Warming oceans will lead to bigger, stronger storms
As if to underscore a new report from the U.S. Government Accountability Office on the costs of global warming, researchers at the University of Vermont this week released a study showing that financial losses from hurricanes could increase more than 70 percent by 2100.
The figures are based on the worst-case rise in ocean temperatures projected by the Intergovernmental Panel on Climate Change, the United Nation-sponsored group that assesses climate change research and issues periodic reports.
The study focused on 13 coastal counties in South Carolina within 50 miles of the coast, including Charleston, using data from a model that simulated hurricane size, intensity, track and landfall locations under two scenarios: if ocean temperatures remain unchanged from 2005 to 2100 and if they warm at a rate predicted by the IPCC’s worst-case scenario.
The findings, published in the journal Sustainable and Resilient Infrastructure. is based on the business-as-usual emissions scenario, and the researchers said their projections are made with an 80 percent confidence level.
In the climate of 2005, the study estimated the expected loss from a severe hurricane would be about $7 billion. Under the warming oceans scenario, the intensity and size of the hurricane at the same risk level is likely to be much greater, and the expected loss figure climbs to $12 billion.
The robust database for the projections comes from 150 years worth of information gathered by NOAA, combined with a detailed FEMA hazards database that estimates losses based on wind speed for costs of repair, replacement, content and inventory, as well as costs resulting from loss of use, such rental income loss, business interruption and daily production output loss.
The researchers did not find that warming oceans will lead to more frequent hurricanes, only that warmer seas will lead to higher wind speeds and storms that are greater in size and therefore cover a larger area.
The losses are calculated based only on wind and wind-driven rain and do not include the large financial impacts of storm surge or flooding.
In a press release, civil engineer David Rosowky, one of the study’s authors, said the research clearly shows coastal communities could take a big hit from global warming.
“To be prepared, we need to build, design, zone, renovate and retrofit structures in vulnerable communities to accommodate that future,” he said.
He also pointed out that the projections are based on the IPCC’s 2014 assessment, which is already slightly outdated.
“That suggests that these scenarios are evolving,” Rosowsky said. “What is today’s worst case scenario will likely become more probable in the IPCC’s future reports if little action is taken to slow the effects of climate change.”
The increasing severity of hurricanes will also affect hurricane modeling, Rosowsky said, and consequent predictions of damage and financial loss. In a postscript to the paper, which will also be published as a chapter in a forthcoming book, Rosowsky cites the three catastrophic storms of the current hurricane season, Harvey, Irma and Maria, as examples of events so severe they will shift the assumptions about the likelihood that such severe hurricanes will occur in the future.