<p>Lake sediments and glacier extents were used to reconstruct late Holocene climate changes from Kurupa Lake (N 68.35&deg;, W 154.61&deg;; 920 m asl) in the north-central Brooks Range, Arctic Alaska. The lake is fed by several tributaries, including meltwater from eight rapidly disappearing cirque glaciers. An age-depth model for the 622-cm-long sediment core was developed using five radiocarbon (¹⁴C) ages and a 239+240Pu profile. Sedimentary chlorin (chlorophyll a and derivatives) content was analyzed at high resolution (0.2 cm = ~2 yr intervals) with visible reflectance spectroscopy for the past 5.7 kyr. Sedimentary bulk density was analyzed with gamma-ray attenuation (1.0 cm = ~10 yr intervals). </p><p> High-resolution measurements of chlorin content from the last 122 yr (top 16 cm of surface sediment) were correlated with a suite of instrumental climate records from Barrow and Bettles, National Center for Environmental Prediction reanalysis data (grid = N&deg;68 to N&deg;70 &times; W&deg;156 to W&deg;154) and with published climate indices for the Arctic (e.g., Arctic Oscillation, North Atlantic Oscillation). Chlorin content correlates most strongly to average June + September temperature (r = 0.68) and a linear inference model was developed using this regression to quantitatively reconstruct summer temperatures for the past 5.7 kyr. The temperature reconstruction (50-year smoothed) shows minimum summer temperature (5.6 &plusmn; 0.9&deg;C) at 650 AD and maximum summer temperature (10.7 &plusmn; 0.9&deg;C) 2.9 ka. </p><p> Fluctuations in bulk density over the past 5.7 kyr were interpreted to reflect changes in up-valley glacier extent. The accumulation-area ratio (AAR) method was used to estimate former equilibrium-line altitudes (ELAs) for the maximum Neoglacial and modern extents of eight cirque glaciers in the study area. Independently dated moraines enable the history of glacier fluctuations to be linked to the lake sediment sequence (r2 = 0.74), and this integrated approach provides a 5.7 kyr quantitative record of centennial-scale ELA variability for Kurupa River valley. The reconstruction supports the previously established onset of Neoglaciation around 4.2 ka, as well as maximum and minimum glacier extents around 700 AD and the present, respectively. The calculated ELA lowering at 700 AD and the LIA, relative to 1982, was 63 and 55 m, respectively. </p>

<p> Landscape-scale forest restoration treatments are planned for four national forests in Northern Arizona: the Coconino, Kaibab, Tonto, and Apache-Sitgreaves National Forests. The first analysis area comprises 900,000 acres on the Coconino and Kaibab National Forests where the U.S. Forest Service is proposing restoration activities on approximately 600,000 acres over a ten year period pending acceptance of an Environmental Impact Statement. These forest restoration treatments are intended to accomplish a number of objectives including reducing the threat of catastrophic wild fire and subsequent flooding and to restore forest health, function, and resiliency. Previous studies suggest that in semi-arid, ponderosa pine watersheds there was a possibility to increase surface water yields 15-40% when basal area was reduced by 30-100%. Because of these results, there is considerable interest in the amount of increased water yield that may recharge from these activities. </p><p> The objectives of this study were to 1) examine the state of knowledge of forest restoration thinning and its hydrological responses and to evaluate the quality and type of related references that exist within the literature and 2) simulate possible changes in recharge and aquifer response following forest restoration treatments and climate change. A systematic review process following the guidelines suggested by the Collaboration for Environmental Evidence was conducted to examine literature relevant to this topic. The Northern Arizona Regional Groundwater-Flow Model was used to simulate the changes expected from forest restoration treatments and climate change. </p><p> The systematic review returned 37 references that were used to answer questions regarding tree removal and the associated hydrological responses. Data from individual studies suggest that forest treatments that reduce tree density tend to increase surface water yield and groundwater recharge while reducing evapotranspiration. On average, there was a 0-50% increase in surface water yield when 5-100% of a watershed was treated. Groundwater results were less conclusive and there was no overall correlation for all studies between percent area treated and groundwater recharge. A majority of studies (33 of 37) reported statistically significant results, either as increases in water yield, decreases in evapotranspiration, or increases in groundwater table elevation. Results are highly variable, and diminish within five to ten years for water yield increases and even quicker (&lt; 4 years) for groundwater table heights. </p><p> Using a groundwater-flow model, it was estimated that over the ten-year period of forest restoration treatment there was a 2.8% increase in annual recharge to aquifers in the Verde Valley compared to conditions that existed in 2000-2005. However, these increases were assumed to quickly decline after treatment due to regrowth of vegetation and forest underbrush. Furthermore, estimated increases in groundwater recharge were masked by decreases in water levels, stream baseflow, and groundwater storage resulting from surface water diversions and groundwater pumping. These results should be used in conjunction with other data such as those recovered from paired-watershed studies to help guide decision-making with respect to groundwater supply and demand issues, operations, and balancing the needs of both natural and human communities. </p>

<p> Stream temperature (ST) is a primary determinant of individual stream species distributions and community composition. Moreover, thermal modifications associated with urbanization, agriculture, reservoirs, and climate change can significantly alter stream ecosystem structure and function. Despite its importance, we lack ST measurements for the vast majority of USA streams. To effectively manage these important systems, we need to understand how STs vary geographically, what the natural (reference) thermal condition of altered streams was, and how STs will respond to climate change. Empirical ST models, if calibrated with physically meaningful predictors, could provide this information. My dissertation objectives were to: (1) develop empirical models that predict reference- and nonreference-condition STs for the conterminous USA, (2) assess how well modeled STs represent measured STs for predicting stream biotic communities, and (3) predict potential climate-related alterations to STs. For objective 1, I used random forest modeling with environmental data from several thousand US Geological Survey sites to model geographic variation in nonreference mean summer, mean winter, and mean annual STs. I used these models to identify thresholds of watershed alteration below which there were negligible effects on ST. With these reference-condition sites, I then built ST models to predict summer, winter, and annual STs that should occur in the absence of human-related alteration (r² = 0.87, 0.89, 0.95, respectively). To meet objective 2, I compared how well modeled and measured ST predicted stream benthic invertebrate composition across 92 streams. I also compared predicted and measured STs for estimating taxon-specific thermal optima. Modeled and measured STs performed equally well in both predicting invertebrate composition and estimating taxon-specific thermal optima (r² between observation and model-derived optima = 0.97). For objective 3, I first showed that predicted and measured ST responded similarly to historical variation in air temperatures. I then used downscaled climate projections to predict that summer, winter, and annual STs will warm by 1.6 &deg;C - 1.7 &deg;C on average by 2099. Finally, I used additional modeling to identify initial stream and watershed conditions (i.e., low heat loss rates and small base-flow index) most strongly associated with ST vulnerability to climate change.</p>

The process to successfully adapt to climate change for farmer communities’ in Vietnam faces a multitude of challenges.  This thesis proposes that institutional barriers to implementing policy related to climate change adaptation occur in key sectors related to farmer’s livelihoods at the local level, which are important to facilitating the adaptation process for farmer communities. It analyses the current state of the climate change policy landscape, investigates water, agricultural and disaster risk management sectors in Vietnam in the literature, and examines more closely how governmental institutions at the local level facilitate these in a field study of Bo De commune. The institutional barriers to successful adaptation to climate change reported at the local level in the field study are similar to the types of barriers identified across the literature, related to communication, technology, leadership facilitated by institutions. The results confirm that institutional barriers are occurring at the local level that are impeding the implementation process of key policies; this limits the ability of the farmer community to adapt successfully to climate change.

The aim of this literature study is to compare and discuss different fields of paleolimnology, with a focus on three main research areas – eutrophication, acidification, and climate change. Pioneering work and the development of paleolimnological methods around these three areas were reviewed and synthesized. Paleolimnology started out as limnology and paleoecology, but has evolved tremendously over the past decades. Early paleolimnological studies focused on lake ontogeny and mechanics in the catchment such as weathering. The focus eventually shifted to nutrient loadings during the 1960s – 1970s as the debate on human induced eutrophication emerged. The important question to answer was which nutrient was the limiting factor in eutrophication. Acidification was the next topic of investigation during the 1980s – 1990s, and paleolimnology developed methods to infer past pH change based on chironomids and diatom fossils preserved in lake sediment. This research resulted in calibration sets and proxies which can be used to reconstruct past conditions. The paleolimnological community eventually shifted focus in the late 1990s to climate change and began to use lake sediment to reconstruct past climatic trends using multiproxy studies such as diatoms, chironomids and geochemistry. Varved lake sediment offered a much needed terrestrial high resolution option to the ice core records. History plays a fundamental role in all environmental issues and paleolimnology has the ability to provide historical records of past environmental conditions. Paleolimnology will most likely play a key role in management and restoration in the future. As technology and training sets develop, fast and cheap ways to interpret sediment proxies will emerge and maybe even fully automated identification of proxies.

Seafood is a global commodity of growing importance. The present study examined contributions to global warming from three significant seafood product chains. Each of these systems were relatively fuel efficient compared to fuel intensities reported for other fisheries globally. As such, processing and transportation phases made relatively important contributions to the overall global warming impact of these systems. Energy inputs to processing were important, as was the emission-intensity of the energy format used. In the context of interest regarding the food miles concept as an indicator of sustainability, results revealed that rather the mode of transport, not the distance travelled, was the most important factor in determining overall greenhouse gas emissions from transportation. Results indicate that further research evaluating the complete supply chain of seafood products (not only the fishing phase) may reveal important opportunities for emission reductions.

Global warming will affect every level of biological organization from the metabolism of individuals to the functioning of ecosystems. I explored the effects of warming on three rock-pool meioinvertebrate communities along a latitudinal gradient (temperate, tropical, and sub-Arctic regions) to determine effects on community and food-web structure and functioning. Warming affected regions differently, having a positive effect on sub-Arctic communities, a negative effect on temperate communities, and intermediate responses in tropical communities in terms of abundance, stability and extinction frequency. Differences in structural properties of the food webs supported the insurance hypothesis: that greater redundancy in webs results in greater stability, and helped to explain why the tropical community was more stable than the temperate community in warmed treatments. My study highlights the importance of considering differential response of species and communities from different latitudes and the importance of food web structure in predicting species response to global climate change.

Coastal communities in Ecuador – and worldwide – are vulnerable to climate change due to both marine and inland pressures. Studies predict that climatic changes will impact strongly on coastal zones, with particularly negative effects on communities that rely on mangrove ecosystems for their livelihoods. Unfortunately, relatively few studies have determined how these communities perceive climate change and other environmental changes witnessed during their lifetime. This research gathered primary information from two Ecuadorian coastal communities, as well as data from non-governmental organizations, global scientists, government, and national institutes in an effort to discover where information gaps or points of collaboration exist. At the community level, environmental change was often attributed to the drastic effects of the shrimp farm industry, deforestation of mangrove and tropical forests, and El Niño (ENSO) events. Participants mentioned God, a displeased nature, and the climate being loco (crazy) as other factors affecting change. The richness of local ecological knowledge in the communities studied indicates a need for more bottom-up information through monitoring and dialogue around entry points. Addressing vulnerabilities and adaptation requires a focus on the local context and pressing issues of food security, freshwater, pollution, and diminishing fish species which are currently overshadowing climate change as priority issues. Accordingly, collaboration around mangrove restoration may be an effective win-win climate adaptation strategy. / Climate change in Ecuador's coastal communities and mangrove ecosystems: Local knowledge, perceptions, and priorities

Tree selection is critical to ensuring that urban forests are diverse, healthy, and adapted to the urban environment. Climate is one of the main controllers of plant distribution around the world, so tree species are expected to redistribute as a result of climate change. This research aimed to identify which eastern North American tree species should be most suited for planting in urban areas in Halifax given impending climate change. A database was developed for 57 tree species and 95 tree characteristics to enable analysis of tree species native to eastern North America. The results of previous climate envelope research and the database were used to identify the tree species most suitable for planting in Halifax. Of the 57 tree species examined, 16 were identified as most suited for the Halifax urban forest of the 21st century.

Pterocarpus officinalis dominated forests are a rare ecosystem, found only in fifteen locations in Puerto Rico, all of which are adjacent to the coast and at risk from sea level rise, as well as nutrient pollution, upstream hydrological modifications, and deforestation. All forests of this type that were located further inland were destroyed by agricultural development during the early decades of the 1900’s, in particular to grow sugarcane. Prior to this study, there was little information on the diversity of organisms that live in these forests. The central objective of this proposal was to examine the diversity and species composition of three Pterocarpus forests in Puerto Rico located near Humacao, Patillas, and Dorado, and to compare and contrast diversity among the three forests, and identify possible differences caused by human impacts or natural factors. The data was collected through surveys and sampling at each location. Transect surveys, plots, pitfall traps, insect traps and audio recordings were carried out to identify organisms including birds, mammals, amphibians and reptiles, insects, mollusks, invertebrates, plants and fungi. The Dorado Pterocarpus forest is the most rich and diverse in terms of organisms and has the highest amount of native and endemic species, while the Humacao Pterocarpus forest is the least rich and diverse. Yet conversely, the Dorado forest is the smallest forest, covering only 2.4 ha, while Humacao is the largest, with an area of 150 ha that comprises 63% of the total Pterocarpus coverage in Puerto Rico. The most obvious factor influencing richness and diversity among the forests is the adjacent land cover and history of the sites. Inflow and water sources may also be a factor that alters richness and diversity. This knowledge will assist in the appropriate management of this rare resource in the context of ongoing sea level rise, climate change, nutrient pollution, upstream hydrological modifications, and deforestation. Coastal managers need this information to manage and protect these valuable and rare ecosystems.