Thesis (M.A.)--Rowan University, 2008. / Typescript. Includes bibliographical references.

Thesis (Ph. D. in Philosophy)--Vanderbilt University, May 2006. / Title from title screen. Includes bibliographical references.

Increases in temperature and precipitation predicted under global warming are expected to be most pronounced and thus have their greatest impact on ecosystems at high latitudes. Insects constitute a major component of the foodwebs of terrestrial ecosystems and should be among the first organisms to show noticeable responses to predicted global warming, especially in the Arctic where climatic conditions are often limiting. However, interactions among species must also be taken into account. The genus Gynaephora Hübner (Lepidoptera: Lymantriidae) is represented in North America by two species, G. groenlandica (Wocke) and G. rossii (Curtis), and their geographic distributions overlap broadly across the Canadian Arctic. Previous studies have examined the biology, ecology, and physiology of these two species and have revealed many adaptations to the Arctic environment, but the immature stages of these insects have been misidentified even in recently published reports. Both species are found at Alexandra Fiord, Ellesmere Island, a High Arctic oasis largely isolated by expanses of ocean and icecap, and the population of G. groenlandica at this site is thought to be limited mainly by parasitoid-induced mortality rather than by climatic conditions. Field observations, surveys, and temperature-manipulation experiments were conducted at Alexandra Fiord during the spring and summer of 1994, 1995, and 1996; laboratory rearing was conducted under controlled conditions at the University of Victoria in the spring of 1996 and 1997. Immature stages of both species of Gynaephora were described and illustrated, and all species of insect parasitoids using Gynaephora species as hosts at Alexandra Fiord were identified. Life histories and seasonal phenologies for Gynaephora species and their insect parasitoids were elucidated from field studies, and temperature/development relationships for selected stages of most of these species were derived from laboratory rearing. The results of field studies and laboratory rearing were compared and used to formulate predictions about the responses of these insects to predicted global warming. Immature stages of the two species of Gynaephora are easily distinguished by differences in the colour patterns, form, and overall length of the larval hairs and by the structure of their cocoons. Both species of Gynaephora complete metamorphosis and reproduction within a single growing season but spread larval development over a number of years. In G. groenlandica, seven larval instars and annual moulting combine to produce a seven year life cycle whereas G. rossii develops through six larval instars at a rate of two or three moults per year, resulting in a three or four year life cycle. The parasitoid complex at Alexandra Fiord consists of three primary parasitoids, Hyposoter pectinatus (Thomson) (Hymenoptera: Ichneumonidae), Exorista n.sp. (Diptera: Tachinidae), and Chetogena gelida (Coquillett) (Diptera: Tachinidae), and one hyperparasitoid, Cryptus leechi Mason (Hymenoptera: Ichneumonidae). All of the parasitoids are univoltine, although H. pectinatus may undergo delayed development in some cases, and each of the primary parasitoids relies primarily on a single larval instar for hosts whereas the hyperparasitoid attacks the primary parasitoids during their metamorphosis. Seasonal phenologies of the parasitoids provide optimal access to new hosts but parasitoid-avoidance strategies of Gynaephora larvae ensure that a proportion of their populations escape parasitism. Laboratory rearing showed that the relative timing of host and parasitoid seasonal phenologies is maintained over a broad range of temperatures; therefore, temperature increases predicted under global warming are unlikely to have any great effect on host-parasitoid interactions. However, increased cloudiness associated with the predicted increase in precipitation might have profound effects resulting from lower ground-level temperatures caused by a lack of solar heating. The extent of this effect is uncertain but might lead to reproductive failure in Gynaephora species, with similar repercussions for the insect parasitoids. / Graduate

No description available.

Some of the more significant effects of global warming are manifested in the rise of temperatures and the increased intensity of hurricanes. This study analyzed data on Annual, January and July temperatures in Miami in the period spanning from 1949 to 2011; as well as data on central pressure and radii of maximum winds of hurricanes from 1944 to present. Annual Average, Maximum and Minimum Temperatures were found to be increasing with time. Also July Average, Maximum and Minimum Temperatures were found to be increasing with time. On the other hand, no significant trend could be detected for January Average, Maximum and Minimum Temperatures. No significant trend was detected in the central pressures and radii of maximum winds of hurricanes, while the radii of maximum winds for the largest hurricane of the year showed an increasing trend.

<p>Increasing CO₂ concentrations in the Earth's atmosphere have led to global warming with climate change effects. Future RCP scenarios per the IPCC suggest that local solutions to limit emissions are necessary but may not suffice to combat the anthropogenic CO₂ problem. Climate intervention has been given increasing consideration. A climate intervention approach of removing CO₂ from the atmosphere through dry ice deposition and storage in Antarctica is considered. While the technology needs continued development, understanding the meteorological response to significant carbon dioxide removal (CDR) in Antarctica takes precedence. Various Antarctica CDR scenarios are simulated through the fully-coupled general circulation model CESM 2.1.1. Modern simulations (15 years) with prognostic CO₂ include 1) anthropogenic emissions (control), 2) no emissions, 3) emissions with ~4.5 ppmv sequestration annually (half sequestration), and 4) emissions with ~9 ppmv sequestration annually (full sequestration). Full sequestration attempts to remove enough CO₂ to achieve pre-industrial concentration by the end of the simulation. Experiments 1) and 3) were continued until mid-21st century (50 years total) with SSP1-2.6 conditions and emissions to examine the CDR impact on the atmosphere under the Paris Treaty Agreement scenario (which limits Earth's warming to 1.5^oC-2^oC above pre-industrial values). </p> <p> Modern simulations show sequestration scenarios have more of an impact on 2m-air temperature and little effect on precipitation patterns in 15 years. SSP1-2.6 simulations show that an additional 1^oC of warming can be inhibited by continuing sequestration and limiting emissions. Further, sequestration shows counteraction to warming in many of the locations that are predicted to warm per the RCP 2.6 scenario in the IPCC (2013), as well as counteraction to the predicted IPCC precipitation changes. These results are obtained from one simulation of each experiment, and it is recognized that ensemble runs in line with IPCC predictions are necessary to examine all possible predictions to CDR. Future considerations include sea level rise, carbon cycle response, convective parameters, and relocation of sequestration.<a></a></p>

<p> Juvenile rainbow trout (Oncorhynchus myldss) were chronically exposed (90 days) in synthetically softened water ([Ca2+]=50, [Na+]=100 J.tequiv·L-1), to sublethal low pH (5.2) and a simulated global warming scenario (+20C), added to the natural summer thermal cycle ofinshore Lake Ontario. Two studies were conducted over the periods June September 1993 and 1994 in order to examine the effects ofthe sublethal stressors under conditions ofunlimited food ration (satiation feeding twice daily= 10% dry body weight·day-1), and a limited food ration (4% dry body weight·day-1) respectively. The addition of 2°C and sulphuric acid was designed to result in four treatment conditions: i) Control conditions; ambient water temperature and pH; ii) ambient water temperature and pH 5.2; iii) simulated global warming at ambient pH; iv) a combination of simulated global warming and pH 5.2. Year to year variation in temperature provided the trout in the satiation-fed study with an ambient ~peraturerange of 13-24°C, while those in the limited ration study experienced a range of 16.5-21°C. Consequently, the trout in the treatments with an additional 2°C experienced temperatures close to the upper incipient lethal level, particularly the trout in the satiation feeding study. Apparent specific dynamic action raised routine metabolic rates in all treatments to -75% and 55% M02(max) in the satiation and limited ration studies respectively, the difference of 20% indicating the influence of an unlimited feeding regime on metabolism. Trout in the satiation feeding study increased in wet body mass by 30-50 g, while trout in the limited ration study increased by only 3-4 g. Whole body proximate composition of the trout fed to satiation changed over time with large increases in lipid content, small increases in protein content, and compensating decreases in water content in all treatments. No such changes occurred in the limited ration trout, although whole body lipid and carbohydrate were highly variable. In both studies, the addition of20C resulted in decreased growth, with an accompanying depression in appetite in the satiation fed trout, especially at peak temperatures. Surprisingly, trout exposed to low pH alone exhibited improved growth in both treatments. Energy budgets indicated that the addition of 2°C reduced gross energy intake and increased fecal (and Ulllidentified) energy losses resulting in lowered conversion efficiencies, while in limited ration trout, energy expenditure was slightly higher. Trout exposed to low pH exhibited higher gross energy intake and gain, and more efficient energy conversion under unlimited food conditions while trout with limited rations expended the least metabolic energy and exhibited lower nitrogen energy losses. The surprising lack of ionoregulatory disturbance in these pH 5.2 exposed trout in both studies suggests tbat the availability of NaCl in the diet was compensating for branchial ion losses, and perhaps driving appetite in the satiation fed trout Where ration was limited, reductions in activity level may have contributed to energy conservation and consequently improved growth. A 22Na+ flux experiment conducted at the end of the limited ration exposure, in which the fish were exposed to a challenge concentration of H+ (pH 4.2), provided evidence for improved recovery of ionoregulatory balance in trout which had been chronically exposed to low pH. Overall, the combination ofincreased global temperatures and sublethal low pH results in increased physiological costs for juvenile rainbow trout, most noticeably when summer temperatures peak. Ration level is of integral importance when considering the degree of impact of such environmental conditions. </p> / Thesis / Master of Science (MSc)

No description available.

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: There is increasing evidence that the rapid and anomalous changes in climate experienced in the last century have had widespread ecological impacts. Indeed, sub- Antarctic Marion Island has experienced particularly large increases in temperature and declines in rainfall. However, the effects of these changes on the island's extensive fellfield vegetation remain largely unexamined. The aim of this study was to examine the sensitivity of a dominant and keystone fellfield plant species, the cushion-forming Azorella selago Hook. (Apiaceae), to changes in climate. Three complementary approaches (two mensurate, one experimental) were used, and all showed that A. selago is likely to change in response to further changes in climate. First, the unimodal age class distribution of A. selago suggested that the species' establishment is episodic, and therefore reliant on specific (possibly climatic) conditions. Azorella selago growth rate was related to environmental factors, suggesting that both the establishment and growth rate of the species is likely to be sensitive to changes in climate. Second, altitudinal variation in A. selago plant attributes suggested that the species' morphology would be responsive to changes in climate (assuming that a spatial gradient in climate is a suitable analogue for similar changes in climate over time). Plant height, leaf size and trichome density differed most consistently over altitude across the island. The altitudinal range of some epiphyte species, as well as the cover and species richness of epiphytes growing on A. selago, also showed consistent patterns along the altitudinal gradient. These cushion plant and epiphyte attributes appeared to be related to climatic factors, and are therefore predicted to change in response to further shifts in climate. Finally, A. selago showed a rapid vegetative response to short-term experimental reductions in rainfall and increases in temperature and shading. Reduced rainfall accelerated autumnal senescence, shortening the species' growing season. Plants were relatively unaffected by the magnitude of warming imposed, although the foliar nutrient concentrations of some elements were higher in warmed plants than in control plants. Experimental shading of A. selago (simulating a predicted indirect effect of climate change: increased cover of the dominant epiphyte species, Agrostis magellanica (Lam.) Vahl (Poaceae)) caused greater stem elongation, and the production of larger, thinner leaves, with lower trichome densities and higher foliar nutrient concentrations of some elements. Given this sensitivity of A. selago to shading, it is possible that changes in epiphyte load could overshadow the direct effects of changes in climate on this species. Ongoing changes in climate are predicted for the next century. Based on the results of this study the following scenarios are proposed. Continued warming and drying of the island will potentially favour the upslope expansion of A. selago (although also shortening its growing season) and decrease the abundance of its dominant epiphyte. Under such a scenario fellfield primary production may decline. In contrast, under warming alone, most epiphyte species could increase in abundance and expand their altitudinal ranges upslope. This would bring about much heavier shading of A. selago plants, leading to a short-term increase in stem growth and leaf nutrient concentrations. However, ultimately a decline in A. selago abundance and production would also be expected if cushion plants experience stem mortality under longer-term shading. Nonetheless, monitoring A. selago leaf size, trichome density and phenology, as well as the altitudinal range of dominant epiphyte species (attributes that this research suggests may be most sensitive to short-term changes in climate), will indicate the biological consequences of these changes in climate. This study, therefore, shows that further climate changes on Marion Island will affect A. selago and its epiphytes, with likely repercussions for fellfield communities. / AFRIKAANSE OPSOMMING: Daar is toemende bewys dat die vinnige en onreëlmatige veranderinge in klimaat oor die laaste half-eeu wye ekologiese gevolge gehad het. Inderdaad, sub-Antarktiese Marion Eiland het 'n ook 'n besondere groot toename in temperature en daling in reënval ervaar. Nogtans is die gevolge van hierdie veranderinge op die eiland se uitgebreide dorveld (fellfield) plantegroei nog nie nagevors nie. Die doel van hierdie studie was om die sensitiwiteit van 'n dominante hoeksteen spesie, die kussingvormige Azorella selago Hook. (Apiaceae), aan veranderinge in klimaat te ondersoek. Drie aanvullende metodes (twee waarnemend, een eksperimenteel) was gebruik, en al drie het aangedui dat A. selago waarskynlik sal reageer op verdere veranderinge in klimaat. Eerstens, die enkelpiek-vormige ouderdomsverspreiding van A. selago dui daarop dat die spesie ongereeld vestig, en is daarom afhanklik van spesifieke (dalk klimatiese) toestande. Verder, was A. selago se groeitempo aan omgewingsfaktore verwant. As gevolg hiervan sal die spesie se vestiging en groeitempo vermoedelik sensitief vir klimaatsveranderinge wees. Tweedens, veranderinge in A. selago eienskappe met 'n toename in hoogte bo seespieël (hoogte) dui daarop dat die spesie se morfologie sal reageer op veranderinge in klimaatstoestande (op voorwaarde dat 'n ruimtelike verandering in klimaat goed ooreenstem met 'n soortgelyke verandering in klimaat oor tyd). Planthoogte, blaaroppervlakte en trigoomdigteid het geleidelik met hoogte verander oor die eiland. Die verspreiding en bedekking van sommige epifitiese spesies, asook epifiet spesie rykheid, was ook aan hoogteverwant. Hierdie verwantskap tussen A. selago (en die epifiete) en hoogte is vermoedelik deur klimatiese faktore veroorsaak, en daarom word voorspel dat dit sal verander soos die klimaat verander. Laastens, het A. selago 'n vinnige vegetatiewe reaksie tot korttermyn eksperimentele vermindering in reënval en toename in temperatuur en beskaduwing gewys. 'n Afname in reënval het blaarveroudering versnel, en dus A. selago se groeiseisoen verkort. Plante het min verander as gevolg van hoër temperature, alhoewel die konsentrasie van sommige plantvoedingstowwe hoër was in blare van verwarmde plante as in die wat gewone temperature ervaar het. Eksperimentele beskaduwing van A. selago (wat 'n verwagde indirek effek van klimaatsverandering naboots, naamlik die toename in bedekking van A. selago deur die dominante epifiet spesie, Agrostis magellanica (Lam.) Vahl (Poaceae)) het stingel groei versnel, en veroorsaak dat groter en dunner blare met laer trigoomdigthede en hoër konsentrasies van sommige plantvoedingstowwe op die plante groei. As gevolg van die sensitiwiteit van A. selago op beskaduwing, is dit moontlik dat die gevolge van veranderinge in die bedekking van epifiete belangriker sal wees as die direkte gevolge van klimaatsverandering. Verdere klimaatsveranderinge word vir die volgende eeu voorspel. Gebasseer op die resultate van hierdie navorsing, word twee moontlike toekomstige omstadighede voorgestel. Toenemende verwarming en verdroging van die eiland sal vermoedelik veroorsaak dat A. selago op hoër hoogtes voorkom (alhoewel die spesie se groeiseisoen ook sal verkort), en dat die volopheid van A. magellanica sal afneem. In so 'n geval sal dorveld se plantproduksie waarskynlik effens verminder. In teenstelling, as die eiland slegs verwarm (sonder 'n verandering in reënval) kan die volopheid en verspreiding van epifiet spesies waarskynlik toeneem. Dit sal vermoedelik tot 'n toename in the verskaduwing van A. selago lei, wat tot 'n kort-termyn verhoging van stingel groeitempo en plantvoedingstof konsentrasies sal lei. Alhoewel, uiteindelik, word 'n vermindering van A. selago volopheid en groei verwag as plantstingels van lang-termyn beskaduwing vrek. Nietemin, as die blaargroote, trigoomdigteid en groeiseisoenlengte van A. selago en die hoogte verspreiding van die dominante epifiet spesie gemonitor word (eienskappe wat deur hierdie studie aangedui is as gevoelig aan kort-termyn veranderinge in klimaat), kan die biologiese gevolge van hierdie klimaatsveranderinge aangewys word. Hierdie navorsing bewys dus dat verdere veranderinge in klimaat op Marion Eiland 'n invloed sal hê op A. selago en geassosieerde epifiete, met moontlike gevolge vir die hele dorveld gemeenskap.

National Geographic is a magazine that inspires people to care about the planet through its articles of exploration, education, and conservation. Magazines are a significant source of knowledge and compete with a variety of other media, constantly rethinking where they can improve in comparison to other media. Research in this dissertation shows that some magazines offer high quality imagery for artwork, photos and advertisements, which remains critical for industries and readers. They often offer greater depth than radio, TV, or even newspapers, so that people interested in an analysis of news and events still depend on magazines for informative and general news. People often turn to media—such as television, newspapers, magazines, radio, and Internet—to help them make sense of the many complexities relating to environmental science and governance that (un)consciously shape our lives. Global warming, as a subject, demands both political and personal responses in all parts of the world, and effective decision making at both scales depends on timely, accurate information, according to Shanahan (2009:145). The quality and quantity of journalism about climate change will therefore be key in the coming years. National Geographic comprises a variety of themes, such as environment, science, wildlife, travel and photography. This study is an analysis of the writing and photography related to one theme - global warming. It provides a critical analysis of the coverage of the global warming discourse in one magazine, examined over an eleven-year period from 2000 to 2010. This theme is powerful in that it represents ethical responsibility and concern for nature and our world and the analysis attempts to define the objects of discourse within the coverage, thus, evaluating if the format of the coverage informs and educates the audience about global warming.