Unprecedented continental drying, shrinking freshwater availability, and increasing land contributions to sea level rise

American Association for the Advancement of Science (AAAS) | July 25th, 2025

Changes in terrestrial water storage (TWS) are a critical indicator of freshwater availability. We use NASA GRACE/GRACE- FO data to show that the continents have undergon

Changes in terrestrial water storage (TWS) are a critical indicator of freshwater availability. We use NASA GRACE/GRACE- FO data to show that the continents have undergone unprecedented TWS loss since 2002. Areas experiencing drying increased by twice the size of California annually, creating “mega-drying” regions across the Northern Hemisphere. While most of the world’s dry/wet areas continue to get drier/wetter, dry areas are now drying faster than wet areas are wetting. Changes in TWS are driven by high-latitude water losses, intense Central American/European droughts, and groundwater depletion, which accounts for 68% of TWS loss over non-glaciated continental regions. “Continental drying” is having profound global impacts. Since 2002, 75% of the population lives in 101 countries that have been losing freshwater water. Furthermore, the continents now contribute more freshwater to sea level rise than the ice sheets, and drying regions now contribute more than land glaciers and ice caps. Urgent action is required to prepare for the major impacts of results presented

Urban Ecological Planning Guide for Santa Clara Valley

San Francisco Estuary Institute (SFEI) | June 20th, 2019

Like most cities, the urbanized region of Santa Clara Valley is a challenging place for plants and animals to make a home. Largely covered with pavement, crisscrossed by

Like most cities, the urbanized region of Santa Clara Valley is a challenging place for plants and animals to make a home. Largely covered with pavement, crisscrossed by major freeways, and fragmented by a variety of land uses, the urban landscape creates barriers to the movement of wildlife and hostile environments for plants. While a small set of species tolerant of cities (such as pigeons and raccoons) can tolerate these difficult conditions, our cities have the potential to support much greater biodiversity. Urban greening projects are already occurring piecemeal across urban landscapes. Harnessing this momentum can help these efforts build greater benefits for biodiversity and for people.  Urban greening projects may take many forms, such as rain gardens beside roadways; bike trails with vegetated medians; planted and expanded riparian vegetation along stream corridors; and landscaping in corporate campuses, municipal parks and private gardens. While often driven by a narrow set of goals such as stormwater capture, public safety, shade, or beautification, these green spaces can be designed and coordinated to support enhanced biodiversity as well. Rain gardens can support native wetland plants, bike trail medians can support ribbons of wildflowers for native insects, street trees can shade pedestrians and provide acorns for birds and squirrels, and stream revegetation or daylighting projects can provide a reflective place for people and strengthen corridors for regional species movement. While each of these types of projects provides benefits, strategically designing these features to reflect ecologically-minded planning, and where possible, coordinating across the landscape, can provide value for humans and nature alike.  This document provides some of the scientific foundation needed to guide planning for urban biodiversity in the Santa Clara Valley region, grounded in an understanding of landscape history, urban ecology and local setting. It can be used to envision the ecological potential for individual urban greening projects, and to guide their siting, design and implementation. It also can be used to guide coordination of projects across the landscape, with the cooperation of a group of stakeholders (such as multiple agencies, cities and counties). Users of this report may include a wide range of entities, such as local nonprofits, public agencies, city planners, and applicants to the Open Space Authority’s Urban Open Space Grant Program.  This document is not intended to inform all aspects of site-specific planning. Much guidance on these topics is already available, and we reference some of those resources here. Rather, it is intended as a companion to existing materials, to inform a broader vision of how such site-scale projects can fit into the larger fabric of the Santa Clara Valley landscape. This document also recommends appropriate habitats and lists of their associated plants for the region, as well as general guidance on practical considerations related to project implementation. 

Urban Growth in California: Projecting Growth (2000–2050) Under Six Alternative Policy Scenarios and Assessing Impacts to Future Dispersal Corridors, Fire Threats, and Climate-Sensitive Agriculture

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

This paper documents the development of land use models that represent different urban growth policy scenarios for California, a contribution to the Public Interest Energ

This paper documents the development of land use models that represent different urban growth policy scenarios for California, a contribution to the Public Interest Energy Research (PIER) Climate Vulnerability and Assessment Project of 2010–2011. The research team produced six UPlan model runs that portray the following policies as footprint scenarios to 2050: Business as Usual, Smart Growth, Fire Adaptation, Infill, Conservation of Projected Connectivity for Plant Movement under Climate Change, and Conservation of Vulnerable Agricultural Lands. This paper compares the outputs from these six scenarios on outputs from three other PIER vulnerability studies: biodiversity, fire return interval, and agricultural sensitivity. While not directly targeting any conservation or agricultural objective, the Infill scenario preserved more open space for other use than any of the other scenarios. The results suggest that combining Infill objectives with other open space goals will produce better conservation goals for those objectives than merely directing growth away from landscape elements of conservation interest.

Urban water and electricity demand data for understanding climate change impacts on the water-energy nexus

Nature Portfolio (Springer Nature) | January 23rd, 2024

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.