There's no selection bias since 1966, when satellite coverage was established. It's hard to imagine any hurricanes going unnoticed for a good while before that - the Atlantic was already carrying a lot of regular traffic in 1850. My grandad used to sail those seas regularly, down to Boners Airs to trade beads for beef. He saw a hurricane or three, and didn't keep it a secret, believe me.
Any kind of bad weather was very bad news, especially back then. You could lose a ship by sheer negligence, of course, but the ships were much more vulnerable to bad weather in those days. Accounts of bad weather were apt to be very well reported.
Since 1966 frequency has gone up decade by decade. Exactly what that signifies is uncertain, but given the warming that's occurred during that period it does not support the hypothesis that warming hampers hurricane production.
No. And, as you say, the frequency has gone up, decade by decade.
rockoon explicitly posits that this is the only unbiased measure; implicit is the assumption that hurricanes making landfall is a good measure of total hurricanes. Can't say I'm convinced of the latter, I'd want to see some evidence.
I'm far from convinced, given that hurricanes sometimes don't even make it to land.
Thanks for that, BobK.
I must just point out that the disappearance of ships is indicative of storms in itself, without delivery of their logs. A severe storm, such as a hurricane, would presumably leave a footprint. The shipping and insurance business have been all over that sort of thing from way back.
Lloyd's of London came about precisely to cover those losses.
The point is Lloyd's might have to pay on a missing ship, but certainly couldn't say it was cause by a hurricane if no one else reported the storm. It would have to be recorded as cause unknown or something similar. Could have been pirates.
Yes, it could. But bad weather was by far the most feared danger of the seas. You could fight pirates, or outrun them - but running into a hurricane was pure disaster.
Just as a point of accuracy. I meant to note that CFLarsen said there were 10 hurricanes in 2006 and that is not correct. There were only 5 hurricanes and 5 tropical storms. To be classified a hurricane requires achieving a wind speed of 64kts for category 1. One of the hurricanes just made it to that category by achieving a peak wind speed of 65kts. Two of them reached 105kts.(category 3) The other two were 75kts and 80kts.(category 1) Tropical storms are 34-63kts.
Correct. What's interesting is that we have a supposedly GW-event influencing another:
Following the intense activity of the 2005 season, forecasts predicted the 2006 season would be very active, though not as active as 2005. However, in 2006, a rapidly-forming El Niño event, combined with the pervasive presence of the Saharan Air Layer over the tropical Atlantic and a steady presence of a robust secondary high related to the Azores high centered around Bermuda, contributed to a slow season and all tropical cyclone activity ceasing after October 2.[3]
Source
It is therefore not correct, as shanek claimed, to imply that the lower number disproves that global warming means more hurricanes.
Its simple. Its obvious. Why are we arguing about it?
We do have a data set spanning 150 years. No, it isn't uniformly collated, and the further back we go, the more insecure data we get. But we do have data.
Now, the data set BobK's used has some value. For instance we can modify the conclusion to 'The mean number of hurricanes which make landfall has increased or decreased in the past 150 years.'
The modified data set does fit the bill because it is reasonable to suppose that an insignificant number of hurricanes that made landfall went unrecorded since 1850. Hurricanes are large enough that no matter where they made landfall a major seaport was in its path.
Now, the number of hurricanes which make landfall has decreased over the past 150 years but not by a very significant amount.
If you want to talk about landfall hurricanes, BobK's numbers show an
increase, 4507, from 1851-1900, to 4854 from 1951-2000. What should also be noted is that the number of landfall hurricanes who were strong enough to reach more than 300 miles inland have increased dramatically.
Hurricanes happen more, and they are stronger.
Shanek didn't. Going from that, he was wrong. Agree?
Its the only data in the data set that isnt effected by selection bias.
The conclusion you drew (the LIE) requires data that isnt biased. You jumped to this conclusion, probably because it fullfilled your expectations, and certainly not because the conclusion had merit.
So, I held your hand (you needed it) and told you specifically which data in that data set is not biased.
You are free to farm the data set for those unbiased samples and then try to draw an unbiased conclusion. Alternately, you can accept that BobK has already done it for you.
If you repeat your misinformation, that makes you a liar.
You are very intent on making me a liar. I can't just be mistaken, I have to be a liar. Odd.
However, I asked you a question: What is the mean number of hurricanes, detected as well as not detected? In other words, how do you know what the number of undetected hurricanes have been?
