The Azores is situated in the North Atlantic Ocean and is one of the most active volcanicregions in the Northern Hemisphere. The volcanic history of the islands is fairly wellknown and several explosive trachytic eruptions have been reported but the geochemicalcompositions of the glass component of the tephra as well as the dispersal oftephras to distal areas are less well known. The purpose of this study is twofold: (1) topresent major element geochemistry of the glass component from several historic aswell as prehistoric tephras, including the trachybasaltic Capelinhos AD 1957‐58eruption on the island of Faial, and the trachytic explosive eruptions of Sete Cidades(c. AD 1440), Fogo A (c. 5000 BP), Fogo AD 1563 and Furnas AD 1630 on the island ofSão Miguel; (2) to present a refined tephrostratigraphy for the island of Pico. Analyses ofmajor element geochemistry suggest that tephras from the three active stratovolcanoeson São Miguel can be separated in biplots showing e.g. FeOtot vs.TiO2 and FeOtot vs. CaO.The tephrostratigraphy of Caveiro bog on the island of Pico is based on a radiocarbondated core with eight tephra layers extending back to c. 7000 BP. All tephras are oftrachybasaltic/basaltic trachyandesitic composition except the oldest layer, which is ofbasanitic composition. An attempt was made to correlate the tephra record of Caveirobog with the previously investigated Lake Caveiro. A tephra‐based correlation betweenthe Caveiro bog and Lake Caveiro is not straightforward and only three tephras inCaveiro bog can possibly be correlated with tephras found in the sediments of LakeCaveiro.Proximal glass data from the Furnas volcano on São Miguel suggest that distal cryptotephrasfound in Ireland may have an origin in the Azores and not on Jan Mayen aspreviously has been suggested. The similarity of the proximal tephras on São Miguel anddistal tephras in Ireland is demonstrated by high similarity coefficients (>0.95) andbiplots showing major element composition also support a correlation between Azoreaneruptions and distal tephras in Ireland. Thus, trachytic tephras erupted from explosiveeruptions on the island of São Miguel may have a potential to contribute to theconstruction of a European‐wide tephrochronology framework.Trachytic tephras erupted from explosive eruptions on the Azores may be more widelydispersed than previously thought and may provide useful isochrones for correlation ofpaleoclimate archives in the north‐central Atlantic, North Africa and the Iberian regions.The trachybasaltic/basaltic trachyandesitic tephras erupted from cinder cones on PicoIsland are probably only useful for a local tephrochronology in the Azores region, andnot for a wider Atlantic or European framework.

No description available.

Klimatförändringen som framförallt beror på den ökade koncentrationen av koldioxid i atmosfären har gjort att internationella och nationella klimatmål har satts upp. Det vanligaste internationella klimatmålet är Parisavtalet vars mål är att temperaturökningen ska begränsas till 1,5 grad fram till 2050 och där det nationella klimatmålet har liknande mål där målet är att vara koldioxidneutralt 2045. Skogen kan, med dess förmåga att binda koldioxid från atmosfären, vara en stor bidragande faktor för att uppnå klimatmålen. Genom att utföra en beskrivande litteraturstudie var syftet med den här studien att undersöka vilken metod som var mest effektiv för att bidra till klimatmålen som kolsänka. Eftersom klimatmålen ligger kort fram i tiden var det mycket som tyder på att kortsiktiga metoder, som genom snabb tillväxt binder koldioxid, är de effektivaste metoderna för att bidra till klimatmålen. Nyckelord: Klimatförändring, Klimatmål, Växthusgaser, Kolbindning, Biologisk mångfald. Keywords: Climate change, Climate goal, Greenhous gas, Carbon sequestration, Biodiversity.

How terrestrial vegetation influences microclimate and what effects this has on associated ecosystems is well studied, but it is less known if and how aquatic macrophytes affect their microclimate. In this study I therefore aim to investigate the question of how aquatic macrophytes influence their microclimate, and how these effects in turn may affect associated aquatic organisms and ecosystems. This was done by conducting a literature search and review of relevant scientific articles. I found that aquatic macrophytes influence microclimate in several ways. First, their photosynthetic activity can affect water and sediment chemistry by changing carbon and oxygen levels, which also influences pH. Secondly, local temperature can also be influenced by macrophytes through shading and heat retention, which in turn also can affect water movement via density differences. Third, aquatic macrophytes can affect light levels in the water column, both negatively through shading, and positively by reduction of particles in the water. I conclude that aquatic macrophytes do influence microclimate. This influence can change the local environment, thus also affecting associated organisms and ecosystems. These conclusions are important for future research of aquatic environments when looking at challenges such as climate change and maintaining and protecting biodiversity and whole ecosystems. / Hur landvegetation påverkar mikroklimatet och vilka effekter detta har på associerade ekosystem är väl studerat, men det är mindre känt om, och i så fall hur, akvatiska makrofyter påverkar sitt mikroklimat. I denna studie syftar jag därför till att undersöka frågan om hur akvatiska makrofyter påverkar sitt mikroklimat, och hur dessa effekter vidare kan påverka associerade vattenlevande organismer och ekosystem. Detta genom att göra en litteratursökning och granskning av relevanta vetenskapliga artiklar. Jag fann att akvatiska makrofyter påverkar mikroklimatet på flera sätt. För det första kan deras fotosyntetiska aktivitet påverka vatten- och sedimentkemin genom att ändra koldioxid- och syrenivåerna, vilket också påverkar pH. För det andra kan lokal temperatur också påverkas av makrofyter genom skuggning och värmebevarande, vilket i sin tur även kan påverka vattenrörelsen via densitetsskillnader. För det tredje kan akvatiska makrofyter påverka ljusnivåerna i vattenpelaren, både negativt genom skuggning, och positivt genom minskning av partiklar i vattnet. Jag drar slutsatsen att akvatiska makrofyter har starkt inflytande på mikroklimatet. Detta inflytande kan förändra den lokala miljön och därmed också påverka associerade organismer och ekosystem. Dessa slutsatser är viktiga för framtida forskning om vattenmiljöer när man tittar på utmaningar som klimatförändringar, bevarande, samt skydd av biologisk mångfald och hela ekosystem.

Loess is a very fine aeolian sediment that can be used as a proxy for stadial and interstadial glacialperiods. To understand how Earth’s climate have changed and what effects that change have had on theplanet and life on it we can use climate archives. The composition of loess and soil often contains asmall amount of magnetic minerals which can be used for identifying warmer and colder periods. Theclimate is recorded in the soil as it is deposited and climate changes. By examining loess as a climatearchive, we can increase our understanding of past climate, with this increased understanding inferencesabout changes to future climate and climate changes can be made. The aim of this study has thereforebeen to understand the depositional environment of the loess sequences on Portlet, Jersey in the EnglishChannel. This was done by examining the magnetic susceptibility of 173 samples taken from the unitsin the sequency of Portelet and interpreting the variations of magnetic susceptibility in them. Thelocation of Portelet on the edge of the glacial maximum and next to the Atlantic Ocean makes it aninteresting study area in connection to climate change. The magnetic susceptibility measurements showa variation in warmer and colder periods during the deposition of the sediments in the sequency and theunits vary in the type of enhancement model that can be applied to them. The study provides a clearerpicture of the depositional environment during the stadial and interstadial during the late Quaternary.

The Indian Summer Monsoon (ISM) plays a vital role in the livelihoods and economy of those living on the Indian subcontinent, including the small, mountainous country of Bhutan. The ISM fluctuates over varying temporal scales and its variability is related to many internal and external factors including the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). In 2015, a Super El Niño occurred in the tropical Pacific alongside a positive IOD in the Indian Ocean and was followed in 2016 by a simultaneous La Niña and negative IOD. These events had worldwide repercussions. However, it is unclear how the ISM was affected during this time, both at a regional scale over the whole ISM area and at a local scale over Bhutan. First, an evaluation of data products comparing ERA5 reanalysis, TRMM and GPM satellite, and GPCC precipitation products against weather station measurements from Bhutan, showed that ERA5 reanalysis was the most suitable product to investigate ISM change in these two years. Using the reanalysis datasets, it was shown that there was disruption to the ISM during this period, with a late onset of the monsoon in 2015, a shifted monsoon flow in July 2015 and in August 2016 and a late withdrawal in 2016. However, this resulted in neither a monsoon surplus nor deficit across both years but instead large spatial-temporal variability. It is possible to attribute some of the regional scale changes to the ENSO and IOD events, but the expected impact of a simultaneous ENSO and IOD events are not recognisable. This may be due to a supposed weakening of the ENSO/ISM relationship and it is likely that 2015/16 monsoon disruption was driven by a combination of factors alongside ENSO and the IOD, including varying boundary conditions, the Pacific Decadal Oscillation, the Atlantic Multi-decadal Oscillation, and more. At a local scale, the intricate topography and orographic processes ongoing within Bhutan further amplified or dampened the already altered ISM. Whilst ENSO and IOD driven monsoon variability can be recognised at a regional scale, a direct link between ENSO and IOD activity and changes to the monsoon at a local scale over Bhutan is hard to distinguish. It is unknown how the ISM, ENSO, and the IOD will evolve under a future changing climate and therefore this presents a concern to Bhutan with its inherent vulnerability to monsoon variability.

This thesis is about the production of knowledge in meteorological research. Meteorology is an interesting case because of its crucial role in defining the climate change problem, but also because of its reliance on simulation modeling, a comparatively little studied scientific practice. The thesis provides an analysis of the central practices of simulation modeling and field experimentation. It draws upon concepts from social world theory, where practice is closely related to work. The thesis also employs the notion of translation, as developed by the actor-network approach, in order to analyse how different practices and entities become associated with each other. Empirical data was collected with interviews and participant observation and most of the fieldwork was conducted at the Department of Meteorology, Stockholm University. The first four chapters are preliminary: Introduction, theory, method and a review of the field and its history (Chapters 1–4). The empirical findings are then presented in four chapters. Chapter 5 presents how meteorological experimentalists organize collaborations by connecting and translating different practices. The use of measuring instruments has an important role in this. In Chapter 6, modeling work is described in detail. The differences between modeling for weather forecasting and for research purposes are analyzed and in particular, the construction of simulation models. It is concluded that this involves a materialization of theoretical models. The next two chapters take their point of departure in intersections where modeling practice meets experimentation. Chapter 7 is focused on model evaluation and I conclude that the comparison of observations and model output is needed to produce reference in simulation modeling and thus, legitimate this practice. The second intersection, discussed in Chapter 8, is the construction of new components of simulation models, so-called parameterizations. In addition to the previously mentioned sources, the analysis in this chapter is also based on research funding applications. It is concluded that climate research is constructed in such a way that parameterizations become potential boundary objects that shape the relationship between experimentalists and modelers. The final chapter discusses the central findings of the thesis. It is structured around different themes within social world theory: subworlds and segmentation, legitimation, arena processes, and intersections. Crucial methodological issues are revisited as well. It is shown how climate modeling shapes meteorological research and the consequences of simulation modeling practice for scientific work more generally are outlined as well. The chapter also includes an extensive discussion of the utility of the concept boundary object.

When measuring weathering intensity of paleosols there arevarious methods and ratios that can be used. This studyexamines several weathering indicators too see which are bestapplied and most effective on loess and paleosols from Yukon,Canada. This region today is considered sub-arctic, but duringpast time this area and its soils has been characterized byglaciations and interglaciations. These changes are the origin ofthe unweathered Kluane loess and the weathered Slims Soilthat are analyzed in the study. Methods used to determine themost sensitive weathering indicator was; CIA (the ChemicalIndex of Alteration), CPA (the Chemical Proxy of Alteration),oxide ratios ((CaO + Na2O + MgO)/TiO2 and (CaO + Na2O +K2O)/TiO2), and elemental ratios (Rb/Sr, Ba/Sr, Ti/Sr). Theresults from the CIA and oxide ratios show that calcium is thevarying factor, and thereby a good weathering indicator forthese samples. The elemental ratios showed a great variationbetween weathered and unweathered samples, and a cleardecrease strontium is apparent. These ratios would also beuseful indicators, but since Sr is associated with Ca, it isprobably calcium that is the main feature. The methods withoutcalcium as a factor did not give any clear separation betweenKluane loess and Slims Soil. Thereby it is concluded that proxyscontaining Ca are the most useful indicators of weathering inthis area.

Greenhouse gas emissions and land subsidence on four cultivated peat soils (Martebo, Örke, Kälkestad, Lidhult) have been investigated by measuring emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in field and lab. Greenhouse emitted gas (mg/h) from undisturbed soil cores was measured in lab. Measurements were performed at four different drainage depths. Soil cores were also kept incubated at constant drainage depth and emitted gas was measured with two-week intervals at three measurement occasions. Field measurements of CO2 emissions (mg/h/m2) were also performed. In addition to gas emissions, irrigation of soil cores has been carried out to investigate the risk of leaching of copper (Cu), phosphorus (P), nitrogen (N) and dissolved organic matter (DOC) during rewetting, and whether turbidity can be used as a measurement of DOC. Land surveying with GPS was done on three of the peat soils. This was to investigate how land subsidence can be related to CO2 emissions. On one of the sites different land surveying methods were used to assess their suitability for tracking land subsidence in peat soils. 30 year land surveying data from the sites have also been compiled and analyzed. The peat soils are part of a long-term experiment that was laid out in 1986. On each site one field was fertilized with copper and one was kept untreated as comparision. The purpose of the copper fertilizer was to reduce the activity of microorganisms. By doing so the degradation of soil organic matter could be reduced, thereby reducing the land subsidence. The results show that the ground surface at all four sites has subsided, but no difference is observed for copper-fertilized fields compared to untreated. Neither could an effect on CO2 emissions from copper fertilization be noted. The greatest land subsidence was observed for Martebo and the least for Kälkestad. By using data from the most recent time period the greatest subsidence was instead observed for Örke. This is consistent with Örke having the greatest CO2 emissions. CO2 emissions alone could not explain land subsidence. The results also show that emitted N2O was higher for nutrient-rich soils with the peak directly after saturation. CH4 was at its lowest initially, but then increased and emitted CH4 was greatest for the soils where easily biodegradable organic matter was available. Turbidity alone could not explain the DOC content in leachate from the irrigated soil cores. Conclusions drawn were that copper fertilization had no effect on land subsidence and CO2 emissions in this case. Copper did however still leach from the soils 30 years after addition. Emissions of CO2, N2O and CH4 varies greatly between the different soils. To be able to obtain reliable levels of greenhouse gas emissions from peat soils in climate models, more research is needed on how different peat soils react to water and nutrient content. It is important to have long time series when measuring land subsidence. Using the same measurement equipment will give better results. GPS for land surveying of peatland can be recommended if the results can be related to a fix point. / Växthusgasavgång och markytesänkning på fyra odlade torvmarker (Martebo, Örke, Kälkestad, Lidhult) har undersökts genom att mäta utsläpp av koldioxid (CO2), metan (CH4) och lustgas (N2O) i fält och labb. Detta genom att ta in ostörda jordprover i stålcylindrar och i labb mäta gasavgången vid fyra olika dräneringsdjup. Jordprover hölls även inkuberade vid konstant dräneringsdjup och gasavgång mättes med två veckors intervall vid totalt tre mättillfällen. Avgången av CO2 mättes även i fält. Utöver gasavgång har bevattning (i labb) av ostörda jordprover hämtade från fält utförts för att undersöka risk för utlakning av koppar (Cu), fosfor (P), kväve (N) och löst organiskt material (DOC) vid återvätning, samt om det går att använda turbiditet som mått på DOC. På tre av torvmarkerna har markytans höjd avvägts med GPS. Detta för att undersöka hur markytesänkning går att relatera till avgång av CO2. Vid höjdmätning av en av provplatserna har olika höjdmätningsmetoder använts och deras lämplighet för ändamålet undersökts. Sedan har data över markytans höjd från de senaste 30 åren också sammanställts och analyserats. Torvmarkerna är med i ett långliggande försök som lades ut 1986 med ett koppargödslat och ett obehandlat led på varje provplats. Syftet med koppargödslingen var att försöka minska aktiviteten hos mikroorganismer. Detta för att minska nedbrytning av organiskt material i marken och därigenom minska markytesänkningen. Resultaten visade att markytan på alla fyra platser hade sänkts, men ingen skillnad observerades på de koppargödslade försöksrutorna jämfört med de obehandlade. Inte heller observerades effekt av koppargödsling på avgång av CO2. Störst ytsänkning var för Martebo och lägst för Kälkestad. Om endast data från den senaste perioden användes hade Örke störst markytesänkning, vilket var konsekvent med att Örke även hade störst avgång av CO2. Dock var avgången av CO2 för låg för att ensamt kunna förklara markytesänkningen.  Resultaten visade även att avgång av N2O var högre för de näringsrika jordarna i studien och högst precis efter att jorden vattenmättats. CH4 började lågt, men ökade sedan och avgången av CH4 var störst för jordarna där lättnedbrytbart organiskt material fanns tillgängligt. Turbiditet kunde inte ensamt förklara halten DOC i lakvatten från lysimetrarna. Slutsatser som kunde dras var att kopparbehandling inte hade effekt på markytesänkning eller avgång av CO2. Koppar kunde däremot fortfarande lakas ut ur jorden 30 år efter gödsling. Avgång av CO2, N2O och CH4 varierade mycket mellan de olika jordarna. För att kunna få tillförlitliga nivåer på växthusgasutsläpp från torvjordar i klimatmodeller krävs mer forskning på hur olika torvjordar reagerar på vattenhalt och näringsinnehåll. Det är viktigt med långa tidsserier vid mätning av ytsänkning och användning av samma mätmetod krävs för att få jämförbara resultat. Användning av GPS för höjdavvägning av torvmark kan rekommenderas om det finns en tydlig fixpunkt att relatera mätresultaten till.

De flesta tvivlar inte på att klimatförändringarna är märkbara. Många vet däremot inte är att metan (CH4 ) är en mycket viktig växthusgas som påverkar klimatförändringen och som inte får försummas. I denna uppsats behandlar jag växthusgasen metan. Det förklaras var och hur metan bildas, var den släpps ut och absorberas samt vilket inflytande människor har på koncentrationen av metan i atmosfären. Med hjälp av en datorsimulering i MATLAB simuleras och utvärderas olika scenarier. Dessa scenarier sträcker sig från den förindustriella eran, genom nutiden, till möjliga framtidsscenarier. Utifrån mätdatan går det att uppskatta hur stor inverkan metan har på den globala uppvärmningen och därmed på klimatförändringen.