The opening of Storm's electronic weather exchange comes at a time when the perceived impact of global warming has created a surge of interest in weather-based trading tools. The Weather Risk Management Association reports that the value of weather-based contracts traded worldwide in both over-the-counter and exchange-traded markets grew from $8.4 billion in 2005 to $45.2 billion in 2006, before falling in 2007, reflecting the move from seasonal to monthly contracts on the Chicago Mercantile