The earlier years of that time period had
a high number of tropical cyclone landfall events, while the latter years experienced relatively few.
So, we can only tell for sure with hindsight whether
the high number of tropical cyclones are an indication of a climate change (let's hope it's not!).
Not exact matches
As the climate changes,
tropical cyclones are expected to produce more rain and the frequency
of the
highest intensity storms is projected to increase even though the overall
number of storms may remain unchanged or perhaps even decrease.
I believe the jury is still out on the question
of the
number of tropical cyclones because the IPCC's assessment has so far not included studies on the relationship between the
number of tropical cyclones and the area
of high sea surface temperature, such as the analysis shown in Fig 2 (1).
NOAA also forecasts a
high hurricane activity for the remainder
of the season, and time will show if this season will match the 2004 in terms
of number of tropical cyclones.
I wonder if the fact the
higher SSTs will lead to somewhat longer seasons (and 2005 certainly had that), and larger sea - surface area where TCs might form, would serve to counteract the effect you describe, and still lead, net - net, to an increase in the
number of tropical cyclones with
higher SSTs.
While there has been a recent increase in the
number of landfalling US hurricanes, the increase in
tropical cyclone - associated heavy events is much
higher than would be expected from the pre-1994 association between the two, indicating that the upward trend in heavy precipitation events is due to an increase in the
number of heavy precipitation events per system.
«For the
high emissions scenario, it is likely that the frequency
of hot days will increase by a factor
of 10 in most regions
of the world», said Thomas Stocker the other Co-chair
of Working Group I. «Likewise, heavy precipitation will occur more often, and the wind speed
of tropical cyclones will increase while their
number will likely remain constant or decrease».
They used an algorithm to count the
number of tropical cyclones that formed in each ocean basin in the world
of 2080 - 2099, when the assumed SSTs were 2.5 C
higher than today's (IPCC A1B scenario).