Roger Pielke, Jr., professor of environmental studies, says the problem is that NOAA excludes certain disasters from the early years of its 1980-2011 record, that would be billion dollar weather events in today's dollars.
"...by focusing on a $1 billion threshold, as $1 billion comes to represent less and less over time, NOAA has built in a strong bias in their analysis which creates the illusion of trend," Pielke wrote in a blog post.
NOAA does not deny its billion dollar weather disaster database could be enhanced.
“...these sub-billion-dollar disasters are important to handle correctly” wrote Justin Kenney, a NOAA spokesperson in an email.
Pielke, to reinforce his point about the underestimation of the count of billion dollar weather disasters, examined 1980, which had just one according to NOAA. He found at least four additional events that he is "certain" would be billion dollar disasters in today's dollars based on existing damage estimates:
* Hurricane Allen - Aug 9, 1980 - $2.0 billion
* Grand Island tornadoes - June 3, 1980 - $1.7 billion
* Western Wisconsin derecho - July 16, 1980 - $3.8 billion
* California/Arizona floods - February 13-21, 1980 - $2.0 billion
He also noted five additional events which may have resulted in $1 billion in damage, but that have not been analyzed.
"No doubt that a reanalysis of the years 1981 to present would turn up many more such events that failed to meet the contemporary billion-dollar threshold but would certainly do so today," Pielke wrote. "NOAA should take immediate steps to improve the scientific quality of its tabulation of 'billion dollar disasters'".
For its part, NOAA is reworking its billion dollar weather disaster record to be more comprehensive says Kenney. Via email, he wrote:
“We are in the process of re-analyzing all of our data on billion-dollar events since 1980. At the upcoming American Meteorological Society meeting in New Orleans, we will present a preliminary analysis that represents one approach to accounting for sub-billion dollar events that, after the CPI adjustment, exceed the one-billion dollar threshold.”
The exclusion of certain sure-to-be billion dollar disasters in NOAA’s record raises the question whether 2011 was truly record-setting.
Pielke thinks economic indicators are the wrong indicators to use to try to answer this question.
"It is extremely misleading to use economic impacts as the basis for making claims about weather and climate.," he wrote.
He noted the “considerable development” since 1980, meaning progessively more property/infrastructure to potentially damage, which can bias economic trends.
NOAA’s Kenney added population growth, population migration, and changes in the frequency and/or intensity of extreme weather and climate events also impact the economic data.
But if you set aside the economic data, and solely examine weather and climate data, there’s little doubt 2011 was an exceptional, if not record-setting year.
As Capital Weather Gang reported yesterday, the U.S. had its most extreme year for precipitation on record, with 58% of the country experiencing severe drought or extreme wet conditions, the most in 100 years.
