Precipitation regime classification for the Mojave Desert: Implications for fire occurrence

Journal of Arid Environments (Elsevier) | September 29th, 2015

Long periods of drought or above-average precipitation affect Mojave Desert vegetation condition, biomass and susceptibility to fire. Changes in the seasonality of preci

Long periods of drought or above-average precipitation affect Mojave Desert vegetation condition, biomass and susceptibility to fire. Changes in the seasonality of precipitation alter the likelihood of lightning, a key ignition source for fires. The objectives of this study were to characterize the relationship between recent, historic, and future precipitation patterns and fire. Classifying monthly precipitation data from 1971 to 2010 reveals four precipitation regimes: low winter/low summer, moderate winter/moderate summer, high winter/low summer and high winter/high summer. Two regimes with summer monsoonal precipitation covered only 40% of the Mojave Desert ecoregion but contain 88% of the area burned and 95% of the repeat burn area. Classifying historic precipitation for early-century (wet) and mid-century (drought) periods reveals distinct shifts in regime boundaries. Early-century results are similar to current, while the mid-century results show a sizeable reduction in area of regimes with a strong monsoonal component. Such a shift would suggest that fires during the mid-century period would be minimal and anecdotal records confirm this. Predicted precipitation patterns from downscaled global climate models indicate numerous epochs of high winter precipitation, inferring higher fire potential for many multi-decade periods during the next century.

Predicting flood damage probability across the conterminous United States

Environmental Research Letters (IOP) | February 21st, 2022

Floods are the leading cause of natural disaster damages in the United States, with billions of dollars incurred every year in the form of government payouts, property da

Floods are the leading cause of natural disaster damages in the United States, with billions of dollars incurred every year in the form of government payouts, property damages, and agricultural losses. The Federal Emergency Management Agency oversees the delineation of floodplains to mitigate damages, but disparities exist between locations designated as high risk and where flood damages occur due to land use and climate changes and incomplete floodplain mapping. We harnessed publicly available geospatial datasets and random forest algorithms to analyze the spatial distribution and underlying drivers of flood damage probability (FDP) caused by excessive rainfall and overflowing water bodies across the conterminous United States. From this, we produced the first spatially complete map of FDP for the nation, along with spatially explicit standard errors for four selected cities. We trained models using the locations of historical reported flood damage events (n = 71 434) and a suite of geospatial predictors (e.g. flood severity, climate, socio-economic exposure, topographic variables, soil properties, and hydrologic characteristics). We developed independent models for each hydrologic unit code level 2 watershed and generated a FDP for each 100 m pixel. Our model classified damage or no damage with an average area under the curve accuracy of 0.75; however, model performance varied by environmental conditions, with certain land cover classes (e.g. forest) resulting in higher error rates than others (e.g. wetlands). Our results identified FDP hotspots across multiple spatial and regional scales, with high probabilities common in both inland and coastal regions. The highest flood damage probabilities tended to be in areas of low elevation, in close proximity to streams, with extreme precipitation, and with high urban road density. Given rapid environmental changes, our study demonstrates an efficient approach for updating FDP estimates across the nation.

Prioritization of State Investments in Delta Levees and Risk Reduction - Initial Statement of Reasons

Delta Stewardship Council (Delta Council) | August 26th, 2022

Prioritization of State Investments in Delta Levees and Risk Reduction Amendment to Existing Regulation

Delta Stewardship Council (Delta Council) | September 21st, 2023

Procedures to evaluate sea-level change: impacts, responses, and adaptation

U.S. Army Corps of Engineers (USACE) | June 30th, 2014

Projected Changes in California’s Precipitation Intensity-Duration-Frequency Curves

California Public Utilities Commission (CPUC) | August 15th, 2018

Traditionally, infrastructure design and rainfall-triggered landslide models rely on the notion of stationarity, which assumes that the statistics of hydroclimati

Traditionally, infrastructure design and rainfall-triggered landslide models rely on the notion of stationarity, which assumes that the statistics of hydroclimatic extremes (e.g., rainfall, streamflow, etc.) do not change significantly over time. However, during the last century, we have observed a warming climate with more intense precipitation extremes in some regions, likely due to increases in the water holding capacity of the atmosphere. Consequently, infrastructure and natural slopes will likely face more severe climatic conditions, with potential human and socioeconomic consequences. Here, we outline a framework for quantifying climate change impacts on natural and man-made infrastructure using bias-corrected multi-model simulations of historical and projected precipitation extremes. The approach evaluates changes in rainfall intensity-duration- frequency (IDF) curves and their uncertainty bounds using a non-stationary model based on Bayesian inference. We show that highly populated areas across California may experience extreme precipitation that is more intense and twice as frequent, relative to historical records, despite the expectation of unchanged annual mean precipitation. Since IDF curves are widely used for infrastructure design and risk assessment, the proposed framework offers an avenue for assessing infrastructure resilience and landslide hazard in a warming climate.

Property Prices in Peril

First Street | February 3rd, 2025

Regional desirability is being reshaped by chronic changes in climate across the country: coastal areas are increasingly threatened by sea level rise, while inland region

Regional desirability is being reshaped by chronic changes in climate across the country: coastal areas are increasingly threatened by sea level rise, while inland regions face intensifying heat waves, droughts, and floods. At the same time, the increased frequency and intensity of natural disasters has triggered unprecedented levels of property damage, prompting insurance providers to increase premiums or withdraw coverage from high-risk areas altogether. Chronic climate changes create additional financial burdens – from surging utility bills to increased maintenance costs. Ultimately, environmental stressors and associated rising homeownership costs are together reshaping home values. With residential real estate representing one of the largest economic sectors in the country, these shifts will result in serious impacts that ripple through communities. Understanding these dynamics is crucial as public and private stakeholders navigate an increasingly complex landscape where housing decisions must balance traditional location value drivers with new climate realities.

Rainfall intensification amplifies exposure of American Southwest to conditions that trigger postfire debris flows

Nature Portfolio (Springer Nature) | June 7th, 2024

Rapid emergence of climate change in environmental drivers of marine ecosystems

Nature Portfolio (Springer Nature) | March 7th, 2017

Climate change is expected to modify ecological responses in the ocean, with the potential for important effects on the ecosystem services provided to humankind

Climate change is expected to modify ecological responses in the ocean, with the potential for important effects on the ecosystem services provided to humankind. Here we address the question of how rapidly multiple drivers of marine ecosystem change develop in the future ocean. By analysing an ensemble of models we find that, within the next 15 years, the climate change-driven trends in multiple ecosystem drivers emerge from the background of natural variability in 55% of the ocean and propagate rapidly to encompass 86% of the ocean by 2050 under a ‘business-as-usual’ scenario. However, we also demonstrate that the exposure of marine ecosystems to climate change-induced stress can be drastically reduced via climate mitigation measures; with mitigation, the proportion of ocean susceptible to multiple drivers within the next 15 years is reduced to 34%. Mitigation slows the pace at which multiple drivers emerge, allowing an additional 20 years for adaptation in marine ecological and socio-economic systems alike.

Recent and Forecasted Increases in Coccidioidomycosis Incidence Linked to Hydroclimatic Swings, California, USA

U.S. Centers for Disease Control and Prevention (CDC) | March 4th, 2025

Incidence of coccidioidomycosis, an emerging infectious disease caused by Coccidioides spp. fungi, has increased dramatically since 2000. In 2023, California, USA, report

Incidence of coccidioidomycosis, an emerging infectious disease caused by Coccidioides spp. fungi, has increased dramatically since 2000. In 2023, California, USA, reported a near-record 9,054 coccidioidomycosis cases (only surpassed by 9,093 cases in 2019). During April 2023–March 2024, a period capturing the full seasonal rise and fall in incidence, California reported 10,519 cases, 39% higher than the same period the previous year. The 2023 spike in incidence might be attributable, in part, to a swing from extreme drought to heavy precipitation during winter 2022–2023. Transitions from dry to wet years have been linked to increased coccidioidomycosis incidence. Soil moisture during wet winters is hypothesized to support fungal growth, contributing to an abundance of spores available for airborne dispersal during hot, dry conditions characteristic of summer and early fall. Drought preceding rainy seasons might enhance fungal growth by eliminating microbial competitors from soils or by affecting rodent populations, a putative reservoir host and nutrient source for the fungus. During 2020–2022, California experienced severe drought. An unusually wet winter followed in 2022–2023; statewide precipitation exceeded 150% of average, among the top 10 wettest seasons in the past century. Statewide precipitation during the 2023–2024 wet season was 115% of the long-term average, marking the second consecutive wetter-than-average season after a severe drought. That pattern suggested high coccidioidomycosis incidence might continue throughout the 2024 transmission year. We developed a disease forecast to guide public health alerts and messages by pinpointing when and where disease risk is expected to be highest. Such targeted messaging can raise awareness about disease risk, leading to earlier diagnosis and more effective disease management.