Assessing regional hydrologic responses to past climate changes can offer a guide for how water resources might respond to ongoing and future climate change. Here we employed a coupled water balance ...and lake evaporation model to examine Walker Lake behaviors during the Medieval Climate Anomaly (MCA), a time of documented hydroclimatic extremes. Together, a 14C‐based shoreline elevation chronology, submerged subfossil tree stumps in the West Walker River, and regional paleoproxy evidence indicate a ~50 year pluvial episode that bridged two 140+ year droughts. We developed estimates of MCA climates to examine the transient lake behavior and evaluate watershed responses to climate change. Our findings suggest the importance of decadal climate persistence to elicit large lake‐level fluctuations. We also simulated the current 2012–2015 California‐Nevada drought and found that the current drought exceeds MCA droughts in mean severity but not duration.
Key Points
Model‐proxy comparisons in terminal lake basins contextualize past and present hydroclimates
Climate conditions require decadal persistence to elicit complete lake‐level oscillations
The current CA‐NV drought exceeds past droughts in mean severity but not duration
Limiting climate warming to <2°C requires increased mitigation efforts, including land stewardship, whose potential in the United States is poorly understood. We quantified the potential of natural ...climate solutions (NCS)-21 conservation, restoration, and improved land management interventions on natural and agricultural lands-to increase carbon storage and avoid greenhouse gas emissions in the United States. We found a maximum potential of 1.2 (0.9 to 1.6) Pg CO
e year
, the equivalent of 21% of current net annual emissions of the United States. At current carbon market prices (USD 10 per Mg CO
e), 299 Tg CO
e year
could be achieved. NCS would also provide air and water filtration, flood control, soil health, wildlife habitat, and climate resilience benefits.
During the termination of the last glacial period the western U.S. experienced exceptionally wet conditions, driven by changes in location and strength of the mid-latitude winter storm track. The ...distribution of modern winter precipitation is frequently characterized by a north-south wet/dry dipole pattern, controlled by interaction of the storm track with ocean-atmosphere conditions over the Pacific and Atlantic Oceans. Here we show that a dipole pattern of similar geographic extent persisted and switched sign during millennial-scale abrupt climate changes of the last deglaciation, based on a new lake level reconstruction for pluvial Lake Chewaucan (northwestern U.S.), and a compilation of regional paleoclimate records. This suggests the dipole pattern is robust, and one mode may be favored for centuries, thereby creating persistent contrasting wet/dry conditions across the western U.S. The TraCE-21k climate model simulation shows an equatorward enhancement of winter storm track activity in the northeastern Pacific, favoring wet conditions in southwestern U.S. during the second half of Heinrich Stadial 1 (16.1-14.6 ka) and consistent with paleoclimate evidence. During the Bølling/Allerød (14.6-12.8 ka), the northeastern Pacific storm track contracted poleward, consistent with wetter conditions concentrated poleward toward the northwest U.S.
Agricultural irrigation accounts for a large fraction of the total water use in the western United States. The Mapping Evapotranspiration at high Resolution with Internalized Calibration (METRIC) ...remote sensing energy balance model is being used to estimate historical agricultural water use in western Nevada to evaluate basin‐wide water budgets. Each METRIC evapotranspiration (ET) estimate must be calibrated by a trained user, which requires some iterative time investment and results in variation in ET estimates between users. An automated calibration algorithm for the METRIC model was designed to generate ET estimates comparable to those from trained users by mimicking the manual calibration process. Automated calibration allows for rapid generation of METRIC ET estimates with minimal manual intervention, as well as uncertainty and sensitivity analysis of the model. The variation in ET estimates generated by the automated calibration algorithm was found to be similar to the variation in manual ET estimates. Results indicate that uncertainty was highest for fields with low ET levels and lowest for fields with high ET levels, with a seasonal mean uncertainty of approximately 5% for all fields. In addition, in a blind comparison, automated daily and seasonal ET estimates compared well with flux tower measurement ET data at multiple sites. Automated methods can generate first‐order ET estimates that are similar to time intensive manual efforts with less time investment.
Shorelines that formed in closed watershed–lake systems record past climate conditions. A simple monthly water balance model was used to explore the link between past climates, paleoclimate proxies, ...and the hydrologic system response of a closed watershed–lake system in the Great Basin, USA. The model was applied at a high spatial resolution and calibrated with available modern hydroclimate and watershed data and then used with existing paleolake shoreline estimates to investigate how climate and hydrologic conditions in the late Pleistocene differed from modern conditions. A range of climate conditions, ∆T (0 to −8 °C) and ∆P (1.9–2.4) from the modern climate, resulted in steady model simulations of the late Pleistocene lake highstand. Modeling results also indicate the watershed–lake system response is much more sensitive to changes in precipitation than to changes in temperature, and that the range of possible combinations of these variables can be reduced significantly when the results are compared with an independent modeling study that inferred paleoclimate conditions from glacial moraines in the Wind River Range near the eastern portion of the Great Basin. The modeling effort also revealed that physiographic heterogeneities and seasonality play a significant role in how the watershed–lake system responds to changes in precipitation and temperature, highlighting the importance of simulating the system behavior with an appropriate degree of spatial resolution. The significance of model calibration and performance evaluation over the modern period was demonstrated through a comparison of the calibrated model results with those obtained using default parameter values with the original model.
Raptors are the most prevalent group of urban apex predators, and the majority of raptor genera in North America have been recorded using urban areas. Prior research assessments along urban-wildland ...gradients show that urban habitat preference varies by raptor species and that raptor nesting preferences within urban settings may vary. Attempts to understand the intra- and inter-specific nesting patterns along an urban gradient would advance extant knowledge. Here we present the locations of individual nest sites of nine raptor species along an urban gradient in Reno-Sparks, NV. We developed an urban density model based on the number of residents, number of employees, and building footprints and number of floors for built structures within each land parcel at four spatial scales, representing nest site, macrohabitat, average nearest-nest, and landscape scales. Cooper’s Hawks (
Accipiter cooperii
), Sharp-shinned Hawks (
Accipiter striatus
), and Red-tailed Hawks (
Buteo jamaicensis
) nested across the widest range of the urban spectrum and closest to the urban core, whereas Golden Eagles (
Aquila chrysaetos
) and Swainson’s Hawks (
Buteo swainsonii
) nested on the urban fringe. Urban density for all nest locations was lowest at the nest-site scale, and the highest at the average nearest-nest and landscape scales. Raptors tended to occupy a wide range of the building-area density spectrum but not the building-height or employee density spectrums indicative of the attractiveness of suburban habitat.
Abstract First- and second-born adolescents' and their parents' perceptions of adolescents' decision-making autonomy were compared from ages 12 to 19 in a longitudinal sample of 145 predominantly ...White, middle class families. Utilizing a multivariate, multilevel modeling approach, differences in perceptions of adolescents' autonomy between parents and each adolescent, as well as by social-cognitive domain were examined. The present study found that when comparing parents' perceptions of their children at the same age, second-borns were granted more autonomy regarding conventional issues than first-borns during early adolescence, but by later adolescence first-borns were granted more autonomy regarding prudential issues than second-borns. However, comparisons between adolescents' and siblings' perceptions showed no differences. Potential reasons for, and implications of, differences in perceptions of adolescent autonomy are discussed.
The structure and design of future urban development can have significant adverse effects on air pollutant emissions as well as other environmental factors. When considering the future impact of ...growth on mobile source emissions, we generally model the increase in vehicle kilometers traveled (VKT) as a function of population growth. However, diverse and poorly planned urban development (i.e., urban sprawl) can force higher rates of motor vehicle use and in return increase levels of pollutant emissions than alternative land-use scenarios. The objective of this study is to develop and implement an air quality assessment tool that takes into account the influence of alternative growth and development scenarios on air quality.
The use of scenario-based techniques in land use planning has been around since the late 1940s and been tested in many different applications to aid in decision-making. In this study, we introduce the development of an advanced interactive scenario-based land use and atmospheric chemistry modeling system coupled with a GIS (Geographical Information System) framework. The modeling system is designed to be modular and includes land use/land cover information, transportation, meteorological, emissions, and photochemical modeling components. The methods and modularity of the developed system allow its application to both broad areas and applications.
To investigate the impact of possible land use change and urbanization, we evaluated a set of alternative future patterns of land use developed for a study area in Southwest California. Four land use and two population variants (increases of 500k and 1M) were considered. Overall, a Regional Low-Density Future was seen to have the highest pollutant emissions, largest increase in VKT, and the greatest impact on air quality. On the other hand, a Three-Centers Future appeared to be the most beneficial alternative future land-use scenario in terms of air quality. For all cases, the increase in population was the main factor leading to the change on predicted pollutant levels.
Studies of future management and policy options based on different assumptions provide a mechanism to examine possible outcomes and especially their likely benefits and consequences. The San Pedro ...River in Arizona and Sonora, Mexico is an area that has undergone rapid changes in land use and cover, and subsequently is facing keen environmental crises related to water resources. It is the location of a number of studies that have dealt with change analysis, watershed condition, and most recently, alternative futures analysis. The previous work has dealt primarily with resources of habitat, visual quality, and groundwater related to urban development patterns and preferences. In the present study, previously defined future scenarios, in the form of land-use/land-cover grids, were examined relative to their impact on surface-water conditions (e.g., surface runoff and sediment yield). These hydrological outputs were estimated for the baseline year of 2000 and predicted twenty years in the future as a demonstration of how new geographic information system-based hydrologic modeling tools can be used to evaluate the spatial impacts of urban growth patterns on surface-water hydrology.
Megadroughts are not devoid of interannual precipitation variability. However, the frequency and magnitude of occasional wet years must be limited in order to be consistent with geologic evidence ...indicating terminal lake lowstands during past megadroughts. We present a series of hydrologic model simulations of Walker Lake, a western Great Basin terminal lake, where varying return intervals of increased cool-season (October–April) precipitation are superimposed upon a megadrought climate. Estimated megadrought lowstands are achieved with wetter years returning every 5–10 years. Total cool season moisture transport derived from the 20th Century Reanalysis between 1895 and 2012 A.D. was positively correlated with cool-season precipitation during the corresponding year (0.49, p < 0.01). Daily moisture transport exceeding the 95th percentile is used as a surrogate for atmospheric river events. Wetter (drier) years had a greater (lesser) fraction of total cool season transport occurring on atmospheric river days, indicating their important role in driving western Great Basin hydroclimate variability.
•Hydrologic modeling identifies frequency/magnitude of wet years during megadrought.•Wetter years can recur no more frequently than at 5–10 year intervals.•Atmospheric rivers important for western Great Basin hydroclimate variability.
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