On the dynamics of the Hadley circulation and subtropical drying

Climate Dynamics (Springer) | April 10th, 2014

Changes in subtropical precipitation and the Hadley circulation (HC) are inextricably linked. The original Halley–Hadley model cannot explain certain aspects of the Ear

Changes in subtropical precipitation and the Hadley circulation (HC) are inextricably linked. The original Halley–Hadley model cannot explain certain aspects of the Earth’s meridional circulation in the tropics and is of limited use in understanding regional changes in precipitation. Here, we expand on previous work on the regional and seasonal aspects of the HC, in particular how land–sea temperature contrasts contribute to the strength and width of the HC. We show that the Earth’s HC is well described by three regionally distinct cells along the eastern edges of the major ocean basins with opposite circulations elsewhere. Moreover, comparable summertime hemisphere cells emerge in each region. While it has been recognized that continents modify the meridional pressure gradient, we demonstrate that a substantial part of the Earth’s HC is driven by zonal pressure gradients (ZPGs) that only exist due to continental heating and air–sea interaction. Projected changes in land–sea temperature contrasts in a warming climate due to the relatively low thermal capacity of land will also affect ZPGs and thus HC strength and width, with implications for extremes in hydroclimate and freshwater resources across the increasingly vulnerable subtropics.

Our Changing Planet: The U.S. Global Change Research Program for Fiscal Year 2025

U.S. Global Change Research Program (USGCRP) | January 3rd, 2025

This Fiscal Year 2025 edition of USGCRP’s annual report to Congress highlights advancements in science and information delivery that show how the Program is meeting nat

This Fiscal Year 2025 edition of USGCRP’s annual report to Congress highlights advancements in science and information delivery that show how the Program is meeting national needs. The Five-Year Progress section provides a longer-term look at USGCRP work on three selected topics: understanding the changing water cycle; responding to needs for climate information; and advancing diversity, equity, inclusion, justice, and accessibility across global change research efforts. We also highlight more recent activities in the 2023 Accomplishments section and look ahead to upcoming work in the Current and Future Priorities section.

Overcoming Organizational Barriers to Implementing Local Government Adaptation Strategies

California Natural Resources Agency (CNRA) | August 27th, 2018

Local governments across California have taken immense strides to combat climate change. However, many local governments still face organizational barriers to comprehensi

Local governments across California have taken immense strides to combat climate change. However, many local governments still face organizational barriers to comprehensively implement climate change adaptation measures. Organizational barriers can delay and even prevent local governments from moving from adaptation planning to implementation due to the wide-reaching scope of climate change impacts. This study aims to further the understanding of the diversity of organizational barriers that California local governments experience and to develop a resource to assist local governments in their efforts to overcome these barriers to more effectively implement climate change adaptation strategies.  The research team conducted a broad literature review, an online survey, multiple regional stakeholder workshops, and focus groups to deepen the understanding of organizational barriers to adaptation in California local governments. These research inputs produced findings on organizational barriers experienced by California local government adaptation practitioners, and enabled the development and testing of the Adaptation Capability Advancement Toolkit. The Toolkit aims to help local governments rapidly assess their current capabilities to overcome organizational barriers and identify key actions and resources for increasing their organizational capability for undertaking climate change adaptation. The Toolkit is based on the Capability Maturity Model process improvement framework, and focuses on developing capabilities within four key process areas which were identified as common sources of organizational barriers: leadership and organizational culture, staffing and technical capacity, stakeholder engagement and partnerships, and operations and institutional processes. The Toolkit was tested by California local government adaptation practitioners in order to ground-truth recommendations and assess the utility of suggested actions and resources. Participants indicated that they view the resource as valuable, particularly if continuously supported. 

Past Groundwater Drought in the North American Cordillera

American Geophysical Union (AGU) | November 11th, 2024

Patterns and projections of high tide flooding along the U.S. coastline using a common impact threshold

National Oceanic and Atmospheric Administration (NOAA) | February 1st, 2018

For forecasting purposes to ensure public safety, NOAA has established three coastal flood severity thresholds. The thresholds are based upon water level heights

For forecasting purposes to ensure public safety, NOAA has established three coastal flood severity thresholds. The thresholds are based upon water level heights empirically calibrated to NOAA tide gauge measurements from years of impact monitoring by its Weather Forecast Offices (WFO) and emergency managers. When minor (more disruptive than damaging), moderate (damaging) or major (destructive) coastal flooding is anticipated (not associated with tropical storms), NOAA issues either a flood advisory(for minor) or warning (for moderate or major). Less than half of NOAA tide gauges located along the U.S. coastline have such ‘official’ NOAA flood thresholds, and where they exist, the heights can vary substantially (e.g., 0.3–0.6 meter within minor category). They differ due to the extent of infrastructure vulnerabilities, which vary by topography and relief, land-cover types or existing flood defenses.

Paying it Forward: The Path Toward Climate-Safe Infrastructure in California

Climate-Safe Infrastructure Working Group | September 1st, 2018

Perceptions and responses to climate policy risks among California farmers

Global Environmental Change (Elsevier) | December 3rd, 2013

This paper considers how farmers perceive and respond to climate change policy risks, and suggests that understanding these risk responses is as important as understandin

This paper considers how farmers perceive and respond to climate change policy risks, and suggests that understanding these risk responses is as important as understanding responses to biophysical climate change impacts. Based on a survey of 162 farmers in California, we test three hypotheses regarding climate policy risk: (1) that perceived climate change risks will have a direct impact on farmer's responses to climate policy risks, (2) that previous climate change experiences will influence farmer's climate change perceptions and climate policy risk responses, and (3) that past experiences with environmental policies will more strongly affect a farmer's climate change beliefs, risks, and climate policy risk responses. Using a structural equation model we find support for all three hypotheses and furthermore show that farmers’ negative past policy experiences do not make them less likely to respond to climate policy risks through participation in a government incentive program. We discuss how future research and climate policies can be structured to garner greater agricultural participation. This work highlights that understanding climate policy risk responses and other social, economic and policy perspectives is a vital component of understanding climate change beliefs, risks and behaviors and should be more thoroughly considered in future work.

Persistent spatial structuring of coastal ocean acidification in the California Current System

Nature Portfolio (Springer Nature) | May 31st, 2017

The near-term progression of ocean acidification (OA) is projected to bring about sharp changes in the chemistry of coastal upwelling ecosystems. The distribution of OA

The near-term progression of ocean acidification (OA) is projected to bring about sharp changes in the chemistry of coastal upwelling ecosystems. The distribution of OA exposure across these early impact systems, however, is highly uncertain and limits our understanding of whether and how spatial management actions can be deployed to ameliorate future impacts. Through a novel coastal OA observing network, we have uncovered a remarkably persistent spatial mosaic in the penetration of acidified waters into ecologically-important nearshore habitats across 1,000 km of the California Current Large Marine Ecosystem. In the most severe exposure hotspots, suboptimal conditions for calcifying organisms encompassed up to 56% of the summer season, and were accompanied by some of the lowest and most variable pH environments known for the surface ocean. Persistent refuge areas were also found, highlighting new opportunities for local adaptation to address the global challenge of OA in productive coastal systems.

Persistent spatial structuring of coastal ocean acidification in the California Current System

Nature Portfolio (Springer Nature) | May 31st, 2017

The near-term progression of ocean acidification (OA) is projected to bring about sharp changes in the chemistry of coastal upwelling ecosystems. The distribution of OA e

The near-term progression of ocean acidification (OA) is projected to bring about sharp changes in the chemistry of coastal upwelling ecosystems. The distribution of OA exposure across these early-impact systems, however, is highly uncertain and limits our understanding of whether and how spatial management actions can be deployed to ameliorate future impacts. Through a novel coastal OA observing network, we have uncovered a remarkably persistent spatial mosaic in the penetration of acidified waters into ecologically-important nearshore habitats across 1,000 km of the California Current Large Marine Ecosystem. In the most severe exposure hotspots, suboptimal conditions for calcifying organisms encompassed up to 56% of the summer season, and were accompanied by some of the lowest and most variable pH environments known for the surface ocean. Persistent refuge areas were also found, highlighting new opportunities for local adaptation to address the global challenge of OA in productive coastal systems.

Perspectives and Guidance for Climate Change Analysis

California Department of Water Resources (DWR) | August 14th, 2015

California's water managers face a climate that changes and is changing as a result of both natural and anthropogenic influences. In some settings and for some variables,

California's water managers face a climate that changes and is changing as a result of both natural and anthropogenic influences. In some settings and for some variables, California’s natural climate variability still dominates anthropogenic influences and will continue to do so for the foreseeable future. In other cases, anthropogenic influences are already evident in important aspects of California's climate. Much research is still required to unravel this tangled web of atmospheric interactions. In any case, California water planning under a changing climate needs to recognize that the causes of variations and changes include both anthropogenic and natural drivers. This technical information record summarizes the scientific and technical guidance and perspectives of the California Department of Water Resources’ (DWR’s) Climate Change Technical Advisory Group (CCTAG) on the use of climate models and associated technical tools for water resource planning. DWR values the work of the members of the CCTAG and will consider this advice as it moves forward in developing specific actions. DWR empaneled this CCTAG in February 2012 to advise DWR on the scientific aspects of climate change, its impacts on water resources, the use of planning approaches and analytical tools, and the development of adaptation responses. DWR requested specific assistance with developing: • A set of future climate scenarios and analysis procedures appropriate for DWR planning. • An approach to extreme climate change scenarios to provide “stress tests.” • Interim guidance on modeling extreme weather events that cause flooding (time permitting within the tenure of the CCTAG).