2023 U.S. Billion-dollar weather and climate disasters in historical context

During the first six months of 2023 there were 12 separate billion-dollar weather and climate disaster events. These include two tornado outbreaks, six general severe weather events, two hail storms, a winter storm event and California flood event: (www.ncei.noaa.gov/access/billions). The cost for these twelve events is more than $34 billion, which is well above the 44-year CPI-inflation adjusted average of $12.9 billion for the first 6 months of each year (1980-2023). However, the second half of the year (July-December) is when the U.S. costs and impacts historically begin to accumulate given that the cost of drought, wildfires and hurricanes peak during the Fall months. For example, the 43-year inflation-adjusted average for all billion-dollar disasters during the first 6 months is $12.9 billion while it is $46.2 billion during the final 6 months. Combined this produces the 43-year, inflation-adjusted annual cost average of $59.1 billion.

During 2022, there were 18 separate billion-dollar weather and climate disaster events across the United States. The total cost from these events of 2022 exceeded $175 billion (as of June 2023) and was the third most costly year on record, behind 2017 and 2005. The total costs for the last five complete years was $617.5 billion while the total over the last seven years (2016-2022) is $10.56 trillion. The U.S. disaster cost total from January 1980 through June 2023 exceeds $2.575 trillion from 360 separate billion-dollar weather and climate events (all inflation-adjusted to 2023 dollars).

The frequency and cost of weather and climate disasters are increasing in the United States due to a combination of increased exposure [more assets at risk], vulnerability [where we build, how we build], and that climate change is increasing the frequency of some types of extremes that lead to billion-dollar disasters. A lot of development has taken place in vulnerable areas along the coasts, the wildland urban interface or in river floodplains. Vulnerability is especially high where building codes are insufficient for reducing damage from extreme events.

The 44-year climatology of U.S. billion-dollar disasters offers a view of risk from extreme events, which are often seasonal in nature. For example, during the spring months (March-May) severe storms including tornadoes, hail and high winds often occur in many Central and Southeast states. During the spring months there is also potential for major river flooding (i.e., deep blue events in chart above). U.S. springtime flooding from snowmelt and/or heavy rainfall is a persistent hazard that affects many towns and agriculture regions within the Missouri and Mississippi River basins, among others. Of note, there were more billion-dollar flood events from 2010-2022 (21) than in the 1980s, 1990s and 2000s combined (19) - all flood events CPI-adjusted to 2023 dollars.

During the fall season, Gulf and Atlantic coast states must be vigilant about hurricane season particularly during August and September. Hurricanes are the most destructive and costly of these events totaling damage losses exceeding $1.3 trillion since 1980. Another concerning trend is that the U.S. has been impacted by landfalling category 4 or 5 hurricanes in five of the last six years (Harvey, Irma, Maria, Michael, Laura, Ida and Ian), which is the highest frequency on record within a six year period.

Also, the peak of the Western U.S. wildfire season occurs during the fall months of September, October and November (i.e., orange events in chart above). California, Oregon and Washington are often states that face wildfire risk and related poor air quality for weeks to months. Western wildfire risk is also becoming more hazardous, as 17 of the 20 largest California wildfires by acreage and 18 of the 20 most destructive wildfires by # of buildings destroyed have occurred since the year 2000. In four of the last six years (2017, 2018, 2020, 2021) California has experienced historically large and costly wildfires with losses well exceeding $70.0 billion: http://www.ncei.noaa.gov/access/billions/mapping

In recent years there has been an increasing exposure and vulnerability of the U.S. to extreme weather and climate events. To better reflect this we have integrated county and census tract socioeconomic vulnerability and exposure analysis to highlight U.S. counties where extremes may cause disproportionate physical, social and economic impacts on vulnerable populations. Historically, the U.S. South, Central and Southeast regions have experienced a higher frequency and cost from billion-dollar disaster events. These same U.S. regions are also projected to have the most negative future impacts across several socioeconomic metrics, See: https://www.ncei.noaa.gov/access/billions/risk

To reflect multi-hazard, socioeconomic vulnerability, NCEI's Billion-dollar disasters analysis enhanced the mapping interface to include U.S. county and census tract data – providing many users with local community-level awareness of hazard risk, exposure and vulnerability across more than 100 combinations of weather and climate hazards. This mapping tool is intended to provide U.S. communities with information and guidance on their susceptibility to weather and climate hazards, as well as potential future impacts from them. This mapping tool gives broad, nationwide comparisons reflecting a county's combined physical exposure, vulnerability and resilience to hazard risks. The mapping also provides insight for compound hazards and cascading risk potential. Each region faces unique hazard combinations, which are useful in a new era of more likely cascading hazard impacts. For example, in California we often see drought-enhanced wildfire seasons that produce mountain-side burn scars, which often enhance debris flows from flooding during the following wet season.

As another example of compound disasters, southern Louisiana has been hit by numerous hurricanes during 2021 and 2020 including two category 4 storms, Ida and Laura. This continual exposure to hazards slows down recovery and makes it costlier. Confronting these monetary and socioeconomic recovery costs is challenging for communities and populations that lack enough resources. The integration of socioeconomic, vulnerability and exposure analysis leveraging the FEMA National Risk Index (NRI), the CDC Social Vulnerability Index and the Census American Community Survey data, among others, seeks to highlight U.S. counties and census tracts where extremes may cause disproportionate physical, social and economic impacts on vulnerable populations.