Global Hurricane Activity Reaches New Lows

So much for Al Gore’s so called “predictions” and scaremongering. The Glogal Warming Cultists are wrong yet again.
Florida State University | Ryan Maue | Mar. 14, 2009

Tropical cyclone (TC) activity worldwide has completely and utterly collapsed during the past 2 to 3 years with TC energy levels sinking to levels not seen since the late 1970s. This should not be a surprise to scientists since the natural variability in climate dominates any detectable or perceived global warming impact when it comes to measuring yearly integrated tropical cyclone activity.

With the continuation (persistence) of colder Pacific tropical sea-surface temperatures associated with the effects of La Nina, the upcoming 2009 Atlantic hurricane season should be above average, as we saw in 2008. Nevertheless, since the Atlantic only makes up 10-15% of overall global TC activity each year (climatological average during the past 30 years), continued Northern Hemispheric and global TC inactivity as a whole likely will continue.

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As previously reported here and here at Climate Audit, and chronicled at my Florida State Global Hurricane Update page, both Northern Hemisphere and overall Global hurricane activity has continued to sink to levels not seen since the 1970s. Even more astounding, when the Southern Hemisphere hurricane data is analyzed to create a global value, we see that Global Hurricane Energy has sunk to 30-year lows, at the least. Since hurricane intensity and detection data is problematic as one goes back in time, when reporting and observing practices were different than today, it is possible that we underestimated global hurricane energy during the 1970s. See notes at bottom to avoid terminology discombobulation.

Using a well-accepted metric called the Accumulated Cyclone Energy index or ACE for short (Bell and Chelliah 2006), which has been used by Klotzbach (2006) and Emanuel (2005) (PDI is analogous to ACE), and most recently by myself in Maue (2009), simple analysis shows that 24-month running sums of global ACE or hurricane energy have plummeted to levels not seen in 30 years. Why use 24-month running sums instead of simply yearly values? Since a primary driver of the Earth’s climate from year to year is the El Nino Southern Oscillation (ENSO) acts on time scales on the order of 2-7 years, and the fact that the bulk of the Southern Hemisphere hurricane season occurs from October – March, a reasonable interpretation of global hurricane activity requires a better metric than simply calendar year totals. The 24-month running sums is analogous to the idea of “what have you done for me lately”.

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