Climate Denial Crock of the Week

Marshall Shepherd in Forbes:

 Scientists are now estimating this to be a 1 in 1000 year event. I actually hate when storms are referred to in that way. It gives people the impression that this event can only happen every 1000 years. However, Jonathan Erdman, a senior meteorology with IBM/The Weather Company, nails the problem in the Tweet below. According to the U.S. Geological Survey (USGS), “In terms of probability, the 1,000-year flood has a 0.1% chance of happening in any given year.” Let’s start being more descriptive for the public and decisonmakers, please.

However, I digress. Let’s get back to the other ingredients. Impervious surfaces in urban environments fundamentally alter the natural water cycle. They cause increased surface runoff and a reduction of infiltration into the ground. The images of inundated roads or airport runways are stark examples of anthropogenic modification to the water cycle.

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Dr. Kieran Bhatia raised another interesting wrinkle in the south Florida floods that could have a climate connection. Bhatia is a Vice President at Guy Carpenter who studies climate and extreme events. His tweet below suggests that warmer sea surface temperatures likely contributed to the water vapor “pump” into these quasi-stationary supercell storms.

Experts have warned us for years that the stormwater engineering for cities was designed under the fatal assumption of “stationarity.” What does that mean? Brian Bledsoe leads the Institute for Resilient Infrastructure Systems (IRIS) at the University of Georgia. He often says that many engineered systems and infrastructure were designed under assumptions that rainstorms of 1970 will be the same in 2023. Nope! They just aren’t.

The peer-review literature is bursting at the spine with studies noting that intensity of rainstorms is changing, particularly at the top 1-2 percent level. Unfortunately the assumptions and data used by engineers is outdated in many cases. There are efforts to update such information, and we need to do it fast. Basic physics tells us that a warming climate allows more water vapor availability to storms. The well-known Clausius-Clapeyron relationship tells us there is a 6-7 percent increase in atmospheric water content for every degree C increase in temperature.

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As someone with over two decades of experience at the intersection of meteorology, climate, and societal impact, there are things that have become abundantly clear to me. One of those things is that people have static “mental models” or reference weather events in their minds. People who experienced Hurricane Katrina (2005) or a particular flooding event often anchor to that event as an exemplar of the “worse-case” scenario. We all need to adjust our reference storms. A dynamic approach will needed in order to adequately prepare and adjust to the new realities of weather and climate.