Sedimentation and ocean warming are two major anthropogenic stressors that directly affect coral recruitment and recovery. Many coral-dominated reefs have undergone phase shifts becoming macroalgae-dominated because of the coral population’s inability to tolerate these increasing stressors. Predicting these phase shifts requires a determination of the relative susceptibility of coral and macroalgae to these stressors. The objective of this study was to quantitatively assess the synergistic effects of sedimentation and elevated temperature on the survival and growth of Montastraea cavernosa newly settled coral juveniles, and fragments of the macroalgae, Dictyota ciliolata. A crossed experimental design tested the two temperatures and four sedimentation levels. After 12 weeks, a 2°C increase in temperature did not significantly affect survival of the M. cavernosa juveniles or fragments of D. ciliolata. Montastraea cavernosa juvenile survival was negatively affected by a decrease in sediment. Dictyota ciliolata survival was highly sensitive to the increase in sedimentation. The survival and growth of both species appeared to be susceptible to an increase in sedimentation, but in opposite ways. This study demonstrates that both M. cavernosa juveniles and D. ciliolata fragments may be more vulnerable to light caused by changes in turbidity rather than temperature.

Magister Legum - LLM / The methods of energy use and production in South Africa are currently unsustainable, and have dire environmental and health impacts. This is largely due to fossil fuel based energy generation and use. Currently 89% of energy generated in South Africa is derived from fossil fuels including coal, oil and gas. This figure is likely to increase in the near future with the construction of new coal-fired electricity generation and coal/gas to liquid fuels stations. South Africa has an abundance of both non-renewable and renewable energy resources.Renewable energy technologies will be key in the battle to reduce carbon and greenhouse gas (GHG) emissions, as they do not produce the large amounts of carbon and GHG emissions that conventional fossil-fuel based methods do. Renewable energy, as the name indicates, can be considered an infinite reserve. Most renewable energy is generated from solar power it can be relied upon as long as the sun keeps shining. Energy efficiency as well as improvements in technologies relating to energy generation can play a significant role in reducing carbon and GHG emissions. For example, the 'Basa njengo Magogo' method used to ignite coal in coal-fired power stations makes use of a 'top-down ignition process' which reduces smoke emissions by 80-90 percent, heats up quicker and uses less coal than the conventional method. The barriers to the implementation of sustainable and renewable energy measures are: the relatively cheap cost of coal based energy, due to the abundance of the resource in South Africa, as well as the uncoordinated nature of legislation dealing with energy, and the implementation of sustainable energy practices. However the means and resources do exist for South Africa to reduce its carbon and GHG emissions and reliance on carbon based energy. Therefore this paper will examine the legislative and international obligations government has to sustainable and renewable energy and what policies have been developed to give effect to these obligations. Section 24 of the Constitution explicitly recognises the obligation to promote justifiable 'economic and social development', which is essential to the well-being of human beings. Development both social and economic require energy, however South Africa's energy is derived mainly from fossil fuels, which when used have a significant detrimental effect on the environment.

Ocean warming near the Antarctic ice shelves has critical implications for future ice sheet mass loss and global sea level rise. A global climate model with an eddying ocean is used to quantify the mechanisms contributing to ocean warming on the Antarctic continental shelf in an idealized 2xCO(2) experiment. The results indicate that relatively large warm anomalies occur both in the upper 100 m and at depths above the shelf floor, which are controlled by different mechanisms. The near-surface ocean warming is primarily a response to enhanced onshore advective heat transport across the shelf break. The deep shelf warming is initiated by onshore intrusions of relatively warm Circumpolar Deep Water (CDW), in density classes that access the shelf, as well as the reduction of the vertical mixing of heat. CO2-induced shelf freshening influences both warming mechanisms. The shelf freshening slows vertical mixing by limiting gravitational instabilities and the upward diffusion of heat associated with CDW, resulting in the buildup of heat at depth. Meanwhile, freshening near the shelf break enhances the lateral density gradient of the Antarctic Slope Front (ASF) and disconnect isopycnals between the shelf and CDW, making cross-ASF heat exchange more difficult. However, at several locations along the ASF, the cross-ASF heat transport is less inhibited and heat can move onshore. Once onshore, lateral and vertical heat advection work to disperse the heat anomalies across the shelf region. Understanding the inhomogeneous Antarctic shelf warming will lead to better projections of future ice sheet mass loss.

The ongoing climate warming is expected to increase thermokarst activity and their impacts by inducing permafrost degradation and active layer deepening. A retrogressive thaw slump, which represents the most dynamic thermokarst landform, was investigated in the Richardson Mountains-Peel Plateau region. The exposed material at the thaw slump represents an opportunity to characterize the cryostratigraphy of the uppermost 5 m of permafrost. Analyses of the stratigraphy, sedimentology, isotope geochemistry and radiocarbon dating is presented. Six sites were also identified on an elevation-vegetation gradient to provide complementary data on thaw layer thickness. Summer air temperatures, vegetation cover type, mesoscale conditions modifying the snowpack, timing of the snow accumulation and winter air temperature inversions are identified as the main drivers of thaw layer thickness in the region. The physical and chemical parameters of the massive ground ice exposed at the thaw slump are characteristic of buried glacier ice that experienced water infiltration and partial refreezing. The layer between the massive ground ice units and the thaw layer in the thaw slump is identified as a relict thaw layer and represents the period of maximum active layer deepening. It dates to the Holocene thermal maximum, which represents a period of important thermokarst activity that resulted in widespread paleo-thaw unconformities across northwestern Canada. Association of the region’s thaw slump activity with paleoclimatic parameters provide indication that the combination of formerly glaciated continuous permafrost, hummocky rolling moraine terrain, stream-incised relief, and massive ground ice, coupled with major rainfall events, represents a set of condition that is favourable to thaw slump activity.

As ocean temperatures continue to rise, the effect of temperature on marine organisms becomes highly relevant. The Red Sea is the warmest sea and is rapidly warming with current surface temperatures (28 – 34 °C) already exceeding those of most tropical systems. This has major consequences for organisms that may already find themselves at their thermal limits. The aim of this project was to define the thermal limits and thresholds of certain Red Sea species. Firstly, to better understand the thermal regimes of the Red Sea, we looked at decadal trends in maximum sea surface temperature across the basin. Then, we tested the thermal capacities of Red Sea mangroves and zooplankton, two key ecological groups, by performing thermal stress experiments in the laboratory. We found that the Red Sea basin is warming faster than the global average (0.17 °C decade-1), the thermal limit of mangrove propagules is between 33 and 35 °C, and the limits among the most common zooplankton groups range from 30 to 36 °C. This project gives us a better understanding of how organisms respond to extreme temperatures and how they may be affected in a future, warmer, ocean.

Thesis advisor: Jeremy D. Shakun / Glaciers in the tropics have retreated over recent decades, but whether the magnitude of this retreat has exceeded the bounds of past Holocene fluctuations is unclear. In this study, we measure cosmogenic 10Be and 14C concentrations from recently exposed bedrock at the margin of five glaciers in the tropical Andes, including four small glaciers and the Quelccaya Ice Cap, the world’s largest tropical ice mass. Concentrations at the Quelccaya Ice Cap margin suggest there was extended exposure during the first half of the Holocene, but that the site was covered by ice for the last 5 kyr. In contrast, nuclide concentrations are strikingly low in all samples at the margins of the four small glaciers, equivalent to ~200 years of 14C and 50 years of 10Be accumulation at surface production rates. These data suggest that the small tropical glaciers are now smaller than they have been at any point during the Holocene, whereas the Quelccaya Ice Cap has not yet retreated to its smallest extent of the Holocene, likely due to its larger size and slower response time. / Thesis (MS) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

In most previous studies that have been conducted on converting waste heat energy from exhaust gases into useful energy, the engine waste heat recovery system has been placed along the exhaust flow pipe where the temperature differs from the temperature just behind the exhaust valves. This means that an important fraction of the energy from the exhaust gases is still lost to the environment. The present work investigates the potential thermodynamic analysis of an integrated exhaust waste heat recovery (EWHR) system based on a Rankine cycle on an engine's exhaust manifold. The amount of lost energy contained in the exhaust gases at the exhaust manifold level, at average temperatures of 500 °C and 350 °C (for petrol and diesel), and the thermodynamic composition of these gases were determined. For heat to occur, a temperature difference (between the exhaust gas and the working fluid) at the pinch point of 20°C was considered. A thermodynamic analysis was performed on different configurations of EWHR thermal efficiencies and the selected suitable working fluids. The environmental and economic aspects of the integrated EWHR system just behind the exhaust valves of an internal combustion engine (ICE) were analysed. Among all working fluids that were used when the thermodynamic analysis was performed, water was selected as the best working fluid due to its higher thermal efficiency, availability, low cost and environmentally friendly characteristics. Using the typical engine data, results showed that almost 29.54% of exhaust waste heat can be converted. This results in better engine efficiency and fuel consumption on a global scale by gaining an average of 1 114.98 Mb and 1 126.63 Mb of petrol and diesel respectively from 2020 to 2040. It can combat global warming by recovering 56.78 1 011 MJ and 64.65 1 011 MJ of heat rejected from petrol and diesel engines, respectively. A case study of a Volkswagen Citi Golf 1.3i is considered, as it is a popular vehicle in South Africa. This idea can be applied to new-design hybrid vehicles that can use the waste heat to charge the batteries when the engine operates on fossil fuel. / Dissertation (MSc)--University of Pretoria, 2016. / Mechanical and Aeronautical Engineering / MSc / Unrestricted

The energy industry is facing serious pressure to reduce carbon dioxide emissions. The purpose of this study was to investigate if there is a statistically significant correlation between certain institutional factors and type of environmental strategy employed by companies in the energy industry. The academic foundation upon which strategy was studied is Institutional Theory. Institutional theory is embedded in the school of sociology and prescribes that behaviour is a function of social norms and routines. At the organisational level, this translates to a high degree of interdependency between organisations and the environment which they operate in. The institutional factors selected for analysis in this study were economic growth, gross domestic product per capita, unemployment, poverty, income inequality, human development index, and national competitiveness. The environmental strategy of energy companies was categorised in two broad measures namely; carbon dioxide reduction and carbon independence. The study has found that there is no significant correlation between any of the institutional factors and combination of carbon reduction and independence strategies. However, an important finding is that the statistical significance of the bi-variate regression analysis increased considerably when national competitiveness was used as an explanatory variable of strategy.From this, it is concluded that it is critical to understand which institutional factors are expected to be determinants of strategy in the energy industry. More importantly, it is concluded that as energy is a primary requirement for national competitiveness, strategy in the energy industry is determined by a combination of factors and not just a single variable. This is an important distinction which must be clear in the mind of both policy makers and business leaders in the energy industry especially those who are seeking to expand into new markets. Copyright / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

This thesis concerns the causes and consequences of magma emplacement in the Earth’slithosphere during the formation of Large Igneous Provinces (LIPs) and continental rifts. Motivated by geological, geophysical, geochemical and paleoclimate data, I formulate geodynamic models to address the following questions: (1) How were the massive volumes of subaerially erupted lava, described in multi-channel seismic data as seaward-dipping reflectors (SDRs), formed and what can SDRs tell us about the rifting processes? (2) What thermal and rheological conditions are required to produce the contrast in topography of the two youngest LIPs: namely that the Columbia Plateau sits ~0.7 km lower than the surrounding region while the Ethiopian Plateau is ~1.5 km higher than its surroundings? (3) Why does significant global warming occur a few hundred-thousand years prior to the main phase of eruptions of the Columbia River Basalts and the Deccan Traps? The major results of my thesis are: (1) The first two-dimensional thermo-mechanical treatment of SDR formation shows how the lithosphere thickness affects the deformation in response to magmatic loads during volcanic margin formation. I provide a quantitative mapping between the shape of SDRs and the strength of the lithosphere and this mapping reveals weak continental margin lithosphere during the initial continental breakup. (2) Cold and strong crust results in slow lower crustal flow and a persistent high plateau like the Ethiopian Plateau. In contrast, a combination of three things can produce a low plateau like the Columbia Plateau. First, hot and weak lower crust flows fast in response to topographic and magmatic loads. Second, a significant fraction of the magma intruded in the crust freezes onto and becomes part of the strong upper crust. Finally, the bulk of the intrusions occur before the main phase of extrusion to explain the geometry of the Columbia River Basalt lava flows. (3) I argue that the major eruptions of continental flood basalts may require densification of the crust by intrusion of larger volumes of magma than are extruded. Simple models show that magma crystallization and release of CO² from such intrusions could produce global warming before the main phase of flood basalt eruptions on the observed timescale.

Climate change is causing water temperature to rise, and many lakes in the boreal zone will experience browning of waters (brownification) due to increased input of dissolved organic carbon (DOC). In fish, warming may cause resource limitation and decrease both fish size and population abundance. Many fish species display ontogenetic niche shifts during their lifetime, shifting to larger prey as they grow. Brownification may change the timing for, the benefits from or prevent individuals from displaying ontogenetic niche shifts by decreasing large prey abundance in the benthic zone or making fast-moving prey harder to see. This can cause resource limitations, suppressing growth and population growth. This study investigated the effects of increasing DOC and water temperature on ontogenetic diet shifts, size structure, and population abundance in nine-spine stickleback (Pungitius pungitius) in an experimental pond system with a warming treatment and a gradient of DOC concentration. Warming had a negative effect on population number, biomass, maximum fish size, stomach fullness, and consumption of large prey. Contrary to expected outcomes, increasing DOC input resulted in higher population, biomass, and larger maximum sized fish as DOC increased. DOC did not negatively affect ontogenetic diet shifts. In the relatively shallow enclosures, the highest DOC concentration may not have reached the threshold where the shading effect of DOC overturns the benefits of extra nutrients associated with DOC. Hence, in shallow lake ecosystems, climate change induced DOC increase may support fish production, while warming may have strong negative effects on fish population abundance and size.