RSS 1.0CLIMAS (Climate Assessment for the Southwest)
ABOUT THE COLLECTION
The Climate Assessment for the Southwest (CLIMAS) - a NOAA funded partnership between the University of Arizona, the Inter Tribal Council of Arizona, and New Mexico State University—has been working with stakeholders from the private sector, academia, local, state, federal, and tribal government since 1998 to help bring the best-available knowledge to challenges related to weather and climate in the Southwest.
These collections include CLIMAS publications originally made available on the CLIMAS website https://climas.arizona.edu.
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Recent Submissions
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Climate and society in the US Southwest: the context for a regional assessmentWe examine the general relationships between climate and society in the US Southwest providing a context for the ongoing Climate Assessment for the Southwest (CLIMAS) Project. We review 5 key contextual elements of the region‹its demography, economy, land, water, and institutions and values‹and indicate how these conditions predispose certain social groups, economic sectors, or geographic areas to be more or less vulnerable, adaptable, or responsive to climate variability, climate information and climate change. Given the rapid influx of people into the region, the significant economic growth, and competing demands for water and other resources, especially in urban areas, vulnerability to climatic variations is already increasing in some areas of the Southwest. Differences in income, access to institutional resources, or employment options make some individuals or groups less able to cope with the adverse effects of climate changes or to use climate information to guide decisions. And the ability to respond to climatic variability and make the best use of climate information often is constrained both by institutional obligations and by the tense politics of some public land management in the region. Yet, improved climate information could assist decision-makers in dealing with these and other climate-related problems within the region, so long as institutional structures, public attitudes, and other internal and external conditions provide the flexibility to use the information in appropriate ways.
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Climate variability and the vulnerability of ranching in southeastern Arizona: a pilot studyFor ranchers in the Southwest, unanticipated droughts pose serious management challenges. Social and economic factors combine with the physical impacts of drought to render ranchers more vulnerable to climate variability. Using agricultural census data and interviews with ranchers, we analyze ranchers¹ responses to drought events in 1996 and 1999. From this analysis we develop an initial assessment of the principal factors contributing to the vulnerability of ranching in southeastern Arizona to climatic variability, and we make some preliminary determinations regarding the potential use of climate information in mitigating this vulnerability. During drought, climatic conditions can combine with poor cattle prices and high feed costs to strain ranchers¹ resources. The ability to cope with drought is further complicated by changes in environmental policy and pressure from urban growth. In these circumstances, ranchers reported being tempted to sell their private ranch property to development interests. Although our pilot study identified smaller operations as the most vulnerable to climatic variability in the context of policy and economic uncertainty, these operations reported less utility in climate information. The multidimensional nature of vulnerability suggests that climate information will be most useful to ranching operations of all sizes if it is integrated with market, policy and other economic information and if existing information distribution channels are used to reach ranchers.
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Factors affecting seasonal forecast use in Arizona water management: a case study of the 1997-98 El NiñoThe 1997-98 El Niño was exceptional, not only because of its magnitude, but also because of the visibility and use of its forecasts. The 3 to 9 mo advance warning of a wet winter with potential flooding in the US Southwest, easily accessible by water management agencies, was unprecedented. Insights about use of this information in operational water management decision processes were developed through a series of semi-structured in-depth interviews with key personnel from a broad array of agencies responsible for emergency management and water supply, with jurisdictions ranging from urban to rural and local to regional. Interviews investigated where information was acquired, how it was interpreted and how it was incorporated into specific decisions and actions. In addition, technical and institutional barriers to forecast use are explored. Study findings emphasize (1) the need for special handling of tailored forecast products on a regional scale, (2) the need for systematic regional forecast evaluation and (3) the potential for climate information to directly affect water management decisions through integrating climate forecasts into water supply outlooks where appropriate.
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Designing Institutions to Support Local-Level Climate Change Adaptation: Insights from a Case Study of the U.S. Cooperative Extension SystemIn light of global climate change, adaptation will be necessary at all levels of social organization. However, the adaptation literature emphasizes that because the impacts of climate change and vulnerability are locally specific, adaptation is inevitably local. In this paper, in order to inform the design of institutions that can encourage and support effective local-level adaptation, the authors derive principles for their design theoretically and use a case study to explore how these principles could be practically implemented. Ten design principles are synthesized from principles derived from reviews of the literatures on local-level adaptation, usable science, and boundary organizations. Bringing these three literatures together highlights the characteristics of boundary organizations that make them particularly valuable for addressing the challenges of local-level adaptation. The case study then illustrates how an existing boundary organization, The University of Arizona Cooperative Extension, of the U.S. Cooperative Extension System (CES), implements these principles in its organizational structure and in the daily practice of Extension professionals. It also highlights the significance of the CES’s existing social networks and social capital for facilitating their implementation. From the case study it is concluded that the CES is uniquely positioned to serve an important role in a national adaptation strategy for the United States in supporting local-level adaptation in urban and rural communities across the country.
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CHANGE: Climate and Hydrology Academic Network for Governance and the EnvironmentRecent research shows profound changes underway in climate and hydrology and their effects on ecosystems and water resources. Along international borders, climate, water, and governance interact at multiple levels, increasing the complexity of managing water and natural resources. Moreover, the effective use of climatological and hydrological information particular to the border areas is constrained by a lack of understanding between scientists and decision makers and by regulatory and legal constraints. Motivated by these concerns, Mexican, American, and Canadian climate specialists, social scientists, and agency representatives attending a workshop on environmental change proposed a collegial North American knowledge network to better infuse climate, water, and policy science into transboundary decision making.
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Wildfire Management and Forecasting Fire Potential: The Roles of Climate Information and Social Networks in the Southwest United StatesContinuing progress in the fields of meteorology, climatology, and fire ecology has enabled more proactive and risk-tolerant wildland fire management practices in the United States. Recent institutional changes have also facilitated the incorporation of more advanced climate and weather research into wildland fire management. One of the most significant changes was the creation of Predictive Services in 1998, a federal interagency group composed, in part, of meteorologists who create climate- and weather-based fire outlooks tailored to fire manager needs. Despite the numerous forecast products now available to fire managers, few studies have examined how these products have affected their practices. In this paper the authors assess how fire managers in the Southwest region of the United States perceive and incorporate different types of information into their management practices. A social network analysis demonstrates that meteorologists have become central figures in disseminating information in the regional interagency fire management network. Interviews and survey data indicate that person-to-person communication during planning phases prior to the primary fire season is key to Predictive Services’ success in supporting fire managers’ decision making. Over several months leading up to the fire season, predictive forecasts based on complex climate, fuels, and fire-risk models are explained to fire managers and updated through frequent communication. The study’s findings suggest that a significant benefit of the information sharing process is the dialogue it fosters among fire managers, locally, regionally, and nationally, which better prepares them to cooperate and strategically plan for the fire season.
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Climate Factors Influencing Coccidioidomycosis Seasonality and OutbreaksAlthough broad links between climatic factors and coccidioidomycosis have been established, the identification of simple and robust relationships linking climatic controls to seasonal timing and outbreaks of the disease has remained elusive. Using an adaptive data-oriented method for estimating date of exposure, in this article I analyze hypotheses linking climate and dust to fungal growth and dispersion, and evaluate their respective roles for Pima County, Arizona. Results confirm a strong bimodal disease seasonality that was suspected but not previously seen in reported data. Dispersion-related conditions are important predictors of coccidioidomycosis incidence during fall, winter, and the arid foresummer. However, precipitation during the normally arid foresummer 1.5–2 years before the season of exposure is the dominant predictor of the disease in all seasons, accounting for half of the overall variance. Cross-validated models combining antecedent and concurrent conditions explain 80% of the variance in coccidioidomycosis incidence.
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Applications of Monsoon Research: Opportunities to Inform Decision Making and Reduce Regional VulnerabilityThis article presents ongoing efforts to understand interactions between the North American monsoon and society in order to develop applications for monsoon research in a highly complex, multicultural, and binational region. The North American monsoon is an annual precipitation regime that begins in early June in Mexico and progresses northward to the southwestern United States. The region includes stakeholders in large urban complexes, productive agricultural areas, and sparsely populated arid and semiarid ecosystems. The political, cultural, and socioeconomic divisions between the United States and Mexico create a broad range of sensitivities to climate variability as well as capacities to use forecasts and other information to cope with climate. This paper highlights methodologies to link climate science with society and to analyze opportunities for monsoon science to benefit society in four sectors: natural hazards management, agriculture, public health, and water management. A list of stakeholder needs and a calendar of decisions is synthesized to help scientists link user needs to potential forecasts and products. To ensure usability of forecasts and other research products, iterative scientist–stakeholder interactions, through integrated assessments, are recommended. These knowledge-exchange interactions can improve the capacity for stakeholders to use forecasts thoughtfully and inform the development of research, and for the research community to obtain feedback on climate-related products and receive insights to guide research direction. It is expected that integrated assessments can capitalize on the opportunities for monsoon science to inform decision making and, in the best instances, reduce regional climate vulnerabilities and enhance regional sustainability.
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Reconstructions of Columbia River Streamflow from Tree‐Ring Chronologies in the Pacific Northwest, USAWe developed Columbia River streamflow reconstructions using a network of existing, new, and updated tree-ring records sensitive to the main climatic factors governing discharge. Reconstruction quality is enhanced by incorporating tree-ring chronologies where high snowpack limits growth, which better represent the contribution of cool-season precipitation to flow than chronologies from trees positively sensitive to hydroclimate alone. The best performing reconstruction (back to 1609 CE) explains 59% of the historical variability and the longest reconstruction (back to 1502 CE) explains 52% of the variability. Droughts similar to the high-intensity, long-duration low flows observed during the 1920s and 1940s are rare, but occurred in the early 1500s and1630s-1640s. The lowest Columbia flow events appear to be reflected in chronologies both positively and negatively related to streamflow, implying low snowpack and possibly low warm-season precipitation. High flows of magnitudes observed in the instrumental record appear to have been relatively common, and high flows from the1680s to 1740s exceeded the magnitude and duration of observed wet periods in the late-19th and 20th Century. Comparisons between the Columbia River reconstructions and future projections of streamflow derived from global climate and hydrologic models show the potential for increased hydrologic variability, which could present challenges for managing water in the face of competing demands
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Weather, Climate, and Environmental Water TransactionsObtaining water for environmental purposes, such as habitat restoration or water quality improvements, has become an important objective in many parts of the world. Such water acquisitions are likely to become more challenging as regional water demand and supply patterns are altered by climate change. In regions where water supplies are already fully claimed, voluntary negotiated transactions have become a key means to obtain water for the environment. The cost of acquiring water in such transactions is hypothesized to vary with regional weather and climate conditions due to both the actual effects of temperature and precipitation on water supply and demand and the perceptions water users may hold about these effects. This article develops econometric models to examine the effect of temperature and precipitation on water lease prices in four U.S. states located in the desert southwest. Water leases for environmental and nonenvironmental purposes are contrasted to understand the differing nature of these lease markets and the role of weather and climate variables. The authors’ analysis finds that temperature, precipitation, regional income, and population changes are variables that have differing effects in the two lease markets. Overall, analysis of over 20 yr of data shows the need to consider climate and weather factors given the growing importance of water leases as a tool to secure water for the environment.
