Tree-ring analyses have contributed significantly to investigations of climate change and climate cycles, including the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO) and El Niño/Southern Oscillation (ENSO). Stable isotope climate proxies (?18O, ?D, and ?13C) have enhanced traditional ring-width data, although poor preservation of ancient wood has generally constrained reconstruction of stable isotope proxy records to the Holocene and Late Pleistocene. An opportunity to apply these stable isotope methods to older wood has been presented by recovery of remains of Mixed-Coniferous Boreal Vegetation, in Early Pliocene (4-5 Ma) deposits at Strathcona Fiord, Ellesmere Island, Canada (~79°N). An exceptionally well-preserved tree trunk, identified as Larix (larch) through wood anatomical characteristics, from this high Arctic site provided a 203-year tree-ring record, from which we present the first high-resolution, secular isotope record of Pliocene climate. ?18O, ?D, and ?13C isotope values indicate a variable climate with alternating intervals of cool/wet to warm/dry weather. These fluctuations in climate may be attributable to phase changes in climate cycles observed in the record. A growing season mean temperature of 14.4 °C was calculated from isotopic analysis of gastropod shells. Palaeoclimatic modeling of tree isotope values has revealed growing season temperatures of 11-15 °C, and estimated isotope values of precipitation of 18.3 (?18O) and 228 (?D). Both palaeotemperature estimates and source water calculations are comparable to those found in a modern Boreal Forest. Time-series wavelet analysis was applied to these data revealing prominent short (<10 years), intermediate (16-35 years) and long-term (~45-50 years) cyclicity. These are the highest resolution climate cycles recovered from the pre-Holocene terrestrial record, providing evidence for decadal scale cyclicity similar to the NAO and/or PDO 4-5 million years ago.

Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments. <p>Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments.

Since the end of World War II, through the mandates of Prime Ministers Pierre Trudeau, Brian Mulroney, Jean Chrétien, Paul Martin and Stephen Harper, the Canadian government has found itself in conflict with the US Administration over the question of Arctic sovereignty. This situation is particularly difficult because of the power imbalance between the two countries. Thus, how Canada deals with the US is critical.<p> John Kirton identifies five ways in which Canada manages its differences with the US on foreign policy issues. The first is the process of ad hoc adjustment and problem-solving on individual issues. A second way is by pursuing solutions that achieve integration and cooperation. The third strategy consists of building defences and taking initiatives to reduce Canadas vulnerability to the US. The fourth strategy involves the deliberate influencing of the US domestic policy process in order to create policy that is more advantageous to Canadians.<p> In the fifth strategy, Canada aligns itself with others in the international community, building coalitions that can match the power and strength of the US; but more importantly, it establishes a place for Canada to lead the discussion and pursue its own interests. John Holmes believed that Canadian foreign policy was best served by multilateralism, as Canada often found it difficult to further its own interests within a bilateral framework. Kirton takes Holmes argument one step further by observing that by playing a leadership role in the multilateral arena on specific issues, Canada can help find global solutions that advance Canadian interests.<p> This thesis uses Kirtons analytical framework to examine the strategies that Canada has employed in dealing with conflicts with the US over the Arctic. It examines the Trudeau, Mulroney, Chrétien, Martin and Harper governments and finds a common thread in their approaches. While showing that each one adopted a number of the strategies identified by Kirton, the thesis draws particular attention to their common utilization of the fifth strategy of working with others to reshape the international or global communitys perspective on Arctic issues in the pursuit of Canadian interests.

The Canadian Arctic is facing new international challenges as global warming melts Arctic ice, opening up new shipping routes and access to untapped, potentially rich resources. As it has in the past, Canada is turning to defense spending to help strengthen its sovereignty in the region. Sovereignty is a multi-dimensional concept which requires a state to demonstrate control over its territory and its citizens. Developing Arctic energy resources is one pathway for Canada to achieve greater control in the region and strengthen its sovereignty claim. This thesis considers realist and liberal policy approaches to the development of Canadas Arctic energy resources. In the past, Canada has used both approaches to encourage the development of its Arctic energy reserves. From the 1950s to the early 1970s Canada relied solely on private companies to explore and produce Arctic resources. Between 1975 and 1984 Canada took a more interventionist approach. In 1975, Petro-Canada was created to help stimulate the development of Arctic resources. One of Petro-Canadas primary goals was to act as a catalyst for private energy companies operating in the Arctic.<p> This thesis seeks to expand upon the literature discussing Canadian Arctic sovereignty. By examining the impact of the two energy approaches on state sovereignty, this study draws a series of conclusion about the role of energy development in improving Canadas sovereignty claim. This thesis argues that government intervention is required to develop working partnerships amongst Canadian oil producers in order to bring Arctic energy reserves online in a timely and efficient manner to help bolster Canadas sovereignty claim.<p> This thesis considers realist and liberal policy approaches to the development of Canadas Arctic energy resources. In the past, Canada has used both approaches to encourage the development of its Arctic energy reserves. From the 1950s to early 1970s Canada relied solely on private companies to explore and produce Arctic resources. Between 1975 and 1984 Canada took a more interventionist approach. In 1975, Petro-Canada was created to help stimulate the development of Arctic resources. One of Petro-Canadas primary goals was to act as a catalyst for private energy companies operating in the Arctic.<p> This thesis seeks to expand upon the literature discussing Canadian Arctic sovereignty. By examining the impact of the two energy approaches on state sovereignty, this study draws a series of conclusion about the role of energy development in improving Canadas sovereignty claim. This thesis argues that government intervention is required to develop working partnerships amongst Canadian oil producers in order to bring Arctic energy reserves online in a timely and efficient manner to help bolster Canadas sovereignty claim.

In the Canadian North, capacity building through post-secondary education is a key policy strategy of territorial and federal governments. However, government support for the University of the Arctic (UArctic), a viable policy instrument that makes an important contribution to the capacity building efforts of the territories, has been inconsistent. This thesis will investigate whether devolution has impacted capacity building through post-secondary education, by using UArctic as a case study.

Canadas Beaufort Sea-Mackenzie Delta Basin possesses significant energy resource potential. Decisions about energy development, however, are largely project-based and do not always provide an opportunity for more efficient and more effective regional and strategic approaches to development impact assessment and management. As such, there are constant messages about the need for a more regional and strategic form of environmental assessment, practiced above the project level and focused on broader planning-based assessment as a means to sustainability assurance. The problem, however, is that there is no formal system of regional or strategic assessment (R-SEA) in northern Canada, and considerations as to what R-SEA is and what it should deliver are far from consolidated. The role of R-SEA must be better understood and a means found to make it a meaningful component and accepted and worthwhile part of planning, regulation and development decision-making. The purpose of this thesis is to identify stakeholder understandings and expectations about R-SEA, and its potential roles and opportunities in Arctic energy planning and assessment. Data were collected using semi-structured interviews with knowledgeable stakeholders in Arctic oil and gas initiatives, including energy regulators, industry, and energy interest groups, as well as Inuvialuit governments and community boards. Four key themes are identified and discussed: the efficacy of the current approach to environmental assessment for offshore energy development; knowledge of R-SEA; RSEA benefits and risks; and opportunities and challenges to advancing R-SEA in the Inuvialuit Settlement Region (ISR). Only consultation and engagement was seen by most participants as working well within the current EA system in the study area. Many challenges were raised, however, which would indicate a need for a new or revised approach to EA in the study area. There was agreement on the need for a more regional and strategic approach to EA in the ISR, but there was no consensus amongst participants as to the nature and scope of R-SEA and what it is intended to deliver. Though there continues to be much confusion regarding the terminology used, it appears that participants are identifying the same deliverables and advantages, suggesting that they are looking for similar benefits. Challenges to moving such a process forward include leadership, coordination of interests, financial resources, legislated versus voluntary approaches, and human capacity in the ISR region. Future research is needed to address the perceived risks and challenges raised by participants for R SEA to be a worthwhile and effective process.

The focus of this study is to examine the mechanisms involved in the interactions among large-scale atmospheric circulation patterns and how they are related to surface air temperature anomalies in the North American Arctic. Historical temperature data sets of Fairbanks, Alaska and Montreal, Quebec have been analyzed with respect to large-scale atmospheric circulation index data sets to investigate surface temperature anomalies in winter during the period 1960 to 2002.

Recent observational and modeling studies indicate a robust dynamical coupling between the stratosphere and troposphere during boreal winter. This coupling occurs in association with the Northern Annular Mode (NAM), which itself accounts for a significant fraction of the variability of the extratropical circulation. While monthly NAM dynamics have been studied previously, the mechanisms that give rise to NAM variability on short intraseasonal timescale are still unclear. We perform regression analyses, case studies, and composites based on periods of dynamical growth/decay to investigate the roles of the different proposed mechanisms in driving the atmospheric variability observed in association with the NAM on short intraseasonal timescales. More specifically, lag-regression analyses are used to identify the mean canonical structures present during the evolution of a typical NAM event. Illustrative case studies of robust stratospheric NAM events but with different tropospheric signals are contrasted in order to identify the underlying dynamical reasons for the observed differences. Finally, composite analyses of NAM tendencies are performed to isolate the structural and dynamical evolution of NAM events. Zonal-mean and three-dimensional eddy-flux diagnoses are used to examine the role of eddy-mean flow interaction in driving the wind tendencies characteristic of the NAM. In particular, Plumb flux analyses are employed to quantify the contribution of regional stationary wave anomalies toward the zonal mean wind tendency field. Potential vorticity inversions are also used to determine the role of stratospheric anomalies in inducing tropospheric circulations. The case study analyses indicate that preexisting tropospheric PV anomalies can mask the downward penetration of an initial stratospheric NAM signal into the troposphere. PV inversions further suggest that a minimum requirement for a direct downward stratospheric influence is that the stratospheric NAM signal be robust in the lower stratosphere. The dynamical composites show a remarkable degree of reverse symmetry between the zonal-mean dynamical evolution of positive and negative NAM events. Anomalous Eliassen-Palm fluxes are observed in the troposphere and stratosphere, consistent with index of refraction considerations and an indirect downward influence of the stratosphere on the troposphere. The patterns of anomalous wave driving, primarily due to low-frequency planetary scale waves, provide the main forcing of the zonal mean wind tendency field. Regional wave activity fluxes indicate that the wave driving pattern represents the manifestation of planetary scale anomalies over the North Atlantic.

Microwave scattering from sea ice ridges is poorly understood. This thesis aims to improve the current knowledge on in situ C-band microwave scattering from first-year sea ice (FYI) pressure ridges during winter, and how C-band backscatter can vary with changes to radar and target parameters. Remotely sensed data of ridged ice were collected at a sea ice mesocosm using a LiDAR laser scanner and a fully-polarimetric C-band scatterometer. Thesis results indicate that using an incidence angle between 30 and 50° and HV polarization will best enable distinguishing between smooth and ridged ice, while using an incidence angle of 40° and HV or HH polarization will best enable detecting variations in ridge height. Overall results indicate that a significant proportion of the variance in FYI snow-free ridge C-band backscatter can be explained by incidence angle, polarization, and ridge height, with almost 88% of the variability in backscatter attributed to ridge height.

Geological records of past sea ice, such as those contained in Arctic marine sediments, offer an opportunity to strengthen our understanding of long-term sea ice variability, provided unambiguous paleo-sea ice proxies can be developed. One such recently proposed proxy is IP₂₅, a highly branched isoprenoid alkene biosynthesized exclusively by sea-ice dwelling diatoms (Haslea spp.), which is well preserved in marine sediments and could be used to reconstruct past changes in spring sea-ice extent. However, little is known about regional-scale controls on IP₂₅ production in sea ice, limiting its wider applicability as a paleo-sea-ice proxy. To address this issue we examined the distributions of IP₂₅ and the marine productivity biomarkers dinosterol and brassicasterol in a suite of surface sediment samples distributed across the Arctic. We find a statistically significant, logarithmic relationship between IP₂₅ and spring sea ice cover in samples from arctic and subarctic sites in the Pacific (n = 96, r² = 0.67, P < 0.0001) and the Atlantic n = 25, r² = 0.50, P < 0.0001), though the absolute concentrations of IP₂₅ are generally higher in the Atlantic (1.6 - 166.4 [mu]g/g OC) than in the Pacific (0 - 38.5 [mu]g/g OC) for equivalent sea-ice cover, and there are regional and basin-specific differences in the slope of the IP₂₅ - sea ice relationship. After normalization of IP₂₅ concentrations to that of a productivity biomarker (e.g., dinosterol; the PDIP₂₅ index) the proxy-sea ice relationship in greatly improved for all regions (r² = 0.86 and r² = 0.75 for Atlantic and Pacific, respectively) and most of the basin specific differences in the rate of change of IP₂₅ with sea ice are removed. This suggests that productivity plays an important secondary role in controlling IP₂₅ concentrations. However, the use of the PDIP₂₅ index does not change the absolute differences in concentrations seen in the Atlantic and the Pacific, and previously published data from Fram Strait remain anomalous when compared to the rest of our data. This suggests that there are additional, yet unidentified controls on the IP₂₅ proxy - sea ice relationship, which may hinder the development of an Arctic-wide calibration but that the PDIP₂₅ index is a viable tool for local and regional sea ice reconstructions. / text