Warming weakens the night-time barrier to global fire

Nature Portfolio (Springer Nature) | February 16th, 2022

Night-time provides a critical window for slowing or extinguishing fires owing to the lower temperature and the lower vapour pressure deficit (VPD). However, fire danger

Night-time provides a critical window for slowing or extinguishing fires owing to the lower temperature and the lower vapour pressure deficit (VPD). However, fire danger is most often assessed based on daytime conditions1,2, capturing what promotes fire spread rather than what impedes fire. Although it is well appreciated that changing daytime weather conditions are exacerbating fire, potential changes in night-time conditions—and their associated role as fire reducers—are less understood. Here we show that night-time fire intensity has increased, which is linked to hotter and drier nights. Our findings are based on global satellite observations of daytime and night-time fire detections and corresponding hourly climate data, from which we determine landcover-specific thresholds of VPD (VPDt), below which fire detections are very rare (less than 95 per cent modelled chance). Globally, daily minimum VPD increased by 25 per cent from 1979 to 2020. Across burnable lands, the annual number of flammable night-time hours—when VPD exceeds VPDt—increased by 110 hours, allowing five additional nights when flammability never ceases. Across nearly one-fifth of burnable lands, flammable nights increased by at least one week across this period. Globally, night fires have become 7.2 per cent more intense from 2003 to 2020, measured via a satellite record. These results reinforce the lack of night-time relief that wildfire suppression teams have experienced in recent years. We expect that continued night-time warming owing to anthropogenic climate change will promote more intense, longer-lasting and larger fires.

Water Ages Explain Tradeoffs Between Long-Term Evapotranspiration and Ecosystem Drought Resilience

American Geophysical Union (AGU) | May 23rd, 2023

Water and climate: Recognize anthropogenic drought

Nature Portfolio (Springer Nature) | August 27th, 2015

Water and Energy Sector Vulnerability to Climate Warming in the Sierra Nevada: Simulating the Regulated Rivers of California’s West Slope Sierra Nevada

California Energy Commission (CEC) | August 7th, 2012

Climate warming is expected to affect the beneficial uses of water in the Sierra Nevada, impacting nearly every resident of California. This paper describes the developme

Climate warming is expected to affect the beneficial uses of water in the Sierra Nevada, impacting nearly every resident of California. This paper describes the development and results from an integrated water resource management model encompassing water operations and hydropower generation for the west slope Sierra Nevada spanning the Feather River basin in the north to the Kern River basin in the south at the weekly time step. This model application includes management of reservoirs, run-of-river hydropower plants, water supply demand locations, conveyances, and instream flow requirement. Model validation indicates that most major hydropower turbine flows were simulated well, with wetter years modeled more effectively than drier years. The results of this work indicated that hydropower generation will be reduced by approximately 8 percent with 6°C (10.8°F) warming, consistent with other studies, with a conservative parameterization of no change in precipitation. Reservoir operations adapt to capture earlier and greater runoff volumes that result from earlier and greater runoff due to climate warming. Seasonal compensation in operations is insufficient to overcome warming mediated losses.

Water and Energy Sector Vulnerability to Climate Warming in the Sierra Nevada: Water Year Classification in Non?Stationary Climates

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

This paper explores the sensitivity of water indexing methods to climate change scenarios to better understand how water management decisions and allocations will be affe

This paper explores the sensitivity of water indexing methods to climate change scenarios to better understand how water management decisions and allocations will be affected by climate change. Many water management decisions, such as environmental flow requirements and water supply allocations, are based on numerical “water year type” designations. Water year type designations vary by region and index, but most are defined by some measure of runoff in the current water year compared to average historical runoff, with numerical thresholds categorizing year types. Climate change is anticipated to alter the timing and volume of runoff, and change the relative frequency of water year types as presently defined. California’s Sacramento Valley and San Joaquin Valley Indices are used as a case study to examine climatic changes. These indices provide a framework for allocating and transferring water among users. Streamflow estimates for 1951–2099 from the climate-forced Variable Infiltration Capacity hydrologic model are used to estimate potential changes in runoff and water year type frequency, using six global circulation models for the A2 and B1 emissions scenarios. Results vary by emissions scenario and global circulation model, but indicate that critically dry water years in the Sacramento Valley and San Joaquin Valley are expected to be about 8 percent and 32 percent more likely by the latter half of the twenty-first century, respectively, if water year type definitions remain unchanged. If current water year type thresholds are maintained, more years will be classified as dry and less water will be allocated for environmental outflows, perhaps failing to provide adequate hydrologic variability to support species, habitats, and ecosystems. If thresholds are redefined to reflect the historical distribution of year types, the burden of climate change falls to consumptive users and water exporters. This case study illustrates how water policy and allocation frameworks were designed assuming climatic stationarity, and that adapting water policy (or maintaining the status quo) affects which users bear the burden of climate change.

Water Demand Projection Accuracy and Demand Management Trends in California Cities

American Geophysical Union (AGU) | November 21st, 2025

This study investigates the accuracy of long-term water demand projections and tracks the evolution of water demand management incentives across 61 California water suppl

This study investigates the accuracy of long-term water demand projections and tracks the evolution of water demand management incentives across 61 California water suppliers from 2000 to 2020. Through a systematic analysis of Urban Water Management Plans, we find that water suppliers consistently overestimated future demand by an average of 25% for 5-year projections and 74% for 20-year projections. This overestimation stems primarily from assumptions about per capita water demand rather than population growth estimates. While suppliers generally projected stable or increasing per capita demand, actual water demand per capita declined by 1.9% annually between 2000 and 2020, leading to a decoupling of water demand from population growth. Concurrently, we document a substantial increase in water demand management incentives, with non-voluntary regulations emerging as the dominant demand management approach by 2020, largely driven by state policies like the Model Water Efficient Landscape Ordinance and California Green Building Standards. Demand management efforts have evolved from primarily indoor and educational initiatives toward outdoor-focused non-voluntary regulations and rebates. This shift appears closely linked to the reduction in per capita demand that suppliers failed to fully capture in their water demand projections. Our findings underscore the importance of incorporating dynamic conservation trends into demand projections and suggest that suppliers should develop more sophisticated forecasting methods that account for the continuing evolution of water efficiency incentives. This research provides valuable insights for water resource planners seeking to improve the accuracy of water demand projections in an era of increasing conservation and climate uncertainty.

Water Forward 2024 Plan Report - Austin's 100 Year Plan

City of Austin | December 6th, 2024

Water Forward 2024 is Austin’s 100-year integrated water resource plan. The purpose of Water Forward is to develop and implement diverse and environmentally conscious w

Water Forward 2024 is Austin’s 100-year integrated water resource plan. The purpose of Water Forward is to develop and implement diverse and environmentally conscious water management strategies to adapt to growth, drought, and climate change and ensure a sustainable, resilient, equitable, and affordable water future for our community for the next 100 years. Austin Water has developed this plan to address near- and long-term water needs through a collaborative process in alignment with guiding principles crafted to reflect the Austin community’s values. 

Water is a master variable: Solving for resilience in the modern era

Water Security, Elsevier | November 21st, 2019

Resilience is increasingly recognized as an imperative for any prospect of sustainable development, as it relates to our ability to sustain human well-being and progress

Resilience is increasingly recognized as an imperative for any prospect of sustainable development, as it relates to our ability to sustain human well-being and progress under the planetary and societal changes that we face now and into the future. Yet, we are ill-prepared to meet this challenge. We neither fully understand nor manage consistently for resilience of the human and natural systems that we must steward through extraordinary change. A unifying approach and common currency would help us to understand and manage for resilience under uncertain futures. Water is an essential, defining element in human and natural systems. Human civilization and water systems have co-evolved as a coupled system, with the majority of natural freshwater systems transformed to meet our demands. Shifting patters of water availability in space and time will define key pathways and tipping points for our resilience, and thus requirements for water system resilience must guide the trajectories and boundaries of human development. Here, we consider the thesis that water offers a key to unlocking the complex challenge of designing and managing for the resilience of coupled human-natural systems. We examine what constitutes a resilient system, what drives freshwater resilience, and how pathways to human resilience may be charted and navigated through the medium of water. Our theoretical treatise frames a portfolio of research that tests this thesis, including modeling and applications to water and water-dependent systems.

Water Recommendations to the Next President

Pacific Institute | September 14th, 2020

The United States faces several severe and worsening water problems. Continuing to neglect these problems will impoverish and sicken this and future generations,

The United States faces several severe and worsening water problems. Continuing to neglect these problems will impoverish and sicken this and future generations, destroy beneficial aquatic ecosystems, and threaten our economy and food supply. Smart water policies will create hundreds of thousands of jobs, improve public health, and speed our economic recovery. In this letter, we offer a short assessment of four key problems and specific recommendations for addressing them.

Water Reliability in the West - 2021 SECURE Water Act Report

U.S. Bureau of Reclamation (USBR) | January 4th, 2021

The Bureau of Reclamation (Reclamation) is the largest wholesaler of water in the country. Reclamation delivers water for municipal, agricultural, tribal, and environment

The Bureau of Reclamation (Reclamation) is the largest wholesaler of water in the country. Reclamation delivers water for municipal, agricultural, tribal, and environmental water uses, including providing one out of five farmers in the Western United States (West) with irrigation water for 10 million acres of farmland that produce 60 percent of the Nation’s vegetables and 25 percent of its fruits and nuts. The Omnibus Public Land Management Act of 2009 (Public Law 111-11), Subtitle F of Title IX of the Act (Science and Engineering to Comprehensively Understand and Responsibly Enhance [SECURE] Water Act) recognizes that changes to temperature, precipitation (rainfall and snowfall), and the timing and quantity of snowpack and runoff pose a significant challenge to the protection and use of water resources. Every 5 years, Reclamation submits a report to Congress under the SECURE Water Act that analyzes projected risks to water supplies in the West using the best available science and highlights collaborative efforts to mitigate those risks. This Water Reliability in the West - 2021 SECURE Water Act Report (2021 Report) provides a West-wide assessment of expected changes to water supplies, uses, and demands; highlights progress; and describes actions taken to increase water supply reliability since the 2016 SECURE Water Act Report. Reclamation has a broad range of programs and projects that help increase the reliability of water and power deliveries. Our activities include science and research, planning, infrastructure sustainability, efficient hydropower production, and on-the-ground actions to increase reliable water supplies to meet water demands. These activities are undertaken in collaboration with our customers, stakeholders, and partners. In the West, competing demands for water for farms, cities, Tribes, the environment, recreation, hydropower, and other uses can lead to conflict. Conflict escalates particularly during droughts, which are expected to be more frequent and severe with climate change. Fostering strong relationships is essential to carry out Reclamation’s everyday operations, conduct long-term planning efforts, and avoid unnecessary conflicts. Reclamation operators and planners rely on information about precipitation, snowpack, streamflow, temperatures, water demands, and groundwater to make informed decisions. Reclamation’s 2021 West-Wide Climate and Hydrology Assessment (2021 Assessment) builds on our 2011 and 2016 West-wide assessments of future temperature and precipitation change by using several complementary approaches, including analyses based in paleohydrology derived from tree rings (dendochronology) that help answer this question: “If droughts in the distant past were to occur today, how would water systems perform?” With our Federal, State, Tribal, and local partners, we address challenges resulting from climate change and shifting demographics. We use a multi-faceted approach to support reliable water and hydropower deliveries; to help maintain healthy ecosystems; to protect federally-listed fish, wildlife, and plants, as well as designated critical habitat; and to manage risks (e.g., droughts, floods, and fires). Implementing the SECURE Water Act has served as a catalyst for collaboration and innovation, improving our understanding of climate change impacts to water resources and our ability to address those impacts.