| 1. |
- Callaghan, Terry V., et al.
(författare)
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A new climate era in the sub-Arctic : Accelerating climate changes and multiple impacts
- 2010
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 37:14, s. L14705-
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Tidskriftsartikel (refereegranskat)abstract
- Climate warming in the Swedish sub-Arctic since 2000 has reached a level at which statistical analysis shows for the first time that current warming has exceeded that in the late 1930' s and early 1940' s, and has significantly crossed the 0 degrees C mean annual temperature threshold which causes many cryospheric and ecological impacts. The accelerating temperature increase trend has driven similar trends in the century-long increase in snow thickness, loss of lake ice, increases in active layer thickness, lake water TOC (total organic carbon) concentrations and the assemblages of diatoms, and changes in tree-line location and plant community structure. Some of these impacts were not evident in the first warm period of the 20th Century. Changes in climate are associated with reduced temperature variability, particularly loss of cold winters and cool summers, and an increase in extreme precipitation events that cause mountain slope instability and infrastructure failure. The long term records of multiple, local environmental factors compiled here for the first time provide detailed information for adaptation strategy development while dramatic changes in an environment particularly vulnerable to climate change highlight the need to adopt global mitigation strategies.
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| 2. |
- Callaghan, Terry V., et al.
(författare)
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Changing snow cover and its impacts
- 2011
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Ingår i: Snow, Water, Ice and Permafrost in the Arctic (SWIPA). - Oslo : Arctic Monitoring and Assessment Programme. - 9788279710714 ; , s. 4:1-4:58
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Bokkapitel (refereegranskat)
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| 3. |
- Callaghan, Terry V., et al.
(författare)
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Ecosystem change and stability over multiple decades in the Swedish subarctic : complex processes and multiple drivers
- 2013
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 368:1624
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Tidskriftsartikel (refereegranskat)abstract
- The subarctic environment of northernmost Sweden has changed over the past century, particularly elements of climate and cryosphere. This paper presents a unique geo-referenced record of environmental and ecosystem observations from the area since 1913. Abiotic changes have been substantial. Vegetation changes include not only increases in growth and range extension but also counterintuitive decreases, and stability: all three possible responses. Changes in species composition within the major plant communities have ranged between almost no changes to almost a 50 per cent increase in the number of species. Changes in plant species abundance also vary with particularly large increases in trees and shrubs (up to 600%). There has been an increase in abundance of aspen and large changes in other plant communities responding to wetland area increases resulting from permafrost thaw. Populations of herbivores have responded to varying management practices and climate regimes, particularly changing snow conditions. While it is difficult to generalize and scale-up the site-specific changes in ecosystems, this very site-specificity, combined with projections of change, is of immediate relevance to local stakeholders who need to adapt to new opportunities and to respond to challenges. Furthermore, the relatively small area and its unique datasets are a microcosm of the complexity of Arctic landscapes in transition that remains to be documented.
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| 4. |
- Callaghan, Terry V., et al.
(författare)
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Multiple Effects of Changes in Arctic Snow Cover
- 2011
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Ingår i: Ambio: a Journal of Human Environment. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40, s. 32-45
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Tidskriftsartikel (refereegranskat)abstract
- Snow cover plays a major role in the climate, hydrological and ecological systems of the Arctic and other regions through its influence on the surface energy balance (e.g. reflectivity), water balance (e.g. water storage and release), thermal regimes (e.g. insulation), vegetation and trace gas fluxes. Feedbacks to the climate system have global consequences. The livelihoods and well-being of Arctic residents and many services for the wider population depend on snow conditions so changes have important consequences. Already, changing snow conditions, particularly reduced summer soil moisture, winter thaw events and rain-on-snow conditions have negatively affected commercial forestry, reindeer herding, some wild animal populations and vegetation. Reductions in snow cover are also adversely impacting indigenous peoples' access to traditional foods with negative impacts on human health and well-being. However, there are likely to be some benefits from a changing Arctic snow regime such as more even run-off from melting snow that favours hydropower operations.
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| 5. |
- Pascual, Didac, et al.
(författare)
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The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study
- 2021
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Ingår i: Ambio. - : Springer. - 0044-7447 .- 1654-7209. ; 50:2, s. 375-392
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Forskningsöversikt (refereegranskat)abstract
- Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.
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| 6. |
- Wolf, Annett, et al.
(författare)
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Future changes in vegetation and ecosystem function of the Barents Region
- 2008
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Ingår i: Climatic Change. - : Springer. - 0165-0009 .- 1573-1480. ; 87:1-2, s. 51-73
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic vegetation model (LPJ-GUESS) is used to project transient impacts of changes in climate on vegetation of the Barents Region. We incorporate additional plant functional types, i.e. shrubs and defined different types of open ground vegetation, to improve the representation of arctic vegetation in the global model. We use future climate projections as well as control climate data for 1981-2000 from a regional climate model (REMO) that assumes a development of atmospheric CO(2)-concentration according to the B2-SRES scenario [IPCC, Climate Change 2001: The scientific basis. Contribution working group I to the Third assessment report of the IPCC. Cambridge University Press, Cambridge (2001)]. The model showed a generally good fit with observed data, both qualitatively when model outputs were compared to vegetation maps and quantitatively when compared with observations of biomass, NPP and LAI. The main discrepancy between the model output and observed vegetation is the overestimation of forest abundance for the northern parts of the Kola Peninsula that cannot be explained by climatic factors alone. Over the next hundred years, the model predicted an increase in boreal needle leaved evergreen forest, as extensions northwards and upwards in mountain areas, and as an increase in biomass, NPP and LAI. The model also projected that shade-intolerant broadleaved summergreen trees will be found further north and higher up in the mountain areas. Surprisingly, shrublands will decrease in extent as they are replaced by forest at their southern margins and restricted to areas high up in the mountains and to areas in northern Russia. Open ground vegetation will largely disappear in the Scandinavian mountains. Also counter-intuitively, tundra will increase in abundance due to the occupation of previously unvegetated areas in the northern part of the Barents Region. Spring greening will occur earlier and LAI will increase. Consequently, albedo will decrease both in summer and winter time, particularly in the Scandinavian mountains (by up to 18%). Although this positive feedback to climate could be offset to some extent by increased CO(2) drawdown from vegetation, increasing soil respiration results in NEE close to zero, so we cannot conclude to what extent or whether the Barents Region will become a source or a sink of CO(2).
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| 7. |
- Bosiö, Julia, et al.
(författare)
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Future vegetation changes in thawing subarctic mires and implications for greenhouse gas exchange-a regional assessment
- 2012
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Ingår i: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 115:2, s. 379-398
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Tidskriftsartikel (refereegranskat)abstract
- One of the major concerns regarding climate change in high latitudes is the potential feedback from greenhouse gases (GHG) being released from thawing peat soils. In this paper we show how vegetational patterns and associated GHG fluxes in subarctic palsa (peat mounds with a permanently frozen core) mires can be linked to climate, based on field observations from fifteen palsa sites distributed in northern Fennoscandia. Fine resolution (100 m) land cover data are combined with projections of future climate for the 21st century in order to model the potential future distribution of palsa vegetation in northern Fennoscandia. Site scale climate-vegetational relationships for two vegetation types are described by a climate suitability index computed from the field observations. Our results indicate drastic changes in the palsa vegetational patterns over the coming decades with a 97 % reduction in dry hummock areas by 2041-2060 compared to the 1961-1990 areal coverage. The impact of these changes on the carbon balance is a decrease in the efflux of CO2 from 130 kilotonnes C y(-1) to a net uptake of 11 kilotonnes C y(-1) and a threefold increase in the efflux of CH4 from 6 to 18 kilotonnes C y(-1) over the same period and over the 5,520 km(2) area of palsa mires. The combined effect is equivalent to a slight decrease in CO2-C emissions, from 182 to 152 kilotonnes C y(-1). Main uncertainties involve the ability of the vegetation community to adapt to new conditions, and long-term changes in hydrology due to absence of ice and frost heaving.
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| 8. |
- Callaghan, Terry V., et al.
(författare)
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Arctic tundra and Polar Desert Ecosystems
- 2005
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Ingår i: Arctic Climate Impact Assessment. - 9780521865098 - 0521865093
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Callaghan, Terry V., et al.
(författare)
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Biodiversity, distributions and adaptations of arctic species in the context of environmental change
- 2004
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Ingår i: Ambio: a Journal of Human Environment. - : Royal Swedish Academy of Sciences. - 0044-7447. ; 33:7, s. 404-417
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Forskningsöversikt (refereegranskat)abstract
- The individual of a species is the basic unit which responds to climate and UV-B changes, and it responds over a wide range of time scales. The diversity of animal, plant and microbial species appears to be low in the Arctic, and decreases from the boreal forests to the polar deserts of the extreme North but primitive species are particularly abundant. This latitudinal decline is associated with an increase in super-dominant species that occupy a wide range of habitats. Climate warming is expected to reduce the abundance and restrict the ranges of such species and to affect species at their northern range boundaries more than in the South: some Arctic animal and plant specialists could face extinction. Species most likely to expand into tundra are boreal species that currently exist as outlier populations in the Arctic. Many plant species have characteristics that allow them to survive short snow-free growing seasons, low solar angles, permafrost and low soil temperatures, low nutrient availability and physical disturbance. Many of these characteristics are likely to limit species responses to climate warming, but mainly because of poor competitive ability compared with potential immigrant species. Terrestrial Arctic animals possess many adaptations that enable them to persist under a wide range of temperatures in the Arctic. Many escape unfavorable weather and resource shortage by winter dormancy or by migration. The biotic environment of Arctic animal species is relatively simple with few enemies, competitors, diseases, parasites and available food resources. Terrestrial Arctic animals are likely to be most vulnerable to warmer and drier summers, climatic changes that interfere with migration routes and staging areas, altered snow conditions and freeze-thaw cycles in winter, climate-induced disruption of the seasonal timing of reproduction and development, and influx of new competitors, predators, parasites and diseases. Arctic microorganisms are also well adapted to the Arctics climate: some can metabolize at temperatures down to -39degreesC. Cyanobacteria and algae have a wide range of adaptive strategies that allow them to avoid, or at least minimize UV injury. Microorganisms can tolerate most environmental conditions and they have short generation times which can facilitate rapid adaptation to new environments. In contrast, Arctic plant and animal species are very likely to change their distributions rather than evolve significantly in response to warming.
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| 10. |
- Callaghan, Terry V., et al.
(författare)
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Climate Change and UV-B Impacts on Arctic Tundra and Polar Desert Ecosystems: Key Findings and Extended Summaries
- 2004
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Ingår i: Ambio: a Journal of Human Environment. - 0044-7447. ; 33:7, s. 386-392
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic has become an important region in which to assess the impacts of current climate variability and amplification of projected global warming. This is because i) the Arctic has experienced considerable warming in recent decades (an average of about 3°C and between 4° and 5°C over much of the landmass); i) climate projections suggest a continuation of the warming trend with an increase in mean annual temperatures of 4–5°C by 2080; ii) recent warming is already impacting the environment and economy of the Arctic and these impacts are expected to increase and affect also life style, culture and ecosystems; and iv) changes occurring in the Arctic are likely to affect other regions of the Earth, for example changes in snow, vegetation and sea ice are likely to affect the energy balance and ocean circulation at regional and even global scales (Chapter 1 in ref. 1). Responding to the urgent need to understand and project impacts of changes in climate and UV-B radiation on many facets of the Arctic, the Arctic Climate Impact Assessment (ACIA) (1) undertook a four-year study. Part of this study (1–10) assessed the impacts of changes in climate and UV-B radiation on Arctic terrestrial ecosystems, both those changes already occurring and those likely to occur in the future. Here, we present the key findings of the assessment of climate change impacts on tundra and polar desert ecosystems, and xtended summaries of its components.
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