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Our objective was to quantitatively characterize the landscape of climate-relevant resource decisions in the southwestern United States. We worked with stakeholders to determine actual uses of climate-relevant information used in natural resource decisions. We used content analysis of federal register records of decisions and stakeholder consultative groups to develop a survey of decision makers querying the use of climate information in decisions. We sought to create a classification of decisions attributes, information needs, and decision processes that rely on climate science. We sought to engage stakeholder consultative groups to define mechanisms for best filtering, delivering and interpreting what has become...
Abstract (from AGU 100): This study investigates snowmelt and streamflow responses to cloudiness variability across the mountainous parts of the western United States. Twenty years (1996–2015) of Geostationary Operational Environmental Satellite‐derived cloud cover indices (CC) with 4‐km spatial and daily temporal resolutions are used as a proxy for cloudiness. The primary driver of nonseasonal fluctuations in daily mean solar insolation is the fluctuating cloudiness. We find that CC fluctuations are related to snowmelt and snow‐fed streamflow fluctuations, to some extent (correlations of <0.5). Multivariate linear regression models of daily snowmelt (MELT) and streamflow (ΔQ) variations are constructed for each...
Future changes in the number of dry days per year can either reinforce or counteract projected increases in daily precipitation intensity as the climate warms. We analyze climate model projected changes in the number of dry days using 28 coupled global climate models from the Coupled Model Intercomparison Project, version 5 (CMIP5). We find that the Mediterranean Sea region, parts of Central and South America, and western Indonesia could experience up to 30 more dry days per year by the end of this century. We illustrate how changes in the number of dry days and the precipitation intensity on precipitating days combine to produce changes in annual precipitation, and show that over much of the subtropics the change...
A new method for automatic detection of atmospheric rivers (ARs) is developed and applied to an atmospheric reanalysis, yielding an extensive catalog of ARs land-falling along the west coast of North America during 1948–2017. This catalog provides a large array of variables that can be used to examine AR cases and their climate-scale variability in exceptional detail. The new record of AR activity, as presented, validated and examined here, provides a perspective on the seasonal cycle and the interannual-interdecadal variability of AR activity affecting the hydroclimate of western North America. Importantly, AR intensity does not exactly follow the climatological pattern of AR frequency. Strong links to hydroclimate...
Abstract (from AMS100): Between water years 2012 and 2017, the Truckee–Carson river system in the western United States experienced both historic-low and record-high Sierra Nevada snowpack, anomalously warm temperatures, and winter and spring flooding. As part of an ongoing collaborative modeling research program in the river system, researchers conduct annual interviews with key local water managers to characterize local climate adaptation strategies and implementation barriers, and identify science information needs to prioritize ongoing research activities. This article presents new findings from a third wave of interviews conducted with the same water managers following the historic 2017 wet year. Comparison...
Abstract (from http://journals.ametsoc.org/doi/abs/10.1175/JHM-D-16-0194.1): This study investigates the spatial and temporal variability of cloudiness across mountain zones in the western United States. Daily average cloud albedo is derived from a 19-yr series (1996–2014) of half-hourly Geostationary Operational Environmental Satellite (GOES) images. During springtime when incident radiation is active in driving snowmelt–runoff processes, the magnitude of daily cloud variations can exceed 50% of long-term averages. Even when aggregated over 3-month periods, cloud albedo varies by ±10% of long-term averages in many locations. Rotated empirical orthogonal functions (REOFs) of daily cloud albedo anomalies over high-elevation...
Abstract (from http://journals.ametsoc.org/doi/abs/10.1175/JHM-D-14-0236.1): Global climate model (GCM) output typically needs to be bias corrected before it can be used for climate change impact studies. Three existing bias correction methods, and a new one developed here, are applied to daily maximum temperature and precipitation from 21 GCMs to investigate how different methods alter the climate change signal of the GCM. The quantile mapping (QM) and cumulative distribution function transform (CDF-t) bias correction methods can significantly alter the GCM’s mean climate change signal, with differences of up to 2°C and 30% points for monthly mean temperature and precipitation, respectively. Equidistant quantile...
The impacts of different emission levels and climate change conditions to landscape-scale natural vegetation could have large repercussions for ecosystem services and environmental health. We forecast the risk-reduction benefits to natural landscapes of lowering business-as-usual greenhouse gas emissions by comparing the extent and spatial patterns of climate exposure to dominant vegetation under current emissions trajectories (Representative Concentration Pathway, RCP8.5) and envisioned Paris Accord target emissions (RCP4.5). This comparison allows us to assess the ecosystem value of reaching targets to keep global temperature warming under 2°C. Using 350,719 km2 of natural lands in California, USA, and the mapped...
Abstract (from RMetS): Over the Upper Colorado River basin (UCRB), temperatures in widely used gridded data products do not warm as much as mean temperatures from a stable set of U.S. Historical Climatology Network (USHCN) stations, located at generally lower elevations, in most months of the year. This is contrary to expectations of elevation‐dependent warming, which suggests that warming increases with elevation. These findings could reflect (a) a genuine absence of elevation‐dependent warming in the region, (b) systematic non‐climatic influences on either the USHCN stations or high‐elevation stations, including known inhomogeneities related to changes in the time of observation and instrumentation, or (c) suppression...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/2015GL067613/full): This empirical study examines the influence of precipitation, temperature, and antecedent soil moisture on upper Colorado River basin (UCRB) water year streamflow over the past century. While cool season precipitation explains most of the variability in annual flows, temperature appears to be highly influential under certain conditions, with the role of antecedent fall soil moisture less clear. In both wet and dry years, when flow is substantially different than expected given precipitation, these factors can modulate the dominant precipitation influence on streamflow. Different combinations of temperature, precipitation, and soil moisture...
This project links climate, hydrological, and ecological changes over the next 30 years in a Great Basin watershed. In recent years, climate variability on annual and decadal time scales has been recognized as greater than commonly perceived with increasing impacts on ecosystems and available water resources. Changes in vegetation distribution, composition and productivity resulting from climate change affect plant water use, which in turn can alter stream flow, groundwater and eventually available water resources. To better understand these links, project researchers implemented two computer-based numeric models in the Cleve Creek watershed in the Schell Creek Range, east of Ely, Nevada. The application of the...
Native Americans in the Southwest United States are thought to be particularly vulnerable to climate change. Tribal resiliency to climate change can be affected by multiple climate-related threats and by tribal communities’ close reliance on natural resources for sustenance, economic development, and maintenance of cultural traditions. A scientifically rigorous assessment of such threats to Native Americans is a pressing need across southwestern landscapes. This project examined factors affecting Native American tribes, including water rights for fish and wildlife, protection of wetlands, and enhancement and recovery of the Pyramid Lake, Nevada fishery, and protection of important fish species. This project aimed...
Abstract (from AMS): The upper Colorado River basin (UCRB) is one of the primary sources of water for the western United States, and increasing temperatures likely will elevate the risk of reduced water supply in the basin. Although variability in water-year precipitation explains more of the variability in water-year UCRB streamflow than water-year UCRB temperature, since the late 1980s, increases in temperature in the UCRB have caused a substantial reduction in UCRB runoff efficiency (the ratio of streamflow to precipitation). These reductions in flow because of increasing temperatures are the largest documented temperature-related reductions since record keeping began. Increases in UCRB temperature over the past...
Abstract (from http://journals.ametsoc.org/doi/full/10.1175/WCAS-D-16-0008.1): Resource managers and decision-makers are increasingly tasked with integrating climate change science into their decisions about resource management and policy development. This often requires climate scientists, resource managers, and decision-makers to work collaboratively throughout the research processes, an approach to knowledge development that is often called “coproduction of knowledge.” The goal of this paper is to synthesize the social science theory of coproduction of knowledge, the metrics currently used to evaluate usable or actionable science in several federal agencies, and insights from experienced climate researchers and...
(Abstract from Springer): There is increasing interest among scholars in producing information that is useful and usable to land and natural resource managers in a changing climate. This interest has prompted transitions from scientist- to stakeholder-driven or collaborative approaches to climate science. A common indicator of successful collaboration is whether stakeholders use the information resulting from the projects in which they are engaged. However, detailed examples of how stakeholders use climate information are relatively scarce in the literature, leading to a challenge in understanding what researchers can and should expect and plan for in terms of stakeholder use of research findings. Drawing on theoretical,...
Abstract (from PLOS ONE): The responses of individuals and populations to climate change vary as functions of physiology, ecology, and plasticity. We investigated whether annual variation in seasonal temperature and precipitation was associated with relative abundances of breeding bird species at local and regional levels in southern California, USA, from 1968–2013. We tested our hypotheses that abundances were correlated positively with precipitation and negatively with temperature in this semiarid to arid region. We also examined whether responses to climate varied among groups of species with similar land-cover associations, nesting locations, and migratory patterns. We investigated relations between seasonal...
Abstract (from Remote Sensing in Ecology and Conservation): The use of unmanned aerial vehicles (UAVs) to map and monitor the environment has increased sharply in the last few years. Many individuals and organizations have purchased consumer‐grade UAVs, and commonly acquire aerial photographs to map land cover. The resulting ultra‐high‐resolution (sub‐decimeter‐resolution) imagery has high information content, but automating the extraction of this information to create accurate, wall‐to‐wall land‐cover maps is quite difficult. We introduce image‐processing workflows that are based on open‐source software and can be used to create land‐cover maps from ultra‐high‐resolution aerial imagery. We compared four machine‐learning...
Cheatgrass (Bromus tectorum) has increased the extent and frequency of fire and negatively affected native plant and animal species across the Intermountain West (USA). However, the strengths of association between cheatgrass occurrence or abundance and fire, livestock grazing, and precipitation are not well understood. We used 14 years of data from 417 sites across 10,000 km(2) in the central Great Basin to assess the effects of the foregoing predictors on cheatgrass occurrence and prevalence (i.e., given occurrence, the proportion of measurements in which the species was detected). We implemented hierarchical Bayesian models and considered covariates for which > 0.90 or < 0.10 of the posterior predictive mass...
Atmospheric rivers (ARs), narrow atmospheric water vapor corridors, can contribute substantially to winter precipitation in the semiarid Southwest U.S., where natural ecosystems and humans compete for over-allocated water resources. We investigate the hydrologic impacts of 122 ARs that occurred in the Salt and Verde river basins in northeastern Arizona during the cold seasons from 1979 to 2009. We focus on the relationship between precipitation, snow water equivalent (SWE), soil moisture, and extreme flooding. During the cold season (October through March) ARs contribute an average of 25%/29% of total seasonal precipitation for the Salt/Verde river basins, respectively. However, they contribute disproportionately...