All $1bn events, by state frequency, from 1980 to 2016. Photograph: Nooa
Since 1980, the NCEI has found that the US has suffered 212 such disasters, collectively costing more than $1.2tn. Texas has had most such events, at 89. The nine events across the US prior to Harvey put 2017 on track to challenge the recent highs of 2016, with 15 such events, and 2011, which saw 16.
The NCEI noted that there were four inland, non-tropical major flooding events causing more than $1bn in damage in the US in 2016. There were two in the first half of 2017 before Harvey, which the experts found “surprising” because before 2016 no more than two $1bn inland flooding events had occurred in any year since 1980.
The magnitude of the impact of a disaster is often proportional to the scale of government response required and paid for by taxpayers, said Adam Smith, a Noaa applied climatologist and the primary researcher for the analysis of $1bn disasters.
“This is particularly true for hurricane and inland flood events,” he said, “since many US households lack flood insurance and are at risk of losing everything. We are now seeing this unfold on an unprecedented scale due to Hurricane Harvey.”
Smith added: “The US has seen an increase in costly, historic flooding disasters in recent years, which is very troublesome when looking into the future. It’s unclear if Harvey’s costs will ultimately surpass Katrina. However, since this is an unprecedented extreme precipitation event over a major city, in addition to the damage to other cities and regions from wind, storm surge and flooding, it’s very possible.”
NCEI cost estimates are based on a range of public and private data sources. They take into account total direct losses incurred in weather and climate events, of both the insured and uninsured, including damage to all buildings and the assets within; the cost of business interruption; damage to vehicles, boats, offshore energy platforms and public infrastructure; and destruction of agricultural assets.
Smith cited analysis from Erwann Michel-Kerjan, a risk management expert, partner at McKinsey and former adviser to the World Bank, which concludes that the cost of catastrophic hurricanes in particular hitting the US is increasingly being borne by the federal government.
The taxpayer shouldered less than 10% of the cost of Hurricane Diane in 1955 and a quarter of the cost of Hurricane Hugo in 1989, according to Michel-Kerjan, but 50% the cost of Katrina in 2005 and 80% of the cost of Hurricane Sandy in 2012.
Noaa has been developing new methods of flood forecasting, which advocates fear will come under threat, with many other aspects of the agency’s work, if federal funding is cut.
The Noaa experts refused to comment on funding issues.
Jeff Watters, director of government relations for the nonprofit Ocean Conservancy, said: “Noaa’s research is crucial in so many aspects and its new methods of flood forecasting, for example, can be a matter of life and death.”
The Senate rejected almost all of Trump’s proposed cuts to Noaa when it reviewed his budget earlier this year. Congress resumes business next week, beginning negotiations to produce a federal budget by the end of September.
Robert Stavins, professor of energy and economic development at the Kennedy School of Government at Harvard, said: “I would hope that Noaa would continue to be a center of scientific excellence for the US government.”