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Mechanisms and their Consequences in a Changing World Alexandra Komissarova Abstract Many migratory species are responding to climate change by altering their migration behaviour, however, we know relatively little about the mechanisms by which such changes are accomplished. One way in which climate change could be influencing migration strategies is through its effect on habitat and territory quality. I tested several hypotheses of different mechanisms by which three aspects of territory quality could affect migration decisions in a partially migrant bird, the robin (Erithacus rubecula). I also used a theoretical individual-based modelling approach to investigate the interaction between migration and dispersal strategies within a population and examined its underlying mechanisms. Migration decisions were not significantly affected by summer territory quality, as measured by breeding success and summer vegetation structure. Winter territory quality was, however, found to be a good predictor of migration behaviour, with aspects of winter vegetation such as ground cover appearing particularly important. However, this effect of winter vegetation structure on migration decisions appeared to be largely due to its correlation with food availability. Migration decisions were strongly affected by winter food availability, with provisioning of food greatly increasing the numbers of resident individuals. The results of the theoretical model showed a that high rates of dispersal within a population reduced the average proportion of migrants, with the effect strongly influenced by dispersal cost and to a lesser extent, kin selection. I hope that this work will ultimately improve our ability to predict species’ responses to climate change by adding to our understanding of the mechanisms behind migration decisions, while also providing a more holistic view of migration by placing it in the context of other life history decisions.

This thesis explores the role of terrestrial vegetation in the global climate system in a series of modelling studies using the University of Victoria Earth System Climate Model (UVic ESCM). The ways that vegetation affects climate, as well as the feedbacks that operate between changing climate and vegetation distributions, are investigated within the framework of three foci: 1) historical land cover changes that have resulted from human modification of natural vegetation cover; 2) historical land cover change and the dynamics of terrestrial vegetation in the context of anthropogenic and natural climate change; and 3) the role of terrestrial vegetation in the global carbon cycle. First, the radiative effect of changing human land-use patterns on the climate of the past 300 years is discussed through analysis of a series of equilibrium and transient climate simulations using the UVic ESCM. These experiments highlight the biogeophysical effects of historical land cover change on climate: those that result from physical changes to the land surface under altered vegetation cover. Results show a global cooling in the range of -0.06 to -0.22 "C, though this effect is not found to be detectable in observed temperature trends. Using a global carbon cycle the climatic effects of land cover change emissions (the biogeochemical effect of historical land cover change) are assessed. The resultant warming is found to exceed the biogeophysical cooling by 0.15 "C. Second, the effect of historical land cover change is compared with the effects of natural forcings (volcanic aerosols, solar insolation variability and orbital changes) and other anthropogenic forcings (greenhouse gases and sulphate aerosols). Transient model runs from the year 1700 to 2000 are presented for each forcing individually as well as for combinations of forcings. I find that the UVic model reproduces well the global temperature data when all forcings are included. In the context of these anthropogenic and natural climate influences, the response of vegetation distributions to changing climate is explored through the use of a dynamic global vegetation model coupled interactively to the UVic ESCM. Transient simulations of the past 300 years are repeated using this new model so as to isolate the biogeophysical feedbacks that operate between vegetation and climate. Dynamic vegetation is found to act as a positive feedback to climate, amplifying both warming and cooling climate trends. Third, the development of a global carbon cycle model allows for investigation of the role of terrestrial carbon cycle dynamics under past and future climate change. When forced by historical emissions of C02 from fossil fuels and land-use change, the coupled carbon cycle model accurately reproduces historical atmospheric C02 trends, as well as terrestrial and oceanic uptake for the past two decades. Under six 21St century C02 emissions scenarios, both terrestrial and oceanic carbon sinks continue to increase, though terrestrial uptake slows in the latter half of the century. The modelled positive feedback between the carbon cycle and climate is relatively small, resulting in an increase in simulated C02 of 60 ppmv at the year 2100. Including non- C02 greenhouse gas forcing and increasing the model's climate sensitivity increases the effect of this feedback to 140 ppmv. The UVic model does not, however, simulate a switch from a terrestrial carbon sink to a source during the 2lSt century, as earlier studies have suggested. This can be explained by a lack of substantial reductions in simulated vegetation productivity due to climate changes.

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Fundamental to an understanding of El Niño/Southern Oscillation climate fluctuations is an understanding of the interannual equatorial Pacific surface flows, which advect the surface waters and change the sea surface temperature. While some knowledge of the observed interannual flows has already been obtained, some key features are still not fully understood. Using the long records of satellite altimeter data, together with long in situ records of current, salinity and temperature from the TAO/TRITON array in the equatorial Pacific, the observed interannual surface flows, their dynamics and link to the El Niño Prediction can be understood better. In the first half of the thesis, I used theoretical arguments and a wind-forced ocean model to understand why the equatorial eastern Pacific flow leads sea level, eastern equatorial thermocline displacement and El Niño indices. This half of the thesis is based on the result that for large zonal scales and low frequencies, wind-forced sea level, even near the equator, can be described by wind-forced long Rossby waves. In the eastern equatorial Pacific where the interannual wind forcing is small, these waves are essentially locally unforced and propagate westward from the boundary. At the boundary the wave’s sea level is in phase because of geostrophy and no normal flow to the boundary. However, because the waves propagate more slowly with increasing latitude, west of the boundary lag increases as latitude increases. Consequently a northward sea level gradient is like a time derivative, and the zonal geostrophic flow is like a time derivative of the sea level. This implies that the equatorial flow should lead the equatorial sea level by about 9 months on El Niño time scales. Analysis shows that when dissipation of the large-scale flow is taken into account, this lead is reduced to about 3 months. This lead time is approximately the dissipation time scale of the second vertical mode, which dominates the zonal surface flow. Since the eastern equatorial Pacific sea level is proportional to eastern equatorial thermocline displacement and El Niño, the zonal equatorial flow leads El Niño indices. Analysis further shows that the zonally-averaged equatorial Pacific sea level leads El Niño, and that this lead is associated with the geostrophic zonal velocity and the long Rossby wave physics in the eastern equatorial Pacific. The second part of this work addresses the influence of the heavy precipitation on the Western equatorial Pacific Ocean. Surface and subsurface salinity and temperature measurements at 137oE, 147oE, and 156oE since the late 1990s from the western equatorial Pacific TRITON moored array indicate that the large interannual sea surface salinity (SSS) fluctuations there change little with depth over the top 50 m of the water column. Beneath this surface layer the SSS signal decreases, and is usually much smaller at about 100 m depth. The isothermal layer depth (ILD) ranges from about 50–70 m and estimates of dynamic height relative to the ILD indicate a near-surface salinity-driven contribution to the monthly sea level anomaly that is uncorrelated with, and smaller than, interannual sea surface height (SSH) estimated from altimeter data. Despite the smaller size of , its meridional gradient dominates the total sea level meridional gradient and thus the corresponding shallow equatorially-trapped interannual fresh water jet dominates the near-surface zonal interannual flow. This jet-like flow has a meridional scale of only about 2–3o of latitude, an amplitude of 23cm/s, and is associated with the zonal back and forth displacement of the western equatorial warm/fresh pool that is fundamental to El Niño. The jet is not forced by the interannual fresh water surface flux but rather by wind stress anomalies that are mostly east of the warm/fresh pool edge during La Niña and mostly west of it during El Niño. / A Dissertation submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2017. / March 9, 2017. / El Nino Prediction, Equatorial Pacific Currents, Oceanography Dynamics, Physical Meteorology and Climatology, Rossby waves, Salinity / Includes bibliographical references. / Allan J. Clarke, Professor Directing Dissertation; Christopher Tam, University Representative; Mark A. Bourassa, Committee Member; William Dewar, Committee Member; William M. Landing, Committee Member.

Critical political economic methods are used in this study to examine climate change editorials published by prestige press newspapers in the United States between the years 2014 to 2017. This includes exploring elements of corporate ownership for each newspaper of interest, editorial sourcing practices and ideological messages perpetuated within global warming editorial coverage. Political economic methods are utilized due to their ability to expose how neoliberal social, political, and economic values shape the tone and substance of editorial content available for mainstream news consumption. The history behind the pro-capitalist agenda of mainstream news media in the United States is reviewed to contextualize how this study is rooted in the methods of a historical, political economic approach. This paper specifically recalls shifts in financial and political power within the news industry beginning in the 1850s while supplementing this information with the corporate histories of each newspaper utilized in the analysis. The three newspapers analyzed in this study include the New York Times, USA Today, and the Wall Street Journal. This thesis was conducted utilizing the search terms “global warming” and “climate change” on ProQuest historical newspaper database. After filtering for results from the desired publications, the editorial content was textually analyzed to examine ownership influence over climate change editorials through an analysis of sourcing patterns and ideologies perpetuated within editorial news content. This study’s results found that while each newspaper of interest showed varying degrees of support for climate change prevention efforts and belief in climate science evidence, all three publications were similar in their unwavering support for pro-market policies as solutions for climate change-related issues. Furthermore, each newspaper examined had a history of close collaborative efforts between ownership and editorial board staff. These cooperative relationships become potential conflicts of interest when understood in the context of modern day newspaper ownership – primarily with regard to the increased investment in newspaper companies by non-news related business entities. Given that all three newspaper companies analyzed in this study have investors directly engaged with the oil and gas industries, climate change coverage in particular can be seen as a potentially risky action that could have a negative impact on corporate profitability. In this context, each newspaper’s affinity for pro-market ideology and sources sympathetic to capitalism can be understood as a consequence of political economic interests that subtly influence the range of available discourses within mainstream news media. / A Thesis submitted to the School of Communication in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2018. / April 19, 2018. / Climate Change, Critical Political Economy, Editorials, Journalism, Neoliberalism, Political Economy of Journalism / Includes bibliographical references. / Jennifer Proffitt, Professor Directing Thesis; Russell Clayton, Committee Member; Andy Opel, Committee Member.

Florida has a high frequency of tornadoes that occur throughout the United States. Together, Florida's large population and expensive property, provides a great risk for injuries, fatalities, and damage to structures for when a tornado occurs. This risk of death or damage continues to increase as the population expands. The goal of this research is to better understand the tornado hazard in Florida by creating a climatology of Florida tornadoes through examining occurrence rates, casualties, and property loss. The tornado reports are obtained from the Storm Prediction Center's Severe Weather database. Descriptive statistics are used to analyze temporal distributions, characteristics, and geographical distributions of tornadoes. Tropical cyclone tornado data from 1995 through 2013 is used for examining temporal distributions throughout the state. In addition, a new property value dataset put together by Georgianna Strode at the Florida Resources and Environmental Analysis Center is used to evaluate property loss from tornadoes throughout the state. Inferential statistics are used for testing hypotheses and modeling future tornado paths using a Monte Carlo simulation. Over the period from 1987 though 2016, there were 1,765 tornado reports in the state. The peak frequency occurs during the month of June with the overall tornado distribution mimicking the tropical cyclone distribution of the North Atlantic hurricane season. Majority of tornadoes occur in the peninsular region of the state, with tornadoes in the panhandle likely being stronger. There is a strong positive correlation between the amount of property exposed and the number of casualties produced by tornadoes. Although the majority of tornadoes that occur throughout Florida are very weak, the path length and width are shown to be increasing in recent years. Additionally, the annual average property loss estimate from tornadoes in Florida is $53 Million. Results of the Monte Carlo simulation indicate a 5% chance that the annual loss will exceed $203 million, a 1% chance that it will exceed $430 million, and a 0.1% chance that it will exceed $1 billion. / A Thesis submitted to the Department of Geography in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2018. / April 6, 2018. / Casualties, Climatology, Florida, Occurrence rates, Property Losses, Tornado / Includes bibliographical references. / James B. Elsner, Professor Directing Thesis; David C. Folch, Committee Member; Mark W. Horner, Committee Member.

It has been hypothesized that local or global climatic conditions can affect societies in a variety of ways. However, to date, it has been difficult to measure the social impact of climate, so the scale and scope of its influence on populations remains mostly theoretical. This dissertation integrates data and quantitative methods from climate science, economics and political science to develop new techniques for empirically measuring the the social impacts of climate. These techniques are used to measure large-scale dynamical relationships between climatological conditions and the response of the societies that are exposed to them. In general, the response of societies to climatological forcing is found to be larger than previously thought. The concluding chapter discusses how these findings may inform policies that govern the global environment and economic development.