No, WaPo, local weather change is NOT resulting in extra devastating rains and floods. Do you agree?

Originally published by ClimateREALISM

A June 26 Washington Post (WaPo) article entitled “The Places in the United States Hardest Hit by Extreme Rainfall” makes this claim in the subtitle: “New data from the nonprofit First Street Foundation shows that climate change leading to even more devastating rainfall.” Flooding in parts of the country.” The claim is completely misleading as it is based on a model and there are factors related to precipitation patterns and measurements that have not been taken into account.

In the article, WaPo cites a climate protection group, First Street, as the source of the claim:

But this area and others across the country are seeing such devastating rainfall become more frequent as the world warms, according to new data released Monday by the nonprofit First Street Foundation.

In a new peer-reviewed model, the group explains that the current US government estimates of precipitation rates, which are considered the authoritative source for nationwide planning and infrastructure design, do not fully capture the frequency and severity of extreme precipitation events in a changing climate. What is now considered a “1-in-100-year storm”—in short, an event with a 1 percent chance of occurring in any given year—is already happening more frequently in some places.

Taking the study with a grain of salt from even the nonprofit First Street Foundation, which has published climate alert predictions in the past, the claim is based on a model output result rather than actual measurements, using humidity-related input data with a short history. These two factors lead to a misleading result.

There are some interesting patterns in the map provided for the WaPo article (see image below):

Figure: Estimation of precipitation rates per hour for extreme precipitation. Source, First Street.

Note that the most intense areas are coastlines, such as the Gulf Coast, East Coast, and parts of the West Coast. This is not surprising as these are areas near oceans with the greatest amount of available precipitation water.

In fact, this map doesn’t really differ from the 30-year precipitation climatology for the contiguous United States, with the exception of the Houston region. This Houston Anomaly can be explained by a single storm: Hurricane Harvey, the first major hurricane to make landfall in the United States since 2005, bringing more than 40 inches of rain to the Houston area. According to Climate.gov:

The highest rainfall was 48.20 inches on a rain gauge at Clear Creek and I-45 near Houston, Texas. It was the heaviest rainfall recorded in a single storm at any location in mainland America.

As we know from Climate at a Glance: Hurricanes, there is no observed climate change signal in the number of hurricanes. Even the United Nations Intergovernmental Panel on Climate Change agrees, finding no increase in the frequency or severity of hurricanes. Even the one-time heavy rains in Houston caused by Hurricane Harvey cannot be linked to climate change.

So where are WaPo and First Street attributing the increase in precipitation levels in the rest of the country? Airports and short term dates. In the summary of the study, First Street says:

The NOAA atlases have provided the standard estimates for precipitation frequency (PFEs) in the United States for over two decades, but are losing that status due to climate change. This study evaluates the atlases against new PFEs developed using the Automated Surface Observing System and Regional Frequency Analysis (ASOS-RFA) benchmark.

For those who don’t know, the Automated Surface Observing System (ASOS) is an observing system managed jointly by the National Oceanic and Atmospheric Administration (NOAA) and the Federal Aviation Administration (FAA) designed to monitor airport runways, not climate change became. Some, but not all, ASOS systems record precipitation observed at airports. This is the precipitation data that First Street fed into their model.

There are two issues with using ASOS data. First, another 2011 peer-reviewed study (not cited in First Street’s study) found that the airport environment tended to provide higher precipitation readings:

Researchers have found that areas near commercial airports sometimes experience a small but measurable increase in rain and snow when planes take off and land under certain atmospheric conditions.

…

“It seems to be a fairly common effect that airplanes inadvertently cause a measurable amount of rain or snow when flying through certain clouds,” says Heymsfield. “That’s not necessarily enough precipitation to affect global climate, but it’s noticeable around major mid-latitude airports.”

The combination of aircraft exhaust gases (soot), which act as condensation nuclei, and turbulence and atmospheric mixing from aircraft appears to be sufficient to produce a clouding effect that leads to more precipitation at the airport.

Therefore, the airport ASOS data First Street used in their model was more highly biased from the start. And as the trend in the number of commercial airport flights has steadily increased over the past two decades, it is safe to assume that the impact on precipitation around airports has also increased. First Street and WaPo didn’t take that into account.

In addition, the length of the precipitation records is questionable. According to NOAA’s ASOS User Guide, ASOS was not implemented until the 1990s, meaning there are only about 30 years (possibly less) of precipitation data to examine. Additionally, the other data source used in the study, Atlas 14, was only created about a decade ago, according to the study itself:

That means some data from Atlas 14 may even be less than a decade old. However, long-term precipitation data for the US shows that rainfall has been increasing naturally for a long time, as shown in the figure below, something First Street failed to mention. The US Environmental Protection Agency (EPA) says:

On average, total annual precipitation over land areas has increased in the United States and worldwide. Since 1901, global precipitation has increased by an average of 0.04 inches per decade, while precipitation in the contiguous 48 states has increased by 0.20 inches per decade.

Finally, the Intergovernmental Panel on Climate Change (IPCC) AR6 report, Chapter 11, Weather and climate extreme events in a changing climateconcludes that changes in the frequency and intensity of most severe weather events (with associated heavy rainfall) have not been detected and are not attributable to human-caused climate change.

First Street really didn’t discover anything new, but they used biased and short-term data to make a claim unsupported by any other climate science.

All in all, First Street did a poor job scientifically, ignoring older data in favor of data that gave them the result they wanted. Apparently lacking the skills to critically examine First Street’s claims, WaPo authors Kevin Crowe, John Muyskens and Brady Dennis published their claims as if they were fact without any critical examination whatsoever. WaPo has done shameful journalism and tricked its readers into thinking something that just isn’t true.

Anthony Watts

Anthony Watts is a Senior Fellow in Environment and Climate at the Heartland Institute. Watts has been in the weather business both on and off camera as an on-air meteorologist since 1978 and currently makes daily radio forecasts. He has developed weather graphic presentation systems for television and dedicated weather instruments, and is a co-author of peer-reviewed articles on climate issues. He runs the world’s most viewed climate website, the award-winning website wattsupwiththat.com.

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