RSS 1.0UA Faculty Research
ABOUT THE COLLECTIONS
These collections include publications and data from University of Arizona faculty, staff and researchers. The UA Faculty Publications collection consists primarily of open access versions of published journal articles, but also contains conference proceedings and other unique materials from faculty, staff and researchers. Organizational collections, such as the College of Agricultural and Life Sciences Publications, and Water Resources Research Center, contain additional faculty publications such as departmentally produced technical bulletins, technical reports, and working papers.
QUESTIONS?
Please contact the UA Campus Repository team at repository@u.library.arizona.edu with questions or comments about items in these collections, or if you are affiliated with the University of Arizona and are interested in adding documents to the UA Campus Repository.
If you need to archive research datasets to meet data retention and sharing requirements from the university, funders, or journals, visit ReDATA, The University of Arizona's Research Data Repository.
Sub-communities within this community
Collections in this community
Recent Submissions
-
Age-Related differences in arm acceleration and center of mass control during a slip incidentArm abduction motion can help reduce lateral center of mass (CoM) excursion and restore balance within the frontal plane during slip perturbations. This study aimed to quantify and compare frontal plane arm kinematics and their relationship with CoM control between older and younger adults experiencing a slip. Eleven older adults (age: 72.0 ± 5.0 years) and eleven younger adults (age: 25.5 ± 6.1 years) underwent an induced slip perturbation while walking. Although peak arm abduction angles were similar between groups, younger adults achieved peak arm abduction significantly earlier (542 ± 67 ms) compared to older adults (853 ± 509 ms; p = 0.03). Additionally, younger adults exhibited significantly higher peak arm abduction acceleration compared to older adults (3593.21 ± 1144.80 vs. 2309.83 ± 1428.48 degrees/s2; p = 0.03). Younger adults also demonstrated significantly reduced lateral CoM excursion relative to older adults (4.6 ± 3.5 cm vs. 10.47 ± 6.6 cm; p < 0.01). Peak arm abduction acceleration negatively correlated with lateral CoM excursion (r = -0.52, p < 0.02), indicating that rapid arm movements are associated with improved balance control. A regression analysis confirmed arm abduction acceleration as a significant predictor of lateral CoM displacement (p = 0.005) meaning every 1000 degrees/s2 increase in arm acceleration results in an approximate 2 cm decrease in lateral CoM displacement during a slip. These findings suggest older adults’ diminished arm acceleration in response to slips potentially compromises their ability to stabilize their CoM effectively, highlighting a possible target for fall-prevention interventions.
-
The effect of wood chip surface depth on peak force during impactsObjective: Playgrounds are essential for children’s physical, social, and mental health. However, only 4.7% of playgrounds meet safety standards for wood chip surface depth around playground structures. This study aimed to quantify peak force attenuation at safety-compliant (9-inch) vs. non-compliant (5-inch) wood chip depths. Methods: Wood chip layers of 5 inches and 9 inches were placed on a calibrated force platform. A 4.54-kg medicine ball was dropped from a consistent height onto the wood chips, and peak forces and time to peak force were measured. Results: The 9-inchwood chip layer significantly reduced peak forces compared to the 5-inch layer, showing a 44% reduction (p < 0.001). No significant differences were observed in time to peak force between the two conditions (p=0.46). Discussion: Compliant wood chip surface depths reduce impact forces substantially, emphasizing the importance of routine inspection and maintenance of playground surfaces to safety standards. This practice can help minimize injuries in children resulting from playground falls.
-
PLAN QUALITY EVALUATION FOR HEAT RESILIENCE GUIDEBOOK: A METHODOLOGICAL GUIDE FOR PRACTITIONERS AND RESEARCHERSIn the face of the record-breaking extreme heat that is threatening lives, economies, and habitats across the world, communities are starting to prepare new plans, develop roadmaps and refine strategies to address extreme heat. This guidebook outlines a systematic method to evaluate the content of plans to advance urban heat resilience. This method, called Plan Quality Evaluation, is an established and widely used content analysis process that is argued to improve knowledge of plans, further implementation of plans, and foster collaboration among plan-making bodies. Plan Quality Evaluation for Heat Resilience draws from a large literature on plan quality evaluation and adapts it specifically to address urban heat issues. The goal of this guidebook is to help practitioners and researchers refine different aspects of plans so that they can effectively foster heat resilience. The Plan Quality Evaluation for Heat Resilience method is comprised of a two-step process. The first step- Quality Principles Evaluation, involves comparing plan content against established criteria related to seven principles of high-quality plans: goals, fact base, strategies, implementation and monitoring, public participation, coordination, and uncertainty recognition. The second step- Heat Strategies Evaluation, involves analyzing the inclusion of strategies that can mitigate and manage heat risks. This guidebook helps planning practitioners and researchers conduct both steps of the Plan Quality Evaluation for Heat Resilience using their own community plans as they are prepared, refined, updated, or monitored during implementation. This guidebook is divided into three chapters. The first chapter introduces the concept of heat resilience planning and the rationale for using plan quality evaluation methodology. The second chapter outlines the two-step process. Finally, the third chapter discusses the interpretation of results. This document is a companion piece to the American Planning Associations’ PAS Report 600: Planning for Urban Heat Resilience and the Plan Integration for Resilience ScorecardTM for Heat guidebook.
-
Advancing Virtual Care Practices Across the Cognitive Impairment ContinuumAs the population of older adults grows, providing high-quality, cost-effective healthcare for those with cognitive impairments is an increasing priority. The COVID-19 pandemic accelerated the shift towards receiving virtual care at home through temporary Medicare flexibilities. However, the uncertainty surrounding the continuing extension of these flexibilities at the federal level and variations in reimbursement policies across the states present challenges for virtual care practices to meet the rising demand for care amid unprecedented workforce shortages. Sustainable, long-term reimbursement at the federal and state levels, a trained and integrated healthcare workforce, and adherence to recognized accreditation standards and guidelines are essential to advance the quality and safety of virtual care for cognitively impaired patients. Furthermore, reimbursement policies that incentivize investments in technology infrastructure and digital literacy outreach are needed to ensure equitable access to virtual care for all patients across the cognitive impairment continuum.
-
Plan evaluation for heat resilience: complementary methods to comprehensively assess heat planning in Tempe and Tucson, ArizonaEscalating impacts from climate change and urban heat are increasing the urgency for communities to equitably plan for heat resilience. Cities in the desert Southwest are among the hottest and fastest warming in the U.S., placing them on the front lines of heat planning. Urban heat resilience requires an integrated planning approach that coordinates strategies across the network of plans that shape the built environment and risk patterns. To date, few studies have assessed cities' progress on heat planning. This research is the first to combine two emerging plan evaluation approaches to examine how networks of plans shape urban heat resilience through case studies of Tempe and Tucson, Arizona. The first methodology, Plan Quality Evaluation for Heat Resilience, adapts existing plan quality assessment approaches to heat. We assess whether plans meet 56 criteria across seven principles of high-quality planning and the types of heat strategies included in the plans. The second methodology, the Plan Integration for Resilience Scorecard™ (PIRS™) for Heat, focuses on plan policies that could influence urban heat hazards. We categorize policies by policy tool and heat mitigation strategy and score them based on their heat impact. Scored policies are then mapped to evaluate their spatial distribution and the net effect of the plan network. The resulting PIRS™ for Heat scorecard is compared with heat vulnerability indicators to assess policy alignment with risks. We find that both cities are proactively planning for heat resilience using similar plan and strategy types, however, there are clear and consistent opportunities for improvement. Combining these complementary plan evaluation methods provides a more comprehensive understanding of how plans address heat and a generalizable approach that communities everywhere could use to identify opportunities for improved heat resilience planning.
-
Assessment of the Contribution of Local and Regional Biomass Burning on PM2.5 in New York/New Jersey Metropolitan AreaThe sources of fine particulate matter (PM2.5, particles with diameter < 2.5 µm) in four monitoring sites in the New York/New Jersey metropolitan statistical area from 2007 to 2017 were apportioned by positive matrix factorization (PMF) of chemical speciation data. Biomass burning, secondary inorganic (i.e., ammonium sulfate and nitrate) and primary traffic exhausts were the predominant PM2.5 sources. The declining trends of PM2.5 mass in all four sites were very well correlated with decreasing secondary sulfate levels due to SO2 emission reductions by coal-fired power plants. The contributions of secondary nitrate, primary traffic exhausts and diesel particles did not change (or slightly increased) over time except for the Queens site, where statistically significant declines were computed. Biomass burning contributions increased in the Queens and Chester sites but declined in the Division Str and Elizabeth Lab sites, although significant interannual variability was observed. Wintertime biomass burning aerosols were most likely due to combustion of contemporary biomass for industrial and domestic heating, and it was linked to the intensity (average minimum temperature) and duration (number of freezing days) of cold weather. The annual summertime biomass burning contributions were correlated with the number of and area burnt by lightning-ignited wildfires. These results indicate that PM2.5 sources in urban environments is changing from anthropogenic secondary sulfate and nitrate to carbonaceous aerosol from local anthropogenic and regional climate-driven biomass burning. This trend may counterbalance emissions controls on anthropogenic activities and modify the biological and toxicological responses and resultant health effects.
-
A Co‐Produced Workflow for Addressing Inequities in Cooling Center AccessIncreasing extreme heat poses challenges to metropolitan areas, such as those areas already experiencing extreme heat in Arizona. Using the US Centers for Disease Control and Prevention (CDC)'s Building Resilience Against Climate Effects (BRACE) Framework, state and local health departments have looked to expand cooling center networks as one option to build heat resilience. We present a method to pick new locations for cooling centers based on demand and current coverage. Using two locations in Arizona, we highlight differences in workflows and how the resulting information can be incorporated into separate but parallel efforts to reduce heat impacts. We used the Network Analyst Location‐Allocation tool in ArcGIS Pro to maximize coverage of cooling centers in each area, so that additional cooling centers are selected to reflect local needs. The input data and parameters of the workflow were co‐produced with input from two county health departments and a cooling center working group to better address the unique challenges related to cooling center access. To facilitate the application of this approach to other regions seeking to address heat health inequities, we provide a detailed protocol and a discussion of alternative selections.
-
Coproducing Opportunities to Advance Heat Resilience in Southern ArizonaLocated in the desert of the U.S. Southwest, the City of Tucson and the counties around the metropolitan area have a long history of engaging in heat-related issues. Tucson Water has hosted 14 annual Urban Heat Island workshops, disseminating knowledge on the latest best practices and resources to address extreme heat to city agencies. Leaders in Southern Arizona have also worked with regional and state coalitions to share information and resources on heat management and mitigation. Following the record-breaking heat in the summer of 2023, Arizona Governor, Katie Hobbs, declared an extreme heat emergency and issued an Executive Order to prepare a plan outlining specific lines of action to address extreme heat in the future. The Arizona Department of Health Services (ADHSs) held a summit quickly in the fall of 2023 in Phoenix to understand statewide gaps and prioritize action items. While open to all state participants, the meeting attendance from Southern Arizona partners was limited due to the increased travel distance and limited timing. In response to state-level planning efforts and to advance the city and county’s own ongoing heat planning efforts, the City of Tucson, Pima County Health Department, and the University of Arizona mobilized to organize the Southern Arizona Heat Planning Summit.
-
Rural heat health disparities: Evidence from the U.S. National Emergency Medical Services Information System (NEMSIS)Background: Increasing average temperatures and extreme heat events due to climate change have adverse effects on human health. Previous studies focus on the heat impacts in urban areas due to the focus on the greater population and urban heat island effect, but this tendency results in the effect of heat on rural health being overlooked. Methods: Using the National Emergency Medical Services Information System (NEMSIS) data from 2021 to 2023, this study compares heat-related illness (HRI) in urban and rural areas of the U.S. Results: We found the odds of EMS events in an urban area resulting with a positive outcome for the patient was 1.24 times that of EMS events in rural areas. This urban-rural disparity was not equal across regions with the odds of EMS events to rural areas of the Western U.S. resulting with a positive outcome for the patient was 54 % less than that for urban areas. Conclusion: This critical evidence of a rural-urban heat health disparity calls attention to the impact of climate change-fueled heat impacts on health in communities of all sizes, and a need for more rural heat resilience research to inform practice.
-
Developing an Integrated Heat Health Information System for Long-Term Resilience to Climate and Weather Extremes in the El Paso-Juárez-Las Cruces Region: report from the workshop held in El Paso, TX, July 13, 2016The workshop, Developing an Integrated Heat Health Information System for Long-Term Resilience to Climate and Weather Extremes in the El Paso-Juárez-Las Cruces Region, was held in El Paso, Texas, on July 13, 2016. Sponsored by a collaborative of universities and local and federal agencies, the workshop brought together individuals in government, practitioner, and academic communities from Mexico and the United States to discuss the intersection of the region’s climate and weather with factors affecting public health risks related to extreme heat. The region is home to approximately 2.4 million people, most of whom are living in or near the urban centers of Ciudad Juárez (Chihuahua), El Paso, and Las Cruces (New Mexico). These cities share characteristics, such as a high proportion of residents of Hispanic origin, median income below the U.S. national average, and a range of climate related environmental issues that include drought, flooding, air pollution, dust storms, and frequent occurrences of extremely high temperatures during the late spring and early summer. With hotter temperatures and more frequent and persistent heat waves projected for the El Paso-Juárez-Las Cruces region, it is critical to develop more robust systems of institutions, social learning, and partnerships to understand risks and strengthen public health resilience.
-
Assessment of the Contribution of Wildfires to Ozone Concentrations in the Central US-Mexico Border RegionThe annual trends and spatiotemporal patterns of monthly 8-hour maximum ozone (8-hr max O3) concentrations in the Paso del Norte region were analyzed, and their associations with fires were examined for the 2001–2010 period. Hourly O3 measurements were retrieved from the Environmental Protection Agency (EPA) Air Quality System, while the times and locations of fires were acquired from the MODIS fire detection module. The absolute 8-hr max O3 concentrations were comparable in urban, rural and background sites. Time series analysis of deseasonalized monthly 8-hr max O3 levels showed statistically significant declining trends for most of the sites located in populated areas, and high correlation coefficients among these. Conversely, a 0.12 ppbv/yr increase of 8-hr max O3 concentration was computed for Chiricahua, a background site located in a Class I protected area. Strong relationships between the monthly 8-hr max O3 concentrations and categorical variables representing the number of fire detections for each month in six buffer zones were computed. Fire incidents near the sites (within 400 km) in central Arizona, central Texas and western Mexico triggered a decrease in the 8-hr max O3 concentration by 1 to 12 ppbv in urban and rural sites, and an increase of 3 ppbv in Chiricahua. Conversely, fire incidents in southeast US, Cuba and central Mexico contributed from 5 up to 19 ppbv. These findings indicated that regional fire incidents may trigger high O3 episodes, which may exceed air quality standards.
-
Climate and Dengue Transmission: Evidence and ImplicationsClimate influences dengue ecology by affecting vector dynamics, agent development, and mosquito/human interactions. Although these relationships are known, the impact climate change will have on transmission is unclear. Climate-driven statistical and process-based models are being used to refine our knowledge of these relationships and predict the effects of projected climate change on dengue fever occurrence, but results have been inconsistent. We sought to identify major climatic influences on dengue virus ecology and to evaluate the ability of climate-based dengue models to describe associations between climate and dengue, simulate outbreaks, and project the impacts of climate change. We reviewed the evidence for direct and indirect relationships between climate and dengue generated from laboratory studies, field studies, and statistical analyses of associations between vectors, dengue fever incidence, and climate conditions. We assessed the potential contribution of climate-driven, process-based dengue models and provide suggestions to improve their performance. Relationships between climate variables and factors that influence dengue transmission are complex. A climate variable may increase dengue transmission potential through one aspect of the system while simultaneously decreasing transmission potential through another. This complexity may at least partly explain inconsistencies in statistical associations between dengue and climate. Process-based models can account for the complex dynamics but often omit important aspects of dengue ecology, notably virus development and host–species interactions. Synthesizing and applying current knowledge of climatic effects on all aspects of dengue virus ecology will help direct future research and enable better projections of climate change effects on dengue incidence.
-
Dramatic response to climate change in the Southwest: Robert Whittaker's 1963 Arizona Mountain plant transect revisitedModels analyzing how Southwestern plant communities will respond to climate change predict that increases in temperature will lead to upward elevational shifts of montane species. We tested this hypothesis by reexamining Robert Whittaker's 1963 plant transect in the Santa Catalina Mountains of southern Arizona, finding that this process is already well underway. Our survey, five decades after Whittaker's, reveals large changes in the elevational ranges of common montane plants, while mean annual rainfall has decreased over the past 20 years, and mean annual temperatures increased 0.25°C/decade from 1949 to 2011 in the Tucson Basin. Although elevational changes in species are individualistic, significant overall upward movement of the lower elevation boundaries, and elevational range contractions, have occurred. This is the first documentation of significant upward shifts of lower elevation range boundaries in Southwestern montane plant species over decadal time, confirming that previous hypotheses are correct in their prediction that mountain communities in the Southwest will be strongly impacted by warming, and that the Southwest is already experiencing a rapid vegetation change.
-
Accelerating Adaptation of Natural Resource Management to Address Climate ChangeNatural resource managers are seeking tools to help them address current and future effects of climate change. We present a model for collaborative planning aimed at identifying ways to adapt management actions to address the effects of climate change in landscapes that cross public and private jurisdictional boundaries. The Southwest Climate Change Initiative (SWCCI) piloted the Adaptation for Conservation Targets (ACT) planning approach at workshops in 4 southwestern U.S. landscapes. This planning approach successfully increased participants’ self-reported capacity to address climate change by providing them with a better understanding of potential effects and guiding the identification of solutions. The workshops fostered cross-jurisdictional and multidisciplinary dialogue on climate change through active participation of scientists and managers in assessing climate change effects, discussing the implications of those effects for determining management goals and activities, and cultivating opportunities for regional coordination on adaptation of management plans. Facilitated application of the ACT framework advanced group discussions beyond assessing effects to devising options to mitigate the effects of climate change on specific species, ecological functions, and ecosystems. Participants addressed uncertainty about future conditions by considering more than one climate-change scenario. They outlined opportunities and identified next steps for implementing several actions, and local partnerships have begun implementing actions and conducting additional planning. Continued investment in adaptation of management plans and actions to address the effects of climate change in the southwestern United States and extension of the approaches used in this project to additional landscapes are needed if biological diversity and ecosystem services are to be maintained in a rapidly changing world.
-
Weather, climate, and hydrologic forecasting for the US Southwest: a surveyAs part of a regional integrated assessment of climate vulnerability, a survey was conducted from June 1998 to May 2000 of weather, climate, and hydrologic forecasts with coverage of the US Southwest and an emphasis on the Colorado River Basin. The survey addresses the types of forecasts that were issued, the organizations that provided them, and techniques used in their generation. It reflects discussions with key personnel from organizations involved in producing or issuing forecasts, providing data for making forecasts, or serving as a link for communicating forecasts. During the survey period, users faced a complex and constantly changing mix of forecast products available from a variety of sources. The abundance of forecasts was not matched in the provision of corresponding interpretive materials, documentation about how the forecasts were generated, or reviews of past performance. Potential existed for confusing experimental and research products with others that had undergone a thorough review process, including official products issued by the National Weather Service. Contrasts between the state of meteorologic and hydrologic forecasting were notable, especially in the former¹s greater operational flexibility and more rapid incorporation of new observations and research products. Greater attention should be given to forecast content and communication, including visualization, expression of probabilistic forecasts and presentation of ancillary information. Regional climate models and use of climate forecasts in water supply forecasting offer rapid improvements in predictive capabilities for the Southwest. Forecasts and production details should be archived, and publicly available forecasts should be accompanied by performance evaluations that are relevant to users.
-
Processes of adaptation to climate variability: a case study from the US SouthwestThe nature of adaptation to climate variability in the Southwest US is explored using the Middle San Pedro River Valley in southern Arizona as a case study. An integrated vulnerability assessment focuses on the dynamic interaction of natural climatic and hydrological systems with socio-economic systems. This approach reveals that residents in the study region do not perceive short-term or long-term vulnerability to climate variability or climate change. The paper uses an ethnographic field approach to examine the technical and organizational factors that constitute the adaptation process and reduce vulnerability to climate in the valley. It concludes by discussing the potential dangers of ignoring climate in a rapidly growing, semi-arid environment.
-
Sensitivity of urban water resources in Phoenix, Tucson, and Sierra Vista, Arizona, to severe droughtWater scarcity is an ever-present fact of life in the arid and increasingly urbanized Southwest. Yet even with the considerable effort expended on drought-proofing urban areas through infrastructure and policy development, droughts of magnitudes found in the historical records of the past 100 yr continue to threaten the region¹s cities. Results of an analysis of the sensitivity of 3 urban areas in Arizona to selected drought scenarios suggest that severe droughts of 1, 5, and 10 yr duration would severely stress existing water supply/demand budgets. The results of the analysis suggest that very considerable conservation efforts would be required to bring demand into balance with existing supply. This article reports on the results of analysis of the sensitivity of urban water systems in the Phoenix and Tucson metropolitan areas as well as in the Sierra Vista subwatershed, which includes the rapidly growing city of Sierra Vista and the adjacent Fort Huachuca Army Base.
-
Spatial modeling of winter temperature and precipitation in Arizona and New Mexico, USAThe development of a statistical modeling technique suitable for producing mean and interannual gridded climate datasets for a topographically varying domain is undertaken. Stepwise regression models at 1 x 1 km resolution are generated to estimate mean winter temperature and precipitation for the Southwest United States for the years 1961-1990. Topographic predictor variables are used to explain spatial variance in the datasets. Kriging and inverse distance weighting interpolation algorithms are utilized to account for model residuals. The final regression models show a high degree of explained variance for temperature (R2 = 0.98, mean bias error [MBE] = -0.15°C, root-mean-squared error [RMSE] = 0.74°C) and a moderate degree of explained variance for precipitation (R2 = 0.63, MBE = -1.4 mm, RMSE = 27.0 mm). Several smaller-scale precipitation regression models are developed for comparison to the domain-wide model, but do not show marked accuracy improvements. Observed values of winter temperature and precipitation from the years 1961-1999 are compared to the 30 yr modeled means, and the differences are interpolated using kriging (temperature) and inverse distance weighting (precipitation). The result is a 39 yr time series of maps and datasets of winter temperature and precipitation at 1 x 1 km resolution for the Southwest United States.
-
The climate of the US SouthwestThis paper summarizes the current state of knowledge of the climate of southwest USA (the 'Southwest'). Low annual precipitation, clear skies, and year-round warm climate over much of the Southwest are due in large part to a quasi-permanent subtropical high-pressure ridge over the region. However, the Southwest is located between the mid-latitude and subtropical atmospheric circulation regimes, and this positioning relative to shifts in these regimes is the fundamental reason for the region¹s climatic variability. Furthermore, the Southwest¹s complex topography and its geographical proximity to the Pacific Ocean, the Gulf of California, and the Gulf of Mexico also contribute to this region¹s high climatic variability. El Niño, which is an increase in sea-surface temperature of the eastern equatorial Pacific Ocean with an associated shift of the active center of atmospheric convection from the western to the central equatorial Pacific, has a well-developed teleconnection with the Southwest, usually resulting in wet winters. La Niña, the opposite oceanic case of El Niño usually results in dry winters for the Southwest. Another important oceanic influence on winter climate of the Southwest is a feature called the Pacific Decadal Oscillation (PDO), which has been defined as temporal variation in sea-surface temperatures for most of the Northern Pacific Ocean. The effects of ENSO and PDO can amplify each other, resulting in increased annual variability in precipitation over the Southwest. The major feature that sets the climate of the Southwest apart from the rest of the United States is the North American monsoon, which in the US is most noticeable in Arizona and New Mexico. Up to 50% of the annual rainfall of Arizona and New Mexico occurs as monsoonal storms from July through September. Instrumental measurement of temperature and precipitation in the Southwest dates back to the middle to late 1800s. From that record, average annual rainfall of Arizona is 322 mm (12.7¹¹), while that of New Mexico is 340 mm (13.4¹¹), and mean annual temperature of New Mexico is cooler (12°C [53°F]) than Arizona (17°C [62°F]). As instrumental meteorological records extend back only about 100 to 120 yr throughout the Southwest, they are of limited utility for studying climate phenomena of long time frames. Hence, there is a need to extend the measured meteorological record further back in time using so-called Œnatural archive¹ paleoclimate records. Tree-ring data, which provide annual resolution, range throughout the Southwest, extend back in time for up to 1000 yr or more in various forests of the Southwest, and integrate well the influences of both temperature and precipitation, are useful for this assessment of climate of the Southwest. Tree growth of mid-elevation forests typically responds to moisture availability during the growing season, and a commonly used climate variable in paleo-precipitation studies is the Palmer Drought Severity Index (PDSI), which is a single variable derived from variation in precipitation and temperature. June-August PDSI strongly represents precipitation and, to a lesser extent, temperature of the year prior to the growing season (prior September through current August). The maximum intra-ring density of higher elevation trees can yield a useful record of summer temperature variation. The combined paleo-modern climate record has at least 3 occurrences of multi-decadal variation (50 to 80 yr) of alternating dry (below average PDSI) to wet (above average PDSI). The amplitude of this variation has increased since the 1700s. The most obvious feature of the temperature record is its current increase to an extent unprecedented in the last 400 yr. Because this warming trend is outside the variation of the natural archives, it is possible that anthropogenic impacts, such as increased atmospheric concentrations of greenhouse trace gases, are playing a role in climate of the Southwest. Accordingly, this pattern merits further research in search of its cause or combination of causes.
