The hilarious South Park episode “Two Days Before the Day After Tomorrow” opens with Eric Cartman and Stan Marsh playing in a motor boat that Cartman falsely claims belongs to his uncle. Cartman persuades Stan to drive the boat. Not knowing how, Stan crashes the boat into the world’s largest beaver dam, flooding the town of Beaverton.

Rather than get help, Cartman and Stan decide to tell no one and pretend they were playing at Eric’s house all afternoon. The flood leads to wild speculation not only in South Park but also in the national media and the scientific community. Stan’s father Randy is a geologist. He and his colleagues determine that global warming caused the Beaverton flood. Worse, they calculate that global warming will strike worldwide “two days before the day after tomorrow.” Randy exclaims: “Oh my God — that’s today!” There is panic in the streets.

Echoing the sermon at the end of the 2004 Sci-Fi disaster film, The Day After Tomorrow, Randy laments: “Stan, I’m afraid us adults just let you children down. We didn’t take care of our earth, and now you’ve inherited our problems. We didn’t listen!” To watch Randy’s mea culpa on YouTube, click here.

We’ve been hearing a lot from Randy’s real-world counterparts of late, which is why in recent posts, I presented evidence that climate change was not the principal factor behind the 2003 European heat wave, the 2010 Russian heat wave, the 2011 Texas drought, or the ongong Midwest drought.

What about floods? Google “global warming” and “floods,” and you’ll get 7.2 million results. Given all that ‘evidence,’ you may surprised that a new scientific study finds no correlation between rising global mean carbon dioxide concentrations (GMCO2) and flooding in the U.S.

The study — “Has the magnitude of floods across the USA changed with global CO2 levels?” — was conducted by R. M. Hirsch and K. R. Ryberg of the U.S. Geological Survey (USGS) and published in Hydrological Sciences Journal. An excellent summary is available at  CO2Science.Org.

Hirsch and Ryberg examined streamflow data at 200 stream gauges operated by the USGS in four regions (Northwest, Southwest, Northeast, Southeast). The records, which go back at least 85 years, are ”from basins with little or no reservoir storage or urban development.” In other words, the stream flow data are unlikely to be contaminated by any local ‘anthropogenic’ factors unrelated to global climate change.

The result? “In none of the four regions defined in this study is there strong statistical evidence for flood magnitudes increasing with increasing GMCO2. One region, the southwest, showed a statistically significant negative relationship between GMCO2 and flood magnitudes.”

In discussing their findings, Hirsch and Ryberg opine that “it may be that the greenhouse forcing is not yet sufficiently large to produce changes in flood behavior that rise above the ‘noise’ in the flood-producing processes.”

“On the other hand,” comment the good folks at CO2Science.Org, “it could mean that the ‘anticipated hydrological impacts’ envisioned by the IPCC and others are simply incorrect.”