The potential of urban irrigation for counteracting carbon-climate feedback

Nature Portfolio (Springer Nature) | March 18th, 2024

The Press and Pulse of Climate Change: Extreme Events in the Colorado River Basin

American Water Resources Association (AWRA) | June 21st, 2022

Extremes in temperature and precipitation are associated with damaging floods, prolonged drought, destructive wildfires, agricultural challenges, compromised human health

Extremes in temperature and precipitation are associated with damaging floods, prolonged drought, destructive wildfires, agricultural challenges, compromised human health, vulnerable infrastructure, and threatened ecosystems and species. Often, the steady and progressive trends (or presses) of rising global temperature are the central focus in how climate impacts are described. However, observations of extreme weather events (or pulses) increasingly show that the intensity, duration and/or frequency of acute events are also changing, resulting in greater impacts on communities and the environment. Describing how the influence of extreme events may shape water management in the Colorado River Basin in clear terms is critical to sound future planning and efforts to manage risk. Three scenario planning workshops in 2019 and 2020 were held as part of a Colorado River Conversations series, identifying potential impacts from multiple intersecting extreme events. Water managers identified climate-related events of concern in the Colorado River Basin that necessitate greater attention and adaptive responses. To support efforts to include consideration of climate-change-driven extremes in water management and planning, we explore the current state of knowledge at the confluence of long-term climate shifts and extreme weather in the Colorado River Basin related to the events of concern that were identified by scenario planning participants.

The Rainfall Intensity-Duration Control of Debris Flows After Wildfire

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

The reduced net carbon uptake over Northern Hemisphere land causes the close-to-normal CO2 growth rate in 2021 La Niña

American Association for the Advancement of Science (AAAS) | June 7th, 2024

The season for large fires in Southern California is projected to lengthen in a changing climate

Nature Portfolio (Springer Nature) | February 17th, 2022

Southern California is a biodiversity hotspot and home to over 23 million people. Over recent decades the annual wildfire area in the coastal southern California region h

Southern California is a biodiversity hotspot and home to over 23 million people. Over recent decades the annual wildfire area in the coastal southern California region has not significantly changed. Yet how fire regime will respond to future anthropogenic climate change remains an important question. Here, we estimate wildfire probability in southern California at station scale and daily resolution using random forest algorithms and downscaled earth system model simulations. We project that large fire days will increase from 36 days/year during 1970–1999 to 58 days/year under moderate greenhouse gas emission scenario (RCP4.5) and 71 days/year by 2070–2099 under a high emission scenario (RCP8.5). The large fire season will be more intense and have an earlier onset and delayed end. Our findings suggest that despite the lack of a contemporary trend in fire regime, projected greenhouse gas emissions will substantially increase the fire danger in southern California by 2099.

The shrinking Great Salt Lake contributes to record high dust-on-snow deposition in the Wasatch Mountains during the 2022 snowmelt season

Environmental Research Letters (IOP) | June 15th, 2023

The Stakes are Rising: Lessons on Engaging Coastal Communities on Climate Adaptation in Southern California

Cities and the Environment | November 16th, 2017

Preparing for climate change is rising as a priority for many public policy agendas, driving a demand for information that allows communities to identify both cur

Preparing for climate change is rising as a priority for many public policy agendas, driving a demand for information that allows communities to identify both current and projected vulnerabilities to climate change at local and regional levels. In response, a developing climate change adaptation service sector is bringing science and technical training to policy-makers. Approaching adaptation planning through a regional lens is critical, due to the large number of stakeholders and the intensely interconnected nature of geographies, communities, and economies. Decisions made in one jurisdiction will undoubtedly affect its neighbors. In this emerging field, boundary organizations play a unique role in building capacity across jurisdictions and bridging the gaps among various community, science and government stakeholders. The University of Southern California (USC) Sea Grant Program, located in Los Angeles, has developed a robust stakeholder engagement process to help communities plan for the impacts of climate change along the urbanized coastline. In 2016, USC Sea Grant analyzed its climate change adaptation outreach program to gain insights about its effectiveness. Drawing from this analysis, this paper explores: 1) stakeholder processes; 2) communications methods, particularly the challenges of communicating scientific information; 3) barriers to planning and implementation; 4) how to identify community needs; and, 5) what kinds of investments have been made to meet those needs. Four primary lessons are identified: 1) place-based boundary organizations can be an effective broker in establishing trust among stakeholders; 2) the ever-evolving and complex nature of climate science can overwhelm stakeholders and stall progress, so it is important to emphasize key messages provided by the scientific information, rather than dive deep into technical details and methods; 3) adaptive management is a promising approach to help communities move forward; and, 4) lack of significant and sustained funding for adaptation will continue to limit progress, however, even modest investments made at the right time can be impactful. Finally, the paper discusses the challenges USC Sea Grant faced in the first six years of its climate adaptation outreach program, and provides thoughts on how to help communities continue to advance their adaptation planning goals in the years to come.

The twenty-first century Colorado River hot drought and implications for the future

American Geophysical Union (AGU) | February 17th, 2017

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15-year drought on record. At least one-sixth to one-half (averag

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15-year drought on record. At least one-sixth to one-half (average at one-third) of this loss is due to unprecedented temperatures (0.9°C above the 1906–1999 average), confirming model-based analysis that continued warming will likely further reduce flows. Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend toward greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend. Moreover, there is a significant risk of decadal and multidecadal drought in the coming century, indicating that any increase in mean precipitation will likely be offset during periods of prolonged drought. Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model-based temperature projections indicate that continued business-as-usual warming will drive temperature-induced declines in river flow, conservatively −20% by midcentury and −35% by end-century, with support for losses exceeding −30% at midcentury and −55% at end-century. Precipitation increases may moderate these declines somewhat, but to date no such increases are evident and there is no model agreement on future precipitation changes. These results, combined with the increasing likelihood of prolonged drought in the river basin, suggest that future climate change impacts on the Colorado River flows will be much more serious than currently assumed, especially if substantial reductions in greenhouse gas emissions do not occur.

The twenty‐first century Colorado River hot drought and implications for the future

American Geophysical Union (AGU) | February 17th, 2017

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15‐year drought on record. At least one‐sixth to one‐half (

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15‐year drought on record. At least one‐sixth to one‐half (average at one‐third) of this loss is due to unprecedented temperatures (0.9°C above the 1906–1999 average), confirming model‐based analysis that continued warming will likely further reduce flows. Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend toward greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend. Moreover, there is a significant risk of decadal and multidecadal drought in the coming century, indicating that any increase in mean precipitation will likely be offset during periods of prolonged drought. Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model‐based temperature projections indicate that continued business‐as‐usual warming will drive temperature‐induced declines in river flow, conservatively −20% by midcentury and −35% by end‐century, with support for losses exceeding −30% at midcentury and −55% at end‐century. Precipitation increases may moderate these declines somewhat, but to date no such increases are evident and there is no model agreement on future precipitation changes. These results, combined with the increasing likelihood of prolonged drought in the river basin, suggest that future climate change impacts on the Colorado River flows will be much more serious than currently assumed, especially if substantial reductions in greenhouse gas emissions do not occur.

The U.S. Infrastructure Investment and Jobs Act: Water Components

Pacific Institute | November 12th, 2021

On November 5, 2021, the U.S. Congress passed President Biden’s major infrastructure bill, HR 3684, the $1.2 trillion Infrastructure Investment and Jobs Act. The Presid

On November 5, 2021, the U.S. Congress passed President Biden’s major infrastructure bill, HR 3684, the $1.2 trillion Infrastructure Investment and Jobs Act. The President is expected to sign the bill into law. The bill is the largest single federal investment in infrastructure in a generation, with the funds to be expended over five years. It aims to rebuild and replace failing, aging, and outdated water, energy, transportation, and communications systems. As the first significant federal investment in climate resilience, it also begins to address the growing consequences of climate change, including intensifying extreme weather events, increasing temperatures, and rising sea levels, on communities throughout the United States. One key component of the Act is the set of proposals to address the wide range of water-related challenges facing the United States. This Pacific Institute analysis provides an overview of how the Infrastructure Act addresses these challenges.