The last year has seen extreme heatwaves affecting much of the world including in China, India, the USA, and Europe. Heatwaves damage infrastructure, overload power grids, reduce work safety and productivity, and have negative impacts on quality of life in general. Moreover, more deaths and illness are due to heatwaves than any other natural disaster, and in the case of the USA and Australia, more than all other natural disasters combined.
Heatwaves can also compound the impacts of other types of disasters. For example, earlier this year Australia experienced extreme flooding followed by a heatwave. This led to a situation where people were outside cleaning up when temperatures were dangerously high.
Heatwave deaths and illness are generally thought of as being entirely preventable. That is, proper mitigation, preparedness and response activities can be undertaken to minimize or eliminate harm e.g., through effective heatwave warning systems and providing the public with “cool places” to get out of the heat.
There is also a strong emphasis on planning and implementing mitigation and adaptation strategies to reduce vulnerability and promote resilience when heatwaves strike. For example:
Urban planning might focus on “green and blue infrastructure” to reduce Urban Heat Island (UHI) effects;
Social welfare groups (e.g., Red Cross) have “opt-in” systems where vulnerable older people are contacted throughout the heatwave event to make sure they are coping well; and/or
Heat-health outreach to help educate the community about the dangers of extreme heat, how to respond to warning messages, and what steps to take.
Heatwave vulnerability and impacts are not spread evenly across populations and geography. This has a lot to do with differences in socioeconomic factors and characteristics of the built environment e.g., low tree cover, poorly designed housing. Just as there is a geography to vulnerability and impacts, there is also a geography to potential solutions. We often think of these as “spatially targeted interventions”.
In this exercise, you will consider these issues in greater detail and use spatial data and analysis to identify patterns of vulnerability and potential impact along with ways of addressing risk and reducing vulnerability.
In this section, you will take a close look at key characteristics of heatwaves, trends related to climate change, and some of the direct impacts of heat on people. You will produce a few graphs and maps that will be incorporated into your write-up in Part 4.
Understanding Heatwaves (2:05)
From the video, take note of these key characteristics of heatwaves:
Source: Australian Bureau of Meteorology Heatwave Forecast Service [2]
Heatwaves are not defined just based on temperature, rather humidity and longer term trends (acclimatization) need to be incorporated. In the map above based on Excess Heat Factor (EHF), heatwaves are classified into three types, based on intensity. Note these mention potential impacts on people, infrastructure and the environment.
Source: Australian Bureau of Meteorology Heatwave Forecast Service [2]
Heatwave occurrence, duration and severity have all been changing over time. There are several important drivers of heatwaves, including reduction in vegetation cover and more built-up (impervious) surfaces in cities. Climate change is perhaps the strongest factor causing changes in heatwave characteristics (see list above).
Consider the following series of maps showing annual temperature trends in the USA. These patterns are similar to what we are observing globally.
In addition to changes in average temperatures, there have also been changes in the occurrence of extreme events. The following diagram illustrates this, where a shift in mean climate results in more hot and extreme days. As an aside, there is a growing interest in the effects 'chronic heat' on health and wellbeing i.e., hot days but not falling into the 'heatwave' range.
You will finish off this section by conducting some analysis of trends in the key heatwave characteristics (mentioned above) in the USA.
This section focuses on some of the "direct effects" of heatwaves on people, including deaths and illness.
The following image is a warning poster produced by the SA Health to help people recognize the signs of heat exhaustion and heat stroke. Note this is advice aimed at everyone and not targeted to specific groups or places.
Heat-Related Illness Signs, Symptoms And Treatment
Public warning message, such as this, provide simple and consistent information. These are linked to dedicated websites focused on heat related health. Have a quick look at these two examples, again noting that heatwave illness and deaths are, in theory, entirely preventable.
Heatwaves also have significant impacts on critical infrastructure and the environment. We won't go into much detail, but watch this short video from the Today Show, noting the reporting on impacts to critical infrastructure and the environment. If you want to learn more, there is no shortage of news coverage and research literature on these impacts.
Record-Shattering Heat Wave Leads To Deaths Across Britain (2:24)
You will finish off this section by looking at some trends in heat related deaths and illness.
So far we have considered broad trends in heatwave characteristics and direct impacts on people (e.g., heat stroke) and infrastructure. In this section you will consider some of the factors that make a person or community more vulnerable to adverse heatwave impacts. We will be taking a much more granular look at the problem in this and the following sections.
We are going to focus on heatwave vulnerability and impacts from the perspective of human health. This figure illustrates the basic problem - people must maintain their body temperature within a specific range to avoid adverse health outcomes. This is influenced by the ambient environment and characteristics of that person e.g., do they have existing health problems that may compromise their ability to thermo-regulate?
There are also a set of broader factors influencing heat health. The framework illustrated in this figure was used in a recent study to understand heat health vulnerability [12]. This is similar to the CDC Social Vulnerability Index (SVI) you would have seen in one of the previous videos, however the focus here is explicitly on heatwaves.
Generally speaking, indices are designed to help us describe concepts that are not able to be measured directly. For example, "Vulnerability" or "Socioeconomic status" are a multidimensional concept that cannot be measured with a single variable. There are many different indices developed for different purposes. Here you will take a closer look at two of the most widely used approaches.
Have a closer look at the FEMA's National Risk Index website [14]. There are three components to the NRI:
Note that the Social Vulnerability component is based on another index called the Social Vulnerability Index, or SoVI. This is one of the first approaches ever developed for emergency management, and it uses principal components analysis PCA) to reduce a set of variables to one index representing low to high vulnerability.
Similarly, Community Resilience is based on another commonly used approach called Baseline Resilience Indices for Communities (BRIC). BRIC also uses a set of indicators to build up the indices, but it does this through a "standardize and rank approach". To learn more, have a look at the NRI website and/or download the NRI manual [15].
When considering index approaches such as these (and any dataset for that matter), it is important to consult available metadata and "data dictionaries" (e.g.,here is the NRI data dictionary [16]), sometimes referred to as the Data Item List (DIL), that goes with a given dataset. You will find the NRI data in the ArcGIS Pro Project accompanying this lesson. I have mapped the SoVI component of the NRI. Have a look at the NRI attribute table, scan the field names, and look up a few variables in the data dictionary.
Next, have a closer look at the CDC Social Vulnerability Index (SVI) [17]. The SVI takes an approach that is similar to BRIC, where individual variables are used to calculate sub-indices (Themes) and then the overall index. For example, Socioeconomic Status cannot be measured directly, so "below poverty" line, "Unemployed", "Income", and "No High School Diploma" are combined to get at this construct.
Note the table accompanying the SVI feature class includes the underlying data that is used in the index calculations. If you want to "unpack" a given index, you can look at individual variables. For example, you may observe a "vulnerability hotspot" and wish to know why that is the case. SVI let's you drill down to themes and individual variables. In a particular area, you may find that socioeconomic status is the most important theme and poverty and unemployment may be the most important single indicators. You will take a closer look at the CDC SVI, and, as with NRI, it is important to have any metadata and data item list handy (open a copy with this link SVI data dictionary [19]).
When we hear about heatwaves, we often focus on weather as the main driver. However, heatwaves are experienced differently in different places due to variation in microclimate related to the build and natural environment.
In addition to broader UHI effects, there is considerable variation in microclimate (e.g., local temperature) related to features of the built environment. In the following thermal image from Los Angeles in Summer 2018, you can clearly see higher temperatures in more built up areas. Major roads, downtown LA, and the Port of Long Beach stand out as hot spots while areas such as Beverly Hills and Santa Monica along the coast are cooler. Note how you can actually see the "hot" road network grid in the area around Anaheim. This illustrates very fine variation in land surface temperatures. A key point to takeaway, is that local conditions can enhance or ameliorate heatwaves e.g., think about the simple example of standing in an open parking lot versus standing under a tree during a heatwave!
Los Angeles Heat Wave. Source: NASA Jet Propulsion Laboratory [21]
You will finish off this section by continuing to looking heat health vulnerability in Los Angeles County, California. All of the spatial data are provided in the ArcGIS Pro Project, GEOG_858_Lesson_3.aprx.
Deliverables 2
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The final part of your analysis will focus on an assessment of a some heatwave mitigation options. The first focuses on "green infrastructure" and the role of tree canopy cover in urban cooling. You will then look at the distribution of "Cooling Centers" in LA County and the populations they serve. For both cases, you will use spatial data to assess the current situation and provide analysis and advice on what could be done in the future.
ASTER Los Angeles from Space - Source: NASA JPL [25]
Bi-variate map legend for Heat Health Action Index and Percent No Tree Cover. Note "Both High" indicates areas with low tree cover and high heat health vulnerability |
Many cities now have designated "cool places" people can go during heatwaves. In this part of the exercise, you will look at whether officially designated cool places in LA County [26] provide good coverage of the city, are easily accessible, and how they may be improved.
Deliverable 3
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For the final part of this assignment, you will draw upon the analysis and key points developed in Parts 1, 2, and 3 to write a short briefing document (500 words) for planners and emergency managements in Los Angeles County. This should cover:
Deliverable 4
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Links
[1] https://www.youtube.com/@bureauofmeteorology
[2] http://www.bom.gov.au/australia/heatwave/knowledge-centre/heatwave-service.shtml
[3] http://climate.gov
[4] https://www.researchgate.net/publication/274699035_Future_Meteorological_Drought_Projections_of_Regional_Climate_Models_for_Europe
[5] https://www.sahealth.sa.gov.au
[6] https://www.sahealth.sa.gov.au/wps/wcm/connect/public+content/sa+health+internet/healthy+living/protecting+your+health/environmental+health/healthy+in+the+heat/heat-related+illness+signs+symptoms+and+treatment
[7] http://https://www.cdc.gov/disasters/extremeheat/index.html
[8] https://ephtracking.cdc.gov/
[9] https://ephtracking.cdc.gov/DataExplorer/
[10] http://ephtracking.cdc.gov/DataExplorer/
[11] https://www.health.qld.gov.au/__data/assets/pdf_file/0031/628267/disaster-emergency-incident-plan.pdf
[12] http://www.pean.gov.au/projects/heatwaves-and-health
[13] https://www.pean.gov.au/projects/heatwaves-and-health
[14] https://hazards.fema.gov/nri/
[15] https://www.e-education.psu.edu/geog858/sites/www.e-education.psu.edu.geog858/files/Lesson_03/Files/fema_national-risk-index_technical-documentation.pdf
[16] https://www.e-education.psu.edu/geog858/sites/www.e-education.psu.edu.geog858/files/Lesson_03/Files/NRIDataDictionary.csv
[17] https://www.atsdr.cdc.gov/placeandhealth/svi/index.html
[18] https://www.atsdr.cdc.gov/placeandhealth/svi/documentation/SVI_documentation_2018.html
[19] https://www.e-education.psu.edu/geog858/sites/www.e-education.psu.edu.geog858/files/Lesson_03/Files/SVI2018Documentation_01192022_1.pdf
[20] https://www.epa.gov/heatislands/learn-about-heat-islands
[21] https://www.jpl.nasa.gov/images/pia23786-los-angeles-heat-wave
[22] https://calepa.ca.gov/urban-heat-island-interactive-maps/
[23] https://www.cal-heat.org
[24] https://www.e-education.psu.edu/geog858/sites/www.e-education.psu.edu.geog858/files/Lesson_03/Files/CHAT_metadata.csv
[25] https://www.jpl.nasa.gov/images/pia02679-los-angeles-from-space
[26] https://ready.lacounty.gov/heat/
[27] https://pro.arcgis.com/en/pro-app/latest/tool-reference/business-analyst/generate-drive-time-trade-area.htm