| 1. |
- Alenljung, Beatrice, 1971-, et al.
(författare)
-
Towards a Framework of Human-Robot Interaction Strategies from an Operator 5.0 Perspective
- 2023
-
Ingår i: Advances in Manufacturing Technology XXXVI. - Amsterdam, Netherlands : IOS Press. - 9781643684666 - 9781643684673 ; , s. 81-86
-
Konferensbidrag (refereegranskat)abstract
- The industrial transition to Industrie 4.0 and subsequently Industrie 5.0 requires robots to be able to share physical and social space with humans in such a way that interaction and coexistence are positively experienced by the humans and where it is possible for the human and the robot to mutually perceive, interpret and act on each other's actions and intentions. To achieve this, strategies for humanrobot interaction are needed that are adapted to operators’ needs and characteristics in an industrial context, i.e., Operator 5.0. This paper presents a research design for the development of a framework for human-robot interaction strategies based on ANEMONE, which is an evaluation framework based on activity theory, the seven stages of action model, and user experience (UX) evaluation methodology. At two companies, ANEMONE is applied in two concrete use cases, collaborative kitting and mobile robot platforms for chemical laboratory assignments. The proposed research approach consists of 1) evaluations of existing demonstrators, 2) development of preliminary strategies that are implemented, 3) re-evaluations and 4) cross-analysis of results to produce an interaction strategy framework. The theoretically and empirically underpinned framework-to-be is expected to, in the long run, contribute to a sustainable work environment for Operator 5.0.
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| 2. |
- Carlsson, Hanna, et al.
(författare)
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Educating for democracy? : The role of media and information literacy education for pupils in Swedish compulsory school
- 2020
-
Ingår i: Sustainable Digital Communities : 15th International Conference, iConference 2020, Boras, Sweden, March 23–26, 2020, Proceedings - 15th International Conference, iConference 2020, Boras, Sweden, March 23–26, 2020, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783030436865 - 9783030436872 ; 12051, s. 307-326
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Konferensbidrag (refereegranskat)abstract
- This paper reports a study of pupils’ experiences of media and information literacy education in five Swedish schools by answering the following overarching question, what roles do the teaching of information seeking and critical assessment of information play for pupils in their school-work as well as in their everyday life? Pupils in ninth grade were asked to fill in a questionnaire regarding their use of digital technology as well as their thoughts on media and information literacy education. The study shows that many pupils are knowledgeable about the terms of production pertaining to content in most online sources they mention. Still, infrastructural meaning-making that take into consideration issues of personalization, data integrity and surveillance, are largely lacking. The study also shows that the school’s teaching is central to the pupils’ development of a critical stance towards the information that they encounter online. These findings underline the importance of how schools choose to treat media and information literacy education. It is concerning then that infrastructural meaning-making is quite absent in the pupils’ responses.
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| 3. |
- Charpentier Ljungqvist, Fredrik, 1982-, et al.
(författare)
-
Northern Hemisphere hydroclimate variability over the past twelve centuries
- 2016
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 532:7597, s. 94-98
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate modelling and prediction of the local to continental-scale hydroclimate response to global warming is essential given the strong impact of hydroclimate on ecosystem functioning, crop yields, water resources, and economic security. However, uncertainty in hydroclimate projections remains large, in part due to the short length of instrumental measurements available with which to assess climate models. Here we present a spatial reconstruction of hydroclimate variability over the past twelve centuries across the Northern Hemisphere derived from a network of 196 at least millennium-long proxy records. We use this reconstruction to place recent hydrological changes and future precipitation scenarios in a long-term context of spatially resolved and temporally persistent hydroclimate patterns. We find a larger percentage of land area with relatively wetter conditions in the ninth to eleventh and the twentieth centuries, whereas drier conditions are more widespread between the twelfth and nineteenth centuries. Our reconstruction reveals that prominent seesaw patterns of alternating moisture regimes observed in instrumental data across the Mediterranean, western USA, and China have operated consistently over the past twelve centuries. Using an updated compilation of 128 temperature proxy records, we assess the relationship between the reconstructed centennial-scale Northern Hemisphere hydroclimate and temperature variability. Even though dry and wet conditions occurred over extensive areas under both warm and cold climate regimes, a statistically significant co-variability of hydroclimate and temperature is evident for particular regions. We compare the reconstructed hydroclimate anomalies with coupled atmosphere-ocean general circulation model simulations and find reasonable agreement during pre-industrial times. However, the intensification of the twentieth-century-mean hydroclimate anomalies in the simulations, as compared to previous centuries, is not supported by our new multi-proxy reconstruction. This finding suggests that much work remains before we can model hydroclimate variability accurately, and highlights the importance of using palaeoclimate data to place recent and predicted hydroclimate changes in a millennium-long context.
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| 4. |
- Charpentier Ljungqvist, Fredrik, 1982-, et al.
(författare)
-
Northern Hemisphere temperature patterns in the last 12 centuries
- 2012
-
Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 8, s. 227-249
-
Tidskriftsartikel (refereegranskat)abstract
- We analyse the spatio-temporal patterns of temperature variability over Northern Hemisphere land areas, on centennial time-scales, for the last 12 centuries using an unprecedentedly large network of temperature-sensitive proxy records. Geographically widespread positive temperature anomalies are observed from the 9th to 11th centuries, similar in extent and magnitude to the 20th century mean. A dominance of widespread negative anomalies is observed from the 16th to 18th centuries. Though we find the amplitude and spatial extent of the 20th century warming is within the range of natural variability over the last 12 centuries, we also find that the rate of warming from the 19th to the 20th century is unprecedented in the context of the last 1200 yr. The positive Northern Hemisphere temperature change from the 19th to the 20th century is clearly the largest between any two consecutive centuries in the past 12 centuries. These results remain robust even after removing a significant number of proxies in various tests of robustness showing that the choice of proxies has no particular influence on the overall conclusions of this study.
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| 5. |
- Finné, Martin, et al.
(författare)
-
Can XRF scanning of speleothems be used as a non-destructive method to identify paleoflood events in caves?
- 2015
-
Ingår i: International Journal of Speleology. - 0392-6672 .- 1827-806X. ; 44:1, s. 17-23
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a novel, quick and non-destructive method for tracing flood events in caves through the analysis of a stalagmite thick section with an XRF core scanner. The analyzed stalagmite has multiple horizons of fine sediments from past flood events intercalated with areas of cleaner calcite. Flood events detected from the elemental XRF core scanning data show good agreement with the position of flood horizons identified in petrographic thin sections. The geochemical composition of the individual flood layers shows that in certain cases the clay horizons had a distinct geochemical fingerprint suggesting that it may be possible to distinguish individual flood layers based on their geochemistry. This presents the possibility for using flood events as marker horizons to chronologically tie different speleothems in a cave to each other.
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| 6. |
- Finné, Martin, et al.
(författare)
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Climate in the eastern Mediterranean, and adjacent regions, during the past 6000 years - A review
- 2011
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Ingår i: Journal of Archaeological Science. - : Elsevier BV. - 0305-4403 .- 1095-9238. ; 38:12, s. 3153-3173
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Forskningsöversikt (refereegranskat)abstract
- The eastern Mediterranean, with its long archaeological and historical records, provides a unique opportunity to study human responses to climate variability. We review paleoclimate data and reconstructions from the region with a focus on the last 6000 years. We aim to provide an up-to-date source of information on climate variability and to outline present limitations and future opportunities. The review work is threefold: (1) literature review, (2) spatial and temporal analysis of proxy records, and (3) statistical estimation of uncertainties in present paleoclimate reconstructions (temperature, C). On a regional scale the review reveals a wetter situation from 6000 to 5400 yrs BP (note: all ages in this paper are in calibrated years before present (i.e. before 1950), abbreviated yrs BP, unless otherwise stated). This is followed by a less wet period leading up to one of fully-developed aridity from c. 4600 yrs BP. There is a need for more high-resolution paleoclimate records, in order to (i) better understand regional patterns and trends versus local climate variability and to (ii) fill the gap of data from some regions, such as the Near East, Greece and Egypt. Further, we evaluate the regional occurrence of a proposed widespread climate event at 4200 yrs BP. This proposed climate anomaly has been used to explain profound changes in human societies at different locations in the region around this time. We suggest that although aridity was widespread around 4200 yrs BP in the eastern Mediterranean region, there is not enough evidence to support the notion of a climate event with rapidly drying conditions in this region.
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| 7. |
- Finné, Martin, 1981-
(författare)
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Climate in the eastern Mediterranean during the Holocene and beyond – A Peloponnesian perspective
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis contributes increased knowledge about climate variability during the late Quaternary in the eastern Mediterranean. Results from a paleoclimate review reveal that regional wetter conditions from 6000 to 5400 years BP were replaced by a less wet period from 5400 to 4600 years BP and to fully arid conditions around 4600 years BP. The data available, however, show that there is not enough evidence to support the notion of a widespread climate event with rapidly drying conditions in the region around 4200 years ago. The review further highlights the lack of paleoclimate data from the archaeologically rich Peloponnese Peninsula. This gap is addressed in this thesis by the provision of new paleoclimate records from the Peloponnese. One stalagmite from Kapsia Cave and two stalagmites from Glyfada Cave were dated and analyzed for stable oxygen (δ18O) and carbon (δ13C) isotopes. The Glyfada record covers a period from ~78 ka to ~37 ka and shows that the climate in this region responded rapidly to changes in temperatures over Greenland. During Greenland stadial (interstadial) conditions colder (warmer) and drier (wetter) conditions are reflected by depleted (enriched) δ13C-values in the speleothems. The Kapsia record covers a period from ~2900 to ~1100 years BP. A comparison between the modern stalagmite top isotopes and meteorological data shows that a main control on stalagmite δ18O is wet season precipitation amount. The δ18O record from Kapsia indicates cyclical humidity changes of close to 500 years, with rapid shifts toward wetter conditions followed by slowly developing aridity. Superimposed on this signal is a centennial signal of precipitation variability. A second speleothem from Kapsia with multiple horizons of fine sediments from past flood events intercalated with the calcite is used to develop a new, quick and non-destructive method for tracing flood events in speleothems by analyzing a thick section with an XRF core scanner.
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| 8. |
- Finné, Martin, et al.
(författare)
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Speleothem evidence for late Holocene climate variability and floods in Southern Greece
- 2014
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Ingår i: Quaternary Research. - : Cambridge University Press (CUP). - 0033-5894 .- 1096-0287. ; 81:2, s. 213-227
-
Tidskriftsartikel (refereegranskat)abstract
- We present stable isotope data (delta O-18, delta C-13) from a detrital rich stalagmite from Kapsia Cave, the Peloponnese, Greece. The cave is rich in archeological remains and there are reasons to believe that flooding of the cave has directly affected humans using the cave. Using a combination of U-Th and C-14 dating to constrain a site-specific correction factor for (Th-232/U-238) detrital molar ratio, a linear age model was constructed. The age model shows that the stalagmite grew during the period from ca. 950 BC to ca. AD 830. The stable oxygen record from Kapsia indicates cyclical changes of close to 500 yr in precipitation amount, with rapid shifts towards wetter conditions followed by slowly developing aridity. Superimposed on this signal, wetter conditions are inferred around 850, 700, 500 and 400-100 BC, and around AD 160-300 and AD 770; and driest conditions are inferred to have occurred around 450 BC, AD 100-150 and AD 650. Detrital horizons in the stalagmite indicate that three major floods took place in the cave at 500 BC, 70 BC and AD 450. The stable carbon isotope record reflects changes in biological activity being a result of both climate and human activities. (c) 2014 University of Washington.
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| 9. |
- Idh, Jonna, et al.
(författare)
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Reduced susceptibility of clinical strains of Mycobacterium tuberculosis to reactive nitrogen species promotes survival in activated macrophages
- 2017
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Ingår i: PLOS ONE. - : PLOS. - 1932-6203. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- Background Drugs such as isoniazid (INH) and pretomanid (PRT), used against Mycobacterium tuberculosis are active partly through generation of reactive nitrogen species (RNS). The aim of this study was to explore variability in intracellular susceptibility to nitric oxide (NO) in clinical strains of M. tuberculosis. Method Luciferase-expressing clinical M. tuberculosis strains with or without INH resistance were exposed to RNS donors (DETA/NO and SIN-1) in broth cultures and bacterial survival was analysed by luminometry. NO-dependent intracellular killing in a selection of strains was assessed in interferon gamma/lipopolysaccharide-activated murine macrophages using the NO inhibitor L-NMMA. Results When M. tuberculosis H37Rv was compared to six clinical isolates and CDC1551, three isolates with inhA mediated INH resistance showed significantly reduced NO-susceptibility in broth culture. All strains showed a variable but dose-dependent susceptibility to RNS donors. Two clinical isolates with increased susceptibility to NO exposure in broth compared to H37Rv were significantly inhibited by activated macrophages whereas there was no effect on growth inhibition when activated macrophages were infected by clinical strains with higher survival to NO exposure in broth. Furthermore, the most NO-tolerant clinical isolate showed increased resistance to PRT both in broth culture and the macrophage model compared to H37Rv in the absence of mutational resistance in genes associated to reduced susceptibility against PRT or NO. Conclusion In a limited number of clinical M. tuberculosis isolates we found a significant difference in susceptibility to NO between clinical isolates, both in broth cultures and in macrophages. Our results indicate that mycobacterial susceptibility to cellular host defence mechanisms such as NO need to be taken into consideration when designing new therapeutic strategies.
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| 10. |
- Johansson, Hanna Sofia, 1976, et al.
(författare)
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Kärnavfallet och demokratins gränser - Förstudie i Nyköping 1995-2001
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sedan tio år tillbaka pågår sökandet efter lämplig plats för slutförvaring av det använda kärnbränslet. Kärnkraftsägarnas företag SKB har under åren 1993-2001 genomfört förstudier av totalt åtta svenska kommuner, där deras lämplighet som plats för ett slutförvar undersökts. En av dessa kommuner var Nyköping. I denna rapport granskas Nyköpings kommuns arbete med förstudien med tonvikt på demokratiska aspekter samt hur kommunen arbetat med informationsinsatser. Genom dokumentstudier och intervjuer med politiker, tjänstemän och representanter för föreningar undersöks hur olika aktörer definierar kärnavfallsfrågan för att därigenom, medvetet eller omedvetet, söka vinna gehör för sitt perspektiv på frågan. De teoretiska utgångspunkterna för analysen är hämtade från vetenskapssociologi och demokratiteori. Med utgångspunkt i dessa ansatser analyseras hur aktörerna definierar kärnavfallsfrågans risker samt hur de anser att beslutsprocessen bör vara utformad. Frågorna kring hur samspelet mellan teknik, vetenskap och politik bör utformas i kärnavfallsfrågan har inget enkelt svar. Syftet med rapporten är att undersöka hur aktörerna i Nyköping agerat för att få genomslag för sina definitioner av kärnavfall och beslutsprocess samt visa på demokratiska implikationer av olika definitioner. Möjligheten till demokratiskt inflytande över denna framtidsfråga bestäms ytterst av hur kärnavfallsfrågan definieras. Av det skälet är det av stor vikt att undersöka hur frågan definieras och omdefinieras i ett lokalsamhälle.
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| 11. |
- Linge, Henriette, et al.
(författare)
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Stable isotope records for the last 10 000 years from Okshola cave (Fauske, northern Norway) and regional comparisons
- 2009
-
Ingår i: Climate of the Past. - 1814-9324. ; 5:4, s. 667-682
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Tidskriftsartikel (refereegranskat)abstract
- The sensitivity of terrestrial environments to past changes in heat transport is expected to be manifested in Holocene climate proxy records on millennial to seasonal timescales. Stalagmite formation in the Okshola cave near Fauske (northern Norway) began at about 10.4 ka, soon after the valley was deglaciated. Past monitoring of the cave and surface has revealed stable modern conditions with uniform drip rates, relative humidity and temperature. Stable isotope records from two stalagmites provide time-series spanning from c. 10 380 yr to AD 1997; a banded, multi-coloured stalagmite (Oks82) was formed between 10 380 yr and 5050 yr, whereas a pristine, white stalagmite (FM3) covers the period from ~7500 yr to the present. The stable oxygen isotope (δ18Oc), stable carbon isotope (δ13Cc), and growth rate records are interpreted as showing i) a negative correlation between cave/surface temperature and δ18Oc, ii) a positive correlation between wetness and δ13Cc, and iii) a positive correlation between temperature and growth rate. Following this, the data from Okshola show that the Holocene was characterised by high-variability climate in the early part, low-variability climate in the middle part, and high-variability climate and shifts between two distinct modes in the late part.
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| 12. |
- Lätt, Ambjörn, et al.
(författare)
-
Avfallets roll i framtidens energisystem
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Avfall uppkommer i alla sektorer i samhället och påverkar miljö-, klimat- och energiarbetet i dessa. Att ha ett systemperspektiv när man belyser avfallshantering och energiåtervinning av avfall är därför viktigt. Projektet avser att dess resultat ska komma att utgöra underlag för att möta de utmaningar energibranschen står inför kring energiåtervinning av avfall samt ge nya perspektiv i avfallsdebatten. Arbetet baseras på intervjuer, workshops samt konsekvens- och scenarioanalys, i vilken scenarier för framtida avfallshantering och dess roll i energisystemet utarbetas. Projektets övergripande mål är att utreda hur avfallets roll i energisystemet kan komma att förändras i framtiden och vad det får för konsekvenser för energibranschen. För att kunna svara på detta undersöker vi hur mycket svenskt avfall som finns tillgängligt för energiåtervinning i framtiden. Vi har inte undersökt hur själva energisystemet förändras utan fokuserat på hur mycket avfall som kan vara tillgängligt. Vi har också ämnat utreda vad energibolagen egentligen har för rådighet över avfallets sammansättning och hur fjärrvärmekunderna ser på detta. Från energibranschen och avfallsbranschen menar man att det handlar mycket om en styrmedelsfråga och att lägga ansvar i rätt del av kedjan om man ska nå ett fossilfritt samhälle och komma längre än idag med fossil plast i hushållsavfallet. Fjärrvärmekunderna håller i stort med om detta och framhäver att samhällets alla aktörer har delad rådighet och skyldighet i att minska plastanvändningen i samhället. Många fjärrvärmekunder har mål om fossilfrihet eller klimatneutralitet som inte går i linje med förbränning av fossil plast för energiåtervinning. Samtidigt är man eniga om att avfallsförbränning behövs, och kommer behövas under lång tid framöver, i det svenska energisystemet som en del av avfallshanteringssystemet. Fem scenarier för framtida avfallsmängder i Sverige har tagits fram i projektet, med utgångspunkt i Konjunkturinstitutets framtidsprognos och i resultatet från workshopen Målbilder 2030 för energiutvinning ur av avfall och osäkerheter för nå dem, som hölls med representanter från energi- och avfallsbranschen. Analysen visar att den svenska avfallsmängden kommer att öka i samtliga scenarier, men att det i alla scenarier utom ett samtidigt kommer leda till konstanta eller minskade avfallsmängder till energiåtervinning, på grund av ökade krav på materialåtervinning och förväntat hög måluppfyllnad. Förutsatt att kapaciteten för avfallsförbränning i Sverige hålls konstant fram till 2035 och utnyttjas fullt ut kommer behovet av importerat avfall som bränsle minska i endast ett scenario, där de framtida återvinningskraven inte är uppfyllda. Från energibranschen trycker man på att det är en internationell klimatfråga och att energiåtervinning av avfall i Sverige kan leda till stor klimatnytta genom att erbjuda avfallsbehandlingstjänster till länder med sämre förutsättningar. Resultat från projektet visar att en övergång från deponering i Europa till energiåtervinning ger stora direkta klimatvinster då utsläpp av deponigas minskar. Vidare visar resultaten att det spelar mindre roll om avfallet energiåtervinns i Sverige eller i ett annat europeiskt land, klimatnyttan blir ändå stor. Det är dock en mycket komplex frågeställning hur det internationella avfallssystemet påverkas av handel med avfall. Kortsiktigt kan frågan vara enklare att besvara, då man ser en direkt nytta med att undvika metanutsläpp från deponier genom att exportera avfall för energiåtervinning. Långsiktigt har handel med avfall dock troligen mer intrikata konsekvenser som inte är lika intuitiva att förutse, till exempel att utveckling av sortering och avfallsförbränning i avfallsexporterande länder påverkas för att incitamenten förändras.
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| 13. |
- Maria Almasi, Alexandra, et al.
(författare)
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Avfallets roll i framtidens energisystem -11 viktiga punkter om avfall
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Avfall uppkommer i alla sektorer i samhället och påverkar miljö-, klimat- och energiarbetet i dessa. Att ha ett systemperspektiv när man belyser avfallshantering och energiåtervinning av avfall är därför viktigt. Projektet avser att dess resultat ska komma att utgöra underlag för att möta de utmaningar energibranschen står inför kring energiåtervinning av avfall samt ge nya perspektiv i avfallsdebatten. Arbetet baseras på intervjuer, workshops samt konsekvens- och scenarioanalys, i vilken scenarier för framtida avfallshantering och dess roll i energisystemet utarbetas. Projektets övergripande mål är att utreda hur avfallets roll i energisystemet kan komma att förändras i framtiden och vad det får för konsekvenser för energibranschen. För att kunna svara på detta undersöker vi hur mycket svenskt avfall som finns tillgängligt för energiåtervinning i framtiden. Vi har inte undersökt hur själva energisystemet förändras utan fokuserat på hur mycket avfall som kan vara tillgängligt. Vi har också ämnat utreda vad energibolagen egentligen har för rådighet över avfallets sammansättning och hur fjärrvärmekunderna ser på detta. Från energibranschen och avfallsbranschen menar man att det handlar mycket om en styrmedelsfråga och att lägga ansvar i rätt del av kedjan om man ska nå ett fossilfritt samhälle och komma längre än idag med fossil plast i hushållsavfallet. Fjärrvärmekunderna håller i stort med om detta och framhäver att samhällets alla aktörer har delad rådighet och skyldighet i att minska plastanvändningen i samhället. Många fjärrvärmekunder har mål om fossilfrihet eller klimatneutralitet som inte går i linje med förbränning av fossil plast för energiåtervinning. Samtidigt är man eniga om att avfallsförbränning behövs, och kommer behövas under lång tid framöver, i det svenska energisystemet som en del av avfallshanteringssystemet. Fem scenarier för framtida avfallsmängder i Sverige har tagits fram i projektet, med utgångspunkt i Konjunkturinstitutets framtidsprognos och i resultatet från workshopen Målbilder 2030 för energiutvinning ur av avfall och osäkerheter för nå dem, som hölls med representanter från energi- och avfallsbranschen. Analysen visar att den svenska avfallsmängden kommer att öka i samtliga scenarier, men att det i alla scenarier utom ett samtidigt kommer leda till konstanta eller minskade avfallsmängder till energiåtervinning, på grund av ökade krav på materialåtervinning och förväntat hög måluppfyllnad. Förutsatt att kapaciteten för avfallsförbränning i Sverige hålls konstant fram till 2035 och utnyttjas fullt ut kommer behovet av importerat avfall som bränsle minska i endast ett scenario, där de framtida återvinningskraven inte är uppfyllda. Från energibranschen trycker man på att det är en internationell klimatfråga och att energiåtervinning av avfall i Sverige kan leda till stor klimatnytta genom att erbjuda avfallsbehandlingstjänster till länder med sämre förutsättningar. Resultat från projektet visar att en övergång från deponering i Europa till energiåtervinning ger stora direkta klimatvinster då utsläpp av deponigas minskar. Vidare visar resultaten att det spelar mindre roll om avfallet energiåtervinns i Sverige eller i ett annat europeiskt land, klimatnyttan blir ändå stor. Det är dock en mycket komplex frågeställning hur det internationella avfallssystemet påverkas av handel med avfall. Kortsiktigt kan frågan vara enklare att besvara, då man ser en direkt nytta med att undvika metanutsläpp från deponier genom att exportera avfall för energiåtervinning. Långsiktigt har handel med avfall dock troligen mer intrikata konsekvenser som inte är lika intuitiva att förutse, till exempel att utveckling av sortering och avfallsförbränning i avfallsexporterande länder påverkas för att incitamenten förändras.
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| 14. |
- Metcalfe, Daniel B., et al.
(författare)
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Patchy field sampling biases understanding of climate change impacts across the Arctic
- 2018
-
Ingår i: Nature Ecology and Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 2:9, s. 1443-1448
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Tidskriftsartikel (refereegranskat)abstract
- Effective societal responses to rapid climate change in the Arctic rely on an accurate representation of region-specific ecosystem properties and processes. However, this is limited by the scarcity and patchy distribution of field measurements. Here, we use a comprehensive, geo-referenced database of primary field measurements in 1,840 published studies across the Arctic to identify statistically significant spatial biases in field sampling and study citation across this globally important region. We find that 31% of all study citations are derived from sites located within 50 km of just two research sites: Toolik Lake in the USA and Abisko in Sweden. Furthermore, relatively colder, more rapidly warming and sparsely vegetated sites are under-sampled and under-recognized in terms of citations, particularly among microbiology-related studies. The poorly sampled and cited areas, mainly in the Canadian high-Arctic archipelago and the Arctic coastline of Russia, constitute a large fraction of the Arctic ice-free land area. Our results suggest that the current pattern of sampling and citation may bias the scientific consensuses that underpin attempts to accurately predict and effectively mitigate climate change in the region. Further work is required to increase both the quality and quantity of sampling, and incorporate existing literature from poorly cited areas to generate a more representative picture of Arctic climate change and its environmental impacts.
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| 15. |
- Miliute-Plepiene, Jurate, et al.
(författare)
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Klimatnyttan med materialåtervinning av byggavfall
- 2022
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Rapport (refereegranskat)abstract
- Syftet med studien har varit att ta fram klimatnyckeltal för materialåtervinning av 15 bygg- och rivningsfraktioner jämfört med jungfrulig produktion. Energiutvinning som ett alternativ till materialåtervinning har också inkluderats för enstaka avfallsfraktioner. Studien är en generisk utvärdering av materialåtervinning med antagande att avfallshanteringen sker i Sverige. Ersatta jungfruliga material antas i de flesta fall vara producerade i Sverige eller i Europa, i enstaka fall används globala data beroende på datatillgänglighet och hur värdekedjor ser ut. Resultatet är inte fallspecifikt (beroende på avfallsåtervinnare, specifika transporteringssträckor) utan beräkningarna är generella och den faktiska klimatpåverkan kan skilja mellan olika återvinnare och kunder.Studien ska inte ses som en fullskalig LCA-analys, utan snarare som en mallbaserad utvärdering som illustrerar storleken och omfattningen av klimatnyttan som materialåtervinning av olika material medför.
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| 16. |
- Mousa, Elsayed, et al.
(författare)
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Reduced Carbon Consumption and CO2 Emission at the Blast Furnace by Use of Briquettes Containing Torrefed Sawdust
- 2019
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Ingår i: Journal of Sustainable Metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; 5:3, s. 391-401
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Tidskriftsartikel (refereegranskat)abstract
- Lowering the carbon consumption and fossil CO2emissions is a priority in blast furnace (BF) ironmaking. Renewablebiomass is one option that can play an important role in future low-carbon ironmaking particularly in the countries rich inbiomass resources. In this study, full-scale trials to investigate the impact of briquettes containing torrefied sawdust on theBF efficiency and process stability have been conducted. Briquettes containing 1.8% of torrefied pelletized sawdust (TPS),86.2% of steel mill residues, and 12% cement with sufficient mechanical strength have been produced on industrial scale. Thebio-briquettes were charged at two different rates: 37% ( ~ 39 kg/tHM) and 55% ( ~ 64 kg/tHM) bio-briquettes to the SSABBF No. 4 in Oxelösund. The gas utilization was higher during bio-briquette-charging periods without change in pressuredrop up to 55% bio-briquettes, indicating sustained shaft permeability. BF dust generation or properties did not change significantly.Measurements of the top gas composition using mass spectrometry did not indicate release of hydrocarbon fromTPS in connection to the charging of bio-briquettes. Evaluation of process data has been carried out using a heat and massbalance model. The evaluation of operational data in the model indicated lowering of thermal reserve zone temperature by45 °C and reduction in carbon consumption by ~ 10 kg/tHM when charging 55% bio-briquettes compared to the referencecase. The total CO2emission was reduced by about 33–40 kg/tHM when using 55% bio-briquettes.
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| 17. |
- Muschitiello, Francesco, et al.
(författare)
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Arctic climate response to the termination of the African Humid Period
- 2015
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 125, s. 91-97
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Tidskriftsartikel (refereegranskat)abstract
- The Earth's climate response to the rapid vegetation collapse at the termination of the African Humid Period (AHP) (5.5-5.0 kyr BP) is still lacking a comprehensive investigation. Here we discuss the sensitivity of mid-Holocene Arctic climate to changes in albedo brought by a rapid desertification of the Sahara. By comparing a network of surface temperature reconstructions with output from a coupled global climate model, we find that, through a system of land-atmosphere feedbacks, the end of the AHP reduced the atmospheric and oceanic poleward heat transport from tropical to high northern latitudes. This entails a general weakening of the mid-latitude Westerlies, which results in a shift towards cooling over the Arctic and North Atlantic regions, and a change from positive to negative Arctic Oscillation-like conditions. This mechanism would explain the sign of rapid hydro-climatic perturbations recorded in several reconstructions from high northern latitudes at 5.5-5.0 kyr BP, suggesting that these regions are sensitive to changes in Saharan land cover during the present interglacial. This is central in the debate surrounding Arctic climate amplification and future projections for subtropical precipitation changes.
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| 18. |
- Nestor, David, 1992-, et al.
(författare)
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Early prediction of blood stream infection in a prospectively collected cohort
- 2021
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Ingår i: BMC Infectious Diseases. - : BioMed Central (BMC). - 1471-2334. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Blood stream infection (BSI) and sepsis are serious clinical conditions and identification of the disease-causing pathogen is important for patient management. The RISE (Rapid Identification of SEpsis) study was carried out to collect a cohort allowing high-quality studies on different aspects of BSI and sepsis. The aim of this study was to identify patients at high risk for BSI who might benefit most from new, faster, etiological testing using neutrophil to lymphocyte count ratio (NLCR) and Shapiro score.METHODS: Adult patients (≥ 18 years) presenting at the emergency department (ED) with suspected BSI were prospectively included between 2014 and 2016 at Örebro University Hospital. Besides extra blood sampling, all study patients were treated according to ED routines. Electronic patient charts were retrospectively reviewed. A modified Shapiro score (MSS) and NLCR were extracted and compiled. Continuous score variables were analysed with area under receiver operator characteristics curves (AUC) to evaluate the ability of BSI prediction.RESULTS: The final cohort consisted of 484 patients where 84 (17%) had positive blood culture judged clinically significant. At optimal cut-offs, MSS (≥3 points) and NLCR (> 12) showed equal ability to predict BSI in the whole cohort (AUC 0.71/0.74; sensitivity 69%/67%; specificity 64%/68% respectively) and in a subgroup of 155 patients fulfilling Sepsis-3 criteria (AUC 0.71/0.66; sensitivity 81%/65%; specificity 46%/57% respectively). In BSI cases only predicted by NLCR> 12 the abundance of Gram-negative to Gram-positive pathogens (n = 13 to n = 4) differed significantly from those only predicted by MSS ≥3 p (n = 7 to n = 12 respectively) (p < 0.05).CONCLUSIONS: MSS and NLCR predicted BSI in the RISE cohort with similar cut-offs as shown in previous studies. Combining the MSS and NLCR did not increase the predictive performance. Differences in BSI prediction between MSS and NLCR regarding etiology need further evaluation.
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| 19. |
- Norström, Elin, et al.
(författare)
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Late Quaternary vegetation dynamics and hydro-climate in the Drakensberg, South Africa
- 2014
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 105, s. 48-65
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Tidskriftsartikel (refereegranskat)abstract
- Abstract A multi-proxy study of a sediment sequence from Braamhoek wetland, covering the last c. 16,000 years, reveals a record of regional climate and vegetation dynamics in the Drakensberg region, South Africa, including signals from both the organic sediment fraction (fossil pollen, charcoal, n-alkane abundance, n-alkane δ13C, TOC) and the inorganic fraction (mineral magnetic properties). The reconstruction, supported by a robust chronology, indicates two major periods of increased regional wetness during the late Pleistocene to early Holocene phase (c. 13,800–12,600 cal yr BP; c. 10,200–8500 cal yr BP) and one during the late Holocene (c. 2000 cal yr BP to present). Drier conditions are recorded during the Younger Dryas (c. 12,600–11,300 cal yr BP) and mid-Holocene (c. 7000–2000 cal yr BP). A major decline in fynbos vegetation during the early Holocene suggests a shift towards warmer temperatures and possibly towards less pronounced winter rains in eastern South Africa from c. 8500 cal yr BP. Comparison with records from interior of South Africa show relatively high inter-site variability, however, the Braamhoek moisture proxies do co-vary with the speleothem isotope records from Makapansgat, suggesting a similar hydro-climate evolution in eastern and interior parts of the summer rainfall region during the studied period. On multi-millennial time scales, an inverse hydro-climatological pattern is evident between these two South African records and reconstructions from tropical locations in southeast Africa. Such a rainfall dipole between eastern tropical and southern Africa, has previously been identified on shorter time scales, i.e. on inter-annual to millennial scales. The Braamhoek study suggests that a similar dipole pattern is acting also on a multi-millennial perspective. These long-term precipitation anomalies are tentatively coupled to teleconnections from multi-millennial changes in the dynamics of the Indian Ocean Dipole (IOD) and El Niño-Southern Oscillation (ENSO).
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| 20. |
- Poulsen, Hanna O., et al.
(författare)
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High genetic diversity of nitrofurantoin- or mecillinam-resistant Escherichia coli indicates low propensity for clonal spread
- 2013
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 68:9, s. 1974-1977
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Tidskriftsartikel (refereegranskat)abstract
- The empirical treatment with trimethoprim or ciprofloxacin of urinary tract infections (UTIs) is now questioned, partly due to the global expansion of a few resistant clonal groups of Escherichia coli. In this study we investigated the clonal structure of 34 strains of E. coli (collected from non-pregnant women aged 1865 years with uncomplicated UTIs in Europe and Canada) resistant to either of two other common treatment alternatives for uncomplicated UTIs, mecillinam or nitrofurantoin, using multilocus sequence typing (MLST). The 34 isolates were, despite high levels of multiresistance, distributed all over the E. coli genetic diversity spectrum with little association of antibiotic resistance to specific clonal groups. The results of this study indicate a low probability of a future clonal spread of resistance to mecillinam and nitrofurantoin.
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| 21. |
- Sundqvist, Hanna S., et al.
(författare)
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Arctic Holocene proxy climate database - new approaches to assessing geochronological accuracy and encoding climate variables
- 2014
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 10:4, s. 1605-1631
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Tidskriftsartikel (refereegranskat)abstract
- We present a systematic compilation of previously published Holocene proxy climate records from the Arctic. We identified 170 sites from north of 58 degrees N latitude where proxy time series extend back at least to 6 cal ka (all ages in this article are in calendar years before present - BP), are resolved at submillennial scale (at least one value every 400 +/- 200 years) and have age models constrained by at least one age every 3000 years. In addition to conventional meta-data for each proxy record (location, proxy type, reference), we include two novel parameters that add functionality to the database. First, climate interpretation is a series of fields that logically describe the specific climate variable(s) represented by the proxy record. It encodes the proxy-climate relation reported by authors of the original studies into a structured format to facilitate comparison with climate model outputs. Second, geochronology accuracy score (chron score) is a numerical rating that reflects the overall accuracy of C-14-based age models from lake and marine sediments. Chron scores were calculated using the original author-reported C-14 ages, which are included in this database. The database contains 320 records (some sites include multiple records) from six regions covering the circumpolar Arctic: Fennoscandia is the most densely sampled region (31% of the records), whereas only five records from the Russian Arctic met the criteria for inclusion. The database contains proxy records from lake sediment (60 %), marine sediment (32 %), glacier ice (5 %), and other sources. Most (61 %) reflect temperature (mainly summer warmth) and are primarily based on pollen, chironomid, or diatom assemblages. Many (15 %) reflect some aspect of hydroclimate as inferred from changes in stable isotopes, pollen and diatom assemblages, humification index in peat, and changes in equilibrium-line altitude of glaciers. This comprehensive database can be used in future studies to investigate the spatio-temporal pattern of Arctic Holocene climate changes and their causes. The Arctic Holocene data set is available from NOAA Paleoclimatology.
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| 22. |
- Sundqvist, Hanna S., 1972-, et al.
(författare)
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Climate change between the mid and late Holocene in the northern high latitudes : Part I: Survey of temperature and precipitation proxy data
- 2010
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 6, s. 591-608
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Tidskriftsartikel (refereegranskat)abstract
- We undertake a study in two parts, where theoverall aim is to quantitatively compare results from climateproxy data with results from several climate model simulationsfrom the Paleoclimate Modelling IntercomparisonProject for the mid-Holocene period and the pre-industrial,conditions for the pan-arctic region, north of 60 N. In thisfirst paper, we survey the available published local temperatureand precipitation proxy records. We also discuss andquantifiy some uncertainties in the estimated difference inclimate between the two periods as recorded in the availabledata. The spatial distribution of available published localproxies has a marked geographical bias towards land areassurrounding the North Atlantic sector, especially Fennoscandia.The majority of the reconstructions are terrestrial, andthere is a large over-representation towards summer temperaturerecords. The available reconstructions indicate that thenorthern high latitudes were warmer in both summer, winterand the in annual mean temperature at the mid-Holocene(6000 BP±500 yrs) compared to the pre-industrial period(1500AD±500 yrs). For usage in the model-data comparisons(in Part 1), we estimate the calibration uncertainty andalso the internal variability in the proxy records, to derive acombined minimum uncertainty in the reconstructed temperaturechange between the two periods. Often, the calibrationuncertainty alone, at a certain site, exceeds the actual reconstructedclimate change at the site level. In high-density regions,however, neighbouring records can be merged into aCorrespondence to: H. S. Sundqvist(hanna.sundqvist@natgeo.su.se)composite record to increase the signal-to-noise ratio. Thechallenge of producing reliable inferred climate reconstructionsfor the Holocene cannot be underestimated, consideringthe fact that the estimated temperature and precipitationfluctuations during this period are in magnitude similar to, orlower than, the uncertainties the reconstructions. We advocatea more widespread practice of archiving proxy recordsas most of the potentially available reconstructions are notpublished in digital form.
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| 23. |
- Sundqvist, Hanna S., et al.
(författare)
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Evidence of a large cooling between 1690 and 1740 AD in southern Africa
- 2013
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- A 350-year-long, well-dated delta O-18 stalagmite record from the summer rainfall region in South Africa is positively correlated with regional air surface temperatures at interannual time scales. The coldest period documented in this record occurred between 1690 and 1740, slightly lagging the Maunder Minimum (1645-1710). A temperature reconstruction, based on the correlation between regional surface temperatures and the stalagmite delta O-18 variations, indicates that parts of this period could have been as much as 1.4 degrees C colder than today. Significant cycles of 22, 11 and 4.8 years demonstrate that the solar magnetic and the El Nino-Southern Oscillation cycle could be important drivers of multidecadal to interannual climate variability in this region. The observation that the most important driver of stalagmite delta O-18 on interannual time scales from this subtropical region is regional surface temperature cautions against deterministic interpretations of delta O-18 variations in low-latitude stalagmites as mainly driven by the amount of precipitation.
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| 24. |
- Sundqvist, Hanna S., et al.
(författare)
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Holocene Climate Variability over Scandinavia
- 2008
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Ingår i: Abstract volume of DAPHNE-2nd Workshop, Heidelberg, Germany 26-28 February 2008. ; , s. 54-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 25. |
- Sundqvist, Hanna S., et al.
(författare)
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Luminescence in fast growing stalagmites from Uppsala, Sweden
- 2005
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Ingår i: Geografiska Annaler. Series A, Physical Geography. - 0435-3676 .- 1468-0459. ; 87:4, s. 539-548
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Tidskriftsartikel (refereegranskat)abstract
- Two fast-growing stalagmites from a cellar vault in Uppsala, southeast Sweden, are ana-lysed for their luminescent properties. The resultsindicate that variations in luminescence intensity in the stalagmites are annual. Due to problems in find-ing a suitable absolute dating method this assump-tion cannot yet be firmly tested; however, results from radiocarbon dating of one of the stalagmites do not contradict the proposal that the laminae are annual. If so, the speleothems have been growing for 10-15 years with a growth rate of 3-8 mm per year, which is a similar rate to other fast-growing speleothems in Great Britain that have formed from the reaction of lime mortar and carbon dioxide. It is likely that the assumed annual laminae of the lumi-nescence record represent a flush of organic mate-rial.
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| 26. |
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| 27. |
- Sundqvist, Hanna S., 1972-
(författare)
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Speleothems as environmental recorders : A study of Holocene speleothems and their growth environments in Sweden
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main aim of this thesis was to contribute with detailed information of regional environmental change during the Holocene through studies of speleothems and their growth environments from two caves, Korallgrottan and Labyrintgrottan in northwestern Sweden, and a cellar vault in Uppsala. This was done through studies of stable isotopes and luminescence properties in the speleothems in combination with a detailed monitoring study in Korallgrottan.The monitoring study suggests that stalagmites fed by stalactites with slow and stable drip rates from deep inside the cave may be suitable as palaeoclimate archives. Similarities between oxygen isotope signals of contemporary samples from Labyrintgrottan and Korallgrottan emphasize the potential of speleothems from Labyrintgrottan to also provide high resolution regional palaeoclimate information.Except for a number of cold events stalagmite δ18O records from northern Scandinavia indicate that temperatures were warmer than today between 9500 and 6000 years ago. During this period the interval between 7800 and 6000 years ago seems to have been the warmest. The area above Labyrintgrottan was most likely covered by much denser vegetation than today at the time of stalagmite growth (9500-7500 years ago) and was, unlike today, probably situated below the local tree-limit between 9000 and 8000 years ago. The δ18O record of a stalagmite from Korallgrottan covering the last 4000 years agrees with the concept of a warmer period, the so called Medieval Warm Period, centred around AD1000 and a colder period, the so called Little Ice Age, somewhere between AD1000 and today.Studies of luminescence properties in fast growing speleothems from Uppsala indicate that the variations in luminescence intensity are annual and that the annual lamiae of the luminescent record represent a flush of organic material.
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| 28. |
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| 29. |
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| 30. |
- Sundqvist, Hanna S., et al.
(författare)
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Stable isotope variations in stalagmites from northwestern Sweden document changes in temperature and vegetation during the early Holocene: a reply to Hammarlund and Edwards
- 2008
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Ingår i: The Holocene. ; 18:6, s. 1009-1010
-
Tidskriftsartikel (refereegranskat)abstract
- In a comment on the paper by Sundqvist et al. (2007a), Hammarlund and Edwards suggest that the oxygen isotope signal of the speleothem records K1 and L4 from northwestern Sweden as well as for the earlier published stalagmite SG93 from northern Norway should mainly reflect variation in the δ18O of mean annual precipitation. The main argument used by the authors is that the SG93 δ18O record should show remarkable similarities with the lacustrine carbonate δ18O record from Lake Tibetanus. The similarities between SG93 and Lake Tibetanus are mainly seen for the period between 10 and 9 ka BP, which is a period where both records have higher δ18O values compared with later in the Holocene. If true, this would indicate that temperatures in northern Scandinavia would have reached their Holocene maximum between 10 and 9 ka BP, which is contrary to what has been reported from other archives in the region which place the Holocene climatic optimum somewhere between 8 and 5 ka BP. Several factors affect the δ18O of speleothems and definitely also by annual mean δ18O of the local precipitation. However, for Holocene speleothems from northern Scandinavia as well as from the Alps this signal seems to be overridden by other factors, such as variable mixing of summer and winter precipitation of cave drip water as well as the temperature-dependent fractionation between calcite and water. But the relative importance of the factors can differ between different timescales, caves and even speleothems from the same cave, depending on hydrological pathways. To better understand the factors controlling the stable oxygen isotopes in precipitation and proxy archives back in time there is a need for more highly resolved records as well as for more atmospheric and hydrological modelling.
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| 31. |
- Sundqvist, Hanna S., et al.
(författare)
-
Stable oxygen isotopes in a stalagmite from Jämtland, NW Sweden, record large temperature variations over the last 4000 years
- 2010
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Ingår i: Boreas. - : John Wiley & Sons, Inc.. - 0300-9483 .- 1502-3885. ; 39:1, s. 77-86
-
Tidskriftsartikel (refereegranskat)abstract
- This study of a 4000-year-old stalagmite from Korallgrottan in northwestern Sweden highlights the potentials and challenges when using stable isotopes in stalagmites as climate proxies, as well as the fact that the relationship between climate and proxy may change through time. Both the oxygen and the carbon isotopes display an overall trend of enrichment together with decreasing growth rates over the time period covered by the stalagmite, which is considered a generally cooling period according to current palaeoclimate understanding. The stable isotope records show enriched isotopic values during the, for Scandinavia, comparatively cold period AD 1300–1700 and depleted values during the warmer period AD 800–1000. The indication of a negative relationship between measured d18O and surface temperature concurs with earlier reported stalagmite records from regions with a seasonal snow cover and is further supported by the fact that the stalagmite d18 O record shows general similarities with both regional and hemispheric temperature reconstructions available for the past 500 and 2000 years, respectively. Compared with a stable isotope record of lacustrine carbonates from northern Sweden, however, shifting correlations over time between the two records indicate that a local hydrological change may have taken place at Korallgrottan, or at the lake, compared with around 1000 years ago. The earlier part of the stalagmite d18O might thus be influenced, to some extent, by another process than the later part, which means that a negative relationship between d18O and surface temperature might not hold for the entire 4000-year-old record.
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| 32. |
- Sundqvist, Hanna S., et al.
(författare)
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Understanding conditions behind speleothem formation in Korallgrottan, northwestern Sweden
- 2007
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 347:1-2, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigate and characterise the environmental factors that control active speleothem growth in Korallgrottan, northwestern Sweden, in order to get a better understanding of seepage processes in karst areas and to determine whether the fossil speleothems from this site are suitable as palaeoclimatic archives. The drip rates from fast-dripping stalactites (>100 ml/day) vary substantially with the season and the snow regime. Comparisons with measurements of river discharge and simulated ground water recharge show that the drip rate from fast-dripping stalactites can be used as an estimation of the weekly to monthly ground water recharge. Slow-dripping stalactites however, have a steadier drip rate, with almost no seasonal variations. The δ18O composition of the drip water from both fast- and slow-dripping stalactites show some seasonal variation (±1.2‰), but is fairly stable compared to outside precipitation (±11.1‰). The δ18O signal from fast-dripping stalactites is biased towards summer conditions, while the signal is dampened at slow-dripping sites and an annual or even longer signal is evident. This holds true even though calcite precipitation may not occur continuously throughout the year. Similarly, the trace elemental composition of drip water is more stable in the slow-dripping stalactites, reflecting mean annual values or longer. Generally the drip water reaches the highest saturation level during the summer and autumn when biological activity in the soil zone is most intense, and the partial pressure of carbon dioxide, which controls limestone dissolution, is high.
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| 33. |
- Sundqvist, Hanna, et al.
(författare)
-
Stable isotopes in a stalagmite from NW Sweden documentenvironmental changes over the past 4000 years.
- 2009
-
Ingår i: Boreas. - : Elsevier. - 0300-9483 .- 1502-3885.
-
Tidskriftsartikel (refereegranskat)abstract
- This study of a 4000-year-old stalagmite from Korallgrottan in northwestern Sweden highlights the potentials and challenges when using stable isotopes in stalagmites as climate proxies, as well as the fact that the relationship between climate and proxy may change through time. Both the oxygen and the carbon isotopes display an overall trend of enrichment together with decreasing growth rates over the time period covered by the stalagmite, which is considered a generally cooling period according to current palaeoclimate understanding. The stable isotope records show enriched isotopic values during the, for Scandinavia, comparatively cold period AD 1300–1700 and depleted values during the warmer period AD 800–1000. The indication of a negative relationship between measured δ18O and surface temperature concurs with earlier reported stalagmite records from regions with a seasonal snow cover and is further supported by the fact that the stalagmite δ18O record shows general similarities with both regional and hemispheric temperature reconstructions available for the past 500 and 2000 years, respectively. Compared with a stable isotope record of lacustrine carbonates from northern Sweden, however, shifting correlations over time between the two records indicate that a local hydrological change may have taken place at Korallgrottan, or at the lake, compared with around 1000 years ago. The earlier part of the stalagmite δ18O might thus be influenced, to some extent, by another process than the later part, which means that a negative relationship between δ18O and surface temperature might not hold for the entire 4000-year-old record.
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| 34. |
- Zhang, Qiong, et al.
(författare)
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Climate change between the mid and late Holocene in northern high latitudes : Part 2: Model-data comparisons
- 2010
-
Ingår i: Climate of the Past. - Göttingen : Copernicus Publications. - 1814-9324 .- 1814-9332. ; 6, s. 609-626
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Tidskriftsartikel (refereegranskat)abstract
- The climate response over northern high latitudesto the mid-Holocene orbital forcing has been investigated inthree types of PMIP (Paleoclimate Modelling IntercomparisonProject) simulations with different complexity of themodelled climate system. By first undertaking model-datacomparison, an objective selection method has been appliedto evaluate the capability of the climate models to reproducethe spatial response pattern seen in proxy data. The possiblefeedback mechanisms behind the climate response havebeen explored based on the selected model simulations. Subsequentmodel-model comparisons indicate the importanceof including the different physical feedbacks in the climatemodels. The comparisons between the proxy-based reconstructionsand the best fit selected simulations show that overthe northern high latitudes, summer temperature change followsclosely the insolation change and shows a commonfeature with strong warming over land and relatively weakwarming over ocean at 6 ka compared to 0 ka. Furthermore,the sea-ice-albedo positive feedback enhances this response.The reconstructions of temperature show a strongerresponse to enhanced insolation in the annual mean temperaturethan winter and summer temperature. This is verified inthe model simulations and the behaviour is attributed to thelarger contribution from the large response in autumn. Despitea smaller insolation during winter at 6 ka, a pronouncedwarming centre is found over Barents Sea in winter in thesimulations, which is also supported by the nearby northernEurasian continental and Fennoscandian reconstructions.This indicates that in the Arctic region, the response of theocean and the sea ice to the enhanced summer insolationis more important for the winter temperature than the synchronousdecrease of the insolation.
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| 35. |
- Zhang, Qiong, et al.
(författare)
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Decadal Rainfall Dipole Oscillation over Southern Africa Modulated by Variation of Austral Summer Land-Sea Contrast along the East Coast of Africa
- 2015
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Ingår i: Journal of the Atmospheric Sciences. - 0022-4928 .- 1520-0469. ; 72:5, s. 1827-1836
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Tidskriftsartikel (refereegranskat)abstract
- A rainfall dipole mode characterized by negative correlation between subtropical southern Africa and equatorial eastern Africa is identified in instrumental observation data in the recent 100 years. The dipole mode shows a pronounced oscillation signal at a time scale of about 18 years. This study investigates the underlying dynamical mechanisms responsible for this dipole pattern. It is found that the southern African rainfall dipole index is highly correlated to the land-sea contrast along the east coast of Africa. When the land-sea thermal contrast strengthens, the easterly flow toward the continent becomes stronger. The stronger easterly flow, via its response to east coast topography and surface heating, leads to a low pressure circulation anomaly over land south of the maximum easterly flow anomalies and thus causes more rainfall in the south. On a decadal time scale, an ENSO-like SST pattern acts to modulate this land-sea contrast and the consequent rainfall dipole. During a wet in the south and dry in the north dipole, there are warm SSTs over the central Indian Ocean and cold SSTs over the western Indian Ocean. The cold SSTs over the western Indian Ocean further enhance the land-sea contrast during austral summer. Moreover, these cold western Indian Ocean SSTs also play an important role in regulating land temperature, thereby suppressing clouds and warming the land via increased shortwave radiation over the less-cloudy land. This cloud-SST coupling acts to further strengthen the land-sea contrast.
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| 36. |
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