JANUARY 15, 2021
By Paul Homewood
There has been much alarum about last year being a “record Atlantic hurricane season”. As I pointed out at the time, the claim was based on the number of named tropical storms, which includes both hurricanes and weaker storms. The number of Atlantic hurricanes alone was not a record.
Because of a tendency to name all sorts of small storms nowadays, not to mention the ability of satellites to spot them, the claim was always a spurious one.
Now we fortunately have the Accumulated Cyclone Energy (ACE) data available for the year, the claim is proven to be nonsensical and deceitful.
Briefly, ACE is a measurement of the intensity of the intensity and duration of Tropical Storms and Cyclones. [Tropical Cyclone is a generic name for storms which are called hurricanes in the Atlantic and typhoons in the W Pacific].
Reliable data for the Atlantic, both number of storms and ACE, is only available since the era of satellites in 1966, as NOAA explain:
However, scientists at the Hurricane Research Division of NOAA have diligently examined older meteorological records to re-analyse hurricanes prior to 1966 – details here.
This allows us to make much more meaningful long term comparisons. Their data shows that last year was a long way from being a record hurricane season, or tropical storm for that matter.
In terms of ACE, it was only the 10th strongest, The record year was 1933.
There is a clear cyclical pattern, with more intense activity in the 1930 to 1970 period, less between 1970 and late 1990s, and an increase since. This is directly related to the Atlantic Multidecadal Oscillation (AMO), a natural cycle which switches from warm to cool over a 50 to 60 year cycle. It was in warm phase in the 1930s to 60s, and has also been in warm mode since the mid 1990s.
NOAA explain the relationship between AMO and Atlantic hurricane activity:
It is also worth pointing out that hurricane activity, even after re-analysis, still likely under records hurricane activity prior to the satellite era. Chris Landsea of the National Hurricane Centre, who has carried out much of the re-analysis work, explained in his paper, Reanalysis of the 1921–30 Atlantic Hurricane Database,
Note how the names of Emmanuel and Mann crop up!
In reality, we are never going to be able to record all of the hurricane activity in the past, as we can now. Nevertheless, it is manifestly clear that there is nothing unprecedented about either last year’s hurricane activity, or that of other recent years.