CLIMATE CHANGE: Financial Risks to Federal and Private Insurers in Coming Decades are Potentially Significant

http://www.gao.gov/new.items/d07285.pdf?source=ra
The key assessments GAO reviewed generally found that rising temperatures are
expected to increase the frequency and severity of damaging weather-related
events, such as flooding or drought, although the timing and magnitude are
as yet undetermined. Additional research on the effect of increasing
temperatures on weather events is expected in the near future, including a
highly anticipated assessment of the state of climate science this year.
Taken together, private and federal insurers paid more than $320 billion in
claims on weather-related losses from 1980 to 2005. Claims varied
significantly from year to year—largely due to the effects of catastrophic
weather events such as hurricanes and droughts—but have generally
increased during this period.