Report: Atmospheric Storms Could Result in $3.2B in Flood Damage by Century’s End

August 25, 2022 by

Atmospheric rivers that bombard the Western U.S. from time to time could result in as much as $3.2 billion in flood damage by century’s end, according to researchers who published a new study in the journal Scientific Reports.

Atmospheric rivers develop in the lower troposphere, and they can be nearly thousands of miles long and hundreds of miles wide. They transport large quantities of water vapor from the tropics poleward – on average, they deliver more than double the mean flow at the mouth of the Amazon River, according to the researchers.

Major flood events that have been attributed to these atmospheric rivers include the 2017 storm that damaged the Oroville Dam in Northern California and resulted in the the evacuation of more than 180,000 people.

The researchers constructed county-level damage models for 11 Western states using 40 years of flood insurance data linked to characteristics of atmospheric rivers at landfall to assess how atmospheric river-related flood damages are likely to respond to climate change.

They applied “damage functions” to global climate models under “intermediate emissions” and “high emissions” scenarios, and based their findings on the assumption variables like vulnerability and flood protection remain at present day levels.

“The models predict that annual expected AR-related flood damages in the western United States could increase from $1 billion in the historical period to $2.3 billion in the 2090s under the RCP4.5 scenario or to $3.2 billion under the RCP8.5 scenario,” the report states.

Six Rare Rain Events

Six rare thousand-year rain events within a month could mean that climate change will force NOAA to update its criteria on such events, an article from Fox Weather asserts.

The events called out include the 9 in. of record rain that fell on St. Louis, Missouri, on July 26, the 10 in.-rain surge in Kentucky days later, Illinois’ foot of rain in August, and the rainfall that led to widespread flooding in the Dallas-Fort Worth area this week.

“All six extreme events reached the local threshold to be classified by the National Weather Service as a ‘1-in-1,000-year’ rainfall event, yet all occurred within the same month, much less a millennium,” the article states.

It points to research from the U.S. Global Change Research Program that shows climate change is increasing the chance of these heavy rainfall events as well as increasing the intensity of them.

The article explains that evaporation due to warmer ocean temperatures lead to an increase in available water vapor, while warmer air can hold more water vapor. So, as the planet’s temperatures rise due to climate change, storms an access even more moisture when heavy rainfall events occur.

China Drought

The worst drought in decades is threatening China’s economic recovery, and a blistering dry summer has taken a toll on Asia’s longest river, which flows some 3,900 miles through the country and feeds farms that provide much of the country’s food and powers many of its hydroelectric stations.

Bloomberg reported in an article on Insurance Journal this week the river’s water level is at the lowest for this time of year since record-keeping began in 1865.

“And it keeps going down,” Wan Jinjun, a 62-year-old retiree who has swum the Yangtze River nearly every day for the past decade, told the news service. Wan recently needed to descend nearly 100 steps to an area historically far beneath the water line to cool off on a sweltering 104 degrees Fahrenheit day.

The Yangtze’s low water levels have interrupted electricity generation at numerous hydropower plants, causing large cities like Shanghai to turn off lights and escalators, and reduce on air conditioning use. Tesla Inc. warned of disruptions in the supply chain for its Shanghai plant, while companies like Toyota Motor Corp. have shuttered factories, Bloomberg reported.

According to BloombergNEF, a research provider covering global commodity markets and disruptive technologies, with climate change poised to deliver more frequent and persistent heat waves and droughts, the outages raise longer-term questions about China’s reliance on hydropower.

Heatwaves

California also faces heatwaves. And the risk of joint heatwave power outages is a danger to business as well as lives.

That was laid out in a report from the Rand Corp.

“Increasingly frequent and intense heatwaves and wildfires remain some of the biggest climate threats facing California,” the author, Kathleen Loa, writes. “Climate-induced hazards disproportionately threaten the health and wellbeing of vulnerable populations. They also underscore the vulnerability of the electric power system, precisely when individuals require cooling the most.”

This paper uses multiple hazard, outage, and patient data sources, to examine associations between hazards, outages, and health outcomes for California cities between 2008 and 2020.

Not surprisingly, the report found summer outages were more than twice as likely to occur on heatwave versus non-heatwave days. Heatwave events were associated with 18% more outage customer hours compared to non-heatwave events.

The report found heatwaves were bad for people, and joint heatwave outages were worse.

Heat illness rates rose by more than 1,000% during joint heatwave outage events compared with 800% during heatwave events.

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