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):

The chart does appear to show significant decadal increases in the number of floods. However, what the chart actually measures is the number of “damaging” floods, and whether or not a flood is classified as “damaging” is influenced by socio-economic and even political factors. As the MEA report explains:

Only events that are classified as disasters are reported in this database. (An event is classified as a disaster if it meets at least one of the following criteria: 10 or more people reported killed; 100 or more people reported affected; international assistance was called; or a state of emergency was declared . . .

Obviously, the database is going to be skewed towards more events in later decades simply because of better reporting, more declared states of emergency, and more calls for international assistance. As the MEA report observes, “although the number has been increasing, the actual reporting and recording of floods have also increased since 1940, due to the improvements in telecommunications and improved coverage of global information.”

The MEA report also identifies several non-climatic factors that influence flood damage risk: wetlands loss and deforestation, changes in engineering practices, irrigation, urbanization, and, perhaps most importantly, population growth and economic development in flood plains.

In short, teasing out a greenhouse warming “signal” from flood damages influenced by both natural climate variability and a host of societal factors is a daunting task. Yet Gore treats flood damage data as unambiguous evidence of a warming-ravaged planet.

Okay, let’s get back to the USGS scientists. Hirsch and Ryberg acknowledge they cannot entirely filter out “reservoir storage, urban development, or other human activities in the watersheds” without narrowing their study “almost entirely to very small watersheds, typically in remote and often mountainous areas.” As a reasonable compromise, they examined flood data from “200 streamgauges operated by the US Geological Survey (USGS) in the coterminous USA, of at least 85 years length through water year 2008, from basins with little or no reservoir storage or urban development (less than 150 persons per square kilometre in 2000).”

What did they find? From the paper’s abstract:

In none of the four regions [Northeast, Southeast, Northwest, Southwest] defined in this study is there strong statistical evidence for flood magnitudes increasing with increasing GMCO2 [global mean carbon dioxide concentration]. One region, the southwest, shows a statistically significant negative relationship between GMOC2 and flood magnitudes.

For further reading, the Center for the Study of Carbon Dioxide and Global Change summarizes the results of 21 peer-reviewed studies on flooding and climate variability in North America. The Center concludes:

Taken together, the research described in this Summary suggests that, if anything, North American flooding tends to become both less frequent and less severe when the planet warms, although there have been some exceptions to this general rule.  Hence, although there could also be exceptions to this rule in the case of future warming, on average, we would expect that any further warming of the globe would tend to further reduce both the frequency and severity of flooding in North America, which, of course, is just the opposite of what the world’s climate alarmists continue to claim would occur.

Last month, the Bureau of Ocean Energy Management, Regulation, and Enforcement (BOEMRE) suspended wildlife biologist Charles Monnett, who is being investigated by the Department of Interior’s (DOI’s) inspector general (IG). Monnett is the lead author of a 2006 study (linking loss of Arctic sea ice to the first documented finding of drowned polar bears.  The paper helped galvanize support for DOI’s listing of the bear as a threatened species under the Endangered Species Act. Al Gore touted the study in An Inconvenient Truth.

Public Employees for Environmental Responsibility (PEER) condemned the IG investigation as a “witch hunt” (Greenwire, Aug. 10, 2011, subscription required). Last week, the Center for Biological Diversity (CBD) and Greenpeace sent a letter to DOI Secretary Ken Salazar accusing BOEMRE of trying to muzzle scientists whose research may impede the granting of permits to drill for oil and gas in the bear’s Arctic habitat.

The transcript of the IG’s February 23, 2011 interrogation of Monnett shows that the IG “sent agents with no scientific training to ask decidedly unscientific questions about bizarre allegations relating to the polar bear paper,” CBD and Greenpeace contend. I can’t help but agree. What’s going on?

DOI officials say the investigation has nothing to do with drilling permits or the scientific integrity of Monnett’s research. As Greenwire reported last week:

BOEMRE spokeswoman Melissa Schwartz in an email said that the investigation has nothing to do with drilling. “There is absolutely no connection between any aspect of our review and approval of Shell’s Exploration Plan and Dr. Charles Monnett,” she said. “As we stated last week, the agency placed Dr. Monnett on administrative leave for reasons having nothing to do with scientific integrity, his 2006 journal article, or issues related to permitting. Any suggestions or speculation to the contrary are wrong.”

According to yesterday’s Greenwire, “a leaked memo to Monnett from the IG referenced possible procurement violations related to an ongoing study at the University of Alberta called Populations and Source of Recruitment in Polar Bears: Movement Ecology in the Beaufort Sea.”

But during the Feb. 23 interrogation, the IG agents do not discuss procurement issues. Rather, they claim to be investigating “allegations of scientific misconduct,” which one agent describes as “basically, uh, wrong numbers, uh miscalculations” (p. 83). Most of the questions relate to the polar bear study — the Monnett team’s observational M.O., their data, and assumptions.

I see no signs of scientific misconduct in Monnett’s study, and the Feb. 23 interview brought none to light. Monnett and his team observed four drowned bears after an abrupt wind storm, three within the “transect” surveyed by their aircraft. Since the transect covers one-nineth (11%) of the total study area (640 square kilometers), the team concluded it is “likely that many other bears also drowned but were not seen.” How many? Well, 9 x 3 = 27.

This is the source of Al Gore’s claim, in An Inconvenient Truth (p. 146), that “A new scientific study shows that, for the first time, polar bears have been drowning in significant numbers.” Gore, naturally, indulges in rhetorical license. ”Shows” suggests empirical proof. Monnett’s team made clear that a “likely” body count of 27 drowned bears depends on the assumption that the transect they surveyed was typical of the larger study area. “Have been drowning” suggests an ongoing process. Monnett’s team observed four drowned bears on one day in September 2004. 

Surely it was inevitable that zealots like Gore would ignore the qualifications and exaggerate the certainity and magnitude of the drowning polar bear problem. Maybe Monnett hoped this would happen. Nonetheless, it is not scientific misconduct to present research that politicians and activists exploit for their own agendas. This was in fact the first recorded observation of drowned polar bears. It coincided with the biggest decline in polar sea ice coverage during the study period (1979-2004). It was worth reporting in a scientific study, and scientists are supposed to draw properly caveated inferences from what they observe.

Could BOEMRE or DOI’s IG be a hotbed of climate change skeptics or a cabal of “drill baby drill” advocates out to punish Monnett for his influential polar bear study? I have no idea. This much is abundantly clear:

• The IG agents’ claim to be investigating “allegations of scientific misconduct” flatly contradicts the DOI spokesperson’s claim that the investigation has “nothing to do with scientific integrity.”
• The IG agents in the Feb. 23 interview bumble and stumble over basic algebra and utterly fail to reveal evidence of scientific misconduct.
• If the transcript is indicative of the larger IG investigation, we may infer that Monnett is “likely” a target of political harassment.
• If that proves to be the case, climate change skeptics, many of whom have been on the receiving end of threats and bullying, should roundly condemn the abuse.

Al Gore’s film An Inconvenient Truth bombarded audiences with image after image of hurricanes, tornadoes, floods, forest fires, and drought, creating the impression of a world in climate chaos. Gore blamed the alleged upsurge in extreme weather on global warming, that is, mankind’s sins of emission. One of Gore’s mighty pieces of evidence was a dramatic increase in insurance payments for weather-related damages. As he writes in his best-selling book of the same title:

Over the last three decades, insurance companies have seen a 15-fold increase in the amount of money paid to victims of extreme weather. Hurricanes, floods, drought, tornadoes, wildfires and other natural disasters have caused these losses [An Inconvenient Truth, p. 101].

Gore presented a chart similar to this one:

Seeing is believing, right? The problem, of course, is not merely that correlation (warmer weather/bigger losses) does not prove causation. More importantly, the economic data depicted in the chart have not been adjusted (“normalized”) to offset increases in population, wealth, and the consumer price index.

Consider this fact: More people today live in just two Florida counties, Dade and Broward, than lived in all 109 coastal counties from Texas to Virginia in 1930. Florida’s population grew by more than 17.5% in the past decade alone and today is 48% larger than in 1980. There’s tons more stuff in harm’s way than there used to be. No wonder damages are bigger than in the good old days!

Most studies that “normalize” economic loss data find no evidence of a trend towards more violent or destructive weather. Here, for example, is a chart from a study on normalized hurricane damages by Pielke, Jr et al. 2008:

Figure description: U.S. hurricane damages, 1900-2005, if all hurricane strikes had hit the same locations but with year 2005 population, wealth, and consumer price index.

A study published earlier this year in the Bulletin of the American Meteorological Society (Bouwer, L.M. 2011. Have disaster losses increased due to anthropogenic climate change?) examines 22 previous studies on the oft-asserted link between climate change and weather-related damages.

Here’s what the researcher, Laurens M. Bouwer of the Institute for Environmental Studies in the Netherlands, found:

All 22 studies show that increases in exposure and wealth are by far the most important drivers for growing disaster losses. Most studies show that disaster losses have remained constant after normalization, including losses from earthquakes (see Vranes and Pielke 2009). Studies that did find increases after normalization did not fully correct for wealth and population increases, or they identified other sources of exposure increases or vulnerability changes or changing environmental conditions. No study identified changes in extreme weather due to anthropogenic climate change as the main driver for any remaining trend.

Bouwer concludes:

The studies show no trends in losses, corrected for changes (increases) in population and capital at risk, that could be attributed to anthropogenic climate change. Therefore, it can be concluded that anthropogenic climate change so far has not had a significant impact on losses from natural disasters.

CO2Science.Org has an excellent review of the Bouwer study. On a related issue, World Climate Report reviews a recent study finding no long-term increase in the number of Atlantic tropical storms and hurricanes over the past 130 years. The apparent increase in storm frequency turns out to be an artifact of the data, that is, a product of the increase in spatial coverage and accuracy of hurricane monitoring systems.