| 1. |
- Felde, Vivian A., et al.
(author)
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Compositional turnover and variation in Eemian pollen sequences in Europe
- 2020
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In: Vegetation History and Archaeobotany. - : Springer Science and Business Media LLC. - 0939-6314 .- 1617-6278. ; 29:1, s. 101-109
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Journal article (peer-reviewed)abstract
- The Eemian interglacial represents a natural experiment on how past vegetation with negligible human impact responded to amplified temperature changes compared to the Holocene. Here, we assemble 47 carefully selected Eemian pollen sequences from Europe to explore geographical patterns of (1) total compositional turnover and total variation for each sequence and (2) stratigraphical turnover between samples within each sequence using detrended canonical correspondence analysis, multivariate regression trees, and principal curves. Our synthesis shows that turnover and variation are highest in central Europe (47-55 degrees N), low in southern Europe (south of 45 degrees N), and lowest in the north (above 60 degrees N). These results provide a basis for developing hypotheses about causes of vegetation change during the Eemian and their possible drivers.
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| 2. |
- Ferraro, Mattia, et al.
(author)
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Establishing the current relation between observed oxygen conditions and oxygen proxies in western Norwegian fjords
- 2022
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In: 14th International Palaeoceanography Congress (ICP), Bergen (Norway).
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Conference paper (other academic/artistic)abstract
- Recently, there have been alarming reports regarding the de-oxygenation of Norwegian fjords due to climate change. Warming coastal waters and a suggested decrease in the renewal frequency of the fjords’ deep, stagnant basin water have been linked to the reduced oxygen concentrations. The fjords are economically important to Norway, and the water quality is (of course) of uttermost importance to the local ecosystem. Here I present a new project, FJO2RD, which investigates recent changes in the physical forcing and the renewal frequency while utilising paleo records from sediment archives to provide information on natural variability in fjord oxygenation during the last ca. 400 years. New multi- and gravity cores will be obtained from two fjords, Masfjorden and Lurefjorden, in western Norway. The oxygenation history will be reconstructed based on benthic foraminiferal assemblages and geochemical analyses. The Mn/Ca ratio will be analysed to study the extent of hypoxic conditions and past oxygen dynamics, and the Ba/Ca ratio to study runoff variability and stratification. The stable carbon isotopes will infer remineralisation associated with the change in oxygen. Dissolved oxygen concentrations will further be quantified using a modified Behl dissolved oxygen index, which is a method that calculates changes in oxygen concentrations by using a weighted average for each oxygen category as 0.1 mL/L for dysoxic, 0.5 mL/L for suboxic, and 1.5 mL/L for weakly hypoxic-oxic conditions. The results of these analyses will be used as the basis for my PhD-thesis
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| 3. |
- Ferraro, Mattia, et al.
(author)
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Multi-century reconstruction of environmental conditions in Lurefjorden, Norway.
- 2024
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In: 24th Nordic Geological Winter Meeting, 10-12th Jan, 2024, Gothenburg, Sweden.
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Conference paper (other academic/artistic)abstract
- Benthic foraminiferal assemblages are identified to reconstruct changes in environmental conditions over the last few centuries in Lurefjorden, a western Norwegian fjord. From ca. 1970 until present days the relative abundance of Brizalina skagerrakkensis, an efficient bio-indicator for organic matter fluxes, is enhanced relative to the preceding time interval. Hence, our results suggest that there is an increase of the organic matter within the Lurefjorden basin in the last 50 years. Over the same period, there is also an increase in the absolute abundance of agglutinated species, indicating lower oxygen concentration in the water. A lowering of the oxygen concentrations may have taken place as a response of a greater oxygen consumption caused by a higher organic matter supply in the water column. Accoridng to Aksnes (2009), Lurefjorden was subject to an increased freshening of Norwegian coastal waters (NCW), which has led to a decrease in sunlight penetration into the water column, affecting the oxygen levels and the behavior of marine life within the basin, between 1935 and 2007. Furthermore, we used diversity indices to study the ecological status of the area, showing significant growth in diversity, abundance, and richness within the benthic foraminiferal community over the past 50 years. Our observations highlight that an increase in the input of organic matter over the last century has led to a change in the benthic foraminifera community in the Lurefjorden basin.
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| 4. |
- Fischer, Hubertus, et al.
(author)
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Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond
- 2018
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In: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 11:7, s. 474-485
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Journal article (peer-reviewed)abstract
- Over the past 3.5 million years, there have been several intervals when climate conditions were warmer than during the pre-industrial Holocene. Although past intervals of warming were forced differently than future anthropogenic change, such periods can provide insights into potential future climate impacts and ecosystem feedbacks, especially over centennial-to-millennial timescales that are often not covered by climate model simulations. Our observation-based synthesis of the understanding of past intervals with temperatures within the range of projected future warming suggests that there is a low risk of runaway greenhouse gas feedbacks for global warming of no more than 2 °C. However, substantial regional environmental impacts can occur. A global average warming of 1–2 °C with strong polar amplification has, in the past, been accompanied by significant shifts in climate zones and the spatial distribution of land and ocean ecosystems. Sustained warming at this level has also led to substantial reductions of the Greenland and Antarctic ice sheets, with sea-level increases of at least several metres on millennial timescales. Comparison of palaeo observations with climate model results suggests that, due to the lack of certain feedback processes, model-based climate projections may underestimate long-term warming in response to future radiative forcing by as much as a factor of two, and thus may also underestimate centennial-to-millennial-scale sea-level rise.
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| 5. |
- Polovodova Asteman, Irina, 1980, et al.
(author)
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Spreading of an alien benthic foraminifer in the North Sea: a reason to be worried?
- 2023
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In: International Congress FORAMS2023, Perugia, Italy, 25-30th June. - Perugia, Italy : Micropress Europe & The Grzybowski Foundation.
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Conference paper (other academic/artistic)abstract
- In the Skagerrak-Kattegat (eastern North Sea), the alien benthic foraminifer Nonionella sp. T1 (previously referred to as “Nonionella stella”) was reported for the first time in 2011 and 2012 in the Swedish and southern Norwegian fjords, respectively. Based on dated sediment cores its first occurrence can be traced back to the 1980s in the Gullmar Fjord, to the 2000s in the Öresund and to 2010 in the Oslofjord. Since then, Nonionella sp T1 has spread all over the Kattegat and coastal Skagerrak, according to sampling campaigns performed between 2016 and 2022. The species is now highly abundant in the entire Kattegat, including the Öresund, as well as in fjord mouths of the seasonally hypoxic Gullmar Fjord, the oxic Hakefjord and the long-term polluted Idefjord as demonstrated by molecular and morphospecies data. At the same time, Nonionella sp T1 is rare to absent in the Baltic Sea, Skagerrak deep basin and in deep fjords of western and northern Norway. This study shows some preliminary results on the species’ present distribution in the study area and raises questions about the driving factors and potential effects on the local biodiversity.
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