Climate change intensification of horizontal water vapor transport in CMIP5

American Geophysical Union (AGU) | June 8th, 2015

Global warming of the Earth’s atmosphere is hypothesized to lead to an intensification of the global water cycle. To determine associated hydrological changes, most pr

Global warming of the Earth’s atmosphere is hypothesized to lead to an intensification of the global water cycle. To determine associated hydrological changes, most previous research has used precipitation. This study, however, investigates projected changes to global atmospheric water vapor transport (integrated vapor transport (IVT)), the key link between water source and sink regions. Using 22 global circulation models from the Climate Model Intercomparison Project Phase 5, we evaluate, globally, the mean, standard deviation, and the 95th percentiles of IVT from the historical simulations (1979–2005) and two emissions scenarios (2073–2099). Considering the more extreme emissions, multimodel mean IVT increases by 30–40% in the North Pacific and North Atlantic storm tracks and in the equatorial Pacific Ocean trade winds. An acceleration of the high-latitude IVT is also shown. Analysis of low-altitude moisture and winds suggests that these changes are mainly due to higher atmospheric water vapor content.

Climate change is narrowing and shifting prescribed fire windows in western United States

Nature Portfolio (Springer Nature) | October 3rd, 2023

Climate Change Research Plan for California

California Environmental Protection Agency (CalEPA) | February 12th, 2015

Over the past 25 years, the State of California has demonstrated national and international leadership in understanding regional climate change impacts, developing strate

Over the past 25 years, the State of California has demonstrated national and international leadership in understanding regional climate change impacts, developing strategies for reducing greenhouse gas (GHG) emissions, and developing knowledge to support adaptation to projected impacts. Successfully negotiating climate change challenges will require integrating a sound scientific basis for climate preparedness into local planning, resource management, infrastructure, and public health, as well as introducing new strategies to reduce GHG emissions or increase carbon sequestration into nearly every sector of California’s economy. This  Climate Change Research Plan (hereafter the Research Plan) presents a strategy for developing the requisite knowledge through a targeted body of policy-relevant, California-specific research. The Research Plan continues support for climate policy and enhances statewide research collaboration. For the first time, it outlines statewide research priorities. It further demonstrates state agency coordination. Nearly 50 authors representing 16 state agencies were involved in authoring the Research Plan, which delineates California’s most critical climate-related research gaps. This is an unprecedented effort resulting in the first comprehensive climate change research plan developed by any state. California-sponsored research informs climate policy issues of unique importance to California. For example, State-sponsored research resulting from the First California Climate Assessment offered new California-specific scientific insights that were not available in 2006 from federal research products and that were instrumental to the passage of AB 32. The recent enhanced support for actionable climate research at the federal level also represents an excellent opportunity to develop a plan that aligns with the national research plan developed by the U.S. Global Change Research Program and contributes to the continuing dialogue with our federal partners. The research needs identified in California’s Research Plan address gaps in knowledge that will help inform the State’s ongoing activities to address climate change without duplicating federal research activities.

Climate Change Trends and Impacts on California Agriculture: A Detailed Review

Agronomy (MDPI) | February 26th, 2018

California is a global leader in the agricultural sector and produces more than 400 types of commodities. The state produces over a third of the country’s vegetables an

California is a global leader in the agricultural sector and produces more than 400 types of commodities. The state produces over a third of the country’s vegetables and two-thirds of its fruits and nuts. Despite being highly productive, current and future climate change poses many challenges to the agricultural sector. This paper provides a summary of the current state of knowledge on historical and future trends in climate and their impacts on California agriculture. We present a synthesis of climate change impacts on California agriculture in the context of: (1) historic trends and projected changes in temperature, precipitation, snowpack, heat waves, drought, and flood events; and (2) consequent impacts on crop yields, chill hours, pests and diseases, and agricultural vulnerability to climate risks. Finally, we highlight important findings and directions for future research and implementation. The detailed review presented in this paper provides sufficient evidence that the climate in California has changed significantly and is expected to continue changing in the future, and justifies the urgency and importance of enhancing the adaptive capacity of agriculture and reducing vulnerability to climate change. Since agriculture in California is very diverse and each crop responds to climate differently, climate adaptation research should be locally focused along with effective stakeholder engagement and systematic outreach efforts for effective adoption and implementation. The expected readership of this paper includes local stakeholders, researchers, state and national agencies, and international communities interested in learning about climate change and California’s agriculture.

Climate Endgame: Exploring catastrophic climate change scenarios

National Academy of Sciences (NAS) | August 1st, 2022

Prudent risk management requires consideration of bad to-worst-case scenarios. Yet, for climate change, such potential futures are poorly understood. Could anthropogenic

Prudent risk management requires consideration of bad to-worst-case scenarios. Yet, for climate change, such potential futures are poorly understood. Could anthropogenic climate change result in worldwide societal collapse or even eventual human extinction? At present, this is a dangerously underexplored topic. Yet there are ample reasons to suspect that climate change could result in a global catastrophe. Analyzing the mechanisms for these extreme consequences could help galvanize action, improve resilience, and inform policy, including emergency responses. We outline current knowledge about the likelihood of extreme climate change, discuss why understanding bad-to-worst cases is vital, articulate reasons for concern about catastrophic outcomes, define key terms, and put forward a research agenda. The proposed agenda covers four main questions: What is the potential for climate change to drive mass extinction events? What are the mechanisms that could result in human mass mortality andmorbidity? What are human societies' vulnerabilities to climate-triggered risk cascades, such as from conflict, political instability, and systemic financial risk? How can these multiple strands of evidence—together with other global dangers—be usefully synthesized into an “integrated catastrophe assessment”? It is time for the scientific community to grapple with the challenge of better understanding catastrophic climate change.

Climate modeling 101: Explanations without equations

Springer | January 1st, 2016

Climate scientists tell us it's going to get hotter. How much it rains and where it rains is likely to shift. Sea level rise is apt to accelerate. Oceans are on their way

Climate scientists tell us it's going to get hotter. How much it rains and where it rains is likely to shift. Sea level rise is apt to accelerate. Oceans are on their way to becoming more acidic and less oxygenated. Floods, droughts, storms, and other extreme weather events are projected to change in frequency or intensity. But how do they know what they know? For climate scientists, numerical models are the tools of the trade. But for the layperson — and even for scientists in other fields — climate models can seem mysterious. What does "numerical" even mean? Do climate models take other things besides the atmosphere into account? How do scientists know if a model is any good? * Two experts in climate modeling, Andrew Gettelman of the National Center for Atmospheric Research and Richard Rood of the University of Michigan, have your answers and more, free of charge. In a new open-access book, "Demystifying Climate Models," the pair lay out the fundamentals. In 282 pages, the scientists explain the basics of climate science, how that science is translated into a climate model, and what those models can tell us (as well as what they can't) — all without using a single equation. *Find the answers on pages 8, 13, and 161, respectively, of the book.

Climate Risk-Informed Flood Inundation Mapping (CRFM) Project

California Department of Water Resources (DWR) | May 1st, 2025

The California Department of Water Resources (DWR) has identified the enhancement of flood inundation mapping under future climate conditions as a fundamental and critica

The California Department of Water Resources (DWR) has identified the enhancement of flood inundation mapping under future climate conditions as a fundamental and critical climate change adaptation strategy. Mapping serves as foundational information upon which future planning and actions depend — necessary, though insufficient, for climate resilience. This innovative study focuses on the Tuolumne River and leverages existing studies’ models, data, and tools to pioneer a risk-informed approach in creating a flood inundation mapping procedure that supports climate resilience. This study moves beyond outdated stationarity-based practices by incorporating non-stationarity into climate change projections, offering a forward-thinking solution to address the limitations of current methodologies.

Climate Vulnerability and Adaptation Study for California: Legal Analysis of Barriers to Adaptation for California’s Water Sector

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

This project focused on the legal and institutional framework associated with California’s water rights allocation system, and identifies changes to that framework that

This project focused on the legal and institutional framework associated with California’s water rights allocation system, and identifies changes to that framework that would facilitate adaptation to climate change. Since such changes may be difficult to accomplish, the project focused largely, but not exclusively, on changes that may be politically feasible now or in the future. There is already conflict in California over water allocation, and climate change will exacerbate that conflict by increasing demand and decreasing supply. Adaptation will be needed both to address already unavoidable impacts from historical emissions, and to address impacts from future emissions. To identify changes that would facilitate adaptation this study looked at recent legislation, policy proposals, and white papers addressing water reform; and off?the record interviews were conducted with individuals familiar with California water law. Having an accurate record of who is diverting water in California, and in what quantity, is the single most important step towards preparing for climate change, and the recommendations reflect that. For groundwater, the changes identified would (1) expand groundwater monitoring and reporting requirements, (2) expand groundwater planning requirements, and (3) require the State Board to improve groundwater management and to prevent the waste or unreasonable use of groundwater. For surface water, the changes we identify would (1) require the State Board to provide information about efficient agricultural water management practices, and streamline State Board procedures for enforcement actions for the waste and unreasonable use of water, (2) increase the enforcement of and penalties for failing to file a Statement of Water Diversion and Use and for illegal diversions, (3) require all beneficiaries of the water rights system to bear the cost of activities related to the administration of those rights, and (4) expand reporting requirements to require diverters to state what they believe their water rights to be.

Climate Warming and Water Management Adaptation for California

Climatic Change (Springer) | June 10th, 2010

The ability of California’s water supply system to adapt to long-term climatic and demographic changes is examined. Two climate warming and a historical climate

The ability of California’s water supply system to adapt to long-term climatic and demographic changes is examined. Two climate warming and a historical climate scenario are examined with population and land use estimates for the year 2100 using a statewide economic-engineering optimization model of water supply management. Methodologically, the results of this analysis indicate that for long-term climate change studies of complex systems, there is considerable value in including other major changes expected during a long-term time-frame (such as population changes), allowing the system to adapt to changes in conditions (a common feature of human societies), and representing the system in sufficient hydrologic and operational detail and breadth to allow significant adaptation. While the policy results of this study are preliminary, they point to a considerable engineering and economic ability of complex, diverse, and intertied systems to adapt to significant changes in climate and population. More specifically, California’s water supply system appears physically capable of adapting to significant changes in climate and population, albeit at a significant cost. Such adaptation would entail large changes in the operation of California’s large groundwater storage capacity, significant transfers of water among water users, and some adoption of new technologies.

Climate warming enhancement of catastrophic southern California debris flows

Nature Portfolio (Springer Nature) | June 29th, 2020

The sequence of wildfires followed by debris flows, frequently affects southern California, reflecting its drought-heavy precipitation climate bipolarity. Organic debris

The sequence of wildfires followed by debris flows, frequently affects southern California, reflecting its drought-heavy precipitation climate bipolarity. Organic debris from incomplete burning is lighter than inorganic matter, and partially inviscid. Hence lower rainfall totals can trigger downslope motion than typically required by the underlying clasts of loose inorganic granular material. After advection downslope, the pebble-laden organic debris has a higher capacity for rilling; a positive feedback process. A mechanism is proposed whereby boulders are ‘rafted’ by organic debris. This coordinated movement of boulders greatly enhances the debris flow erosion capacity. This climate change sensitive debris flow enhancing mechanism, through organic–inorganic granular material interaction, is supported by observations and the numerical simulations. Using a model explicitly parameterizing erosion processes, including runoff entrainment, rilling incision, and bank collapse, the lifecycle of the Montecito debris flow of January 9, 2018 is simulated, providing quantitative estimates of mass conveyed and debris sorting at the terminus. Peak rafting speeds are ~ 12.9 m/s at ~ 300 m asl. Total boulder (effective diameter > 25 cm) volume involved for the Ysidro Creek area alone is ~ 5 × 104 m3, scattered between the region 50–260 m asl. Debris flows are highly repeatable and locations prone to debris flows are identified and their likelihood of realization estimated.