Tornadoes. In An Inconvenient Truth, Al Gore and company said that global warming was increasing the number of tornadoes in the US. He claimed 2004 was the highest year ever for tornadoes in the US. In his PowerPoint slide deck (on which the movie was based) he sometimes uses this chart (form the NOAA): Whoa, thats scary. Any moron can see there is a trend there. Its like a silver bullet against skeptics or something. But wait. Hasnt tornado detection technology changed over the last 50 years? Today, we have doppler radar, so we can detect even smaller size 1 tornadoes, even if no one on the ground actually spots them (which happens fairly often). But how did they measure smaller tornadoes in 1955 if no one spotted them? Answer: They didnt. In effect, this graph is measuring apples and oranges. It is measuring all the tornadoes we spotted by human eye in 1955 with all the tornadoes we spotted with doppler radar in 2000. The NOAA tries to make this problem clear on their web site. With increased national doppler radar coverage, increasing population, and greater attention to tornado reporting, there has been an increase in the number of tornado reports over the past several decades. This can create a misleading appearance of an increasing trend in tornado frequency. To better understand the true variability and trend in tornado frequency in the US, the total number of strong to violent tornadoes (F3 to F5 category on the Fujita scale) can be analyzed. These are the tornadoes that would have likely been reported even during the decades before Dopplar radar use became widespread and practices resulted in increasing tornado reports. The bar chart below indicates there has been little trend in the strongest tornadoes over the past 55 years. What most of you don't know is that a wedge tornado (see example below) which can have multiple vortexes can wreak billions of dollars in damage if it lands in a populated city it could be designated an EF-5. However, what most of you probably don't know is that if the same tornado lands in the middle of a grass field and causes no damage - it would be rated an EF-0. It could have 300 mph winds and still be classified as such. We also have more trained spotters, storm chasers, computer equipment and technology that helps us detect a tornado from thousands of miles away. Right now I can hope onto my GRLevel3 software and look out for hook echos and have the software analyze one and it would estimate the winds inside of the tornado. In fact, it can even create a composite 3D image of the tornado. With all of this software, it is no wonder why there are more tornadoes being reported. But Al Gore won't tell you that. Al Gore will tell you that Global Warming is the reason why there's an increase in the frequency of tornadoes. And he's wrong. And he knows he's wrong. But he also knows that you don't know that he's wrong and that you'll buy his BS which makes him a multi-multi-millionaire.