But I thought someone said the science was settled

Excerpt from this article:

"January tornadoes and more heat records is something you would expect in a warming climate," said Jeff Masters, director of meteorology at Weather Underground, a popular meteorology Web site.

But many scientists aren't ready to say the weather has turned more extreme because the planet is warming.

"There is a lot of natural variability in our weather systems," Masters said. "Climate change is only just now barely beginning to be evident in the observations. That's why there is so much controversy."