Urban Water Demand in California to 2100: Incorporating Climate Change

Pacific Institute | August 28th, 2012

Climate change will have significant impacts in California not just on water supply, but also on water demand. A new, free tool from the Pacific Institute* helps water

Climate change will have significant impacts in California not just on water supply, but also on water demand. A new, free tool from the Pacific Institute* helps water managers to forecast urban water demand with four global climate change models and compare different possible futures to the year 2100 by altering greenhouse gas emissions, population projections, conservation and efficiency measures, and more. The research shows climate change will cause increased water use in California’s cities and suburbs, even as water supply is expected to diminish. Urban water use – residential plus commercial, industrial, and institutional uses – accounts for over 20% of the water use in California, and up to half of urban water use is outdoors. The new report Urban Water Demand in California to 2100: Incorporating Climate Change describes how warming due to climate change is causing increases in water demand for landscapes, and will continue to drive up future water demand, particularly as more Californians settle in warmer, drier inland areas. The Pacific Institute ran a number of scenarios through 2100. The analysis finds that climate change alone could increase urban water demand in 2100 by 8% percent, or around 1 million acre-feet, under a medium-high greenhouse gas emissions scenario. That is the amount of water needed to satisfy the current household needs of 6.7 million Californians. “A million acre-feet of water is significant, and, of course, climate is not the only driver affecting demand. But factoring levels of climate change into the mix is critical,” said Dr. Juliet Christian-Smith of the Pacific Institute Water Program. “Future water use in California depends on a range of factors – technological, political, and economic – many of which are uncertain, but water utilities still need to plan. We created a flexible modeling tool that allows users to run their own scenarios, comparing how a range of factors in a range of climate change scenarios is likely to affect future patterns of water use in their specific areas.”

Urbanization alters atmospheric dryness through land evapotranspiration

Nature Portfolio (Springer Nature) | September 23rd, 2023

User’s Manual for the Draper Climate-Distribution Software Suite with Data-Evaluation Tools

U.S. Geological Survey (USGS) | March 20th, 2019

Development of a time series of spatially distributed climate data is an important step in the process of developing physically based environmental models requiri

Development of a time series of spatially distributed climate data is an important step in the process of developing physically based environmental models requiring distributed inputs of climate data beyond what is available from observations collected at climate stations. To prepare inputs required for model-mapping units across the study area, climate data (temperature and precipitation) are distributed by combining data from gridded surfaces of mean-monthly climate-data values with (often) widely spaced daily pointobservations. Examples of climate-data files used to develop PRMS-formatted input files for the Merced River Basin Precipitation-Runoff Modeling System (PRMS) are includedin this manual. The Draper Climate-Distribution Software Suite (Draper Suite) consists of the Draper climate-distribution program (Draper) and several supporting pre- and post-processing applications. Draper combines spatially distributed input in the form of monthly averaged values for precipitation, maximum temperature, and minimum temperature with daily observed data from climate stations to estimate distributed climate-data values at predefined locations across a study area (typically adrainage basin) on a daily time step. Alternative methods are used when station data are limited or missing for a particular day. Draper uses a set of required and optional input andoutput files with defined formats and naming conventions. Ashell application also is available to manage multiple runs of the Draper application. Other applications in the Draper Suite include (1) a toolto find and interactively remove outliers in the input data, (2) atool to check and enforce a minimum daily temperature range, and (3) a tool to view output diagnostic information as time- series graphs. These tools can be used iteratively to evaluate and improve the results from Draper as part of a work flow involving physically-based environmental models, such as the Precipitation-Runoff Modeling System (PRMS).

USGS Science at Work in the Delta Estuary

U.S. Geological Survey (USGS) | November 19th, 2013

The San Francisco Bay and Sacramento-San Joaquin Delta form one of the largest estuaries in the United States. The “Bay-Delta” system provides water to more than 25 m

The San Francisco Bay and Sacramento-San Joaquin Delta form one of the largest estuaries in the United States. The “Bay-Delta” system provides water to more than 25 million California residents and vast farmlands, as well as key habitat for birds, fish, and other wildlife. To help ensure the health of this crucial estuary, the U.S. Geological Survey, in close cooperation with partner agencies and organizations, is providing science essential to addressing societal issues associated with water quantity and quality, sediment transportation, environmental contamination, animal health and status, habitat restoration, hazards, ground subsidence, and climate change.

Utah's Land, Water and Air 2022 Report to the Governor

Utah State University | November 30th, 2022

Variability and Trends in Precipitation, Temperature and Drought Indices in the State of California

Hydrology (MDPI) | March 28th, 2016

This study presents a comprehensive assessment of the variability and trends of the precipitation and temperature along with the trends in drought indices over the State

This study presents a comprehensive assessment of the variability and trends of the precipitation and temperature along with the trends in drought indices over the State of California. The non-parametric Mann–Kendall trend test is applied with a trend-free pre-whitening procedure in trend identification. A dataset containing 120-year (water years 1896–2015) monthly precipitation, average temperature, maximum temperature, minimum temperature and the Palmer Index for seven climatic regions of the state is used for this purpose. The results confirm previous work indicating that no clear trends are observed in precipitation, while a distinct warming trend is evident in temperature over the state. New findings of this study include: (1) in general, the variability of annual, winter (December–February) and spring (March–May) precipitation shows an increasing tendency, implying intensified frequency of the occurrence of dry or wet extremes; (2) on the annual scale and in the summer, statewide meteorological, hydrological and agricultural drought indices all have decreasing trends, indicating the more frequent occurrence of drought events; and (3) among seven regions, the South Coast Drainage region generally has the most significant warming trend, as well as the most significant declining trends in drought indices. Overall, these findings are highly meaningful from both theoretical and practical perspectives, in the context of providing critical information in developing prediction models and guiding water resources management practices, respectively.

Variable coastal hypoxia exposure and drivers across the southern California Current

Nature Portfolio (Springer Nature) | May 25th, 2021

Declining oxygen is one of the most drastic changes in the ocean, and this trend is expected to worsen under future climate change scenarios. Spatial variability in disso

Declining oxygen is one of the most drastic changes in the ocean, and this trend is expected to worsen under future climate change scenarios. Spatial variability in dissolved oxygen dynamics and hypoxia exposures can drive differences in vulnerabilities of coastal ecosystems and resources, but documentation of variability at regional scales is rare in open-coast systems. Using a regional collaborative network of dissolved oxygen and temperature sensors maintained by scientists and fishing cooperatives from California, USA, and Baja California, Mexico, we characterize spatial and temporal variability in dissolved oxygen and seawater temperature dynamics in kelp forest ecosystems across 13° of latitude in the productive California Current upwelling system. We find distinct latitudinal patterns of hypoxia exposure and evidence for upwelling and respiration as regional drivers of oxygen dynamics, as well as more localized effects. This regional and small-scale spatial variability in dissolved oxygen dynamics supports the use of adaptive management at local scales, and highlights the value of collaborative, large-scale coastal monitoring networks for informing effective adaptation strategies for coastal communities and fisheries in a changing climate.

Variable vertical land motion and its impacts on sea level rise projections

American Association for the Advancement of Science (AAAS) | January 29th, 2025

Coastal vertical land motion (VLM), including uplift and subsidence, can greatly alter relative sea level projections and flood mitigations plans. Yet, current projection

Coastal vertical land motion (VLM), including uplift and subsidence, can greatly alter relative sea level projections and flood mitigations plans. Yet, current projection frameworks, such as the IPCC Sixth Assessment Report, often underestimate VLM by relying on regional linear estimates. Using high-resolution (90-meter) satellite data from 2015 to 2023, we provide local VLM estimates for California and assess their contribution to sea level rise both now and in future. Our findings reveal that regional estimates substantially understate sea level rise in parts of San Francisco and Los Angeles, projecting more than double the expected rise by 2050. Additionally, temporally variable (nonlinear) VLM, driven by factors such as hydrocarbon and groundwater extraction, can increase uncertainties in 2050 projections by up to 0.4 meters in certain areas of Los Angeles and San Diego. This study highlights the critical need to include local VLM and its uncertainties in sea level rise assessments to improve coastal management and ensure effective adaptation efforts.

Vegetation Responses to 2012–2016 Drought in Northern and Southern California

American Geophysical Union (AGU) | March 7th, 2019

In this study, we investigated California vegetation responses to the recent prolonged 2012–2016 drought, which was potentially the driest 4‐year span in the last 1,2

In this study, we investigated California vegetation responses to the recent prolonged 2012–2016 drought, which was potentially the driest 4‐year span in the last 1,200 years. The overall vegetation of the state has been presumed to be severely affected. However, Normalized Difference Vegetation Index (NDVI) satellite data related to vegetation greenness show that the large‐scale drought impacts on observable vegetation health were principally focused in Southern California regions, where the vegetation communities experienced striking declines in greenness. By contrast, some areas of Northern California have demonstrated significant NDVI increase and this difference in NDVI trends is evident over the past 19 years. The distinct vegetation behavior in Northern and Southern California seems to be related to a climatic dipole in the western United States, which is influenced by the large‐scale ocean‐atmosphere interactions. Some climate models predict an extension of such a dipole with greater precipitation in Northern California and less in Southern California by the end of the 21st century. Increased water demand in the south could intensify statewide intersectoral and interregional water competition in the future. However, increasing drought damage to wildlands and their terrestrial ecosystems in the south will not be relieved by any type of traditional water reallocation and irrigation effort.

Vulnerability and Adaptation to Climate Change in California Agriculture

California Energy Commission (CEC) | July 31st, 2012

To build public support for adapting to and mitigating climate change, it will be necessary to develop greater awareness of a broad set of biophysical and socioeconomic f

To build public support for adapting to and mitigating climate change, it will be necessary to develop greater awareness of a broad set of biophysical and socioeconomic factors that influence agricultural vulnerability and resilience. First, the study developed a spatially explicit agricultural vulnerability index for California derived from 22 climate, crop, land use, and socioeconomic variables. Results of the agricultural vulnerability index suggest that the Sacramento?San Joaquin Delta, the Salinas Valley, the corridor between Merced and Fresno, and the Imperial Valley merit special consideration due to their high agricultural vulnerability. The underlying factors contributing to vulnerability and resilience differ among these regions, indicating that future studies and responses could benefit from adopting a contextualized “place based” approach. As an example of this approach, the research team summarized the findings from a recent study on climate change adaptation in Yolo County. The Yolo County study consists of: (1) an econometric analysis of crop acreages under future climate change projections; (2) a hydrologic model of the Cache Creek watershed that simulates the impact of future climate and crop acreage projections on local water supplies; (3) a countywide inventory of agricultural greenhouse gas (GHG) emissions and how it might be used to inform local Climate Action Plans; (4) a survey of farmers’ views on climate change, its impacts and what adaptation and mitigation strategies they might be inclined to adopt; and (5) an urban growth model that evaluates various future development scenarios and the impact on Yolo County farmland and GHG emissions. Since farmland throughout the state is vulnerable to urbanization, the study also used urban growth projections for 2050 to examine the possible impacts on statewide agricultural production, land use patterns, and soils. Lastly, the study examined two on?farm case studies (Fetzer/Bonterra Vineyards and Dixon Ridge Farms) that highlight the possible benefits of innovative agricultural practices (for example, vineyard carbon storage and renewable energy production from crop residues) that link adaptation and mitigation.