring ocean currents suggest a recent weakening of the Gulf Stream, and the transport of heat to the North Atlantic region may well decrease in the future as a result of increased precipitation. Such a scenario might lead to less warming in Europe than predicted by the IPCC, but we will probably not face an arctic climate, summarizes Svante Björck.
Further information can be obtained from Svante Björck +46 46 222 79 85, Karl Ljung +46 46 222 78 88 or Dan Hammarlund +46 46 222 79 85
Göran Frankel | idw
International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy