Climate Science and Policy

Microclimates can behave differently from the larger regional climate, and it is essential to consider various spatiotemporal scales when studying how climate change affects local ecosystems. This research identifies small-scale climate variations within Channel Islands National Park (CINP), particularly in areas where species might find refuge to adapt to climate change. The study identifies different climate characteristics in this region by creating a microclimate framework and analyzing historical data accordingly. It also explains the need for scaling down climate information to the ecosystem level and provides a literature review of all known criteria necessary. The goal is to help inform park managers of local conditions and potential threats to prioritize areas for conservation and restoring biodiversity and natural resources. While global and regional climate models help understand broad trends, they often need more detail to grasp ecological changes at the community or individual species level. Scaling down climate information can enhance the accuracy of predictive models used in environmental assessments and impact studies, and identifying existing microclimates can help assess the overall health of an ecosystem. The research categorizes the scaling process into four levels: macro, meso, topo, and micro. It outlines the procedure for identifying microclimates, analyzes model predictions, illustrates future climate scenarios, and highlights correlations between various physical factors using recent climatological observations. The study starts with a review of existing literature to provide context for each climate variable's impact on the overall ecosystem, explains the research methods, presents the results, and concludes with a discussion of the findings and suggestions for future research beyond the scope of this study. The research was conducted in collaboration with The Nature Conservancy and the National Park Service to address the specific needs of the park.

Salt marshes and other coastal ecosystems are pivotal in the sequestration and storage of carbon, commonly known as "coastal blue carbon." However, these ecosystems face severe degradation and anthropogenic impacts. This study focuses on assessing the carbon storage potential within the salt marshes of the Batiquitos Lagoon. Our investigation reveals significant carbon stocks ranging from 2.56 to 238.70 MgCorg ha-1, influenced by crucial factors such as maximum sediment depth and carbon density. Additionally, we compare the determined carbon stocks with regional benchmarks, yielding valuable insights to inform future conservation strategies aimed at safeguarding the carbon sinks of salt marshes. This work contributes to the expanding body of research on blue carbon ecosystems, emphasizing the vital role of ongoing research, monitoring, and conservation efforts.

This study examines the relationship between extreme heat events and violent crime in San Diego County, providing a climate action analysis that focuses on climate mitigation and crime prevention. Through a comprehensive analysis utilizing space-time hot spot analysis in ArcGIS Pro, the study explores the underlying mechanisms connecting extreme heat to violent crime. While the analysis did not reveal a significant correlation between high temperature days and increased incidence of violent crimes, it did identify areas for targeted interventions to reduce both extreme heat events and violent crime incidents. The analysis of the current City of San Diego 2022 Climate Action Plan suggests that actions promoting the creation of inviting and safe public spaces and increasing tree canopy coverage can have dual benefits in addressing climate change and crime prevention.

Anthropogenic climate change has raised global temperatures and thrown standard weather patterns into disarray. For the Valle de Guadalupe, an agricultural region that specializes in vitis vinifera grapes used to make wine, impacts go much further than what’s experienced above ground. Extraction from the area’s aquifer and primary water source has increased signicantly and become overexploited to meet infrastructural development demands for tourism. Natural rain-fed recharge rates have not kept up and the aquifer is experiencing a dramatic decline in water levels. Valle locals have implemented strategies to conserve and optimize water usage, but also stress the need to slow down the accelerated pace of development so it can be done sustainability and strategically. Interviews were conducted with Valle winemakers and employees to understand the issues and their perceptions of these topics rst hand. These insights are presented throughout, as well as the adaptations and ongoing work of scientists and residents who work to preserve the longevity of this region.

It is important to understand the complex physical and biological interactions of the climate system for the adaptation to and mitigation of the many consequences of climate change. This study aimed to understand the impacts of Atmospheric Rivers (ARs) on Harmful Algal Bloom (HAB) causing phytoplankton taxa. ARs are ephemeral corridors of the atmosphere carrying massive amounts of water vapor from the tropics to mid latitudes and are strongly correlated with orographic precipitation. ARs are defined and characterized by the vertically Integrated Vapor Transport (IVT), which is the measured amount of water and its movement in the atmospheric column. Abundances of 13 different taxa of phytoplankton associated with HABs at 12 different monitoring stations along the California Coast were obtained from CalHABMAP. IVT magnitudes as well as a chronology of AR occurrences at 0.25° by 0.25° grid cells at each of these 12 locations were obtained from the CW3E, which acquired the information from ECMWF ERA5 Reanalysis data. Here I attempt to answer two questions: 1) When a specific HAB-causing phytoplankton taxon was present, was its abundance correlated with the IVT magnitude the week prior to sampling? 2) When this HAB-causing phytoplankton taxon was present, was its abundance different when an AR occurred during the week prior to sampling versus no AR? To reveal potential relationships between phytoplankton abundance with the IVT magnitude or presence of ARs, I quantified correlations between the phytoplankton abundances and the IVT magnitude or AR occurrence the week before phytoplankton sampling. Some dinoflagellate taxa showed consistent positive correlations in Northern California, while different dinoflagellate taxa showed more consistent negative correlations in Southern California. AR presence consistently was associated with a decrease in the abundance of phytoplankton in most diatom and dinoflagellate taxa. With little latitudinal trend in the sign of the correlation, different taxa were significantly negatively correlated with AR presence in Southern California than in Northern California. Further research should be conducted to understand the mechanisms behind these correlations and dive deeper into the nuances of these relationships. This study was meant to serve as an introduction to understanding the relationships between AR occurrence, IVT magnitude, and HAB-forming phytoplankton taxa, to advise decision making for HAB warning systems and education in the face of a changing climate.

This study assesses the increasing flood risks in Ho Chi Minh City due to climate change and urbanization, and proposes the implementation of the sponge city concept as a solution to enhance flood resilience. Through a comprehensive analysis of literature, data, and models, coupled with GIS techniques, the study reveals the escalating flood risks in the city, both from inland and from the coast. The sponge city concept, which integrates nature-based solutions such as green spaces and water storage facilities, is presented as a means to improve flood resilience. The study analyzes the opportunities and constraints in the application process, provides recommendations to utilize opportunities and overcome constraints, and suggests some potential locations for implementation. The findings highlight the importance of incorporating nature-based solutions into urban planning and development strategies to create sustainable and resilient cities. While focusing on Ho Chi Minh City, the study's recommendations can be applicable to other urban areas facing similar flood challenges. Further research and feasibility studies are recommended to fully implement the sponge city concept.

As rising sea levels are anticipated to threaten coastal communities around the world within the next century, many low-lying coastlines are already experiencing threats of coastal flooding. The scientific research community is contributing to our understanding of these hazards by collecting data on historically significant flood events, developing short-term flood forecasting models, and projecting future coastal flood risks and vulnerabilities that combine with rising sea levels. For coastal leaders, hazard managers, planners, and residents, effective communication of this data is important to how well it is applied to local impacts, policies, and adaptive measures. A number of U.S. government agencies (e.g., NOAA, NASA) have developed educational guidelines and data mapping tools to enhance understanding of science and coastal flood risks. However, these resources often require a general understanding of flood science, coastal oceanography, or climatic influences. Accessible online communication tools can provide a public benefit by increasing community risk perception and engagement, but these resources should understand their specific audience needs to ensure that relevant language, data, and local priorities are incorporated. In Imperial Beach, California, the low-lying coastal city currently experiences occasional coastal flooding during periods of high tides concurrent with winter storms or large wave events. To better prepare and mitigate the impacts of these events, the City of Imperial Beach has become a longstanding collaborator with the Scripps Institution of Oceanography. This partnership has led to increased technical guidance and support, as well as an abundance of Imperial Beach coastal flood data. Utilizing the flood risk science available in Imperial Beach, this research project sought to work with city staff to identify opportunities and limitations of communicating flood risk in Imperial Beach. The research design included four components. First, a review of flood risk literature and three types of flood risk communication available for Imperial Beach: historical flooding, short-term flood forecasting, and projections of future flood frequency. An ArcGIS storymap was then developed compiling and demonstrating potential methods for communicating Imperial Beach flood risk data in a centralized and publicly accessible format. The storymap was used to facilitate an informal interview and survey with Imperial Beach staff to obtain input on the utility and effectiveness of flood risk communication formats. Finally, an analysis of limitations and opportunities was conducted based on climate risk communication literature and input received from Imperial Beach government staff. This assessment found that communicating historical flood data that could be validated using in-situ observations such as images, videos, or other media was effective for communicating past events. However, historical flood risk communication could be improved if it better described what the different coastal flood drivers were. The short-term flood forecasting system was found to be useful in increasing collaboration between researchers and city officials, as well as increasing hazard response capabilities. However, future workshops between specialists and the public could increase public understanding and engagement, while offering feedback and validation of forecasting models and warning systems. Future projections of sea level rise and coastal flooding communication often relies too much on projections of worst-case scenarios in the long term (100+ years into the future). Additionally, flood frequency projection tools were useful for establishing a future timeline of increasing flood events, but inconsistent vocabulary defining flood days and events may complicate communication. Future coastal flood research projects could significantly benefit from increased stakeholder engagement, and relying on a bottom-up approach to communication and educational resource development.

Climate change and over-allocation of the Colorado River have resulted in difficult negotiations amongst the seven states (Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming) that rely on the river. The Lower Basin and Federal Government recently came to an agreement (May 2023) for voluntary users to conserve water in trade for financial compensation, resulting in an estimated 3 million acre-feet (MAF) of total conserved water by the end of 2026. Southern California imports more water from the Colorado River than any other user. The majority (80%) of California’s 4.4 MAF allotment from the Colorado River is used to irrigate the region’s $11.6 billion agriculture industry, and only 20% is used for municipal water. This study examines the annual consumptive use of the four largest importers of Colorado River water in California from 1964 – 2021 to identify extreme variations and understand the effect that precipitation plays in those variations. This study also focuses on the time period of 2002 – 2003, in which Southern California’s imports were reduced by 1 MAF due to the Quantification Settlement Agreement (QSA), as a proxy to understand what major cuts in imports will mean to California’s agriculture industry today. The study finds that local precipitation had a negative moderate-strong correlation with consumptive use prior to the 2003 QSA in three of the water districts, but a negative weak correlation following the 2003 QSA in all but one district. Reductions from the QSA were widespread but unevenly distributed; Metropolitan Water District decreased its consumptive use by nearly 50% (~0.5 MAF) while Imperial Irrigation District, the largest user of Colorado River water, decreased by less than 6% (0.2 MAF). Irrigated crop acreage (ICA) of all crops decreased by <1% between 2002 and 2003, with the largest decrease in alfalfa at 51,000 acres. Irrigated crop acreage of all crops increased, on average, in the years following the 2003 QSA, even though consumptive use decreased >12%; the ICA of alfalfa had an overall decrease of ~4% while common produce crops increased by ~3%. Similarly, the total water consumed water by alfalfa decreased >13% in the years following the QSA, while the consumptive use of common produce increased nearly 3%. Overall, alfalfa accounted for ~30% of the total irrigated crop acreage and ~44% of total water consumed within the water districts.

Sea level rise resulting from human-induced global warming poses a grave threat to our planet, particularly endangering low-lying coastal areas susceptible to flooding. Effective beach monitoring can help vulnerable coastal communities anticipate the adverse impacts of sea level rise. CoastSnap, a worldwide beach monitoring program, collects and analyses coastline photos contributed by smartphone users. The primary objective is to study how beaches change over time while engaging and educating communities about the dynamic nature of their coastlines. CoastSnap employs community science, which empowers communities to actively participate in the scientific data collection and inquiry process, catering to the unique needs of each community. This capstone project focuses on establishing CoastSnap stations in and around the City of Imperial Beach, an exceptionally vulnerable coastal region within San Diego County. Three locations, including two on Imperial Beach Pier and one at Border Field State Park, have been identified as suitable sites for new stations. Additionally, an analysis of CoastSnap data from the Torrey Pines station explored the accuracy of image-derived beach width measurements in comparison to data obtained through physical beach surveying (in-situ), to demonstrate CoastSnap’s suitability for monitoring coastlines in Southern California. The comparison of CoastSnap measurements with in-situ measurements revealed an overall mean deviation of 1.35 meters, with CoastSnap measurements tending slightly more seaward. When considering tide levels, low tide events resulted in a lower mean deviation (mean = 0.94 meters) compared to high tides (mean = 1.78 meters). The analysis also found that CoastSnap-derived shorelines from Winter showed the strongest seaward deviation (mean = 4.30 meters), while Fall measurements tended to deviate slightly landward on average (mean = -0.61 meters).

In light of anthropogenic climate change and increasing global temperatures, coastal flooding and erosion from sea level rise are becoming more prevalent. Historically, adaptation techniques to protect the coastline have focused on gray infrastructure; however, nature-based solutions (NBS) are rapidly emerging as a viable long-term approach for successful adaptation. Due to the relative novelty of the climate adaptation field as a whole and nature-based solutions specifically, barriers to their implementation include a lack of funding and general support. Thus, quantifying and communicating the benefits of NBS is crucial to their successful widespread implementation. This report addresses this issue in the specific context of NBS to sea level rise in Imperial Beach, California. It aims to create a framework that adequately quantifies the benefits of NBS to sea level rise and expresses them in a manner that allows for seamless implementation. A cost-benefit analysis is used, which consists of five steps: (1) project identification, (2) project attributes identification, (3) cost summary, (4) benefits summary, and (5) comparative analysis. The Bayshore Bikeway Resiliency Project and beach nourishment events are considered highly cost-effective solutions based on key findings. Dune restoration, however, is not considered a cost-effective method, given only the current quantitative benefits. If the broader range of additional benefits is included, the City may still designate this project as a plausible response to sea level rise. The most cost-effective method of adaptation considered in this study is beach nourishment. However, a single-project approach is not recommended in climate adaptation. A hybrid adaptation approach is usually the most effective and beneficial as there is no “one-size-fits-all” procedure to planning. Future studies may expand upon this research by utilizing a similar framework for other NBS in different jurisdictions. The City may also utilize this information to further the planning process of climate adaptation projects as they and many other cities work to build resilient communities in the presence of climate change.