Edwin P. Maurer

• Ph.D.
• Santa Clara University

Presented succinctly by the United Nations, “Climate change is the defining issue of our time.” As flooding, heatwaves, and ice sheet failure become more frequent in the coming decades, considering cascading climate change impacts is critical, particularly when planning for infrastructure with long design lives. Identification of marginalized block...

Anthropogenic climate change amounts to a rapidly approaching, “new” stressor in the Sacramento–San Joaquin Delta system. In response to California’s extreme natural hydroclimatic variability, complex water-management systems have been developed, even as the Delta’s natural ecosystems have been largely devastated. Climate change is projected to cha...

The increasingly warmer temperatures and changes in precipitation patterns expected from climatic changes in the Sierra Nevada are projected to drive declines in snowpack, earlier streamflow timing, shifts in evapo-transpiration and soil moisture, and substantial increases in summer stream temperatures with associated declines in water quality. Her...

Statistical downscaling is a commonly used technique for translating large-scale climate model output to a scale appropriate for assessing impacts. To ensure downscaled meteorology can be used in climate impact studies, downscaling must correct biases in the large-scale signal. A simple and generally effective method for accommodating systematic bi...

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....

Most recent climate change impact studies are using Coupled Model Intercomparison Project Phase 5 (CMIP5) projections to replace older generation CMIP3 projections. Here we evaluate whether differences between projections based on comparable high emission pathways of a seven-member general circulation model CMIP3 versus CMIP5 ensemble change our un...

Water temperature is a primary physical factor regulating the persistence and distribution of aquatic taxa. Considering projected increases in air temperature and changes in precipitation in the coming century, accurate assessment of suitable thermal habitats in freshwater systems is critical for predicting aquatic species' responses to changes in...

We describe the expansion of a publicly available archive of downscaled climate and hydrology projections for the United States. Those studying or planning to adapt to future climate impacts demand downscaled climate model output for local or regional use. The archive we describe attempts to fulfill this need by providing data in several formats, s...

Background/Question/Methods Downscaling is necessary to translate coarsely resolved global climate model (GCM) projections to regional and local changes. However, climatic extremes are often as important to ecosystems as long-term means, and often, means and the extremes are not tightly correlated. But downscaling efforts thus far have focused mo...

Water temperature is a primary physical factor regulating the persistence and distribution of aquatic taxa. Considering projected increases in temperature and changes in precipitation in the coming century, accurate assessment of suitable thermal habitat in freshwater systems is critical for predicting aquatic species responses to changes in climat...

When applied to remove climate model biases in precipitation, quantile mapping can in some settings modify the simulated difference in mean precipitation between two eras. This has important implications when the precipitation is used to drive an impacts model that is sensitive to changes in precipitation. The tendency of quantile mapping to alter...

This paper describes a publicly available, long-term (1915-2011), hydrologically consistent dataset for the conterminous United States, intended to aid in studies of water and energy exchanges at the land surface. These data are gridded at a spatial resolution of 1/16° latitude/longitude and are derived from daily temperature and precipitation obse...

Due to global warming the climate of central Chile is expected to experience dramatic changes in the 21st century including declining precipitation, earlier streamflow peaks, and a greater proportion of precipitation falling as rain. We used 12-member ensembles of General Circulation Models (GCMs) from the Coupled Model Intercomparison Project Phas...

When applied to remove climate model biases in precipitation, quantile mapping can in some settings modify the simulated trends. This has important implications when the precipitation will be used to drive an impacts model that is sensitive to changes in precipitation. We use daily precipitation output from 12 general circulation models (GCMs) over...

In the Upper Colorado River Basin (UCRB), the principal source of water in the southwestern U.S., demand exceeds supply in most years, and will likely continue to rise. While General Circulation Models (GCMs) project surface temperature warming by 3.5 to 5.6°C for the area, precipitation projections are variable, with no wetter or drier consensus....

SWAT model efficiency statistics for the Upper Colorado River Basin. (XLSX)

Downscaled and hydrologically modeled projections from an ensemble of 16 Global Climate Models suggest that flooding may become more intense on the western slopes of the Sierra Nevada mountains, the primary source for California's managed water system. By the end of the 21st century, all 16 climate projections for the high greenhouse-gas emission S...

Climate model simulations disagree on whether future precipitation will increase or decrease over California, which has impeded efforts to anticipate and adapt to human-induced climate change. This disagreement is explored in terms of daily precipitation frequency and intensity. It is found that divergent model projections of changes in the inciden...

Climate change is already affecting many fish and wildlife populations. Managing these will require an understanding of the nature, magnitude, and distribution of current and future climate impacts. Scientists and managers have at their disposal a wide array of models for projecting climate impacts that can be used to build such an understanding. H...

When correcting for biases in general circulation model (GCM) output, for example when statistically downscaling for regional and local impacts studies, a common assumption is that the GCM biases can be characterized by comparing model simulations and observations for a historical period. We demonstrate some complications in this assumption, with G...

Key Points Stream temperature is expected to increase by 1 to 5.5 oC Dissolved oxygen concentrations are expected to decrease Sediment concentrations are projected to decrease by about 50%

Central Chile is facing dramatic projections of climate change, with a consensus for declining precipitation, negatively affecting hydropower generation and irrigated agriculture. Rising from sea level to 6000 m within a distance of 200 km, precipitation characterization is difficult because of a lack of long-term observations, especially at higher...

When correcting for biases in general circulation model (GCM) output, for example when statistically downscaling for regional and local impacts studies, a common assumption is that the GCM biases can be characterized by comparing model simulations and observations for a historical period. We demonstrate some complications in this assumption, with G...

We describe a publicly available, long-term (1915 2010), hydrologically consistent data set for the conterminous United States, intended to aid in studies of water and energy exchanges at the land surface. These data are gridded at a spatial resolution of 1/16 degree latitude-longitude and are derived from daily temperature and precipitation observ...

Precipitation from the Eastern Sierra Nevada watersheds of Owens Lake and Mono Lake is one of the main water sources for Los Angeles' over 4 million people, and plays a major role in the ecology of Mono Lake and of these watersheds. We use the Variable Infiltration Capacity (VIC) hydrologic model at daily time scale, forced by climate projections f...

The Californian Mono Lake Basin (MLB) is a fragile ecosystem, for which a 1983 ruling carefully balanced water diversions with ecological needs without the consideration of global climate change. The hydroclimatologic response to the impact of projected climatic changes in the MLB has not been comprehensively assessed and is the focus of this study...

Sierra Nevada snowmelt and runoff is a key source of water for many of California’s 38 million residents and nearly the entire population of western Nevada. The purpose of this study was to assess the impacts of expected 21st Century climatic changes in the Sierra Nevada at the subwatershed scale, for all hydrologic flow components, and for a suite...

When applying a quantile mapping-based bias correction to daily temperature extremes simulated by a global climate model (GCM), the transformed values of maximum and minimum temperatures are changed, and the diurnal temperature range (DTR) can become physically unrealistic. While causes are not thoroughly explored, there is a strong relationship be...

When applying a quantile-mapping based bias correction to daily temperature extremes simulated by a global climate model (GCM), the transformed values of maximum and minimum temperatures are changed, and the diurnal temperature range (DTR) can become physically unrealistic. While causes are not thoroughly explored, there is a strong relationship be...

The sustainability of water resources in future decades is likely to be affected by increases in water demand due to population growth, increases in power generation, and climate change. This study presents water withdrawal projections in the United States (U.S.) in 2050 as a result of projected population increases and power generation at the coun...

Sixteen global general circulation models were used to develop probabilistic projections of temperature (T) and precipitation (P) changes over California by the 2060s. The global models were downscaled with two statistical techniques and three nested dynamical regional climate models, although not all global models were downscaled with all techniqu...

We develop a stream temperature model within the Soil and Water Assessment Tool (SWAT) that reflects the combined influence of meteorological (air temperature) and hydrological conditions (streamflow, snowmelt, groundwater, surface runoff, and lateral soil flow) on water temperature within a watershed. SWAT currently uses a linear air-stream temper...

Precipitation from the Eastern Sierra Nevada watersheds of Owens Lake and Mono Lake is one of the main water sources, and the one of highest quality, for Los Angeles' more than 4 million people. Winter snow is stored in the large snowpack reservoir, and meltwater (~0.2-0.5 million acre-feet) is delivered annually to the city in the dry season by th...

Changes in snowmelt runoff due to climate change are expected to impact seasonal stream temperatures and associated biogeochemical processes. Many hydrologic models, such as the soil water assessment tool (SWAT), determine stream temperature based solely on a linear relationship with air temperature. However, in situations where warmer spring tempe...

The Sierra Nevada mountain range is a key source of water for many of California's 37 million residents and nearly the entire population of Western Nevada. SWAT was successfully calibrated and validated at 35 unimpaired historical streamflow sites throughout the Sierra Nevada. SWAT was then driven by climate output from 16 General Circulation Model...

Scientists and others from academia, government, and the private sector increasingly are using climate model outputs in research and decision support. For the most recent assessment report of the Intergovernmental Panel on Climate Change, 18 global modeling centers contributed outputs from hundreds of simulations, coordinated through the Coupled Mo...

Downscaling climate model output for regional impact analysis must accommodate the biases in the climate model, since the biases tend to be large enough to confound meaningful local and regional scale impacts analysis. The bias correction is generally based on the assumption that the bias, as estimated for some base period, is stationary, so the sa...

Widespread acceptance that humans are affecting climate has lead to a growing demand for climate change information that is suitable for use in real-world decisions. Two key properties of such information are fine spatial resolution and rigorously quantified uncertainties. Here we compare contributions to future-climate uncertainty from imperfect k...

Recent efforts have generated a new empirical downscaling technique that is well-positioned to inform climate change vulnerability assessments for ecosystems as well as studies on future storm and flood frequency. The technique combines bias-correction (BC) of general circulation model (GCM) outputs with a constructed analogs approach (CA) for spat...

While a plethora of studies have investigated the changes in surface runoff and streamflow associated with climate change, only a few have investigated how warmer climates could affect stream temperature and water quality, and thus aquatic ecosystems. In this study, the Soil and Water Assessment Tool (SWAT) was used to assess the impact of climate...

Maurer, Edwin P., Levi D. Brekke, and Tom Pruitt, 2010. Contrasting Lumped and Distributed Hydrology Models for Estimating Climate Change Impacts on California Watersheds. Journal of the American Water Resources Association (JAWRA) 46(5):1024–1035. DOI: 10.1111/j.1752-1688.2010.00473.x Abstract: We compare the projected changes to streamflows for t...

Range distributions for many animal species across North America are shifting, many in directions consistent with anthropogenic climate change over the last century. Assuming climate change continues to act as a driver for geographic range shifts, theoretical northern range shift movements can be calculated using a bioclimatic envelope approach tha...

Three statistical downscaling methods were applied to NCEP/NCAR reanalysis (used as a surrogate for the best possible general circulation model), and the downscaled meteorology was used to drive a hydrologic model over California. The historic record was divided into an "observed" period of 1950–1976 to provide the basis for downscaling, and a "pro...

The old and useful paradigm used by water resource engineers, that hydrology in a given place is stationary, and hence it is sufficient to look into the past to plan for the future, does not hold anymore, according to climate change projections. This becomes especially true in snow-dominated regions like California, where not only the magnitude but...

Three statistical downscaling methods were applied to NCEP/NCAR reanalysis (used as a surrogate for the best possible general circulation model), and the downscaled meteorology was used to drive a hydrology model over California. The historic record was divided into an "observed" period of 1950–1976 to provide the basis for downscaling, and a "proj...

Temperature and precipitation change by country during 1951–2002 (same as Figure 4, except countries with >20% area changing are labeled). (6.00 MB TIF)

Seasonal temperature trends during 1951–2002. Both the magnitude of the trends (left) and p-value significance (right) of the trends are mapped out, and the area of significant change in each of the magnitude and p-value significance categories are provided at the bottom. The total height (positive plus negative) of the graph of trend magnitude is...

Climate Wizard interactive results web page. (3.65 MB TIF)

Model agreement in precipitation change. Map showing areas where at least 80% (13 of the 16 models) of the GCMs agree precipitation will either increase (blue areas) or decrease (brown areas). Areas in grey have less than 80% agreement in the direction of change in precipitation. Note that this map was created by overlaying all positive values from...

Seasonal precipitation trends during 1951–2002. Both the magnitude of the trends (left) and p-value significance (right) of the trends are mapped out, and the area of significant change in each of the magnitude and p-value significance categories are provided at the bottom. Terrestrial areas in white did not have sufficient station coverage for the...

Background: Although the message of "global climate change" is catalyzing international action, it is local and regional changes that directly affect people and ecosystems and are of immediate concern to scientists, managers, and policy makers. A major barrier preventing informed climate-change adaptation planning is the difficulty accessing, anal...

Global climate models encapsulate our best understanding of the physics of the climate system, but at a spatial scale that is too coarse to meet the needs of societal impacts researchers and decision makers. To meet these needs, we are undertaking systematic spatial downscaling of CMIP5 GCM simulations now being performed by modeling groups around...

Presentation highlights status and plans for a public-access archive of downscaled CMIP3 climate projections. Incorporating climate projection information into long-term evaluations of water and energy resources requires analysts to have access to projections at "basin-relevant" resolution. Such projections would ideally be bias-corrected to accoun...

This study provides an assessment of the potential impacts of climate change on the Eastern Sierra Nevada snowpack and snowmelt timing, using a combination of empirical (i.e., data-based) models, and computer simulation models forced by GCM-projected 21st century climatology (IPCC 2007 AR4 projections). Precipitation from the Eastern Sierra Nevada...

Virtually all fields of study and parts of society---from ecological science and nature conservation, to global development, multinational corporations, and government bodies---need to know how climate change has and may impact specific locations of interest. Our ability to respond to climate change depends on having convenient tools that make past...

Spatial downscaling of global climate model projections adds physically meaningful spatial detail, and brings the results down to a scale that is more relevant to human and ecological systems. Statistical/empirical downscaling methods are computationally inexpensive, and thus can be applied to large ensembles of global climate model projections. He...

This study evaluated 1950–2005 summer [June–August (JJA)] mean monthly air temperatures for two California air basins: the South Coast Air Basin (SoCAB) and the San Francisco Bay Area (SFBA). The study focuses on the more rapid post-1970 warming period, and its daily minima temperature Tmin and maxima temperature Tmax values were used to produce av...

1] Risk-based planning offers a robust way to identify strategies that permit adaptive water resources management under climate change. This paper presents a flexible methodology for conducting climate change risk assessments involving reservoir operations. Decision makers can apply this methodology to their systems by selecting future periods and...

Climate change is predicted to be one of the greatest drivers of ecological change in the coming century. Increases in temperature over the last century have clearly been linked to shifts in species distributions. Given the magnitude of projected future climatic changes, we can expect even larger range shifts in the coming century. These changes wi...

Temperature and precipitation from 16 climate models each using two emissions scenarios (lower B1 and mid-high A2) were used to characterize the range of potential climate changes for the Rio Lempa basin of Central America during the middle (2040–2069) and end (2070–2099) of the 21st century. A land surface model was applied to investigate the hydr...

Recent studies have indicated that generally warmer temperatures have led to reduced snowpack and earlier timing of peak snowmelt throughout California and the West, potentially resulting in serious consequences for ecosystems and human water supplies. While the link between increased temperatures and shifts in streamflow timing appears well establ...

As the world grapples with the challenge of quantifying the potential impacts of climate change, demand for local to regional-scale projections of relevant climate indicators is increasing. These projections provide essential information for decision-making in a broad range of sectors, including agriculture, water, and ecosystem management. Here, w...

We examine potential regional-scale impacts of climate change on sustainability of irrigated agriculture, focusing on the western San Joaquin Valley in California. We consider potential changes in irrigation water demand and supply, and quantify impacts on the hydrologic system, soil and groundwater salinity with associated crop yield reductions. O...

A primary challenge facing resource managers in accommodating climate change is determining the range and uncertainty in regional and local climate projections. This is especially important for assessing changes in extreme events, which will drive many of the more severe impacts of a changed climate. Since global climate models (GCMs) produce outpu...

Downscaling of climate model data is essential to local and regional impact analysis. We compare two methods of statistical downscaling to produce continuous, gridded time series of precipitation and surface air temperature at a 1/8-degree (approximately 140 km2 per grid cell) resolution over the western U.S. We use NCEP/NCAR Reanalysis data from 1...

To investigate possible future climate changes in California, a set of climate change model simulations was selected and evaluated. From the IPCC Fourth Assessment, simulations of twenty-first century climates under a B1 (low emissions) and an A2 (a medium-high emissions) emissions scenarios were evaluated, along with occasional comparisons to the...

Ensembles of historical climate simulations and climate projections from the World Climate Research Programme’s (WCRP’s) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset were investigated to determine how model credibility affects apparent relative scenario likelihoods in regional risk assessments. Methods were developed an...

Climate projections at relevant temporal and spatial scales are essential to assess potential future climate change impacts on climatologically diverse regions such as the northeast United States. Here, we show how both statistical and dynamical downscaling methods applied to relatively coarse-scale atmosphere-ocean general circulation model output...

A new data set enhances the abilities of researchers and decision‐makers to assess possible future climates, explore societal impacts, and approach policy responses from a risk‐based perspective. The data set, which consists of a library of 112 fine‐resolution climate projections, based on 16 climate models and three greenhouse gas emissions scenar...

Large changes in stiffness associated with cracking and yielding of reinforced concrete sections may be expected to occur during the dynamic response of reinforced concrete frames to earthquake ground shaking. These changes in stiffness in stories that experience cracking might be expected to cause relatively large peak interstory drift ratios. If...

1] Observed changes in the timing of snowmelt dominated streamflow in the western United States are often linked to anthropogenic or other external causes. We assess whether observed streamflow timing changes can be statistically attributed to external forcing, or whether they still lie within the bounds of natural (internal) variability for four l...

A simplified approach for modeling transmission losses in a stream is presented. A theory relating seepage from a channel with the depth of flow is simplified to a one-parameter relationship. A power relationship is then utilized for the stage-discharge relationship, which is coupled with the seepage relationship. This combined equation is integrat...

A hydrologic model was driven by the climate projected by 11 GCMs under two emissions scenarios (the higher emission SRES A2 and the lower emission SRES B1) to investigate whether the projected hydrologic changes by 2071–2100 have a high statistical confidence, and to determine the confidence level that the A2 and B1 emissions scenarios produce dif...

We combine 21st century projections from 32 global climate model (GCM) simulations produced for the Intergovernmental Panel on Climate Change Fourth Assessment, 16 GCMs each using both the lower SRES B1 and the higher SRES A2 greenhouse gas emissions scenarios. We use an established statistical downscaling procedure to produce sequences of precipit...

Using the latest available General Circulation Model (GCM) results we present an assessment of climate change impacts on California hydrology and water resources. The approach considers the output of two GCMs, the PCM and the HadCM3, run under two different greenhouse gas (GHG) emission scenarios: the high emission A1fi and the low emission B1. The...

In this paper we have presented a modeling and observational study of climatological surface temperature analyses for Coastal California. It was found that regional minimum temperatures are strongly correlated with regional sea surface temperature increases, a result in agreement with claims of global warming due to green house gases. Further analy...

Incorporating climate change information into long-term evaluations of water and energy resources requires analysts to have access to climate projection data that have been spatially downscaled to "basin-relevant" resolution. This is necessary in order to develop system-specific hydrology and demand scenarios consistent with projected climate scena...

An assessment of potential climate change scenarios projected to the year 2100 concluded that irrigated agriculture in the western San Joaquin Valley may adapt for a wide range of climate change scenarios. Projected reductions in surface water supply are expected to be offset in part by reduced crop water requirements due to faster crop development...

We examine the seasonal timing of flows on four major rivers in California, and how these are affected by climate variability and change. We measure seasonal timing of soil runoff and river flows by the "center timing" (CT), defined as the day when half the annual flow has passed a given measurement point. We use a physically-based surface hydrolog...

Two hydrologic models were used to study climate change runoff impacts in California's Central Valley. One model is a state-of-the-art, uncalibrated land surface model (Variable Infiltration Capacity model) while the other is an operational, calibrated rainfall-runoff model (NOAA/NWS Sacramento Soil Moisture Accounting model). The focus of the anal...

Simulation of whether precipitation arrives at the land surface in a liquid or frozen state can have a pronounced effect on the peak flows produced by a hydrologic model. While many hydrologic models rely on surface air temperature to discriminate precipitation type, both past studies and the current effort indicate that there can be substantial sh...

Erosion and sediment transport in a temperate forested watershed are predicted with a new sediment model that represents the main sources of sediment generation in forested environments (mass wasting, hillslope erosion, and road surface erosion) within the distributed hydrology-soil-vegetation model (DHSVM) environment. The model produces slope fai...

Some El Niño events produce unusually large precipitation amounts in Northern and Central California. We use a high-resolution global model of the atmosphere coupled to a physically-based model of surface hydrology to investigate effects of increased atmospheric CO2 and this type of El Niño, both individually and in combination, on monthly river fl...

Recent analyses of climate change over California have provided projections of the range of warming and other changes that the region may face by the end of the 21stcentury. The projected reduction in surface water availability, especially later in the growing season, and potentially increased water requirements is expected to cause California's fa...

The streams that flow from California's Sierra Nevada Mountains supply a major portion of the managed water in the state. These streams are showing discernable changes consistent with a warming climate, and continued warming over the next century will have dramatic effects. Projections of future climate assume different levels of greenhouse gas emi...

We use diagnostic studies of off-line variable infiltration capacity (VIC) model simulations of terrestrial water budgets and 21st-century climate change simulations using the parallel climate model (PCM) to estimate the time required to detect predicted changes in annual precipitation (P), evapotranspiration (E), and discharge (Q) in three sub-bas...

Quantifying the uncertainty, and source of uncertainty in the projected impacts of climate change on hydrology will help decision-makers interpret the confidence in different projected future hydrologic impacts. In this study the focus is on California, which is vulnerable to hydrologic impacts of climate change. Temperature and precipitation proje...

[1] Understanding the uncertainty in the projected impacts of climate change on hydrology will help decision-makers interpret the confidence in different projected future hydrologic impacts. We focus on California, which is vulnerable to hydrologic impacts of climate change. We statistically bias correct and downscale temperature and precipitation...

Understanding the uncertainty in the projected impacts of climate change on California's Sierra Nevada hydrology will clarify where hydrologic impacts can be expected with higher confidence, and will help address scientific questions related to possible improvements in climate modeling. In this study, we focus on California, a region that is vulner...

Understanding the space-time variability of runoff has important implications for climate because of the linkage of runoff and evapotranspiration and is a practical concern as well for the prediction of drought and floods. In contrast to many studies investigating the space-time variability of precipitation and temperature, there has been relativel...