The effect of global warming on methane (CH₄) and nitrous oxide (N₂O) emissions from agriculture was investigated and simulated from a soil warming experiment. Experiments were designed and installed in a temperature controlled greenhouse. The relationships between elevated temperatures and CH₄ and N₂O emissions were determined and calculated as the Q₁₀s of production, emission and oxidation. A study of the populations of methanogens and methanotrophs at a range of soil temperatures was performed based on soil molecular DNA analysis. This study showed that global warming would increase CH₄ emissions from rice agriculture and that the resultant emissions will be potentially large enough to cause changes in the present atmospheric concentrations. This research also showed that this increase was most evident for soil temperatures below 30⁰C, above which emissions decreased with increasing temperature. The seasonal average Q₁₀s of CH₄ emission, production, oxidation, methanogen and methanotroph populations were found to be 1.7, 2.6 and 2.2, 2.6 and 3.8, respectively, over a temperature of 20-32⁰C. Considering that the processes of CH₄ production and emission are similar to those in natural wetlands, which is the largest source of atmospheric CH₄, the contribution of this feedback is likely to cause a significant increase to the present CH₄ atmospheric budget if the current global warming trend persists over the next century. The Q₁₀s of N₂O emissions and production were 0.5-3.3 and 0.4-2.9, respectively. The low Q₁₀ values found for N₂O suggest that although global warming will have a direct impact on the production and emission rates. Nevertheless, the magnitude of the impact of global on both CH₄ and N₂O emissions from agriculture is likely to vary from one region to another due to the spatial variations in agricultural soil temperatures and the likely changes in the global regional distribution of water resources (water tables, rainfall patterns), water management practices and the responses of terrestrial CH₄ and N₂O sources such as natural wetlands and plants.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21426号 / 農博第2304号 / 学位論文||H30||N5154(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 縄田 栄治, 教授 舟川 晋也, 教授 白岩 立彦 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

No description available.

Evidence continues to mount regarding the impact of climate change on the ecosystems of the world with increasingly dire predictions about the need for global action to slow warming and its downstream effects. Human beings are not immune to changes in their environment. Growing research demonstrates the impact of climate change on cardiovascular, pulmonary, psychiatric, neurologic and renal diseases, as well as its disruption of overall health through malnutrition, infectious disease, and pregnancy and developmental complications. Stress is known to precipitate, worsen, and maintain chronic disease. Social and community factors are known to impact individual and community mental health. The psychological stress of loss of goods, identity, and social support through weather events brought about by climate change has the potential to worsen the health and wellbeing of populations. Climate change does not impact communities equally. Populations historically and currently disadvantaged by inequitable policies may live in environments more at-risk to natural disaster, and have access to fewer financial, governmental, social, and healthcare resources to respond to climate events. Limitation of individual and community ability to respond to stressors reduces resilience and perpetuates chronic stress. The aim of this thesis is to examine the intersection of mental health and climate change with a particular focus on how social injustice has shaped the capability of populations, particularly those in urban settings, to respond to environmental changes with Philadelphia as a particular example. / Urban Bioethics

No description available.

The framing of news stories is found to be changing throughout time. This thesis advances a quantitative, longitudinal content analysis to examine the news coverage on climate change in five different countries over a period of ten years. Applying Chyi and McCombs two-dimensional measurement scheme, this thesis finds that the international frame was the most deployed spatial frame, while the present frame was the most used temporal frame. The political action, environmental risk and science frames, in their own regard, were the most deployed topical frames. Centrally, the analysis showed that the environmental risked frame is increasingly superseded by the science frame. This suggests that scientific considerations have become increasingly important in climate change journalism. Additionally, a higher climatological vulnerability of a country does not appear to translate to a risk focused framing of news articles. Moreover, the analysis finds that the societal spatial frame is increasingly used, pointing to emphasised national considerations in climate change journalism. Finally, the data of the thesis supports the emergence of a previously unconsidered climate action frame.

Greenhouse gases (GHGs) emissions due to human activities have considerably increased in the past decades which are the main contributors of global warming. In order to limit the consequences of the global climate change happening, all sectors must reduce their carbon emissions and especially the building industry which represents 19% of the carbon footprint of human activities. This paper is giving methods to help reduce the carbon footprint of a building when designing it such as life cycle assessment which allow project teams to compare the global warming potential of all building materials. Those methods are used and challenged in a case study of an architectural competition project named quai d’Issy in Paris, France. Using biobased materials help reduce the carbon footprint of a building, a structure made of timber and concrete elements can emit less than 21% of GHGs than a classic concrete structure. By sourcing reused and recycled building materials, by using geothermal heat pump as heating and cooling systems for example, we have been able to reach for the quai d’Issy project a carbon footprint of 930kgC02eq/m2 of floor area, which is less than level needed for the highest French environmental certification. However, these results can be obtained only if the building materials companies continue their work to develop low-carbon materials and promote recycled and reused materials. This study emphasises the need to spread knowledge of the tools to design low-carbon building to all the actors of the building industry in order to promote behaviours that will limit the consequences of climate change.

A worldwide shift from fossil fuels to zero carbon energy sources is imperative to limit global warming to 1.5°C. While integrating high penetrations of VRE into the grid may introduce the need for upgrading an aging electrical system, renewable energy represents a new opportunity to decarbonize multiple sectors. Otherwise curtailed solar and wind energy can accelerate deep decarbonization in hard-to-reach sectors - transportation, industrial, residential, and commercial buildings, all of which must be decarbonized to limit global warming. With renewable energy as its input, electrolytic H₂ represents a solution to the supply-demand mismatch created by the proliferation of VREs on a grid designed for on-demand power. Electrolytic H₂ can stabilize the grid since the H2 created can be stored and transferred. Thus, Chapter 1 introduces the opportunity of green H2 in the context of low-cost VREs as a means of deep decarbonization through sector coupling, and an overview of the techno-economics, key technologies, and life cycle assessment versus the incumbent steam methane reformation. The growing imbalances between electricity demand and supply from VREs create increasingly large swings in electricity prices. Capable of operating with variable input power and high current densities without prohibitively large ohmic losses, polymer electrolyte membrane (PEM) electrolyzers are well suited to VREs. In Chapter 2, polymer electrolyte membrane (PEM) electrolyzers are shown to help buffer against these supply demand imbalances, while simultaneously minimizing the levelized cost of hydrogen (LCOH) by ramping up production of H2 through high-current-density operation when low-cost electricity is abundant, and ramping down current density to operate efficiently when electricity prices are high. A techno-economic model is introduced that optimizes current density profiles for dynamically operated electrolyzers, while accounting for the potential of increased degradation rates, to minimize LCOH for any given time-of-use (TOU) electricity pricing. This model is used to predict LCOH from different methods of operating a PEM electrolyzer for historical and projected electricity prices in California and Texas, which were chosen due to their high penetration of VREs. Results reveal that dynamic operation could enable reductions in LCOH ranging from 2% to 63% for historical 2020 pricing and 1% to 53% for projected 2030 pricing. Moreover, high-current-density operation above 2.5 A cm−2 is shown to be increasingly justified at electricity prices below $0.03 kWh−1. These findings suggest an actionable means of lowering LCOH and guide PEM electrolyzer development toward devices that can operate efficiently at a range of current densities. Chapter 3 uses techno-economic modeling to analyze the benefits of producing green (zero carbon) hydrogen through dynamically operated PEM electrolyzers connected to off-grid VREs. Dynamic electrolyzer operation is considered for current densities between 0 to 6 A cm-2 and compared to operating a PEM electrolyzer at a constant current density of 2 A cm-2. The analysis was carried out for different combinations of VRE to electrolysis (VRE:E) capacity ratios and compositions of wind and solar electricity in 4 locations – Ludlow, California, Dalhart, Texas, Calvin, North Dakota, and Maple Falls, Washington. For optimal VRE:E and wind:PV capacity ratios, dynamic operation of the PEM electrolyzer was found to reduce the LCOH by 5% to 9%, while increasing H₂ production by 134% to 173%, and decreasing excess (i.e. curtailed) electrical power by 82% to 95% compared to constant current density operation. Under dynamic electrolyzer operation, the minimum LCOH is achieved at higher VRE:E capacity ratios than constant current density operation and a VRE mix that was more skewed to whichever VRE source with the higher capacity factor at a given location. In addition, dynamically operated electrolyzers are found to achieve LCOH values within 10% of the minimum LCOH over a significantly wider range of VRE:E capacity ratios and VRE mixes than constant electrolyzers. As demonstrated, the techno-economic framework described herein may be used to determine the optimal VRE:E capacity and VRE mix for dynamically-operated green hydrogen systems that minimize cost and maximize the amount of H2 produced. Chapter 4 focuses on the production of high-purity water and H₂ from seawater. Current electrolyzers require deionized water so they need to be coupled with desalination units. This study shows that such coupling is cost-effective in H₂ generation, and offers benefits to thermal desalination, which can utilize waste heat from electrolysis. Furthermore, it is shown that such coupling can be optimized when electrolyzers operate at high current density, using low-cost solar and/or wind electricity, as such operation increases both H₂ production and heat generation. Results of techno-economic modeling of PEM electrolyzers define thresholds of electricity pricing, current density, and operating temperature that make clean electrolytic hydrogen cost-competitive with H₂ from steam methane reforming. By using 2020 hourly electricity pricing in California and Texas, H₂ is shown to be produced from seawater in coupled desalination-electrolyzer systems at prices near $2, reaching cost parity with SMR-produced H₂. Chapter 5 concludes the dissertation with an overview of the challenges and research needs for PEM electrolyzers at scale, including projected iridium needs, iridium thrifting, recycling methods, key degradation mechanisms, a failure modes and effects analysis, and LCOH projections.

Global warming is a serious threat to the existence of human life on earth. Greenhouse gas emission is the major cause of global warming. Carbon dioxide is the major greenhouse gas emitted due to human activity. Road transport accounts for 15% of CO2 emissions worldwide. There are many initiatives adopted worldwide to minimize the emission of CO2 due to road transportation. Vehicle engines are upgraded to make it environment friendly, electric vehicles are promoted, public transport is promoted, etc. Apart from these, proper road network planning could also reduce emissions. It is not practical to completely replace the road transport system due to its importance in the transport of passengers and goods. This thesis is focused on finding ideal road conditions, that produce minimum CO2 emissions. The road network parameters that are studied in this thesis are speed limit, the number of vehicle lanes, and junction design. Due to time constraints, it is not feasible to do this study on a real road network. Hence, a simple artificial road network is created using a traffic simulator named SUMO for analysis. Both traffic congestion and the higher speed of the vehicles cause higher emissions. Roads are heavily interconnected in cities and road parameters of the adjacent roads should be adjusted together with the road being studied, to have an impact on the overall traffic. As adjacent road networks are too many numbers in cities, it is not feasible to validate every possible option. There is no algorithm invented so far to analyze such problems having too many possible states. However, there are optimization algorithms that can determine approximate solutions for such problems. In this thesis, I compared the performance of five nature-inspired metaheuristic algorithms on the sustainable road network problem. The five algorithms studied in this study are Particle Swarm Optimization, Genetic Algorithm, Artificial Bee Colony, Differential Evolution, and Harmony Search. The differential evolution algorithm generated the best result and was able to reduce the emissions by 6% and it is followed by genetic algorithms. Statistical tests are performed to evaluate whether the differences are significant or not.

The potential impact of carbon dioxide as a major source of global warming has led to extensive research in order to mitigate the greenhouse effect. In this work, four adsorbents were synthesized and studied. The adsorbents were obtained by grafting and sol-gel of amino-containing molecules such as bis[3-(trimethoxysilyl)propyl]amine as monoamine and [3-(2-aminoethylamino)propyl]- trimethoxysilane as diamine on the surface of silica gel. CO2 passed through adsorbents at room temperature for its capture, then desorbed at moderate heating, and stored in the form of insoluble BaCO3. The adsorbent synthesized by sol-gel synthesis was found to be more efficient due to its high content of amino groups. A demonstration experiment on reversible adsorption of CO2 on mesoporous modified silica gel was developed. This experiment visualizes a technology of post-combustion CO2 sequestration from industrial emission gases and its storage.