R.M. Hirsch

Post image for Heat Waves, Droughts, Floods — We Didn’t Listen!

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.

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Post image for Is Flood Magnitude in the USA Correlated with Global CO2 Levels?

No — or, more precisely, not  yet — conclude R.M. Hirsch and K.R. Ryberg of the U.S. Geological Survey in a recent study published in Hydrological Sciences Journal.

“One of the anticipated hydrological impacts of increases in greenhouse gas concentrations in the atmosphere is an increase in the magnitude of floods,” note Hirsch and Ryberg. Righto! Google “global warming” and “flood predictions,” and you’ll find more than 2.7 million sites where this hypothesis is affirmed or at least discussed. The researchers explain:

Greenhouse gases change the energy balance of the atmosphere and lead to atmospheric warming, which increases the water-holding capacity of the atmosphere, which in turn, potentially changes the amount of precipitable water.

Sounds plausible, but all weather is local or regional, and a lot more goes into making weather than average global temperature.  In addition, all flooding is local or regional, and a lot more goes into determining flood risk than local or regional weather patterns.

As Hirsch and Ryberg point out, “human influences associated with large numbers of very small impoundments and changes in land use also could play a role in changing flood magnitude,” and “at time scales on the order of a century it is difficult to make a quantitative assessment of the changes in these factors over time.”

That, however, did not stop good ol’ Al Gore from claiming that global warming is responsible for a decade-by-decade increase in the number of large floods around the world (An Inconvenient Truth, p. 106). Gore’s source was a chart from the Millennium Ecosystem Assessment (Figure 16.5, p. 448): [click to continue…]