| 1. |
- Birks, HH, et al.
(författare)
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The Krakenes late-glacial palaeoenvironmental project
- 1996
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Ingår i: JOURNAL OF PALEOLIMNOLOGY. - : KLUWER ACADEMIC PUBL. ; 15:3
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Krakenes is the site of a small lake on the west coast of Norway that contains a long sequence of late-glacial sediments. The Younger Dryas is well represented, as a cirque glacier developed in the catchment at this time. This site offers unique opportuni
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| 2. |
- Bjorck, S, et al.
(författare)
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Synchronized terrestrial-atmospheric deglacial records around the North Atlantic
- 1996
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Ingår i: SCIENCE. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075. ; 274:5290, s. 1155-1160
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- On the basis of synchronization of three carbon-14 (C-14)-dated lacustrine sequences from Sweden With tree ring and ice core records, the absolute age of the Younger Dryas-Preboreal climatic shift was determined to be 11,450 to 11,390 +/- 80 years before
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| 3. |
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| 4. |
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| 5. |
- Hajdas, I., et al.
(författare)
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Radiocarbon and absolute chronology of the Late-Glacial record from Hauterive/Rouges-Terres, Lake Neuchdtel (CH)
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 223, s. 308-312
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Tidskriftsartikel (refereegranskat)abstract
- Radiocarbon ages of 87 samples made up of terrestrial macrofossils (mainly twigs of Salix sp.) were washed out from sediments sampled at Hauterive/Rouges-Terres, Lake Neuchatel, Switzerland, and measured using the AMS dating technique. These radiocarbon ages, which range from 8000 to 14,500 BP, were used to construct an absolute chronology of the record. A model of a sequence with known calendar ages for the period between 9000 to 17,500 cal BP was used to calibrate the 14 C ages. Three known calendar ages were set by pollen based dating (biozones) of palaeoclimatic events at 11,450 cal BP (Younger Dryas/Preboreal), 13,450 cal BP (Gerzensee Oscillation) and 14,650 cal BP (Oldest Dryas/ Bolling; see figure). This study shows that high resolution radiocarbon dating combined with such a calibration approach provides a powerful tool for dating stratigraphic sections by minimizing effects such as inversions in calendar ages and large errors caused by wiggles and plateaus in the radiocarbon time-scale.
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| 6. |
- Sim, Thomas G., et al.
(författare)
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Regional variability in peatland burning at mid-to high-latitudes during the Holocene
- 2023
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Ingår i: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 305
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Tidskriftsartikel (refereegranskat)abstract
- Northern peatlands store globally-important amounts of carbon in the form of partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency and severity in peatlands and the rapid loss of carbon to the atmosphere. However, our understanding of the patterns and drivers of peatland burning on an appropriate decadal to millennial timescale relies heavily on individual site-based reconstructions. For the first time, we synthesise peatland macrocharcoal re-cords from across North America, Europe, and Patagonia to reveal regional variation in peatland burning during the Holocene. We used an existing database of proximal sedimentary charcoal to represent regional burning trends in the wider landscape for each region. Long-term trends in peatland burning appear to be largely climate driven, with human activities likely having an increasing influence in the late Holocene. Warmer conditions during the Holocene Thermal Maximum (similar to 9e6 cal. ka BP) were associated with greater peatland burning in North America's Atlantic coast, southern Scandinavia and the Baltics, and Patagonia. Since the Little Ice Age, peatland burning has declined across North America and in some areas of Europe. This decline is mirrored by a decrease in wider landscape burning in some, but not all sub-regions, linked to fire-suppression policies, and landscape fragmentation caused by agricultural expansion. Peatlands demonstrate lower susceptibility to burning than the wider landscape in several instances, probably because of autogenic processes that maintain high levels of near-surface wetness even during drought. Nonetheless, widespread drying and degradation of peatlands, particularly in Europe, has likely increased their vulnerability to burning in recent centuries. Consequently, peatland restoration efforts are important to mitigate the risk of peatland fire under a changing climate. Finally, we make recommendations for future research to improve our understanding of the controls on peatland fires.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 7. |
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| 8. |
- Birks, H.H., et al.
(författare)
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The development of the aquatic ecosytem at Kråkenes Lake, western Norway, during the late glacial and early Holocene - a synthesis.
- 2000
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Ingår i: Journal of Paleolimnology. - 0921-2728 .- 1573-0417. ; 23:1, s. 91-114
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Tidskriftsartikel (refereegranskat)abstract
- This paper synthesises the palaeoecological reconstructions, including palaeoclimatic inferences, based on the available fossil record of plants (pollen, macrofossils, mosses, diatoms) and animals (chironomids, Cladocera, Coleoptera, Trichoptera, oribatid mites) in the late-glacial and early-Holocene sediments of Kråkenes Lake, western Norway, with special emphasis on changes in the aquatic ecosystem. New percentage and influx pollen diagrams for selected taxa provide insights into the terrestrial setting. The information from all the proxies is collated in a stratigraphical chart, and the inferred changes in the lake and its catchment are discussed. The individual fossil sequences are summarised by detrended correspondence analysis (DCA), and sample scores on the first DCA axes are plotted against an estimated calendar-year timescale for comparison of the timing and magnitude of changes in assemblage composition. The DCA plots show that the large late-glacial biotic changes were synchronous, and were driven by the overriding forcing factor of temperature. During the early Holocene, however, the changes in different groups were more gradual and were independent of each other, showing that other factors were important and interactive, such as the inwash of dissolved and particulate material from the catchment, the base and nutrient status of the lake-water, and the internal processes of ecosystem succession and sediment accumulation. This multi-disciplinary study, with proxies for changes in the lake and in the catchment, highlights the dependence of lake biota and processes not only on regional climatic changes but also on changes in the lake catchment and on internal processes within the lake. Rates of change for each group are also estimated and compared. The reaction times to the sharp temperature changes at the start and end of the Younger Dryas were very rapid and occurred within a decade of the temperature change. Aquatic organisms tracked the temperature and environmental changes very closely, and are probably the best recorders of late-glacial climatic change in the fossil record.
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| 9. |
- Birks, H.H., et al.
(författare)
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The Kråkenes Late-glacial Palaeoenvironmental Project.
- 1996
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Ingår i: Journal of Paleolimnology. - 0921-2728 .- 1573-0417. ; 15:3, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- Krakenes is the site of a small lake on the west coast of Norway that contains a long sequence of late-glacial sediments. The Younger Dryas is well represented, as a cirque glacier developed in the catchment at this time. This site offers unique opportunities to reconstruct late-glacial environments from independent sources of evidence; physical evidence (glacial geomorphology, sedimentology, palaeomagnetism, radiocarbon dating), and biological evidence from the remains of animals and plants derived from both the terrestrial and aquatic ecosystems. This report describes the background to the site, and the international multidisciplinary project to reconstruct late-glacial and early Holocene environmental and climatic changes at Krakenes.
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| 10. |
- Björck, S., et al.
(författare)
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Synchronized terrestrial-atmospheric deglacial records around the North Atlantic.
- 1996
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 274:5290, s. 1155-1160
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Tidskriftsartikel (refereegranskat)abstract
- On the basis of synchronization of three carbon-14 (C-14)-dated lacustrine sequences from Sweden With tree ring and ice core records, the absolute age of the Younger Dryas-Preboreal climatic shift was determined to be 11,450 to 11,390 +/- 80 years before the present. A 150-year-long cooling in the early Preboreal, associated with rising Delta(14)C values, is evident in all records and indicates an ocean ventilation change. This cooling is similar to earlier deglacial coolings, and box-model calculations suggest that they all may have been the result of increased freshwater forcing that inhibited the strength of the North Atlantic heat conveyor, although the Younger Dryas may have begun as an anomalous meltwater event.
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