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Identifying Drivers of Extreme Urban Heat and Generating a High-Resolution Vulnerability Index

San Diego, California

Featured image for the project, Identifying Drivers of Extreme Urban Heat and Generating a High-Resolution Vulnerability Index

Results

  • Team 
    • Julia Chase, City of San Diego Planning Department
    • NASA DEVELOP
      • Dr. Kenton Ross, NASA Langley Research Center (Project Advisor)
      • Dr. David Hondula, Arizona State University (Project Advisor)
      • Dr. John Dialesandro (Project Lead)
      • Meryl Kruskopf
      • M. Colin Marvin 
      • Mireille Vargas
  • The Initial Challenge 
    • The city is currently in the process of developing a Climate Adaptation and Resiliency Plan to reduce vulnerability to projected climate changes. They are working collaboratively with stakeholders and community members on its development.  One major challenge they are planning for is increased heat. Like many other large urban areas, San Diego has seen an increase in heat-related hospitalizations and morbidity in response to hot-weather episodes. The NASA DEVELOP team was challenged to utilize NASA Earth Observations to Identify Drivers of Extreme Urban Heat and Generate a High-Resolution Vulnerability Index for Urban Planning and Climate Resiliency in San Diego, California. 
  • The Methods
    • The DEVELOP team used Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS), and ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) imagery to identify areas of highest heat based on land surface temperature from 2015-2020. They also explored the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) urban cooling model to investigate changes in cooling rates in current and future scenarios for the city. Inputs into this model included land use/land cover, tree canopy, and building intensity derived from the City of San Diego geospatial data along with albedo derived from Landsat 8.
  • The Results 
    • Through this project, the DEVELOP team developed geospatial layers, a technical report, and story map for the City of San Diego. The DEVELOP team analyses showed the City of San Diego is on average 4.1°C (7.3°F) warmer in the daytime than undisturbed areas or natural landscape patches such as Torrey Pines State Natural Reserve. The coolest areas were those that had a similar surface complexion as the reference sites (i.e., low amounts of buildings, and roads, tree canopy), as well as areas close to the bay and the Pacific Ocean. The team also analyzed social and health indicators and found that health demographics such as obesity and cardiovascular health were the strongest indicators for heat vulnerability. Additionally, the InVEST model results showed that cooling is expected to occur with as little as a 5% increase in tree canopy. In response to the team’s findings on the benefits of increasing green spaces throughout San Diego communities, a Living Wall was constructed outside of a YMCA in a particularly affected community. The wall will not only serve as an educational piece for community members, but contribute to reducing urban heat, supporting cleaner air, absorbing rain water, and beautifying effects.
  • What is next
    • The city’s planning department will utilize the technical report and geospatial layers developed in the TEX project to complement their Climate Resilience planning. Project partners hope to install similar walls in other impactful areas across San Diego both as educational and changing climate adaptation tools.

Description

The City of San Diego has a population of 1.4 million, making it the eighth-largest city in the United States. It is an incredibly diverse population with nearly 41% of the population speaking a language other than English at home. The city is currently in the process of developing a Climate Adaptation and Resiliency Plan to reduce vulnerability to projected climate changes. They are working collaboratively with stakeholders and community members on its development.  One major challenge they are planning for is increased heat. Like many other large urban areas, San Diego has seen an increase in heat-related hospitalizations and morbidity in response to hot-weather episodes. This impact has been especially prominent along the coast where residents may not have air conditioning or be acclimated to the heat. This is explored in Guirguis et al., 2018 where Heat, Disparities, and Health Outcomes in San Diego County’s Diverse Climate Zones are discussed.

 

City Planners currently use geospatial layers such as tree canopy, landcover, and urban heat to make policy and management decisions. However, the scale of these products is too coarse to make location specific climate-adaptation decisions. They would like to further explore the feasibility of determining vulnerability at the block-scale. The planners also recognize the potential to incorporate new datasets into evaluating heat vulnerability and are interested in investigating available datasets further.

 

The Project

 

The San Diego Planning Department sees two main objectives for this Thriving Earth Exchange project. The first is to identify social and environmental vulnerability variables that drive heat vulnerability and collect associated datasets. This would include a summary of dataset scales and ranking of variable importance. The second is to identify a methodology that combines the drivers to create a new heat vulnerability index, preferably at the block-scale. Geospatial layers derived from this project will potentially be incorporated in a future app that would allow residents to search heat vulnerability in their area. The outputs will also be utilized when evaluating appropriate climate adaptation strategies for certain areas.

 

Project Outputs:

  • A technical report outlining a repeatable methodology for heat vulnerability index creation.
  • Scripts used to generate the new index and accompanying ReadMes.
  • The heat vulnerability index geospatial layer in Geotiff format.
  • Geotiffs of all geospatial layers used to derive new heat vulnerability index.

 

Timeline

 

The collaboration between the community and the scientist(s) should start as soon as possible. The duration of the project will be approximately 6 months. Key milestones include: 1) review of literature and available data products, 2) methodology proposal, 3) index creation, and 4) handoff of project products.

Project Team

Community Lead

Julia Chase

 The scientist will work with Julia Chase, Senior Planner for the City of San Diego. She is a project manager for the City of San Diego’s climate adaptation and resilience planning initiatives. She will provide insight on the cities current process of evaluating heat vulnerability and feedback on index development. She has provided a list of current datasets used to determine heat vulnerability.

 

Julia Chase is a Senior Planner with the City of San Diego’s Planning Department leading the City’s climate adaptation and resiliency work program. She has led the efforts to complete the City’s Sea Level Rise Vulnerability Assessment and the Citywide Multi-hazard Climate Change Vulnerability Assessment and is currently leading the development of Climate Resilient SD, the City’s comprehensive climate adaptation plan.

 

Community Science Fellow

Kristen O’Shea

Kristen O’Shea works as a Center Lead and Geoinformatics Fellow for the NASA DEVELOP program. She manages two research teams of recent graduates/early career professionals at the program’s Colorado location. She oversees their work on remote sensing feasibility projects that help inform policy and management decisions for an array of partners both domestic and international. She also utilizes her skillset in coding, remote sensing, GIS, spatial modeling, and spatial analysis to support all 11 locations in their geoinformatics needs.