There has been much speculation and many headlines about the relationship between global warming and extreme weather. For example, see this recent alarmist story from the AP in the Arizona Daily Star: “World warned to prepare for extreme weather.” The first line of that story says, “Global warming is leading to such severe storms, droughts and heat waves that nations should prepare for an unprecedented onslaught of deadly and costly weather disasters, an international panel of climate scientists said in a new report issued Wednesday.” Apparently the story authors got their information from alarmist press releases and interviews rather than the report itself. (They got the page count wrong too.)
The basic conclusion of the Intergovernmental Panel on Climate Change’s (IPCC) new report on the subject of extreme weather is: “While there is evidence that increases in greenhouse gases have likely caused changes in some types of extremes, there is no simple answer to the question of whether the climate, in general, has become more or less extreme.”
While storm damage makes the news, the damage is largely an artifact of our propensity for building infrastructure in the areas subject to extreme weather rather than any imagined increase in such weather.
IPCC: “There is medium evidence and high agreement that long-term trends in normalized losses have not been attributed to natural or anthropogenic climate change.”
Some other interesting quotes from the IPCC report:
“The statement about the absence of trends in impacts attributable to natural or anthropogenic climate change holds for tropical and extratropical storms and tornados.”
“The absence of an attributable climate change signal in losses also holds for flood losses.”
“Some authors suggest that a (natural or anthropogenic) climate change signal can be found in the records of disaster losses (e.g., Mills, 2005; Höppe and Grimm, 2009), but their work is in the nature of reviews and commentary rather than empirical research.”
You can download the 582-page report here: http://www.ipcc-wg2.gov/SREX/ That page allows you to download either the Summary for Policy Makers (11.8 Mb) or the full report (44 Mb).