Global Climate Change increasing number of Tornado's

Not two weeks since tornadoes killed at least 23, and flattened parts of Missouri, Oklahoma, Georgia, North Carolina and Mississippi, a big twister killed one person in northern Colorado, the AP reports. Several homes were destroyed, trucks and tractor trailers flipped, and other damage reported.

A rare pair of tornadoes in Southern California also derailed a freight train and caused other damage, according to the Los Angeles Times.

And though spring is typically only the start of tornado season, this is just the latest spate of killer tornadoes in the United States this year. Already, the death toll from tornadoes is 101, nearly 63% above the average over the past three years. It's the deadliest on record since 1998, and it's on pace to be the deadliest ever recorded.

The 868 reported tornadoes through May 18 is far ahead of the total typically seen by this time of year. It's typically July by the time this many tornadoes have been recorded in the past, according to the Storm Prediction Center.

The U.S. has already been hit by 68% of the tornadoes expected in an typical year, when compared to the 10-year average. The year is only about one-third through, and we've only just entered the typical tornado season. 2008 has been unusual because the winter produced so many damaging storms.

However, the preliminary count used to make these comparisons is somewhat inflated. Experts expect the final count to be somewhat lower, given that the same storm can be reported several times, and so overcounted.

Still, this could be a harbinger of things to come. Some scientists have warned that global warming will create conditions that make violent tornadoes more frequent.