Tree rings have long been used to make inferences about the environmental factors that influence tree growth. Great Basin bristlecone pine is a long-lived species and valuable dendroclimatic resource, but often with mixed growth signals; in many cases, not all trees at one location are limited by the same environmental variable. Past work has identified an elevational threshold below the upper treeline above which trees are limited by temperature, and below which trees tend to be moisture limited. This study identifies a similar threshold in terms of temperature instead of elevation through fine-scale topoclimatic modeling, which uses a suite of topographic and temperature-sensor data to predict temperatures across landscapes. We sampled trees near the upper limit of growth at four high-elevation locations in the Great Basin region, USA, and used cluster analysis to find dual-signal patterns in radial growth. We observed dual-signal patterns in ring widths at two of those sites, with the signals mimicking temperature and precipitation patterns. Trees in temperature-sensitive clusters grew in colder areas, while moisture-sensitive cluster trees grew in warmer areas. We found thresholds between temperature- and moisture-sensitivity ranging from 7.4 degrees C to 8 degrees C growing season mean temperature. Our findings allow for a better physiological understanding of bristlecone pine growth, and seek to improve the accuracy of climate reconstructions.

In this thesis, I explore the implications of integral theory for sustainable development and climate change response. Integral theory seeks to integrate objective and subjective perspectives using a developmental orientation. It addresses issues of subjectivity that have received inadequate attention in mainstream approaches to sustainable development, while also providing theoretical grounding for the developmental aspect of sustainable development. According to integral theory, there are four main epistemological approaches to any problem: behavioural, systemic, psychological and cultural. The first is objective and individual, the second objective and collective, the third subjective and individual and the fourth subjective and collective. Development occurs within each of these realms. To test the value and implications of integral theory for sustainable development, I adopt a case study on climate change response in Australia. I begin the case study by using the four perspectives of integral theory to guide a review of the energy and climate change literature. I follow the literature review with a critical review of Australian energy and greenhouse policy, providing the starting point for development of an integral climate change response. While there is attention to subjectivity in the literature, it is not reflected in Australian policy practices. An objective perspective and an instrumental form of rationality dominate policy. In the literature review, I identify two gaps in the literature that deserve attention. The first is the role of public subsidies in creating the observed cost differential between renewable energy sources and fossil fuel energy. I examine the relative magnitude of subsidies to fossil fuels and renewable energy in the Australian energy and transport sectors and conclude that the distribution of these subsidies distorts the market in favour of fossil fuels, particularly in the transport sector. The second is the application of a developmental perspective to cultural theories of climate policy discourse. I introduce a method called meta-discourse analysis to identify consistencies and relationships across discourse descriptions by different authors and demonstrate that aspects of each discourse can be related developmentally. Drawing on the literature review, policy review and other work, I propose an integral policy response to climate change that could be applied in Australia. The policy response combines participatory integrated assessment, normative futures work, a modified version of the cooperative discourse model for public participation, an evolutionary policy orientation and several methods to promote subjective development. The proposed policy approach should be equally applicable to other sustainable development issues.

In this thesis, I explore the implications of integral theory for sustainable development and climate change response. Integral theory seeks to integrate objective and subjective perspectives using a developmental orientation. It addresses issues of subjectivity that have received inadequate attention in mainstream approaches to sustainable development, while also providing theoretical grounding for the developmental aspect of sustainable development. According to integral theory, there are four main epistemological approaches to any problem: behavioural, systemic, psychological and cultural. The first is objective and individual, the second objective and collective, the third subjective and individual and the fourth subjective and collective. Development occurs within each of these realms. To test the value and implications of integral theory for sustainable development, I adopt a case study on climate change response in Australia. I begin the case study by using the four perspectives of integral theory to guide a review of the energy and climate change literature. I follow the literature review with a critical review of Australian energy and greenhouse policy, providing the starting point for development of an integral climate change response. While there is attention to subjectivity in the literature, it is not reflected in Australian policy practices. An objective perspective and an instrumental form of rationality dominate policy. In the literature review, I identify two gaps in the literature that deserve attention. The first is the role of public subsidies in creating the observed cost differential between renewable energy sources and fossil fuel energy. I examine the relative magnitude of subsidies to fossil fuels and renewable energy in the Australian energy and transport sectors and conclude that the distribution of these subsidies distorts the market in favour of fossil fuels, particularly in the transport sector. The second is the application of a developmental perspective to cultural theories of climate policy discourse. I introduce a method called meta-discourse analysis to identify consistencies and relationships across discourse descriptions by different authors and demonstrate that aspects of each discourse can be related developmentally. Drawing on the literature review, policy review and other work, I propose an integral policy response to climate change that could be applied in Australia. The policy response combines participatory integrated assessment, normative futures work, a modified version of the cooperative discourse model for public participation, an evolutionary policy orientation and several methods to promote subjective development. The proposed policy approach should be equally applicable to other sustainable development issues.

We investigated the climatic sensitivity of oak species across a wide elevation range in the southern Appalachian Mountains, an area where greater knowledge of oak sensitivity is desired. We developed three tree-ring chronologies for climatic analyses from oak cores taken from the Jefferson National Forest, Virginia, and Great Smoky Mountains National Park, Tennessee. We statistically compared the three chronologies with monthly climatic data from 1930 to 2005. The results of our analyses suggest that oak species in the southern Appalachian Mountains require a cool, moist summer for above average-growth to occur. The climate signal increased in duration from high to low elevational and latitudinal gradients, indicating a strong moisture-preconditioning signal during the previous fall at our lowest elevation site. A notable finding of this research was the degree of responsiveness in oaks that are growing in forest interior locations where strong climate sensitivity would not be expected because of the effects of internal stand dynamics. Furthermore, the relationships between evapotranspiration rates and the geographic factors of elevation, latitude, and aspect influence the climate signals at the three sites. Our research suggests that oaks located in a warm and xeric climate experience more physiological stress and put forth a more varied climatic response.

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Do changes in how cross-equatorial energy transport is partitioned between the ocean and atmosphere impact the hemispheric climate response to forcing? To find out, we alter the cross-equatorial ocean heat transport in a state-of-the-art GCM and ascertain how changes in energy transport and its partitioning impact hemispheric climate and precipitation sensitivity following abrupt CO2-doubling. We further evaluate the applicability our results in CMIP6-class ESMs, where AMOC facilitates the northward cross-equatorial ocean heat transport. In our experiments, changes in ocean cross-equatorial energy transport trigger compensating changes in atmospheric energy transport through changes in the Hadley cells and a shift in the Intertropical Convergence Zone. However, the climate sensitivity in each hemisphere is linearly related to the ocean heat transport convergence, not atmospheric energy transport convergence, due to the impact of ocean heating on evaporation and atmospheric specific humidity. Similarly, we also find that ocean heat transport convergence controls the hemispheric precipitation sensitivity through the impact of ocean heating on surface evaporation. This relationship is also evident in CMIP6 models, where we find differences in hemispheric precipitation sensitivity to be related to the Atlantic Meridional Overturning Circulation (AMOC). Changes in the AMOC control hemispheric differences in upper ocean heat content, which then affect how the hydrologic cycle responds to CO2 forcing in each hemisphere. These results suggest that ocean dynamics impact the hemispheric climate response to CO2 forcing, particularly how much regional precipitation changes with warming. / Graduate