| 1. |
- Jakobsson, Martin, 1966-, et al.
(författare)
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An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data
- 2010
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 29:25-26, s. 3505-3517
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Tidskriftsartikel (refereegranskat)abstract
- The hypothesis of floating ice shelves covering the Arctic Ocean during glacial periods was developed in the 1970s. In its most extreme form, this theory involved a 1000 m thick continuous ice shelf covering the Arctic Ocean during Quaternary glacial maxima including the Last Glacial Maximum (LGM). While recent observations clearly demonstrate deep ice grounding events in the central Arctic Ocean, the ice shelf hypothesis has been difficult to evaluate due to a lack of information from key areas with severe sea ice conditions. Here we present new data from previously inaccessible, unmapped areas that constrain the spatial extent and timing of marine ice sheets during past glacials. These data include multibeam swath bathymetry and subbottom profiles portraying glaciogenic features on the Chukchi Borderland, southern Lomonosov Ridge north of Greenland, Morris Jesup Rise, and Yermak Plateau. Sediment cores from the mapped areas provide age constraints on the glaciogenic features. Combining these new geophysical and geological data with earlier results suggests that an especially extensive marine ice sheet complex, including an ice shelf, existed in the Amerasian Arctic Ocean during Marine Isotope Stage (MIS) 6. From a conceptual oceanographic model we speculate that the cold halocline of the Polar Surface Water may have extended to deeper water depths during MIS 6 inhibiting the warm Atlantic water from reaching the Amerasian Arctic Ocean and, thus, creating favorable conditions for ice shelf development. The hypothesis of a continuous 1000 m thick ice shelf is rejected because our mapping results show that several areas in the central Arctic Ocean substantially shallower than 1000 m water depth are free from glacial influence on the seafloor.
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| 2. |
- Apel, Jan, et al.
(författare)
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Early Holocene human population events on the island of Gotland in the Baltic Sea (9200-3800 cal. BP)
- 2018
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Ingår i: Quaternary International. - : Elsevier BV. - 1040-6182 .- 1873-4553. ; 465, s. 276-286
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Tidskriftsartikel (refereegranskat)abstract
- The summed probability distribution of 162 radiocarbon dates from Gotland was analysed with reference to archaeological and environmental data in order to evaluate possible variations in settlement intensity on the island. The data indicated variations in demographic development on the island, with probably several different colonization events and external influences; the pioneer settlement reached the island around 9200 cal. BP. After the initial colonization, the radiocarbon dates were rather evenly distributed until around 7700–7600 cal. BP, then there was a drop in the number of dates between 8300 and 8000 cal. BP that may be associated with the 8200 cold event. A marked decline in the number of dates between 7600 and 6000 cal. BP may be associated initially with the Littorina I transgression, but this transgression cannot explain why the Late Mesolithic period is not well represented on Gotland: the climatic development was favourable but did not result in increased human activity. The number of radiocarbon dates indicated that the population size remained low until around 6000 cal. BP, after which there was a gradual increase that reached a first ‘threshold’ after 5600 cal. BP and a second ‘threshold’ after 4500 cal. BP. The first apparent population increase was associated with the appearance of the Funnel Beaker Culture (FBC) and the second with Pitted Ware Culture (PWC) complexes. A decline in the number of dates occurred after 4300 cal. BP, i.e. towards the Late Neolithic. There was an association between the frequency distributions of the radiocarbon dates and the number of stray finds from different time periods but any correlation was not straightforward.
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| 3. |
- Hasper, Thomas Berg, et al.
(författare)
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Water use by Swedish boreal forests in a changing climate
- 2016
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 30:5, s. 690-699
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Tidskriftsartikel (refereegranskat)abstract
- The rising levels of atmospheric carbon dioxide concentration ([CO2]) and temperature have the potential to substantially affect the terrestrial water and energy balance by altering the stomatal conductance and transpiration of trees. Many models assume decreases in stomatal conductance and plant water use under rising [CO2], which has been used as a plausible explanation for the positive global trend in river run-off over the past century. Plant water use is, however, also affected by changes in temperature, precipitation and land use, and there is yet no consensus about the contribution of different drivers to temporal trends of evapotranspiration (ET) and river run-off. In this study, we assessed water-use responses to climate change by using both long-term monitoring and experimental data in Swedish boreal forests. Historical trends and patterns in ET of large-scale boreal landscapes were determined using climate and run-off data from the past 50 years, while explicit tree water-use responses to elevated [CO2] and/or air temperature were examined in a whole-tree chamber experiment using mature Norway spruce (Picea abies (L.) Karst.) trees. The results demonstrated that ET estimated from water budgets at the catchment scale increased by 18% over the past 50 years while run-off did not significantly change. The increase in ET was related to increasing precipitation and a steady increase in forest standing biomass over time. The whole-tree chamber experiment showed that Norway spruce trees did not save water under elevated [CO2] and that experimentally elevated air temperature did not increase transpiration as decreased stomatal conductance cancelled the effect of higher vapour pressure deficit in warmed air. Our findings have important implications for projections of future water use of European boreal coniferous forests, indicating that changes in precipitation and standing biomass are more important than the effects of elevated [CO2] or temperature on transpiration rates.
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| 4. |
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| 5. |
- Wallin-Norman, Karin, 1948-
(författare)
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Kontorätt : Rätt till kontoförda värdepapper
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Paper-backed securities are no longer the norm in today´s financial world. However, securities laws are still often based on traditional legal principles for paper-backed securities. Therefore legal rules as well as doctrine relating to modern financial instruments not only uses fictions as a tool, but is actually dominated by fiction. This fiction is termed by the author the "Physical Model" (den Fysiska Modellen). One aim of the work is to investigate and clarify the content of the current Swedish rules relating to book-entry securities as a legal construct. The investigation explores how the Physical Model influences both legal theory and practice pertaining to rights in relation to financial instruments. However the overarching objective of the investigation, which is presented in the thesis, is to form a foundation for a totally new perception of book-entry securities as objects of property. The author suggests that the traditional legal principle of specificity, as applied to book-entry securities, needs to be re-constructed. Also the traditional assumption, the so called Commission Sales Construct, i.e. the perception of all dealings in securities as fundamentally "trades in commission" is questioned. The application of the Physical Model - it is argued - leads to unnecessary and incoherent rules and regulations. Comparison between book-entry securities and book-entry money suggests that these two kinds of property are rather two sides of the same "thing". All in all the author concludes and suggests that property consisting of book-entry securities - and possibly in the long run also other book-entry rights - should be classified in all legal context, theory and practice, as a class of property of its own. To facilitate this, the author launches a new legal term (in Swedish) - kontorätt - meaning "the rights of an account holder in relation to an account provider as regards securities credited to the account". This term is also the title of the book.
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