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Trends In Atlantic Hurricanes

September 20, 2017

By Paul Homewood



With Hurricane Maria tearing heading towards Puerto Rico, there will be yet more alarmist claims about how climate change is making hurricanes worse.

Maria is the fourth major hurricane in the Atlantic this year, following Harvey, Irma and Jose. But how unusual is this?

Fortunately we don’t have to rely on Al Gore or Jennifer Lawrence. The reality is that it is not unusual at all.

Leading tropical cyclone expert, Chris Landsea of NOAA’s Hurricane Research Division has put together a list of Atlantic storms back to 1851.

This is what he has to say:

The Atlantic hurricane database (or HURDAT) extends back to 1851. However, because tropical storms and hurricanes spend much of their lifetime over the open ocean – some never hitting land – many systems were “missed” during the late 19th and early 20th Centuries (Vecchi and Knutson 2008). Starting in 1944, systematic aircraft reconnaissance was commenced for monitoring both tropical cyclones and disturbances that had the potential to develop into tropical storms and hurricanes. This did provide much improved monitoring, but still about half of the Atlantic basin was not covered (Sheets 1990). Beginning in 1966, daily satellite imagery became available at the National Hurricane Center, and thus statistics from this time forward are most complete (McAdie et al. 2009).

For hurricanes striking the USA Atlantic and Gulf coasts, one can go back further in time with relatively reliable counts of systems because enough people have lived along coastlines since 1900.

Thus, the following records for the period of reliable data hold for the entire Atlantic basin (from 1966-2016) and for the USA coastline (1900-2016):




& Landsea et al. (2010) documented a rather large increase in short-lived tropical storms and hurricanes in the last decade, which is likely due to improved monitoring capabilities, that may be influencing the climatological average number of TCs in the Atlantic basin. With the artificial jump in the 2000s in the frequency of short-lived systems, a more realistic estimate of the long-term climatology may be closer to 13 tropical storms and hurricanes per year.
* 1950 is recorded as the busiest season in the whole database for number of Major Hurricanes with 8.
+ 1886 is recorded as the most active hurricane season for the continental USA with 7 landfalling hurricanes.

The full list is included in the above link.



It is worth re-emphasising these points:

  • Many storms were missed over the open ocean prior to hurricane hunter aircraft in 1944.
  • Even then half of the Atlantic basin was not covered.
  • Satellite coverage began to improve matters in 1966.
  • But even then monitoring has considerably improved since 1966, particularly regarding short lived storms.



The effect of this improved coverage can be seen in NOAA’s graph of named storms:




Yet when we look at major hurricanes, we get a totally different picture:


It is still obvious that many storms were, unsurprisingly, not picked up before 1900, and even prior to 1940.

However, since the introduction of hurricane hunters, there has been no increase in the number of major hurricanes. We simply see the dip during the 1970s and 80s, when the AMO was in cold phase.

Contrary to popular myth, the year with most major hurricanes was not 2005, but 1950, when there were eight.

To have four, as we have so far had this year, is not in the slightest unusual. In fact, there have been 27 years on the record, when there has been four or more major hurricanes.



But are hurricanes getting more powerful?

Well, not according to the ACE index (1), which shows hurricane seasons in the past every bit as strong as the past couple of decades.

The worst year of the lot was 1933.


(1) ACE measures the Accumulated Cyclone Energy – An index that combines the numbers of systems, how long they existed and how intense they became. It is calculated by squaring the maximum sustained surface wind in the system every six hours that the cyclone is a Named Storm and summing it up for the season. It is expressed in 104 kt2.


All graphs and data are from the Hurricane Research Division:

  1. Broadlands permalink
    September 20, 2017 4:53 pm

    ‘Fortunately we don’t have to rely on Al Gore or Jennifer Lawrence. The reality is that it is not unusual at all.”

    But, cynically?… even if it is, what can us humans hope to do about it? Signing an agreement in Paris will not make any difference to these natural events, nor will arguing about the details or whose data are the best. It does seem to keep the media and the politicians occupied however…not to mention Al Gore and a few Hollywood “experts”.

    • Curious George permalink
      September 21, 2017 12:39 am

      To be on a safe side, blame it on Trump.

  2. September 20, 2017 6:10 pm

    The very fact that they want to conjure up a long-term trend from a couple of hurricanes, or even a busy season, says a lot about the desperation to find some evidence that just isn’t there.

  3. A C Osborn permalink
    September 20, 2017 6:13 pm

    The Wind speeds for Maria being banded about by the MSM bear no relation to reality.
    The over hyping is an absolute disgrace.

    • MrGrimNasty permalink
      September 20, 2017 9:11 pm

      A buoy in just about the ‘worst’ position recorded a max. 94mph gust, whereas the media are reporting high level satellite estimates of 160mph as if that’s what everyone on the ground has experienced.

  4. September 20, 2017 6:46 pm

    The all-knowing BBC would beg to disagree with leading tropical cyclone expert, Chris Landsea of NOAA’s Hurricane Research Division. Ditto Channel 4, the Grauniad etc etc.

  5. Sheri permalink
    September 20, 2017 8:32 pm

    I was looking up the frequency of hurricanes and a google hit, TripSavvy, caught my eye. The article talked about how there are hurricanes in varying strengths every year in the Caribbean. It’s normal. Not all islands have an equal chance of being hit and some years there are more hurricanes some years than others. There’s nothing unusual about hurricanes this year.

  6. September 20, 2017 10:35 pm

    I looked at the post 1944 data for all basins and found no trends in the NA basin 1945-2014.

    Trends are one thing but the real buzz about this hurricane season is its assumed anthropogenic cause. Humans and fossil fuel emissions are to blame apparently. But for that a necessary (though not sufficient) condition is a corresponding relationship between emissions and SST. That relationship does not exist in the data.

    • September 21, 2017 9:06 am

      Of course, but as we all know in climate change fantasy land it’s about shouty headlines not data.

  7. September 20, 2017 10:52 pm

    I should add that anthropogenic effects on tropical cyclone activity are also found in climate model projections to the year 2100 but these forecasts are for globally averaged TC activity.
    Model projections are 2-11% increase in TC intensity, 6-34% decrease in TC counts, & 20% increase in TC rainfall per century measurable only in globally averaged data for TC in all 7 TC basins over long time periods. The models tell us nothing about individual basins. Model projections assume that warming in SST is related to emissions but this relationship does not found in the data.

    TC activity for a single TC season in a single TC basin contains no useful information about the relationship between AGW and TC in the real world or in the model world. The models cannot make basin by basin projections. The generally held belief that this TC season in the North Atlantic basin has a human cause has no statistical or scientific basis either in the data or in the climate models. It is an emotional thing.

  8. jim permalink
    September 21, 2017 11:52 am

    According to Mrs May, the US should be joining the UK in ‘keeping to the rules’, which means following Paris , paying $bns to China and India to keep on building coal-fired P.Stations…!
    I have followed the trail of Irma and Maria looking at ground-based weather stations and NONE have recorded sustained wind speeds above Cat 1.
    Compare this with the ground recorded wind speeds of the most recent big Scottish storm, Bawbag in 2011, when sustained speeds were over 100mph across the central belt.
    It got so bad Glasgow Council stopped running double decker buses (!). After the storm in 1968 Glasgow improved its council housing stock and there was no major damage to buildings. 150k lost electricity supply, but two days later just 2k were still off supply.
    It pays to have good sea defences, build out of stone and brick, and underground the power network in urban areas.
    The hype about this year’s Caribbean hurricanes and the NHC’s role should be ridiculed.

  9. September 21, 2017 12:22 pm

    Reblogged this on WeatherAction News and commented:
    Like most records, the paucity of data and the non standardisation of recording techniques means we are often comparing apples to bricks. Whilst models are a good tool for analysis and understanding (not forecasting or projecting) we still have much to learn from the past and it seems that the interest in that is not on the academic community, who rely on the former, but in the online community of the curious.
    As H.H. Lamb said;
    …it was clear that the first and greatest need was to establish the facts of the past record of the natural climate in times before any side effects of human activities could well be important.

  10. PETER EVANS permalink
    September 21, 2017 12:40 pm


    A very relevant post from xmetman

    • dave permalink
      September 21, 2017 1:41 pm

      Tne National Hurricane Center of the USA Government summed up on September 1 (just after Irma) that the Atlantic season’s activity, up to that date, was “normal” – but what do they know, when compared to the real experts – the BBC and the rest of the MSM?

  11. September 21, 2017 10:20 pm

    Only three of the top seven years in ACE have occurred since 1950, first place goes to 1933, and in fourth place we have 1893! This is a remarkable bit of news from NOAA, most anti-AGW data from any government agency I have ever seen.

  12. September 22, 2017 8:37 pm

    Reblogged this on Climate Collections.

  13. Jay permalink
    September 27, 2017 2:05 pm

    My reply to a post by George Monbiot – Don’t Look Now Posted: 02 Sep 2017 12:07 AM PDT which conflated Hurricane Harvey with global warming and where Monbiot was upset that newspapers had not connected the two!

    Hi George
    I am a regular reader of your posts. However, in your post ‘Don’t Look Now’ I cannot see how you can use Hurricane Harvey as an example of manmade global warming and make a plausible case that newspaper reporting should connect the two.
    I’ll get straight to the point. It is evident from the history of hurricanes in the area (see NOAA Hurricane History), that there have been similar and worse hurricanes before Hurricane Harvey. It also does not appear from records that hurricanes have become worse. In fact on the contrary, Hurricane Mitch of 1998, according to NOAA records, killed 9000 people with 9000 missing. Also even as far back as 1780 (well before human induced global warming could take place) The Great Barbados Hurricane is reported to have killed more than 20,000 people.
    If Hurricane Harvey is no worse than previous hurricanes and there has been no increase in the severity of hurricanes, can you explain how Hurricane Harvey and hurricanes in general, can demonstrate the effect of human contribution to global warming?
    Please see my references:
    NOAA 100 year hurricane history:
    Great Barbados Hurricane of 1780


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