Are Recent Heat Waves A Result of Climate Change?

"The last couple of years have certainly felt unusually hot in many parts of the U.S., but are they really all that unusual?"

"Many people wonder whether a warming climate is turning up the temperature or whether it's all just part of the normal variation in the weather. Among scientists, there's a growing view that these latest heat waves are indeed a result of climate change."

"NASA climate scientist James Hansen has looked at the past century's temperatures all over the world. He has measured hot spells with what you might call a "unit of weirdness" — a standard deviation. It's a measure of abnormality."

"One standard deviation from what's normal might be throwing snake eyes three times in a row. The more snake eyes you roll in a row, the more standard deviations away from normal you are."