Is Increased Variability a Good Way to Prove Global Warming?

From the EnergyTribune, http://cr4.globalspec.com/thread/50604 (Sorry, link no longer available.)

"How can your prediction be wrong if you forecast everything to happen? The answer is you can't. This silly notion is what we are being told to swallow. We are being "educated" into believing that record cold is the result of warmer temperatures. Something is very wrong with this picture.

"Despite all the shouting about an increase in more extreme storms, the reality is that there has been no increase in the variability of weather. Let's look at record high and low temperatures in the United States. By far the highest level of extreme temperatures was in the decade of the 1930s. There were many more record high and low temperatures in the '30s than at anytime in the last 130 years. In fact the most recent decade of the 2000s had the lowest number of record high and record low temperatures since the 1880s! This means that in terms of temperature the weather has been much more stable, not more extreme.

"How about hurricanes? The global warming alarmists have been telling us that these storms will become more powerful as the earth warms. An examination of the World Accumulated Cyclone Energy Index reveals the opposite. This index measures the total energy output of tropical storms and hurricanes around world. It shows that worldwide tropical cyclone energy levels are now lower than anytime in the last 30 years. Hurricanes are not increasing in intensity around the world, they are getting weaker.

"How about tornadoes in the US? There are about 1,200 tornadoes in the US each year. No other place on earth even comes close. Global warming theory says these violent whirlwinds should become more common and stronger. The opposite is happening. An examination of strong and violent tornadoes shows us that the number of powerful tornadoes has been decreasing since the 1970s."

Why doesn't the data (variability of the weather) match the hypothesis?