| 1. |
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| 2. |
- Holmlund, Erik S., et al.
(författare)
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Constraining 135 years of mass balance with historic structure-from-motion photogrammetry on Storglaciaren, Sweden
- 2019
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Ingår i: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 101:3, s. 195-210
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Tidskriftsartikel (refereegranskat)abstract
- Geodetic volume estimates of Storglaciaren in Sweden suggest a 28% loss in total ice mass between 1910 and 2015. Terrestrial photographs from 1910 of Tarfala valley, where Storglaciaren is situated, allow for an accurate reconstruction of the glacier's surface using Structure-from-Motion photogrammetry, which we used for past volume and mass estimations. The glacier's yearly mass balance gradient and net mass balance was also estimated back to 1880 using weather data from Karesuando, 170 km north-east of Storglaciaren, through neural network regression. These combined reconstructions provide a continuous mass change series between the end of the Little Ice Age and 1946, when field data become available. The resultant reconstruction suggests a state close to equilibrium between 1880 and the 1910s, followed by drastic melt until the 1970s, constituting 76% of the 1910-2015 ice loss. More favourable conditions subsequently stabilized the mass balance until the late 1990s, after which Storglaciaren started losing mass again. The 1910 reconstruction allows for a more accurate mass change series than previous estimates, and the methodology can be used on other glaciers where early photographic material exists.
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| 3. |
- Holmlund, Per, et al.
(författare)
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Recent climate-induced shape changes of the ice summit of Kebnekaise, Northern Sweden
- 2019
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Ingår i: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 101:1, s. 68-78
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Tidskriftsartikel (refereegranskat)abstract
- The ice summit of Kebnekaise is slowly melting down as a consequence of climate change. In August 2018 this peak, which for a long time has been the highest in Sweden, reached an elevation a few decimetres lower than the nearby situated northern summit in solid rock. It has become a symbol of the fragility of nature. Its areal extent and shape have varied over time and its height has ranged within approximately 15 m during the twentieth century. Since the turn of the century, the ice summit has decreased to a new lower and smaller level but the changes are not uniform, and they show a complex relation between weather parameters and the shape and size of the summit. Layers in the ice include climate information of past changes. But what changes are we able to determine by examining gradually exposed dust layers, or by coring the summit. In this paper, we are analysing the late changes in shape and volume of the ice summit and we place the results into a paleo climate discussion. We have used photogrammetric methods to map the geometry of the summit at different dates when data has been available. We have also done a multiple regression to analyse the relation between the summit elevation and the net mass balance of the nearby located Storglaciaren. The correlation is good from mid 1970s until now but weak prior to that. It is herein explained by former uncertainties of the geographic position of the summit.
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| 4. |
- Kirchner, Nina, et al.
(författare)
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High-resolution bathymetric mapping reveals subaqueous glacial landforms in the Arctic alpine lake Tarfala, Sweden
- 2019
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Ingår i: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 34:6, s. 452-462
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Tidskriftsartikel (refereegranskat)abstract
- In Arctic alpine regions, glacio-lacustrine environments respond sensitively to variations in climate conditions, impacting, for example,glacier extent and rendering former ice-contact lakes into ice distal lakes and vice versa. Lakefloors may hold morphological records of past glacier extent, but remoteness and long periods of ice cover on such lakes make acquisition of high-resolution bathymetric datasets challenging. Lake Tarfala and Kebnepakte Glacier, located in the Kebnekaise mountains, northern Sweden, comprise a small, dynamic glacio-lacustrine system holding a climate archive that is not well studied. Using an autonomous surface vessel, a high-resolution bathymetric dataset for Lake Tarfala was acquired in 2016, from which previously undiscovered end moraines and a potential grounding line feature were identified. For Kebnepakte Glacier, structure-from-motion photogrammetry was used to reconstruct its shape from photographs taken in 1910 and 1945. Combining these methods connects the glacial landform record identified at the lakefloor with the centennial-scale dynamic behaviour of Kebnepakte Glacier. During its maximum 20(th) century extent, attained c. 1910, Kebnepakte Glacier reached far into Lake Tarfala, but had retreated onto land by 1945, at an average of 7.9 m year(-1).
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| 5. |
- Klingbjer, Per, 1964-
(författare)
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Glaciers and climate in northern Sweden during the 19th and 20th century
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Our understanding of the climate of northern Sweden during the late Holocene is largely dependent on proxy-data series. These datasets remain spatially and temporally sparse and instrumental series are rare prior to the mid 19th century. Nevertheless, the glaciology and paleo-glaciology of the region has a strong potential significance for the exploration of climate change scenarios, past and future. The aim of this thesis is to investigate the 19th and 20th century climate in the northern Swedish mountain range. This provides a good opportunity to analyse the natural variability of the climate before the onset of the industrial epoch. Developing a temporal understanding of fluctuations in glacier front positions and glacier mass balance that is linked to a better understanding of their interaction and relative significance to climate is fundamental in the assessment of past climate.I have chosen to investigate previously unexplored temperature data from northern Sweden from between 1802 and 1860 and combined it with a temperature series from a synoptic station in Haparanda, which began operation in 1859, in order to create a reliable long temperature series for the period 1802 to 2002. I have also investigated two different glaciers, Pårteglaciären and Salajekna, which are located in different climatic environments. These glaciers have, from a Swedish perspective, long observational records. Furthermore, I have investigated a recurring jökulhlaup at the glacier Sälkaglaciären in order to analyse glacier-climate relationships with respect to the jökulhlaups. A number of datasets are presented, including: glacier frontal changes, in situ and photogrammetric mass balance data, in situ and satellite radar interferometry measurements of surface velocity, radar measurements, ice volume data and a temperature series. All these datasets are analysed in order to investigate the response of the glaciers to climatic stimuli, to attribute specific behaviour to particular climates and to analyse the 19th and 20th century glacier/climate relationships in northern Sweden.The 19th century was characterized by cold conditions in northern Sweden, particularly in winter. Significant changes in the amplitude of the annual temperature cycle are evident. Through the 19th century there is a marked decreasing trend in the amplitude of the data, suggesting a change towards a prevalence of maritime (westerly) air masses, something which has characterised the 20th century. The investigations on Salajekna support the conclusion that the major part of the 19th century was cold and dry. The 19th century advance of Salajekna was probably caused by colder climate in the late 18th and early 19th centuries, coupled with a weakening of the westerly airflow. The investigations on Pårteglaciären show that the glacier has a response time of ~200 years. It also suggests that there was a relatively high frequency of easterly winds providing the glacier with winter precipitation during the 19th century.Glaciers have very different response times and are sensitive to different climatic parameters. Glaciers in rather continental areas of the Subarctic and Arctic can have very long response times because of mass balance considerations and not primarily the glacier dynamics. This is of vital importance for analyzing Arctic and Subarctic glacier behaviour in a global change perspective. It is far from evident that the behaviour of the glacier fronts today reflects the present climate.
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| 6. |
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| 7. |
- Ahlström, A. P., et al.
(författare)
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Historically unprecedented global glacier decline in the early 21st century
- 2015
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Ingår i: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 61:228, s. 745-
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Tidskriftsartikel (refereegranskat)abstract
- Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (similar to 42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (similar to 5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.
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| 8. |
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Arktis i fokus : historiska fotografier från svenska polarexpeditioner
- 2013
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Samlingsverk (redaktörskap) (populärvet., debatt m.m.)abstract
- Under perioden 2012-2014 pågår ett forskningsprojekt finansierat av Vetenskapsrådet, där vi digitaliserar äldre arkiverade fotografier från polar-områdena. Arbetet sker vid Stockholms universitet, Uppsala universitet, Göteborgs universitet, Centrum för vetenskapshistoria vid Kungl. Vetenskapsakademien och Naturhistoriska riksmuseet. Det är ett unikt material som förväntas bli ett betydande jämförelsematerial till dagens polarfotografier. Förutom att vi räddar ett ovärderligt kulturarv så kommer fotografierna att ge klimatforskare, vetenskapshistoriker och författare ny kunskap om polarområdena, forskningsexpeditionerna och betingelserna kring dessa.
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| 9. |
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| 10. |
- Björklund, Anders, 1950-, et al.
(författare)
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Arbetsmarknaden
- 2014. - 4
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Bok (övrigt vetenskapligt/konstnärligt)
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| 11. |
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| 12. |
- Carling, Kenneth, et al.
(författare)
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Unemployment duration, unemployment benefits, and labor market programs in Sweden
- 1996
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Ingår i: JOURNAL OF PUBLIC ECONOMICS. - : ELSEVIER SCIENCE SA LAUSANNE. - 0047-2727. ; 59:3, s. 313-334
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Tidskriftsartikel (refereegranskat)abstract
- Standard search theory as well as some empirical evidence suggest that an unemployed individual's probability of entering employment increases as he approaches the time when unemployment benefits are due to expire. This pattern may not carry over to a cou
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| 13. |
- Christiansen, H. H., et al.
(författare)
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The Thermal State of Permafrost in the Nordic Area during the International Polar Year 2007-2009
- 2010
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Ingår i: Permafrost and Periglacial Processes. - : Wiley. - 1099-1530 .- 1045-6740. ; 21:2, s. 156-181
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides a snapshot of the permafrost thermal state in the Nordic area obtained during the International Polar Year (IPY) 2007-2009. Several intensive research campaigns were undertaken within a variety of projects in the Nordic countries to obtain this snapshot. We demonstrate for Scandinavia that both lowland permafrost in palsas and peat plateaus, and large areas of permafrost in the mountains are at temperatures close to 0 degrees C, which makes them sensitive to climatic changes. In Svalbard and northeast Greenland, and also in the highest parts of the mountains in the rest of the Nordic area, the permafrost is somewhat colder, but still only a few degrees below the freezing point. The observations presented from the network of boreholes, more than half of which were established during the IPY, provide an important baseline to assess how future predicted climatic changes may affect the permafrost thermal state in the Nordic area. Time series of active-layer thickness and permafrost temperature conditions in the Nordic area, which are generally only 10 years in length, show generally increasing active-layer depths and risings permafrost temperatures. Copyright (C) 2010 John Wiley & Sons, Ltd.
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| 14. |
- Clason, Caroline C., et al.
(författare)
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Controls on the early Holocene collapse of the Bothnian Sea Ice Stream
- 2016
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Ingår i: Journal of Geophysical Research - Earth Surface. - 2169-9003 .- 2169-9011. ; 121:12, s. 2494-2513
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Tidskriftsartikel (refereegranskat)abstract
- New high-resolution multibeam data in the Gulf of Bothnia reveal for the first time the subglacial environment of a Bothnian Sea Ice Stream. The geomorphological record suggests that increased meltwater production may have been important in driving rapid retreat of Bothnian Sea Ice during deglaciation. Here we apply a well-established, one-dimensional flow line model to simulate ice flow through the Gulf of Bothnia and investigate controls on retreat of the ice stream during the post-Younger Dryas deglaciation of the Fennoscandian Ice Sheet. The relative influence of atmospheric and marine forcings are investigated, with the modeled ice stream exhibiting much greater sensitivity to surface melting, implemented through surface mass balance and hydrofracture-induced calving, than to submarine melting or relative sea level change. Such sensitivity is supported by the presence of extensive meltwater features in the geomorphological record. The modeled ice stream does not demonstrate significant sensitivity to changes in prescribed ice stream width or overall bed slope, but local variations in basal topography and ice stream width result in nonlinear retreat of the grounding line, notably demonstrating points of short-lived retreat slowdown on reverse bed slopes. Retreat of the ice stream was most likely governed by increased ice surface meltwater production, with the modeled retreat rate less sensitive to marine forcings despite the marine setting.
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| 15. |
- Clason, Caroline C., et al.
(författare)
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Modelling Late Weichselian evolution of the Eurasian ice sheets forced by surface meltwater-enhanced basal sliding
- 2014
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Ingår i: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 60:219, s. 29-40
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Tidskriftsartikel (refereegranskat)abstract
- We simulated the Late Weichselian extent and dynamics of the Eurasian ice sheets using theshallow-ice approximation ice-sheet model SICOPOLIS. Our simulated Last Glacial Maximum ice-sheetextents closely resemble geomorphological reconstructions, and areas of modelled fast flow areconsistent with the known locations of palaeo-ice streams. Motivated by documented velocity responseto increased meltwater inputs on Greenland, we tested the sensitivity of the simulated ice sheet to thesurface meltwater effect (SME) through a simple parameterization relating basal sliding to local surfacemelt rate and ice thickness. Model runs including the SME produce significantly reduced ice volumeduring deglaciation, with maximum ice surface velocities much greater than in similar runs that neglectthe SME. We find that the simple treatment of the SME is not applicable across the whole ice sheet;however, our results highlight the importance of the SME for dynamic response to increased melting.The southwest sector of the Scandinavian ice sheet is most sensitive to the SME, with fast flow in theBaltic ice stream region shutting off by 15 kaBP when the SME is turned on, coincident with a retreat ofthe ice-margin position into the Gulf of Bothnia.
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| 16. |
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| 17. |
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| 18. |
- Edin, Per-Anders, et al.
(författare)
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The Swedish youth labor market in boom and depression
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper is concerned with the labor market experience of Swedish youths during the 1980s and the 1990s. The first objective is to portray early economic attainment among young Swedes. The second objective of the paper is to examine the impact of labor market programs on youth employment. We find that the slump in the 1990s has been associated with dramatic increases in youth unemployment and youth participation in active labor market programs. The impact on unemployment rates by age and education has been roughly proportional, however. The evolution of employment and unemployment does not offer much ground for the popular hypothesis that the recent rise in unemployment is driven by large and pervasive shifts in the demand for labor by skill attributable to technological innovation. The employment crisis has been met by an unprecedented increase in active labor market programs, in large part targeted at unemployed youths. There is a risk that these programs may crowd out regular youth employment, a hypothesis that is supported in our empirical investigation of regular youth employment in Swedish municipalities.
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| 19. |
- Edin, Per-Anders, et al.
(författare)
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The Swedish youth labor market in boom and depression
- 1999
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Ingår i: Youth Employment and Joblessness in Advanced Countries. - : University of Chicago Press.
-
Bokkapitel (refereegranskat)abstract
- This paper is concerned with the labor market experience of Swedish youths during the 1980s and the 1990s. The first objective is to portray early economic attainment among young Swedes. The second objective of the paper is to examine the impact of labor
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| 20. |
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| 21. |
- Eisen, Olaf, et al.
(författare)
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Ground-based measurements of spatial and temporal variability of snow accumulation in East Antarctica
- 2008
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Ingår i: Reviews of Geophysics. - 8755-1209. ; 46, s. 1-39
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Tidskriftsartikel (refereegranskat)abstract
- The East Antarctic Ice Sheet is the largest, highest, coldest, driest, and windiest ice sheet on Earth. Understanding of the surface mass balance (SMB) of Antarctica is necessary to determine the present state of the ice sheet, to make predictions of its potential contribution to sea level rise, and to determine its past history for paleoclimatic reconstructions. However, SMB values are poorly known because of logistic constraints in extreme polar environments, and they represent one of the biggest challenges of Antarctic science. Snow accumulation is the most important parameter for the SMB of ice sheets. SMB varies on a number of scales, from small-scale features (sastrugi) to ice-sheet-scale SMB patterns determined mainly by temperature, elevation, distance from the coast, and wind-driven processes. In situ measurements of SMB are performed at single points by stakes, ultrasonic sounders, snow pits, and firn and ice cores and laterally by continuous measurements using ground-penetrating radar. SMB for large regions can only be achieved practically by using remote sensing and/or numerical climate modeling. However, these techniques rely on ground truthing to improve the resolution and accuracy. The separation of spatial and temporal variations of SMB in transient regimes is necessary for accurate interpretation of ice core records. In this review we provide an overview of the various measurement techniques, related difficulties, and limitations of data interpretation; describe spatial characteristics of East Antarctic SMB and issues related to the spatial and temporal representativity of measurements; and provide recommendations on how to perform in situ measurements.
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| 22. |
- Ek, Susanne
(författare)
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Essays on Unemployment Insurance Design
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Essay 1: This paper adds to the literature on the effects of unemployment insurance (UI) on post-unemployment outcomes. A vast literature has established a relationship between the generosity of UI and unemployment duration. However, little is known about the impact of UI benefits on subsequent labor market outcomes. UI reduces search efforts but provides workers with more time to find a suitable job. To estimate the causal impact of benefit levels on several measures of job quality, I use a kink in the relationship between previous wages and benefits that is induced by the cap on UI benefits in Sweden. Like those of previous research, my findings indicate that higher UI benefits prolong unemployment duration. I also find that higher UI benefits decrease annual earnings and monthly wages. This negative effect on incomes continues to persist up to nine years after entry into unemployment. I find no effects of UI benefits on the probability of obtaining a full-time job, the employment probability in subsequent years, the duration of future employment or unemployment spells. In combination, these results suggest that workers gain, in monetary terms, from lower unemployment benefits.Essay 2: (with Bertil Holmlund) The paper develops an equilibrium search and matching model where two-person families as well as singles participate in the labor market. We show that marital status as well as spousal labor market status matter for wage outcomes: members of two-worker families receive higher wages than employed singles and also higher wages than employed members of two-person families where spouses are unemployed. The model is applied to a welfare analysis of alternative unemployment insurance systems, recognizing the role of spousal employment as a partial substitute for public insurance.Essay 3: (with Bertil Holmlund) A significant fraction of the labor force consists of employed workers who are part-time unemployed (underemployed) in the sense that they are unable to work as much as they prefer. This paper develops a search and matching model to study the design of optimal unemployment insurance in an economy with unemployment as well as part-time unemployment. Part-time unemployment provides income insurance and serves also as a stepping stone to full-time jobs. Unemployment benefits for part-timers increase the outflow from unemployment to part-time work but reduce the outflow from part-time work to full-time employment. We examine the optimal structure of benefits for unemployed and underemployed workers. The results indicate non-negligible welfare gains associated with time limits for unemployment benefits as well as for part-time benefits. The welfare gains from optimal UI are larger when wages are fixed than when they are flexible.Essay 4: This paper studies whether the optimal unemployment benefit levels should vary over the business cycle. Previous research suggests that policy makers should indeed make unemployment insurance (UI) dependent on the business cycle because the UI can be used to smooth consumption across different economic states. However, high benefits increase unemployment. An alternative way to redistribute income is to vary tax rates over the business cycle. In this paper, we develop an equilibrium search and matching model with risk-averse workers and two states, namely, a good and a bad state. The model yields potential ambiguity concerning the welfare effects of business cycle-dependent UI. The model is calibrated to United States (U.S.) labor market data. The numerical results suggest that higher benefits in the bad state are optimal, but the benefit differential is small. A more efficient way for policy makers to redistribute income over the business cycle is to decrease consumption taxes in the bad state. Compared to an optimal uniform system, however, differentiation yields small welfare gains. Nevertheless, imposing two tax rates strictly dominates imposing two benefit levels. This finding is robust to a wide range of sensitivity checks.
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| 23. |
- Engström, Per, 1974-
(författare)
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Optimal Taxation in Search Equilibrium
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of four self-contained essays.Essay 1 (with Bertil Holmlund and Ann-Sofie Kolm) develops a two-sector general equilibrium search model where ``goods'' are produced exclusively in the market and ”services” are produced both in the market and within the households. We use the model to examine how unemployment and welfare are affected by labor taxes in general and sectoral tax differentiation in particular. We find that a tax cut on services reduces unemployment whereas a tax cut on goods has no effect. A reform involving tax differentiation, with lower taxes on services, is welfare improving. Numerical calibrations of the model suggest that the welfare gains from tax differentiation are large if the government absorbs a substantial fraction of GDP.Essay 2 extends the basic Stiglitz (1982) model of optimal income taxation into general search equilibrium. The analysis of a labor market with unemployment introduces some new interesting mechanisms. When wages are fixed we find that a ''work-hour effect''\ gives the government incentives to lower the marginal tax rates for both high- and low-skilled workers, relative the outcome in a Walrasian economy. The optimal marginal tax on high-skilled workers is negative, whereas the marginal tax on low-skilled workers can take either sign. The results are changed when wages are determined by bargaining between firms and workers. Both marginal tax rates are of ambiguous signs. The tax systems' effects on the wage formation and the unemployment rates result in new intricate redistribution channels.Essay 3 explores the rationale for unemployment benefits as a complement to optimal non-linear income taxation. High-skilled workers and low-skilled workers face different exogenous risks of being unemployed. As long as the low-skilled workers face a higher unemployment risk, we find that there is a case for over-insuring the low-skilled, hence the unemployment benefits intended for the low-skilled should be higher than the pure insurance purpose would prescribe. This effect is likely to prevail in a model with\ a more realistic treatment of the labor market.Essay 4 explores the optimal mix of tax-transfer systems in a two-type model. The labor markets are imperfect due to search frictions. The tax instruments at the government's disposal are a non-linear tax function and unemployment benefits that may differ between the two types of workers. We find that even though workers are risk-neutral -- so there is no insurance purpose of unemployment benefits -- there are reasons to use unemployment benefits to the low-skilled as an important part of the optimal redistribution system.
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