There were more tornado deaths in April than any other time in history. The cause is unknown, but the damage is enormous.

The weekend's tornado in Joplin, Mo., was just the latest--and most devastating--of what has been a rash of tornadoes. In April, more than 360 people were killed by tornadoes. The previous record was 267, in 1974. As of yesterday, there had been 1,151 tornadoes this year. Last year at this time, there had only been 506. NOAA has documented the tornadoes reported in the month in this chilling video:

Are there more tornadoes, or just more people in the path of them? Scientists are still debating whether or not this season is an aberration or part of a climate-change-fueled trend in larger storms. A head scientist at NOAA recently said there was no connection, but back in 2007 NASA predicted that climate change would lead to a large increase in deadly storms. And, as we wrote, insurance companies have noticed a large uptick in weather events like these--and the costs associated with them.