Remember when global warming was going to cause severe hurricanes?

NASA jumped on this theory with both feet in 2005.

PASADENA, Calif. (AP) — The frequency of extremely high clouds in Earth's tropics — the type associated with severe storms and rainfall — is increasing as a result of global warming, according to a study by scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

In a presentation today to the fall meeting of the American Geophysical Union in San Francisco, JPL Senior Research Scientist Hartmut Aumann outlined the results of a study based on five years of data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft.

The AIRS data were used to observe certain types of tropical clouds linked with severe storms, torrential rain and hail. The instrument typically detects about 6,000 of these clouds each day. Aumann and his team found a strong correlation between the frequency of these clouds and seasonal variations in the average sea-surface temperature of the tropical oceans.

Environmentalists tried to blame Hurricane Katrina on global warming.

The work of hurricane expert Dr. Kerry Emanuel indicates that Global Warming provided the extra margin of energy that gave Hurricane Katrina enough power to break the levees in New Orleans. This is the conclusion of scientists, Global Warming observers along the Gulf Coast and others.

Hurricanes get their strength directly from the heat in the oceans they travel over, so it has long been expected that Global Warming would have an effect on the frequency and/or the intensity of tropical cyclones, which are called hurricanes in the United States. Observations have confirmed a sharp increase in intensity. The result is that the number of dangerous Category 3, 4, and 5 storms has increased. Dr. Emanuel’s innovation, the “power dissipation index,” helps track this intensification over time.

Al Gore tried to link Hurricane Katrina to global warming in his 2006 documentary An Inconvenient Truth.

Now I’m going to show you, recently released, the actual ocean temperature. Of course when the oceans get warmer, that causes stronger storms...

The actual truth is hurricane activity is currently at a 40 year low.

During the past 6-years since Hurricane Katrina, global tropical cyclone frequency and energy have decreased dramatically, and are currently at near-historical record lows.  According to a new peer-reviewed research paper accepted to be published, only 69 tropical storms were observed globally during 2010, the fewest in almost 40-years of reliable records.

Furthermore, when each storm’s intensity and duration were taken into account, the total global tropical cyclone accumulated energy (ACE) was found to have fallen by half to the lowest level since 1977.