| 1. |
- Skarin, Anna, et al.
(författare)
-
Reindeer use of low Arctic tundra correlates with landscape structure
- 2020
-
Ingår i: Environmental Research Letters. - : Institute of Physics (IOP). - 1748-9326. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- Rapid climate change in Arctic regions is linked to the expansion of woody taxa (shrubification), and an increase in biomass as tundra becomes greener. Reindeer and caribou (Rangifer tarandus) are considered able to suppress vegetative greening through grazing and trampling. Quantifying reindeer use of different land cover types can help us understand their impact on the growth and recruitment of deciduous shrubs, many of which serve as fodder (e.g. Salix spp.), in favourable habitats, such as naturally denuded landslides in permafrost areas. Understanding the spatial distribution of reindeer pressure on vegetation is important to project future patterns of greening, albedo, snow capture, active layer development, and the overall resilience of tundra rangelands under ongoing climate change. Here we quantify reindeer habitat use within the low Arctic tundra zone of Yamal, West Siberia estimated from pellet-group counts, and also how active layer thickness (ALT) relates to reindeer use. Our results confirm intensive use by reindeer of terrain with high June-July time integrated normalised difference vegetation index, steeper slopes, ridges, upper slopes and valleys, and a preference for low erect shrub tundra. These sites also seem to have a shallower ALT compared to sites less used by reindeer, although we did not find any direct relationship between ALT and reindeer use. Low use of tall Salix habitats indicated that reindeer are unlikely to suppress the growth of already tall-erect woody taxa, while they exert maximum pressure in areas where shrubs are already low in stature, e.g. ridgetops. Reindeer ability to suppress the regrowth and expansion of woody taxa in landslide areas (i.e. concavities) seems limited, as these types were less used. Our results suggest that reindeer use of the landscape and hence their effects on the landscape correlates with the landscape structure. Future research is needed to evaluate the role and efficiency of reindeer as ecosystem engineers capable of mediating the effects of climate change.
|
|
| 2. |
- Lundmark, Linda, 1975-, et al.
(författare)
-
Effects of climate change and extreme events on forest communities in the European North
- 2008
-
Ingår i: Climatic Change. - : SpringerLink. - 0165-0009 .- 1573-1480. ; 87:1-2, s. 235-249
-
Tidskriftsartikel (refereegranskat)abstract
- The European north is increasingly affected by changes in climate and climate variability. These changes and their causes are global in scope but specific impacts vary considerably between different regions. Recent incidents and events show that forest-resource based regions have difficulties in alleviating adverse effects of these changes. Also, the future socio-economic impact is to date unexplored. Norrbotten in Sweden, Lappi in Finland and Arkhangelsk oblast in Russia are regions that differ significantly in terms of their socio-economic characteristics and capacities. A modified employment multiplier model is used to predict future changes. Scenarios of changing forest resources provide quantitative estimations of the sensitivity of regional employment. These estimates are used to assess and discuss the adaptive capacities of the regions. Results show that Arkhangelsk oblast is more vulnerable to climate variability than Norrbotten and Lappi. This is due to the continued dependency on natural resources in combination with different capacities to counteract negative effects or to take advantage of the opportunities offered by climate change in this region
|
|
| 3. |
- Johansson, Madelaine, 1962-, et al.
(författare)
-
Vem äger frågan? : Förutsättningar för kommunikation i svenskt miljömålsarbet
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Ständiga förändringar i samhället ökar kraven på flexibilitet och nya strategier för att hantera miljöproblematiken och arbetet med att nå en hållbar utveckling.Det kan uppstå problem när samhället ska anpassa sig efter nya strukturer och nyuppkomna behov, exempelvis när det gäller miljöhot. De nya krav som kopplas till hållbar utveckling och dess ekologiska dimensionreser krav på förändrad politisk styrning. I Sverige har det beslutats attmiljöfrågor ska vara övergripande för alla politiska områden. Formulering avplaner och program för ekologisk hållbar utveckling införs därför i olika typerav styrningssystem som bygger på olika sorts logik vilket kan leda till intressekonflikter.Det övergripande målet för svensk miljöpolitik är att till nästa generation lämnaöver ett samhälle där de stora miljöproblemen är lösta och där mänskligpåverkan på miljön är långsiktigt hållbar. År 1999 fastställdes en ny struktur ihållbarhetsarbetet genom framtagandet av 15 nationella miljökvalitetsmål och inovember 2001 antog riksdagen regeringens förslag om delmål och riktlinjer förhur dessa miljömål ska uppnås. Tanken är att miljökvalitetsmålen ska gevägledning för allt miljöarbete inom såväl olika samhällssektorer som på olikanivåer i miljömålsadministrationen. Regionala mål och sektorsmål ska utvecklasmed utgångspunkt i de mål som beslutats av riksdagen. Syftet med studien som ligger till grund för denna rapport var att identifierahinder för kommunikation i miljömålsarbetet och därigenom underlätta överbryggandet av kommunikationsbarriärer i framtida miljöarbete. Vi harstuderat hur aktörer på olika nivåer inom miljömålsadministrationen ser på målstyrning och arbetet med de svenska miljökvalitetsmålen med syfte att synliggöra hur kommunikationen kring miljömålen uppfattas.Vi har särskilt fokuserat på:kommunikation mellan administrativa nivåer, i allmänhet och rörandeuppföljningsarbetet i synnerhethur målstyrning fungerar i praktiken• vad som kan och bör mätas i uppföljningen av miljömålsarbetetmöjligheter till feedback mellan olika aktörer och administrativa nivåer.
|
|
| 4. |
- Berndtsson, Ronny, et al.
(författare)
-
Drivers of changing urban flood risk : A framework for action
- 2019
-
Ingår i: Journal of Environmental Management. - : Elsevier. - 0301-4797 .- 1095-8630. ; 240, s. 47-56
-
Tidskriftsartikel (refereegranskat)abstract
- This study focuses on drivers for changing urban flood risk. We suggest a framework for guiding climate change adaptation action concerning flood risk and manageability in cities. The identified key drivers of changing flood hazard and vulnerability are used to provide an overview of each driver's impact on flood risk and manageability at the city level. We find that identified drivers for urban flood risk can be grouped in three different priority areas with different time horizon. The first group has high impact but is manageable at city level. Typical drivers in this group are related to the physical environment such as decreasing permeability and unresponsive engineering. The second group of drivers is represented by public awareness and individual willingness to participate and urbanization and urban sprawl. These drivers may be important and are manageable for the cities and they involve both short-term and long-term measures. The third group of drivers is related to policy and long-term changes. This group is represented by economic growth and increasing values at risk, climate change, and increasing complexity of society. They have all high impact but low manageability. Managing these drivers needs to be done in a longer time perspective, e.g., by developing long-term policies and exchange of ideas.
|
|
| 5. |
- Zhao, Xiaoyun
(författare)
-
Government vs Market in Sustainable Residential Development? : Microdata analysis of car travel, CO2 emission and residence location
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Increasing car usage and travel demands between residential locations and destinations in order to fulfill the various needs of residents is a primary cause of CO2 emissions. To win the battle against climate change, a better understanding of the question relating to which urban residential form may most effectively mitigate the CO2 emissions is the key pathway.This dissertation is concerned with the above problem and it mainly considers three objectives in providing insights on answering the question. The first objective is to comprehensively and microscopically understand intra-urban car travel behavior. The second objective is to estimate the induced CO2 emissions from daily intra-urban car travel and to ex-ante evaluate residential plans. The third objective is to assess whether the governmental sustainable residential development objective is aligned with the objectives of the estate market actors. To explore the research questions related to the objectives, a microdata analysis process (data collection, data assessment and transformation, data storage, data analysis and decision-making) is applied and is found essential in gaining access to key variables in exploring the answer of a preferable urban form. The dissertation offers many new solutions to various technical aspects through a microdata analysis process.The primary contribution of this dissertation is that it outlines an operational model that comprehensively integrates the investors’ investment strategy, the residents’ choice behavior, and the governmental sustainability objective in the interest of making an ex-ante assessment of residential plans. This ex-ante assessment provides decision-support in sustainable residential development at foremost local level.The first finding from the implementation of the model on the case study is that the market actors’ objectives are, in general, aligned with the government’s sustainable residential development objective. The second finding indicates that re-shaping the urban form into a compact city is preferable in mitigating CO2 emissions, in spite of the fact that the case city is of a polycentric urban form. These findings provide support for those advocating the compact city as the ideal for sustainable residential development, and also provide foresight on settling the answer to the preferred re-shaping of urban forms in climate change.
|
|
| 6. |
- Nordström, Jonas, et al.
(författare)
-
Do parents counter-balance the carbon emissions of their children?
- 2020
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:4, s. 1-16
-
Tidskriftsartikel (refereegranskat)abstract
- It is well understood that adding to the population increases CO2 emissions. At the same time, having children is a transformative experience, such that it might profoundly change adult (i.e., parents') preferences and consumption. How it might change is, however, unknown. Depending on if becoming a parent makes a person "greener" or "browner," parents may either balance or exacerbate the added CO2 emissions from their children. Parents might think more about the future, compared to childless adults, including risks posed to their children from environmental events like climate change. But parenthood also adds needs and more intensive competition on your scarce time. Carbon-intensive goods can add convenience and help save time, e.g., driving may facilitate being in more places in one day, compared to public transportation or biking. Pre-prepared food that contain red meat may save time and satisfy more household preferences, relative to vegetarian food. We provide the first rigorous test of whether parents are greener or browner than other adults. We create a unique dataset by combining detailed micro data on household expenditures of all expenditure groups particularly important for CO2 emissions (transportation, food, and heating/electricity) with CO2 emissions, and compare emissions from Swedish adults with and without children. We find that parents emit more CO2 than childless adults. Only a small fraction of adults permanently choose not to have children, which means any meaningful self-selection into parenthood based on green preferences is unlikely. Our findings suggest that having children might increase CO2 emissions both by adding to the population and by increasing CO2 emissions from those choosing to have children.
|
|
| 7. |
- Gál, Csilla V
(författare)
-
A városi tér szerkezete és hatása a mikroklímára [Urban space and structure and its effect on the urban microclimate]
- 2017
-
Ingår i: 43. Meteorológiai Tudományos Napok. 2017. November 23-24. Mikro- és mezoskálájú légköri folyamatok modellezése. Az előadások összefoglalói.. - Budapest, Hungary. - 9789639931145
-
Konferensbidrag (refereegranskat)abstract
- A városok sajátos éghajlata, a városklíma, a természetes környezethez képest módosult éghajlattal jellemezhető. A klímaparaméterek városi módosulásának hátterében a beépített felszínek megváltozott energiaháztartása áll. Míg a városok éghajlata markánsan elkülönül a környező természetes területek éghajlatától, a városokon belül is jelentős klimatikus különbségek alakulnak ki. Ezen különbségek kialakulására alapvető hatással van a beépítettség foka, valamint a zöld területek részaránya. A városokon belüli éghajlati különbségek tanulmányozása mérések és numerikus szimulációk révén lehetséges. Utóbbiak segítségével széleskörűen tanulmányozható a beépítettség, a városokra jellemző mesterséges anyagok, valamint a városon belül alkalmazott zöld- és kék infrastruktúra elemeinek hatása a kialakuló mikro- és lokális éghajlatra, illetve mindezek hatása a lakosok komfortérzetére. Eme ismeretanyagra alapozva megfogalmazhatók olyan várostervezési irányelvek, melyekkel az éghajlatváltozással kombinálódó városklíma negatív hatásai mérsékelhetőek, s a városlakók számára klimatikus szempontból élhetőbb környezet teremthető.Tanulmányomban Budapest jellemző városi beépítési formáit, s a köztük lévő mikroklimatikus különbségeket vizsgálom numerikus szimulációk útján, különös tekintettel a nyári hőterhelés mérséklésére irányuló várostervezési beavatkozások eredményességére az egyes beépítési formák esetén. Az egyik ilyen beavatkozás az épülethomlokzatok albedójának növelése nagyobb sugárzás-visszaverő képességű anyagok, illetve festékek alkalmazása révén. Egy másik jellemző beavatkozás a zöldterületek részarányának növelése, melyet tanulmányomban a lombkorona borítás értékének változtatásával vizsgálok. A különféle beépítési formák, homlokzat albedók és korona borítottság értékek komplex hatásának feltárására az ENVI-met szimulációs software-t alkalmaztam. Az eredmények alapján elmondható, hogy a megnövekedett albedó következtében a napsugárzásnak kitett homlokzatok hőmérséklete – s ez által az épületek hőterhelése is – csökken. A visszavert sugárzási hányad megnövekedése azonban az épületek között sugárzás többletként jelenik meg, mely többlet a nem módosított albedójú felületek (utak, terek) nagyobb sugárzási terheléséhez és ezáltal a városi határréteg felmelegedéséhez vezet. Ezzel ellentétben, a korona borítottság növelése a városi határrétegben a rövidhullámú sugárzás és a léghőmérséklet csökkenését eredményezi. Mivel ezen tényezők hatása a lakosok komfortérzetét és az épületeket érő hőterhelést is előnyösen befolyásolja, a közterületek fásítása a nyári hőterhelés mérséklésére irányuló várostervezési beavatkozás egyik hatásos eszköze lehet.
|
|
| 8. |
- Gál, Csilla V, et al.
(författare)
-
Heat mitigation with shade trees : the role of landscape design and tree parameters in ameliorating summertime heat stress in a Central-European square
- 2017
-
Konferensbidrag (refereegranskat)abstract
- Climate change projections for Central Europe indicate a significant rise in summertime temperatures and an increase in the frequency and severity of extreme heat events. Combined with the peculiar climate of cities—characterized by the Urban Heat Island effect and reduced ventilation due to high building density—climate change is expected to have more pronounced effects in urban environments. Shade trees are demonstrated to be one of the most effective means to mitigate heat stress in cities. However, very few studies have evaluated systematically the impact of different landscape design and tree parameters (e.g. the species selection or the spatial distribution) on the heat mitigation effectiveness of shade trees. This study aims to assess the role of vegetation transmissivity, canopy size and tree distribution in a medium-sized Central-European square. The rectangular Bartók Square, located in the inner city of Szeged (Hungary), was selected as a study area. The numerical simulations were carried out with the radiation model SOLWEIG (v.2015a). The necessary meteorological data, collected on clear and warm summer day, was obtained from a nearby weather station run by the Hungarian Weather Service. The default model was built on the basis of available GIS data and utilized tree related parameters from detailed field measurements (tree location, canopy size and shape, etc.). Crown transmissivity data originated from a preliminary, long-term radiation measurement survey covering the vegetation period. Alternative scenarios were constructed with the following characteristics:1) keeping the original tree layout of the square, the initial tree crown transmissivity of 0.0678 was changed to small (0.0243) and high (0.1328) values;2) keeping the original canopy volume, two additional scenarios were introduced with evenly distributed trees of different crown sizes: that of several small trees and of fewer large ones;3) keeping the original canopy volume and using the same number and size of trees, we assessed the role of tree distribution by introducing a scenario were the trees were arranged along the bounding facades of the square—this scenario was compared to the evenly distributed configuration. In order to evaluate the impact of vegetation, all scenarios are reported in reference to a theoretical, nonvegetated square. Since several studies revealed that mean radiant temperature (Tmrt) plays a key role in summertime heat stress in the European context, this parameter was selected as performance indicator. Tmrt combines the heat effect of all short-and long-wave radiation fluxes reaching the human body. Our results indicate that when shade is provided for the facades only, the nighttime Tmrt surplus nearly disappears. However, while horizontal long-wave radiation fluxes have a greater impact on human thermal comfort due to the different absorption coefficients of the human body (0.7 vs. 0.95 for short and long-wave radiation, respectively), providing shade for the facades only is not a successful daytime heat mitigation strategy in open urban places. Comparing the influence of vegetation transmissivity revealed that low transmissivity species were able to reduce Tmrt by only 2C on average during the day. According to our case study, when transmissivity and canopy volume is kept constant, considerable mean radiant temperature reduction can be achieved by evenly distributed mature trees.
|
|
| 9. |
- Gál, Csilla V
(författare)
-
Mean radiant temperature modeling, A comparative model evaluation
- 2018
-
Konferensbidrag (refereegranskat)abstract
- As a result of the changing climate with trends of rising temperatures and increasing extreme heat events, urban planners and city officials have recently taken a great interest in improving the climate of cities and maintaining comfortable outdoor conditions in spite of these trends.In order to meet the demand for this special knowledge and to deliver scientific assistance, several numerical models have emerged with an aim to assess the microclimate of cities and their influence on human thermal comfort over the course of the past decade. While these tools differ both in the human thermal comfort indices they deliver and in their numerical modeling approach, they all rely on the calculation of mean radiant temperature—the driving parameter of outdoor human thermal comfort. While the assessment of models lags behind the perpetual software updates and releases, the documentation of many such models is also lacking or insufficient. In addition, a great deal of existing validation studies assess clear cut situations where the site is either sunlit or in shade, whereas conditions in the urban environment are generally more complex. Given both the growing importance the outdoor thermal environment of cities and the role played by these tools, reporting on their performance is of high importance.The aim of this study is to assess the ability of several recently emerged or updated microclimate models to reproduce mean radiant temperature (Tmrt) in a complex urban setting. The evaluation is made against field data obtained by integral radiation measurements. Results indicate that most microclimate models underestimate Tmrt both at sunlit locations and at night, whereas in shade Tmrt is generally overestimated. These errors are related to the surface temperature parametrization, the isotropic sky assumption, simplifications in the reflected shortwave radiation calculation and the incorrect representation of a standing person.
|
|
| 10. |
- Gál, Csilla V, et al.
(författare)
-
Mean radiant temperature modeling outdoors : A comparison of three approaches
- 2020
-
Konferensbidrag (refereegranskat)abstract
- As a result of both urbanization and climate change, the thermal environment of cities is deteriorating steadily. Thus, urban planner and city officials are increasingly under the pressure maintain livable environments in cities. The quickest and most economic means to assessing the performance of various urban heat mitigation strategies is via numerical modeling. Owing to these advantages, the approach gained popularity over the past decade, as well as resulted in the proliferation of microclimate models. The driving parameter of outdoor human thermal comfort is radiation, which is accounted for via mean radiant temperature (Tmrt). While this parameter is at the center of most outdoor thermal comfort indices, it is also rather challenging to measure and calculate. Along with the recent emergence of microclimate models, the ways of calculating outdoor Tmrt also multiplied. However, beyond individual model validations, very few studies have attempted to compare the performance of different models. Thus, the aim of this paper is to assess the performance of three microclimate models in estimating Tmrt in the urban environment. The reviewed models are VTUF-3D, the Grasshopper add-ons of Rhinoceros 3D and the latest ENVI-met version utilizing the Indexed View Sphere (IVS) algorithm. The adopted spatial resolution in each model were not identical. In the case of ENVI-met and VTUF-3D, 3 and 5 meter resolutions were used, respectively. The Grasshopper add-on was set to calculate surface temperatures at 6 m resolution and view factors (along with Tmrt) for a denser, 3-meter spatial grid. The model assessment utilized data from a 26-hours-long integral radiation measurement, conducted in Szeged (Hungary). The observations were undertaken along the four bounding facades of Bartók Square during a clear summer day in 2016. According to the preliminary results, ENVI-met performs the best when the observation sites are exposed to direct solar radiation. However, it underestimates Tmrt values by up to 10 ºC when the sites are in shade and during night. In general, both VTUF-3D and the Grasshopper add-on underestimate Tmrt values considerably during sunlit conditions (exceeding 20 ºC at times), but reproduce radiative conditions well at night (with errors remaining below 4 ºC). One reason for the above errors is the way Tmrt is calculate by these models. While Tmrt calculations differ in each model, at the core of their adopted approaches is a Tmrt estimation developed for indoor environments---which was later adopted to outdoors. One of the lingering simplification is the assumption of a seated posture and/or the conceptualization of the human body as a sphere. The other transferred simplification is the assumption of small temperature differences between the surrounding surfaces. These assumptions not only diminish the impact of horizontal fluxes, but also depict a less diverse radiative environment.
|
|
