About the increasing number of hurricanes

About the oft-mentioned increase in hurricanes, of which we heard so many warnings after Katrina (global warming, you know).  It’s probably false (another doomster fable shot to hell).  Here’s one look at the evidence:  “Counting Atlantic Tropical Cyclones Back to 1900“, Christopher W. Landsea (NOAA), EOS (Transactions of the American Geophysical Union), 1 May 2007 — Excerpt:

The Atlantic is the one tropical cyclone basin that has quantitative records back to the mid-nineteenth century for the whole basin (i.e., North Atlantic Ocean, Caribbean Sea, and Gulf of Mexico) [Jarvinen et al., 1984; Landsea et al., 2004].  Mann and Emanuel [2006] used this data set to find a positive correlation between sea surface temperatures and Atlantic basin tropical cyclone frequency for the period of 1871– 2005. Likewise, Holland and Webster [2007] analyzed Atlantic tropical cyclone frequency back to 1855 and found a doubling of the number of tropical cyclones over the past 100 years.

Both papers linked these changes directly to anthropogenic greenhouse warming. However, both analyses, with no indication of uncertainty or error bars, presumed that tropical cyclone counts are complete or nearly complete for the entire basin going back in time for at least a century. This article will show that this presumption is not reasonable and that improved monitoring in recent years is responsible for most, if not all, of the observed trend in increasing frequency of tropical cyclones.

… Moreover, new tools and data sources that have become available just in the past few years are already producing another artificial increase in tropical cyclone frequency (Figure 3c). Quikscat [Atlas et al., 2001], the advanced microwave sounding unit [Brueske and Velden, 2003], and the cyclone phase space analyses [Hart, 2003] are the primary reasons that the U.S. National Weather Service’s National Hurricane Center recognized that Ana of 2003, Otto of 2004, the unnamed subtropical storm of 2005, and the unnamed tropical storm of 2006 (see respective tropical cyclone reports online at the National Hurricane Center) were tropical cyclones and thus included in the Atlantic tropical cyclone database. These systems would have been considered extratropical cyclones previously and thus not counted as tropical cyclones before the start of the 21st century.

… Apparent in the adjusted tropical cyclone frequency record are the multidecadal quiet and active periods (quiet up to 1925, active from 1926 to 1970, quiet from 1971 to 1994, and active from 1995 onward) associated with the Atlantic multidecadal oscillation [Goldenberg et al., 2001]. A reanalysis of the trends with the inclusion of these additional tropical cyclones leads to an insignificant trend for both the periods between quiet eras and active eras. This is consistent with the findings of Solow and Moore [2002], who did a similar calculation using the U.S. landfalling record.

Other articles about hurricanes

  1. Global hurricane activity reaches new lows“, Ryan N. Maue (Center for Ocean-Atmospheric Prediction Studies, Florida State U), Climate Audit, 12 March 2009 — Here’s the COAPS website with the underlying data.
  2. Tropical cyclones and climate change“, Thomas R. Knutson et al, Nature Geoscience, 21 February 2010 — For a brief description by Roger Pielke Jr. see here.


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