Try me … what exactly is the correlation between the instantaneous water temperature in the western Gulf of Mexico, where Harvey formed, and the instantaneous water temperature in the eastern Atlantic, where Irma formed … and please do explain in simple terms how these are connected in temporal terms … looks to me like their paths cross in Illinois …
I don’t know what you’re trying to say here … we take a grossly invalid statistic A, add it to another grossly invalid statistic B, and you seem to be saying that the result is grossly invalid because of some imagined correlation (which you haven’t specified yet) …
Maybe you’re not using “correlation” properly … there’s an over 90% correlation between having daylight in Chicago and having daylight in Des Moines … that does NOT mean daylight in Chicago causes daylight in Des Moines … please explain how the causation of flooding in Houston is exactly the same as the causation of flooding in Miami in each and every circumstances of flooding in either …
And gee whiz … could you please define what amount of area we’re talking about … dA or a hundred million square miles …
I won’t Google to look for temperature correlations between Western and Eastern Atlantic, but your post indicts itself! Why “instantaneous”? Did Harvey really “form” in the western Gulf? Do you deny that late August temperatures are correlated with early September temperatures? Do you deny that hurricanes acquire more energy after they’re formed? What does Illinois have to do with it?
In the following I’ve taken the liberty of painting red the text I’ll comment on.
Here you are addressing a Doper who asserts the correlation is exactly one. Who is that Doper you are addressing? Marvin the Martian asserts that the correlation is non-zero.
“Rolling Stone” magazine said Hurrican Katrina in 2005 was the harbinger of strong hurricanes due to global warming. The United States promptly went on a decade scarcity of strong hurricanes not since since Rutherford Hayes was President.
When a cold spell hit New York last month, sports writer Peter Botte of the Daily News said it was due to global climate change, the other name used when some one has an agenda to push.
There is a core of unassailable and well understood science here, stuff that is not in the least controversial. We have a very good understanding of how hurricanes work. They are powered by warm water, and there is a well established direct link from the sea surface temperature to the existence and strength of hurricanes. This is why hurricanes occur in specific regions on the planet and not others. And why they die out when they run up over land - and simply turn into big rain storms.
The upshot is that if sea surface temperatures rise - hurricanes will have a wider spread over the globe, and may become, on average, stronger. If sea surface temperature drops, the converse happens. There is no politics or agenda here. Simple physics.
Sea surface temperature has other very significant influences on weather - el Nino, la Nina is basically sea surface temperature. As are other oscillating effects - Antarctic Annulus, Indian Ocean Dipole, and so on. Each of these effects causes significant changes to the weather for those regions where the weather is generated over those seas. The most noticeable is rain versus drought, but bouts of cold and bouts of heat come as well.
What bothers climate scientists is that a general rise in sea surface temperature is likely to mean greater variation in the weather controlled by sea surface temperature. So more and worse extreme weather.
So far there is no mention of anthropogenic warming. What is described above is simply a reasonable expectation about that will happen, and noting that a key part of the problem is the temperature of the sea surface. The only point where any controversy might come to play is whether the observed severe weather seen is evidence of a general rise in global temperature. Temperatures have risen, that is not in dispute. Whether they have risen enough to sheet home this year’s hurricanes to that rise is probably a lot harder to nail down. Indeed I doubt a definitive answer to that will be known for some time. Still no actual mention of anthropogenic warming. So, the difficult question is how much of a risk anyone is willing to take. Politicians are driven by many factors, and sadly political ideology seems to be one that is capable of directing their actions even when it flies in the face of reality. Neither side is immune. Whether you believe that human CO[sub]2[/sub] emissions are the key cause of any global rise in temperature, or believe that it is a natural cycle of weather we have no control over, or believe that it is statistical glitch, and on average the global temperature is not rising and will not rise, the simple reality of weather is that the temperature matters, and matters in a big way. Very small changes in sea surface temperature make for dramatic changes in weather patterns. YMMV.
I am curious what you think it is that global warming does wrt hurricanes, esp North Atlantic?
We’ve had some very quiescent recent years, and in the last 70 years at least I don’t see much evidence that suggests anything “empirically.”
And note that the first half of the 20th century had some doozies…
I do see an incredible amount of confirmation bias. If we have a quiescent season, then global warming did something to create more saharan dust and chill out the hurricanes. If we get some biggies, lo and behold those stupid Deniers cannot see the writing on the wall.
As to Irma being superly massive…she is currently a 3. She was incredibly powerful for 37 hours–a “record.” But do you have some kind of idea what that record was 100 years ago? I have trouble believing we would have known, given the state of technology at the time to measure hurricanes that remote. Wouldn’t she have been just another big hurricane since the measurements were not as precise or comprehensive over the life of a hurricane as they are now? Yet everyone seems super excited to mention this “biggest hurricane on record”–without mentioning that it’s a pretty recent record set against which we are measuring hurricanes.
For me, as a skeptic of human nature (not necessarily AGW itself, but skeptical of what happens to our reason when we are behind a Great Cause), it’s pretty easy to see people get caught up in the hoopla of hurricanes without much supporting data…
Actually, and there were many previous discussions on this, it is clear that most scientists think that there is little to say about the number of hurricanes. I have seen that while some do propose that the numbers will increase they point out that the effect will possibly be seen in the middle of the century if nothing is done to control emissions.
What it is clear is that the hurricanes are getting more intense and that is based on one item that deniers have not been able to dismiss:
One more thing about supporting data, again it is clear that there are many doubts about how many hurricanes we can expect on a warming world, but as pointed many times before: besides the increase in water vapor in the atmosphere, hurricanes become more intense because the oceans are rising. Again, thanks to global warming due to humans not controlling global warming gas emissions.
It’s fairly common for hurricanes to cross over FL and make a second landfall on the Gulf Coast.
Miami and Houston’s flood probabilities are co-related because they could easily be hit by the same hurricane.
Yes, after we add the probabilities, we would then subtract the probability of those events that are directly linked …
However … consider the probability of one tropical storm: stalling over Miami and producing a 500-year flood, then moving off to the west and stalling over Houston to produce a 500-year flood there … seems very unlikely to make any difference …
One study by Metstat is saying Harvey brought 1,000-year rain over a 24-hour period over much of the area, widespread 25,000-year rain over a 120-hour period, and 500,000-year rain over 120 hours in some isolated locations.
Without looking it up I was going to post about this based on my memory. The way I remember it is that 2004 and 2005 were bad hurricane years but that things had otherwise been relatively calm since then until this year (other than Ike and Sandy).
The correlation is high in your daylight case because they have the same root cause - the sun is up.
You are describing 100% correlation. I never said that. If surface water temperatures are rising in the Atlantic basin, it seems reasonable to assume that there is some correlation between the surface water temperature in the Atlantic itself and the Gulf.
Exactly the point I was trying to make. For two adjacent areas, the correlation between the weather is going to be near 100%. The further apart you measure, the weaker the correlation is going to get. If the correlation is 100%, then the probability of at least one of the two areas experiencing a 0.2% probability event is 0.2%. If the correlation is 0%, then the probability increases to 0.4%. If the correlation is in between, then the probability is in between.
All I am doing is objecting to the statement that if you look at 500 places on earth you would expect a 500 year event on the average of once a year. That is only true if the probability of an event in every location is completely uncorrelated with the probability in every other location. For weather-driven events this is clearly not true.
Again the same root cause, the sun is up … and the correlation between sea surface temperatures and 500-year floods is quite thin … sometimes these flood events are due to rainfall + snowmelt …
I thought that was the point you were making … I think we both dove down our own private rabbit holes … which is why I referred back to Buck Godot’s post where he doesn’t exactly say we simply add the probabilities together, rather the probabilities of 500-year floods anywhere in the USA is higher than 0.2% … and considering the remnants of Hurricane Sandy in 2012, Baton Rouge 2016 and now Hurricane Harvey in 2017 … I can see where someone might agree …
The challenge here is finding a 500-year flood event that covered more than 100 thousand square miles … not far out of Houston, say 100 miles, we didn’t even see a 100-year flood event …
Correlation ≠ causation … when we look at what weather events that cause 500-year flood events we find them to be very localized …
I see nothing in post 
