New maps show the unfair geography of the danger season
The 2023 Danger Season has been unleashed like never before.
In June and July, heat waves bringing temperatures exceeding 113 degrees Fahrenheit swept through the Southwest and Southeast. By the end of July, Phoenix, Arizona had experienced 31 straight days with a temperature of at least 110 degrees Fahrenheit. During most of June, an unprecedented heat wave in Puerto Rico sent temperatures soaring to 125 degrees Fahrenheit.
In early August, devastating fires on Maui spread rapidly due to dry conditions and winds caused by a distant hurricane. Nearly 40,000 wildfires across the United States had burned nearly 2 million acres by the end of August.
Hillary was the first tropical storm to hit California in 84 years, and triggered flood warnings for Arizona, Colorado, Idaho, Oregon and Washington state as well.
In late August, Florida faced simultaneous storm surge and flooding threats from Hurricane Idalia on its west coast, and extreme heat warnings along most of the state’s Atlantic coast. Catastrophic flooding and river overflows occurred across much of Vermont in early July.
Combined, extreme heat, flooding, wildfires and storms have affected most populations across the United States and its territories since the danger season began on May 1. In fact, as of September 6, 96% of people in the US have experienced at least one of these alerts.
But these impacts are unequally distributed across the social and physical geography of the danger season. Low-income people—many of whom are people of color—are under greater pressure than others to stay safe from the impacts of adverse weather events. These and other demographic characteristics shape how populations are able to respond to and remain safe from extreme weather events during the danger season.
To understand how the danger season might affect different populations, I combined the total number of heat, flood, fire weather, and flood warnings issued by the National Weather Service (NWS) since May 1 with the Centers for Disease Control and Prevention’s Social Vulnerability Index (CDC SVI ).
The SVI ranks counties on 16 social factors, including unemployment, race, ethnicity, and disability, and also groups them into four related themes (see CDC SVI graph below). Each county receives a rating for each of the census variables and for each of the four themes in addition to an overall rating.
I also obtained, from the daily count of NWS alerts running the UCS Danger Season website, the total number of heat, flood, fire weather, and storm alerts issued for each county between May 1, 2023, and September 11, 2023.
Next, I categorized each county, both for the SVI’s overall vulnerability rating and the total number of alerts, as low, medium, or high. I did this to gain a better understanding of how populations with different resources and socioeconomic and physiological characteristics are able to resist danger season threats. Below I break this down for each alert type.
Season of danger and extreme heat
This year’s extreme heat has been brutal and record-breaking – across North America, the Caribbean, Europe and China.
In the United States, the largest number of heat warnings are issued in counties in the southwest (particularly south Texas) and similar counties. Municipalities In Puerto Rico (there were no temperature advisories for Hawaii or Alaska).
Population vulnerability in these places scores highly in the four themes of socioeconomic characteristics, household characteristics, people of color, and housing and transportation in the Small Migration Index. This means that pink residents experienced between 31-90 heat warnings and were mostly people of color, lacked health insurance and formal education levels, lived on low incomes, in multifamily structures and had little ability to speak English.
All of these factors are associated with worse health outcomes from exposure to extreme heat. This risk assessment is not hypothetical – as of August, Maricopa County, Arizona (where Phoenix is the largest population center) had 180 confirmed heat-related deaths, and many more deaths in counties in that state as well as in Texas and Nevada, which are believed to be fewer deaths Actual heat-related.
Academic performance in low-income school districts, as well as among black and Hispanic students in the United States, is lower on hot school days. Note that while Municipalities Puerto Rico’s blues may appear less vulnerable than pinks in the contiguous United States, and these are not directly comparable because the CDC created SVI classifications separately for Puerto Rico. There were also no data available on social vulnerability for the US Virgin Islands, so they were not included in the analysis.
Season of danger and floods
Floods have been widespread this dangerous season. Up to 12 inches of rain fell in Kentucky and Illinois, and up to eight inches in the Northeast. 70,000 people attending the Burning Man festival were stuck in the mud for days in the northern Nevada desert after a storm dropped about half an inch in the state that is usually the driest in the country. In much of the Northeast, many of these places triple their annual precipitation during the first two weeks of July.
The largest number of flood warnings were issued in Arizona, California, Colorado, Idaho, Nevada, New Mexico, Wyoming, and coastal areas of Florida, South Carolina, North Carolina, and New England.
Many counties with at least 30 flood alerts in these areas have moderate or high levels of population vulnerability. Additionally, many counties in the Northeast that were inundated during the Great Vermont Flood of 2023 have moderate to high levels of vulnerability.
In particular, many northeastern counties have high rates of households that do not have an available vehicle (making it difficult to escape) or live in mobile homes, which increases flood risk compared to other housing types because they tend to be located in floodplains. Flooding from tropical storms and hurricanes threaten coastal communities like the United Houma Nation in Louisiana.
Many of these communities have been hit by successive disasters, and are also facing coastal erosion, the impacts of COVID-19, and climate-enhancing storms like Hurricane Ida. Some of those who can afford flood insurance policies are facing rising prices and even losing their policies as climate change has made it riskier for insurance companies to provide protection.
Season of danger and fiery weather
In addition to burning nearly 2 million acres of land across the United States, wildfires in the United States and Canada have choked the skies this dangerous season, bringing some of the world’s worst air quality to the Midwest and Northeast.
Fire weather alerts are issued by the NWS when a combination of sustained high winds (at least 15 mph on average), low relative humidity, and temperatures of 75 degrees Fahrenheit or higher occurs, or when there are persistent wildfires and these conditions are also Present.
Weather alerts for fires were concentrated in the Pacific Northwest and southwest of the country. In particular, Alaska, Arizona, Colorado, New Mexico, Utah, Oregon and Washington counties experienced between 21 and 51 such alerts.
Counties in Hawaii had a small number of such alerts, which contributed to the horrific deaths and devastation caused by the Maui wildfires earlier in August.
Season of danger and storms
Storm alerts this year were far fewer in number than other types of hazard season alerts. Only a few have been released along coastal areas in Florida, Georgia, Hawaii, Puerto Rico, North Carolina and South Carolina.
Storms also bring inland flooding and the potential for storm surge, so these storm threats are usually captured in flood alerts (for example, local NWS offices in Los Angeles and San Diego issued flood alerts rather than storm alerts in anticipation of Tropical Storm Hillary).
However, counties in southeastern states that were under storm warnings also had high levels of population vulnerability.
Most places in the United States experience two or more types of danger season threats
Although I presented the danger season threats of heat, storms, floods, and fires individually, they were not experienced in isolation. In fact, 95% of all counties that were under alerts experienced at least two types of alerts during the hazard season. Notably, 53 counties in Florida and Georgia in Hurricane Idalia’s path faced the quadruple whammy of at least one of each type of storm, flood, heat, and fire alert.
Disaster aid must be adequately funded to help address the increasingly dramatic and inequitable impacts of the danger season
By early August, 15 confirmed extreme weather events and climate-related disasters had exceeded $1 billion each in cost since the start of 2023.
The danger season is not over yet, but the Federal Emergency Management Agency’s (FEMA) disaster relief fund is nearly exhausted. Hurricanes appear to have increased late in the season and wildfire season is not over yet, so more disasters may occur before the danger season is over. Legal authority to respond to extreme heat — the number one killer of extreme weather in the United States — is hampered because it is not included in the Stafford Act, which governs presidential disaster declarations and federal disaster response.
Clearly, Congress needs to replenish the Disaster Relief Fund. Additionally, Congress should permanently reauthorize the National Flood Insurance Program, update its policies, and codify the Flood Insurance Affordability Program. The effects of the danger season come at us faster than we can respond to them. We need to put policies and resources in place to avoid climate impacts that are getting worse every year.