The current flooding in Colorado may rank among the top 10 floods in the state. Some of the news media are conflating it as a “once in a thousand years” flood. Other media (and Senator Harry Reid ) are saying it is a sign of global warming; for instance see an NBC News report here: “The exact role of global climate change in the deluge is uncertain, but it certainly played a part, according to climate, weather and policy experts.” Policy experts? Those policy experts should pass a law against flooding. If global warming “certainly played a part,” how do they account for the other major floods listed below?
A report from The Colorado Climate Center at Colorado State University in Boulder puts the current flood in perspective:
“As is typical of Colorado storms, some parts of the state were hard hit and others were untouched. Still, this storm is ranking in the top ten extreme flooding events since Colorado statehood,” said Nolan Doesken, State Climatologist at CSU. “It isn’t yet as extreme or widespread as the June 1965 floods or as dramatic as the 1935 floods but it ranks right up there among some of the worst.”
Among the worst, according to Climate Center data, occurred in May 1904, October 1911, June 1921, May 1935, September 1938, May 1955, June 1965, May 1969, October 1970, July 1976, July 1981, and, of course, the Spring Creek Flood of July 1997 that ravaged Fort Collins and the CSU campus.
“Every flood event in Colorado has its own unique characteristics,” said Doesken. “But the topography of the Colorado Front Range makes this area particularly vulnerable when the necessary meteorological conditions come together as they did this week.”
I was attending Colorado School Mines in Golden, Colorado, in 1965 and remember that flood. You can read about the 1965 flood details from the National Center for Atmospheric Research here.
“The Rocky Mountains have long been prone to flash floods. Native Americans warned Boulder’s founders of flooding, according to historical accounts. The U.S. Geological Survey has mapped the remnants of ancient flash floods all along the Colorado Front Range, where steep mountain canyons send debris pouring into town, along with the rocks that give Boulder its name.” (Source)
UPDATE: Dr. Roger Pielke, Jr. professor of environmental studies at the Center for Science and Technology Policy Research at the University of Colorado at Boulder:
On the Colorado floods: Over the past few days I’ve been engaged with a lively debate with a colleague over whether it is meaningful to proclaim that the extreme rainfall observed in Colorado several weeks ago are “consistent with” predictions of more intense rainfall associated with human-caused climate change.
Motivated by this discussion, I downloaded precipitation records from NOAA for Boulder (here in .dat), which covers a period from May 1, 1897 to August 31, 2013.
In the first half of that time period, covering 58 years or so, Boulder experienced 24 days with measured rainfall of 2 inches or more. In the second half of that period (also 58 years or so) Boulder experienced 20 days with rainfall of 2 inches or more.
How about really extreme, say 4 inches or more? There is only one data point in the record at that level, July 31, 1919. Now, there is a second.
So what is this data “consistent with”? Pretty much anything, and that is the point.