Signals Summary: Climate change is increasing the frequency and intensity of a variety of extreme weather events.
Article Excerpt: Since 1980, the U.S. has sustained 258* weather and climate disasters where the overall damage costs reached or exceeded $1 billion (including adjustments based on the Consumer Price Index, as of January 2020). The cumulative cost for these 258 events exceeds $1.75 trillion.
During 2019, the U.S. experienced a very active year of weather and climate disasters. In total, the U.S. was impacted by 14 separate billion-dollar disasters including: 3 major inland floods, 8 severe storms, 2 tropical cyclones (Dorian and Imelda), and 1 wildfire event. 2019 also marks the fifth consecutive year (2015-19) in which 10 or more separate billion-dollar disaster events have impacted the U.S.
The 14 separate U.S. billion-dollar disasters in 2019 represent the fourth highest total number of events (tied with 2018), following the years 2017 (16), 2011 (16) and 2016 (15). The most recent years of 2019, 2018 and 2017 have each produced more than a dozen billion-dollar disasters to impact the United States—totaling 44 events. This makes a 3-year average of 14.6 billion-dollar disaster events, well above the inflation-adjusted average of 6.5 events per year (1980-2019).
Keep in mind that these estimates do not reflect the total cost of U.S. weather and climate disasters, only those associated with events in excess of $1 billion in damages. However, these extreme events do account for the majority (>80%) of the damage from all recorded U.S. weather and climate events (NCEI; Munich Re). These billion-dollar disaster events are becoming an increasingly larger percentage of the cumulative damage from the full distribution of weather-related events at all scales and loss levels.
Clearly, the historically large U.S. losses from hurricanes and wildfires over the last few years have further skewed the total distribution of extreme weather costs. This increase reflects a combination of increased exposure, vulnerability and the fact the climate change is playing an increasing role in the frequency of some types of extremes that lead to billion-dollar disasters.
The increase in population and material wealth over the last several decades, are an important cause for the rising costs. These trends are further complicated by the fact that much of the growth has taken place in vulnerable areas like coasts and river floodplains. Vulnerability is especially high where building codes are insufficient for reducing damage from extreme events.
Climate change is also paying a role in the increasing frequency of some types of extreme weather that lead to billion-dollar disasters—most notably the rise in vulnerability to drought, lengthening wildfire seasons in the Western states, and the potential for extremely heavy rainfall becoming more common in the eastern states. Each of these changes in extremes are becoming more visible in relation to the influence of climate change (NCA 2018, Chapter 2).