| 1. |
- Boy, M., et al.
(författare)
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Interactions between the atmosphere, cryosphere, and ecosystems at northern high latitudes
- 2019
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 19:3, s. 2015-2061
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Tidskriftsartikel (refereegranskat)abstract
- The Nordic Centre of Excellence CRAICC (Cryosphere-Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011-2016, is the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual centre with the objectives of identifying and quantifying the major processes controlling Arctic warming and related feedback mechanisms, outlining strategies to mitigate Arctic warming, and developing Nordic Earth system modelling with a focus on short-lived climate forcers (SLCFs), including natural and anthropogenic aerosols. The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special issue of the journal Atmospheric Chemistry and Physics. This paper presents an overview of the main scientific topics investigated in the centre and provides the reader with a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Faced with a vast amount of scientific discovery, we do not claim to completely summarize the results from CRAICC within this paper, but rather concentrate here on the main results which are related to feedback loops in climate change-cryosphere interactions that affect Arctic amplification.
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| 2. |
- Fang, Keyan, et al.
(författare)
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Climate of the late Pleistocene and early Holocene in coastal South China inferred from submerged wood samples
- 2017
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Ingår i: Quaternary International. - : Elsevier BV. - 1040-6182. ; 447, s. 111-117
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Tidskriftsartikel (refereegranskat)abstract
- Tree-ring variability of submerged wood specimens in coastal areas provides important clues about sea level change and climate variability of the past. We dated submerged wood samples from coastal Fujian province in China using the radiocarbon methods and investigated their tree-ring variability. The submerged wood samples from the Shenhu Bay that date to the early Holocene (similar to 8000 calibrated years B.P.) may be related to the rise of the sea level after the Last Glacial Maximum (LGM). The submerged wood samples from the Qianhu Bay site dated to the Marine Isotope Stage 3 (MIS 3) (> 40,000 calibrated years B. P.). Most of the submerged wood samples are from coniferous trees with frequent branching tree rings. Frequent branching tree rings in this region are mostly found from the currently endangered coniferous species with narrow ecological amplitude at humid sites. Tree rings of the submerged sample show conspicuous interdecadal variability (similar to 20 years) than interannual variations, which differs from modern tree rings of nearby regions which have stronger interannual and multi-decadal variability. Our study highlights the potential to use submerged samples of coastal Southeast China for paleoclimate studies.
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| 3. |
- Trondman, Anna-Kari, et al.
(författare)
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Pollen-based quantitative reconstructions of Holocene regional vegetation cover (plant-functional types and land-cover types) in Europe suitable for climate modelling
- 2015
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 21:2, s. 676-697
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Tidskriftsartikel (refereegranskat)abstract
- We present quantitative reconstructions of regional vegetation cover in north-western Europe, western Europe north of the Alps, and eastern Europe for five time windows in the Holocene [around 6k, 3k, 0.5k, 0.2k, and 0.05k calendar years before present (bp)] at a 1 degrees x1 degrees spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant-functional types and three land-cover types [evergreen trees, summer-green (deciduous) trees, and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen, and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k bp and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However, the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k, 0.5k, and 0.2k bp is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe, in particular Britain and Ireland. Furthermore, the relationship between summer-green and evergreen trees, and between individual tree taxa, differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance, when Pinus is dominant over Picea as pollen percentages, Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover-climate interactions, biodiversity and human resources.
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| 4. |
- Battarbee, Richard W., et al.
(författare)
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John Birks: Pioneer in quantitative palaeoecology
- 2015
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 25:1, s. 3-16
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Forskningsöversikt (refereegranskat)abstract
- We describe the career of John Birks as a pioneering scientist who has, over a career spanning five decades, transformed palaeoecology from a largely descriptive to a rigorous quantitative science relevant to contemporary questions in ecology and environmental change. We review his influence on students and colleagues not only at Cambridge and Bergen Universities, his places of primary employment, but also on individuals and research groups in Europe and North America. We also introduce the collection of papers that we have assembled in his honour. The papers are written by his former students and close colleagues and span many of the areas of palaeoecology to which John himself has made major contributions. These include the relationship between ecology and palaeoecology, late-glacial and Holocene palaeoecology, ecological succession, climate change and vegetation history, the role of palaeoecological techniques in reconstructing and understanding the impact of human activity on terrestrial and freshwater ecosystems and numerical analysis of multivariate palaeoecological data.
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| 5. |
- Fang, Keyan, et al.
(författare)
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Oceanic and atmospheric modes in the Pacific and Atlantic Oceans since the Little Ice Age (LIA): Towards a synthesis
- 2019
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 215, s. 293-307
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the variability of the oceanic and atmospheric modes from the Little Ice Age (LIA,similar to 1250 - 1850) to the present can help evaluate their behaviors under future warming scenarios. Numerous proxy-based reconstructions of the oceanic and atmospheric modes were presented. It is highly needed for a synthesis study to evaluate the existing reconstructions of the dominant oceanic and atmospheric modes since the LIA. We found that the El Nino-Southern Oscillation (ENSO) reconstructions are only robust on interannual and interdecadal scales, while the reconstructed Pacific Decadal Oscillation (PDO) and Atlantic Multi-decadal Oscillation (AMO) are robust on multi-decadal (50-100 years) timescales. We generated synthesized ENSO, PDO and AMO reconstructions as the average of the existing reconstructions on the most suitable timescales identified using timescale dependent correlation methods. In the 20th century, the interannual variability and periodicity of the ENSO and the multi-decadal periodicity of the PDO and AMO were most pronounced. The ENSO shows the strongest multi-decadal periodicity from mid-18th century onwards, while the multi-decadal periodicity of the PDO and AMO was particularly low in the 18th century. Multi-decadal variations of the AMO showed a prompt and positive response to solar irradiation, while the ENSO showed a lagged and negative response to solar irradiation from the 18th century to the present. (C) 2019 Elsevier Ltd. All rights reserved.
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| 6. |
- Marquer, Laurent, et al.
(författare)
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Quantifying the effects of land use and climate on Holocene vegetation in Europe
- 2017
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Ingår i: Quaternary Science Reviews. - : Pergamon Press. - 0277-3791 .- 1873-457X. ; 171, s. 20-37
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Tidskriftsartikel (refereegranskat)abstract
- Early agriculture can be detected in palaeovegetation records, but quantification of the relative importance of climate and land use in influencing regional vegetation composition since the onset of agriculture is a topic that is rarely addressed. We present a novel approach that combines pollen-based REVEALS estimates of plant cover with climate, anthropogenic land-cover and dynamic vegetation modelling results. This is used to quantify the relative impacts of land use and climate on Holocene vegetation at a sub-continental scale, i.e. northern and western Europe north of the Alps. We use redundancy analysis and variation partitioning to quantify the percentage of variation in vegetation composition explained by the climate and land-use variables, and Monte Carlo permutation tests to assess the statistical significance of each variable. We further use a similarity index to combine pollen based REVEALS estimates with climate-driven dynamic vegetation modelling results. The overall results indicate that climate is the major driver of vegetation when the Holocene is considered as a whole and at the sub-continental scale, although land use is important regionally. Four critical phases of land-use effects on vegetation are identified. The first phase (from 7000 to 6500 BP) corresponds to the early impacts on vegetation of farming and Neolithic forest clearance and to the dominance of climate as a driver of vegetation change. During the second phase (from 4500 to 4000 BP), land use becomes a major control of vegetation. Climate is still the principal driver, although its influence decreases gradually. The third phase (from 2000 to 1500 BP) is characterised by the continued role of climate on vegetation as a consequence of late-Holocene climate shifts and specific climate events that influence vegetation as well as land use. The last phase (from 500 to 350 BP) shows an acceleration of vegetation changes, in particular during the last century, caused by new farming practices and forestry in response to population growth and industrialization. This is a unique signature of anthropogenic impact within the Holocene but European vegetation remains climatically sensitive and thus may continue to respond to ongoing climate change. (C) 2017 Elsevier Ltd. All rights reserved.
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