This thesis consists of five papers. Paper [1] analyzes one possible way of replacing dynamic Pigouvian taxes by a static approximation of such taxes from the point of view of social accounting. The idea is to approximate a Pigouvian emission tax by using the instantaneous marginal willingness to pay to reduce the stock of pollution. If this approximation is close enough to the correct Pigouvian tax it will be useful for at least two reasons: (i) it brings the economy close to the socially optimal solution; and (ii) it provides information relevant for social accounting by closely approximating the value of additions to the stock of pollution. Paper [2] analyzes the welfare effects of an agreement between countries to slightly increase their emission taxes. The results indicate that such an agreement need not necessarily increase the global welfare level, even if each individual country has set its prereform emission tax to be lower than the marginal social cost of pollution. Paper [3] provides an economic framework for analyzing the global warming problem, emphasizing the use of forests as a means of carbon sequestration. We explore the difference between the decentralized economy and the socially optimal resource allocation, and discuss the appropriate tax system required to implement the first best optimum. Paper [4] incorporates the uncertainty involved in the production of nuclear energy into a dynamic general equilibrium growth model. We compare the resource allocation in the decentralized economy with the socially optimal resource allocation and design the dynamic Pigouvian taxes that make the decentralized economy reproduce the socially optimal resource allocation. Paper [5] treats externalities from nuclear power in a dynamic differential game framework involving two countries, which differ with regard to their nuclear technology. The model is solved numerically, where one country is considered relatively safe and the other relatively less safe. / <p>Härtill 5 delarbeten.</p> / digitalisering@umu

As the third most important greenhouse gas, nitrous oxide (N2O) is a stable greenhouse gas and also plays a significant role in stratospheric ozone destruction. The primary anthropogenic source of N2O stems from the use of nitrogen in agriculture, with soils being the major contributors. Currently, the annual N2O emissions from this “soil–microbe-plant” system is more than 2.6 Tg (one Tg equals a million metric tons) of N2O-N globally. My doctoral studies aimed to explore innovative strategies for N2O mitigation, in the context of environmental microbiology’s potential contribution to alleviating global warming. The bacterial enzyme nitrous oxide reductase (N2OR), naturally found in some soils, is the only known enzyme capable of catalyzing the final step of the denitrification pathway, conversion of N2O to N2. Therefore, to “scrub” or reduce N2O emissions, bacterial N2OR was heterologously expressed inside the leaves and roots of transgenic plants. Others had previously shown that the functional assembly of the catalytic centres (CuZ) of N2OR is lacking when only nosZ is expressed in other bacterial hosts. There, coexpression of nosZ with nosD, nosF and nosY was found to be necessary for production of the catalytically active holoenzyme. I have generated transgenic tobacco plants expressing the nosZ gene, as well as tobacco plants in which the other four nos genes were coexpressed. More than 100 transgenic tobacco lines, expressing nosZ and nosFLZDY under the control of rolD promoter and d35S promoter, have been analyzed by PCR, RT-PCR and Western blot. The activity of N2OR expressed in transgenic plants, analyzed with the methyl viologen-linked enzyme assay, showed detectable N2O reducing activity. The N2O-reducing patterns observed were similar to that of the positive control purified bacterial N2OR. The data indicated that expressing bacterial N2OR heterologously in plants, without the expression of the accessory Nos proteins, could convert N2O into inert N2. This suggests that atmospheric phytoremediation of N2O by plants harbouring N2OR could be invaluable in efforts to reduce emissions from crop production fields.

The importance of utilizing different types of energy and their technical application is discussed. Awareness around the globe about the world energy crisis and its critical environmental condition has put more emphasis on the use of renewable energies in every corner of life. It is a well‐known fact that global warming, inefficient use of energy and greenhouse gases are damaging the environment, species and human life drastically. These issues will be discussed in recently conducted research. To address the crucial state of our environment, two simultaneous scenarios are considered. Initially, energy conservation and the switch to a low carbon/no carbon fuel are studied. As for energy conservation in buildings, smart methods in the use of energy in buildings are discussed. Based on different research reported, humans must change their attitude toward the use of resources, and in particular, be conscientious about energy consumption. Next, renewable energy promises a suitable alternative to energy needs in this century, and the best means to overcome the environmental issue and energy crisis is discussed. The practical methods of calculation for solar technology equipment, ground source heat pumps, and wind turbines are explained. In the application part of the study, four buildings are chosen as case studies; two of them from residential sectors, one is a commercial/institutional building, and the fourth is an industrial building. A ground source heat pump for heating and cooling, a solar water heater for heating space or hot water, and a photovoltaic panel for generating electricity are designed for the case studies. Even projects under hybrid systems combined from two technologies are designed. 36 different energy options are calculated for the four case studies. Results show that if a target is reducing CO2 emissions, what systems are the best. In contrast, when decision making is based on budget, what system is the first choice? Not only are technology, environmental protection and cost the main parameters for deciding on renewable technologies, but so are reliability, installation, maintenance and ease of use. Hence, renewable energy systems are categorized based on a broad vision.

Non-indigenous species can profoundly alter the ecosystems they invade and impact local economies. Growth and body condition declines of commercially fished Great Lakes lake whitefish coincide with the establishment of non-native dreissenid mussels and the cladoceran Bythotrephes longimanus. Declines in lake herring abundance—a key prey item for other commercially important species—have also been reported. Though additional stressors such as climate change may have contributed to changes in coregonid populations, they have not been thoroughly evaluated. Here, I present data that condition and contaminant declines in coregonids are associated with increasing density or warming climate, but growth declines in lake whitefish are likely due to ecosystem changes associated with dreissenids and Bythotrephes. In South Bay, Lake Huron, changes in lake whitefish diet composition and stable isotope signatures were consistent with increased reliance on nearshore resources after dreissenid establishment; lake whitefish occupied shallower habitats and experienced declines in mean diet energy densities post-dreissenid invasion. Growth of South Bay lake whitefish declined after environmental effects were statistically removed, whereas condition declines were explained best by changes in lake whitefish density. Among four lake whitefish populations, growth declined after dreissenids established, but not in uninvaded reference populations. Growth also declined among four lake whitefish populations after the establishment of Bythotrephes relative to reference populations. In contrast with growth, condition of lake whitefish did not change as a result of dreissenid or Bythotrephes invasion. Bioenergetic models revealed that activity rates increased and conversion efficiencies decreased in lake whitefish populations exposed to dreissenids, despite higher consumption rates in populations with dreissenids present. Condition declines among many lake whitefish and lake herring populations (and declines in mercury among herring populations) reflected regional differences and were not related to the presence of Bythotrephes or Mysis relicta. Declines in condition were more pronounced in northwest Ontario populations where climate has changed more dramatically than in southern Ontario. This work suggests that projected range expansions of dreissenid mussels and Bythotrephes will likely affect native fisheries, and their effect on these fisheries may be exacerbated by declining fish condition associated with climate change.

Non-indigenous species can profoundly alter the ecosystems they invade and impact local economies. Growth and body condition declines of commercially fished Great Lakes lake whitefish coincide with the establishment of non-native dreissenid mussels and the cladoceran Bythotrephes longimanus. Declines in lake herring abundance—a key prey item for other commercially important species—have also been reported. Though additional stressors such as climate change may have contributed to changes in coregonid populations, they have not been thoroughly evaluated. Here, I present data that condition and contaminant declines in coregonids are associated with increasing density or warming climate, but growth declines in lake whitefish are likely due to ecosystem changes associated with dreissenids and Bythotrephes. In South Bay, Lake Huron, changes in lake whitefish diet composition and stable isotope signatures were consistent with increased reliance on nearshore resources after dreissenid establishment; lake whitefish occupied shallower habitats and experienced declines in mean diet energy densities post-dreissenid invasion. Growth of South Bay lake whitefish declined after environmental effects were statistically removed, whereas condition declines were explained best by changes in lake whitefish density. Among four lake whitefish populations, growth declined after dreissenids established, but not in uninvaded reference populations. Growth also declined among four lake whitefish populations after the establishment of Bythotrephes relative to reference populations. In contrast with growth, condition of lake whitefish did not change as a result of dreissenid or Bythotrephes invasion. Bioenergetic models revealed that activity rates increased and conversion efficiencies decreased in lake whitefish populations exposed to dreissenids, despite higher consumption rates in populations with dreissenids present. Condition declines among many lake whitefish and lake herring populations (and declines in mercury among herring populations) reflected regional differences and were not related to the presence of Bythotrephes or Mysis relicta. Declines in condition were more pronounced in northwest Ontario populations where climate has changed more dramatically than in southern Ontario. This work suggests that projected range expansions of dreissenid mussels and Bythotrephes will likely affect native fisheries, and their effect on these fisheries may be exacerbated by declining fish condition associated with climate change.

As the third most important greenhouse gas, nitrous oxide (N2O) is a stable greenhouse gas and also plays a significant role in stratospheric ozone destruction. The primary anthropogenic source of N2O stems from the use of nitrogen in agriculture, with soils being the major contributors. Currently, the annual N2O emissions from this “soil–microbe-plant” system is more than 2.6 Tg (one Tg equals a million metric tons) of N2O-N globally. My doctoral studies aimed to explore innovative strategies for N2O mitigation, in the context of environmental microbiology’s potential contribution to alleviating global warming. The bacterial enzyme nitrous oxide reductase (N2OR), naturally found in some soils, is the only known enzyme capable of catalyzing the final step of the denitrification pathway, conversion of N2O to N2. Therefore, to “scrub” or reduce N2O emissions, bacterial N2OR was heterologously expressed inside the leaves and roots of transgenic plants. Others had previously shown that the functional assembly of the catalytic centres (CuZ) of N2OR is lacking when only nosZ is expressed in other bacterial hosts. There, coexpression of nosZ with nosD, nosF and nosY was found to be necessary for production of the catalytically active holoenzyme. I have generated transgenic tobacco plants expressing the nosZ gene, as well as tobacco plants in which the other four nos genes were coexpressed. More than 100 transgenic tobacco lines, expressing nosZ and nosFLZDY under the control of rolD promoter and d35S promoter, have been analyzed by PCR, RT-PCR and Western blot. The activity of N2OR expressed in transgenic plants, analyzed with the methyl viologen-linked enzyme assay, showed detectable N2O reducing activity. The N2O-reducing patterns observed were similar to that of the positive control purified bacterial N2OR. The data indicated that expressing bacterial N2OR heterologously in plants, without the expression of the accessory Nos proteins, could convert N2O into inert N2. This suggests that atmospheric phytoremediation of N2O by plants harbouring N2OR could be invaluable in efforts to reduce emissions from crop production fields.

Är det möjligt att reducera utsläppen av växthusgaser och samtidigt nå en hållbar utveckling? Regionförbundet i Kalmar län antog utmaningen 2006 och är därmed en föregångsregion i arbetet med detta. Till år 2030 är målet att Kalmar län ska bli en fossilbränslefri region. Den största potentialen anses finnas inom nya alternativ till fordonsbränsle. Hushållens sopor innehåller organiskt matavfall som skulle kunna bli fordonsgas. Allt fler biogasmackar öppnas och gasen har vunnit framgång i takt med att kollektivtrafiken gjort satsningar. I Oskarshamns kommun sker i dagsläget ingen utsortering av organiskt matavfall. Hushållsavfallet skickas tillsammans med det organiska matavfallet till förbränning med energiutvinning i Linköping. Syftet med min studie är att göra en utvärdering av miljöpåverkan utifrån två scenarier; förbränning av allt hushållavfall jämfört med att producera biogas av matavfallet och förbränna resterande. Detta sett utifrån potentialen för området i Oskarshamns kommun. Syftet är även att titta på ekonomiska aspekter. Detta är en livscykelanalys där två metoder har använts, Global Warming Potential med ett 100 års perspektiv samt ReCiPe Endpoint. Den funktionella enheten är 1 ton hushållsavfall. Genom att röta det organiska hushållsavfallet och förbränna det övriga kan man minska miljöpåverkan till 74,6 % jämfört med att förbränna allt tillsammans. Växthusgaserna minskar då med 780 kg koldioxidekvivalenter per ton hushållsavfall. Den främsta miljövinsten blir i form av minskande klimatförändringar men att det fordrar ganska omfattande ekonomiska investeringar. / Is it possible to reduce greenhouse gas emissions while achieving sustainable development? The Regional Council in Kalmar County accepted the challenge in 2006 and is thus a leading region in this work. By 2030, the goal is that Kalmar shall become a fossil fuel free region. The greatest potential is considered to be the new alternative to vehicle fuel. Household waste includes organic waste that could become fuel for vehicles. An increasing number of biogas stations have opened and the gas has been successful as the public transports have made investments. In Oskarshamn is there no current sorting of organic waste. Household waste is sent along with the organic food waste to incineration with energy recovery in Linköping. The purpose of my study is to evaluate the environmental impact based on two scenarios: the burning of all household waste compared to producing biogas from food waste and burn the remaining. This is seen by the potential of the area in Oskarshamn. Also examining the economic perspective there is. This is a LCA where two methods were used, the Global Warming Potential with a 100-year perspective and ReCiPe Endpoint. The functional unit is 1 ton of waste. By digesting the organic waste and burning the rest, one can reduce the environmental impact to 74, 6 % compared to burning it all. The greenhouse gases then will decrease by 780 kg carbon dioxide equivalent per ton household waste. The main environmental benefits are in terms of reducing climate change, but it requires quite a significant financial investment

Global climate change (GCC) may be the most pressing social and environmental issue of our time. The use of fossil fuels tops the list of human behaviors that contribute to GCC. Several ‘alternative’ energy sources are now being considered in an effort to mitigate GCC, including—controversially—nuclear energy. Examined here were environmental worldview and faith in science as moderators of the relationship between beliefs about and attitudes toward nuclear energy (ATNE). Participants were 272 college students who completed an on-line survey. Predictor variables were beliefs about whether nuclear energy contributes to GCC (GCC-beliefs) and to energy independence (EI-beliefs). Results indicated that environmental worldview moderated the negative relationship between GCC-beliefs and ATNE. Results implied that the effectiveness of arguments salient to the current nuclear energy debate concerning GCC have a medium effect on ATNE except when people are more ecocentric in their environmental worldviews.

The most devastating effects of climate change may be avoided if humans reduce activities that produce greenhouse gases and engage instead in more sustainable ecological behaviors. The current mixed methods study of 279 undergraduate students explored whether environmental worldview, belief in climate change, knowledge of climate change, personal efficacy, and intention to address climate change influenced participants’ engagement in ecological behavior. Results indicated that those with a stronger intention to address climate change and a more ecocentric worldview reported significantly more ecological behavior. Next, the study examined whether participants’ intentions to address climate change mediated the relationship between their belief in climate change and engagement in ecological behavior and whether intentions mediated the relationship between efficacy and ecological behavior. Intentions to address climate change did not mediate the relationship between belief and ecological behavior but fully mediated the relationship between efficacy to address climate change and ecological behavior.

Arktis är den plats där den globala uppvärmningen är som mest märkbar på hela jorden (Arktiska rådet). Därför är Arktis ett intressant område att studera ur klimatsynpunkt. Enligt Gore (2006) så kan en ökning av jordens medeltemperatur på 1,5 °C leda till att de ekvatoriala områdena får en temperaturökning på 0,5 °C medan temperaturen vid Arktis kan stiga med hela 6 °C. De senaste 30 åren har medeltemperaturen vid Arktis stigit med drygt en grad per decennium (Anisimov, 2007) medan den globala medeltemperaturen för samma period endast stigit med ca 0.15 grader per decennium. Arktis tros ha varit isfritt under en värmeperiod för ca 6000 – 8500 år sedan (Founder, 2011) men det som är unikt med den aktuella situationen är att avsmältningen går så snabbt. Mycket snabbare än naturliga cykler (Gore, 2006) och det råder inom forskarvärlden ingen tvekan om att det är de antropogena utsläppen av växthusgaser som är orsaken. Frågeställningen som ligger till grund för den här rapporten är att ta reda på vilket årtal som Arktis kommer att vara isfritt. Detta görs genom att undersöka hur den Arktiska isutsträckningen minskat under perioden 1979-2011.  Isdata till beräkningarna i den här rapporten är tagna från National Snow and Ice Data Center, Boulder, Colorado USA, och värdena för temperaturerna kommer från National Aeronautics and Space Administration (NASA). Genom att med minstakvadratanpassning göra en linjär approximation av varje års minsta värde av isutsträckningen vid Arktis för perioden 1979-2011 erhålls att Arktis kommer att vara isfritt år 2062. / The Arctic is the place where global warming is most significant in the whole world (Arctic Council). That is why the Arctic is an interesting area to study from a climate perspective. According to Gore (2006), an increase in global temperature of 1.5 °C might lead to an increase of 0.5 °C in the equatorial regions while the Arctic could receive a teperature rise by as much as 6 °C . During the past 30 years, average temperatures in the Arctic have risen by more then one degree per decade (Anisimov, 2007) while the global average teperature for the same period only increased by about 0.15 degrees per decade. Arctic is believed to have been ice-free during a heating period for about 6000 - 8500 years ago (Founder, 2011) but what is unique about the current situation is that the melting is so quickly. Much faster than natural cycles (Gore, 2006) and there is within the scientific community no doubt that the anthropogenic emissions of greenhouse gases is the cause. The issue which forms the basis for this report has been to investigate how the Arctic extent decreased over the period 1979-2011 and then to attempt to determine a year for when the Arctic will be ice free. Ice data to the calculations in this report are taken from the National Snow and Ice Data Center, Boulder, Colorado USA, and the temperature values comes from the National Aeronautics and Space Administration (NASA). By making a linear approximation with the least square method of each year’s minimum value of the Arctic sea ice extent for the period 1979-2011 it is obtained that the Arctic sea will be ice free by the year of 2062.