April 13, 2012

Insurance Rates & Extreme Storms

I was surprised that there was no mention of the influence of climate change in either of the two front page stories in the Boston Globe  "2011 storms trigger home insurance rate hikes" and "South, Midwest assess ruin after tornadoes that killed 38".

Dr. Kevin Trenberth, former head of the Climate Analysis Section of the National Center for Atmospheric Research, explained here in 2010: "There is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It's about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms." 
He told the NY Times, "It's not the right question to ask if this storm or that storm is due to global warming, or is it natural variability. Nowadays, there's always an element of both."
Regarding the most recent storms he said, "What we can say with confidence is that heavy and extreme precipitation events often associated with thunderstorms and convection are increasing and have been linked to human-induced changes in atmospheric composition."
Here is a chart showing the trend from the Property Claims Service of Munich Re.
Incredibly fast-moving storms
The speed with which some of the storms moved was truly exceptional, thanks to jet stream winds of up to 115 mph that pushed the thunderstorms forward at amazing speeds. A number of the tornadoes ripped through Kentucky with forward speeds of 70 mph, and two tornado warnings in Central Kentucky were issued for parent thunderstorms that moved at 85 mph. If damage surveys reveal that these thunderstorms did indeed spawn tornadoes, they will set the record for fastest-moving tornadoes in recorded history. The record for the fastest moving tornado is 73 mph, set in 1925.

It should be noted that these tornadoes were not only very strong for so early in the season, but they were also the strongest ever observed in some areas:
Confirmed EF3 Tornadoes Strongest Ever Observed in At Least 3 Counties



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