Well well well. 15 named storms this year after all. The last (um, we think) is in the Caribbean right now, spinning way past the season's official endpoint. Its name is Olga. It started out subtropical, but has since become a fully tropical storm with maximum sustained winds of 50 knots at its apparent peak (although the storm has since weakened).
But any way you slice it, it's an anomaly to have a storm like Olga so late in the year. As I put it in my latest "Storm Pundit" item: "It was the most average of hurricane seasons, and the most unpredictable of hurricane seasons."
Indeed, whatever else you say about the 2007 Atlantic storm season, it was damn long. It began all the way back on May 9 with Subtropical Storm Andrea. And now it is going well into December.
This has, inevitably, prompted murmurs about whether global warming may be lengthening season length. My take:
A number of scientists do indeed expect lengthening of the average tropical cyclone season as a result of global warming. Simply put, the tropical oceans ought to warm up enough to sustain hurricanes earlier in the year, and also ought to remain warm enough to sustain them later into the year.
This logic suggests that our traditional June/November Atlantic hurricane season bookends may indeed need to topple - that is, provided that no countervailing changes occur as a result of global warming that have the effect of hemming the hurricane season back in again.
But of course, there are a lot of complexities here. For example, you will note that our earliest and latest named storms of 2007, Andrea and Olga, were both subtropical in nature.[Note: Olga later became fully tropical.] And as I mentioned previously, the National Hurricane Center didn't even start naming these types of storms until 2002. So I can already hear the argument from skeptics: The season isn't really getting any longer, it's just that now we're paying more notice to subtropical storms....
Maybe that's right. I, however, remain convinced that global warming is already changing hurricanes in myriad ways - but that due to the complexity of the science and the general unpredictability of weather, it is exceedingly hard to detect the effect definitively at this point.
In any event, the 2007 Atlantic hurricane season continues to tantalize. In some sense, I'm going to be glad it's over (whenever it finally ends) just so it will stop thwarting, at every turn, my attempts to put it in a box and categorize it.
You can read my full Daily Green "Storm Pundit" item on Olga here.
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Chris,
You say,
"This has, inevitably, prompted murmurs about whether global warming may be lengthening season length."
Well why not? Every other possible way to salvage the idea that this utterly uneventful hurricane season is somehow still proof of global warming has been illogically asserted. Why not try this angle?
"I, however, remain convinced that global warming is already changing hurricanes in myriad ways - but that due to the complexity of the science and the general unpredictability of weather, it is exceedingly hard to detect the effect definitively at this point."
So you concede that the science is complex, weather is unpredictable and that a definitive effect is "exceedingly hard to detect", but you are "convinced that global warming is changing hurricanes in myriad ways".
It would seem to me that you have convinced yourself on grounds other than empirical evidence. Certainly the scientific community does not share your conviction on the matter.
Chris -- I appreciate your candor in this post. You finally make it explicit that your belief in the hurricane/global warming connection is faith-based. And, like any other religious zealot, you can always find evidence for your cherished belief.
Lance and Neuro,
It seems to me that Chris is saying exactly what he said in Storm World (click my name for my review).
To wit:
The sea surface temperatures are rising, and since hurricanes are affected by many factors including SSTs, one would expect some changes in the patterns, intensity, or frequency of hurricanes.
Scientists differ on what the expected changes will be, so to evaluate and refine their models and theories, it makes sense to look at the changes that are happening.
This year's season and a previous one (2005 or 2006) that had a tropical storm in early January of the next year suggest that the length of the hurricane season is getting longer.
You don't have to be religiously committed to the idea that humans are causing climate change to find that suggestion interesting and worth further evaluation.
Fred,
Chris didn't say that he found the idea that human caused climate change was influencing hurricanes "interesting and worth further evaluation". He said he was "convinced" that it was so.
There is quite a bit of distance between those two statements.
Lance,
I, too, am convinced that global warming is bound to affect hurricanes in myriad ways, but we don't know in what ways or how much.
Chris makes the same point when he adds, in the same paragraph, "...it is exceedingly hard to detect the effect definitively at this point."
I think you're making too much of one word here.
Addendum:
Lance,
Note that neither Chris nor I are saying anything that depends on whether global warming is anthropogenic. We are only saying that GW is happening, and regardless of the cause, it will affect hurricanes in many ways.
Now it is true that Chris and I accept the IPCC consensus that GW is anthropogenic, and you do not. That is a different argument, and we have rehashed it many times. I'm not inclined to go there.
Fred,
Now you're trying to water down what Chris said to the point of it being meaningless. I could rightly claim that throwing a BB across the room "affects the earth in myriad ways" and be technically correct. It would certainly be true and "exceedingly hard to detect the effect definitively at this point".
I doubt that is what Chris meant by his claim that he was "convinced" that AGW was affecting hurricanes in "myriad" ways.
As a scientist I think you know the weight a word like "convinced" carries in regard to scientific inquiry. Chris has long since crossed the threshold from unbiased science journalist to outright environmental advocate.
Let's not be coy on this obvious point.
Lance -- I am convinced that poverty affects child development in myriad ways, and that these ways are extremely complex, variable, and hard to pin down exactly, and although some consistent effects can be mapped even these vary with precise circumstance. Nevertheless, I am fully justified in my belief that poverty affects child development.
When what you are seeing varies away from the "normal" baseline significantly in the presence of a given influence, even if you do not exactly understand how the interaction works you are still justified in thinking that something significant is happening. This, as they say, is not rocket science.
Luna,
Your remark, "When what you are seeing varies away from the 'normal' baseline significantly in the presence of a given influence, even if you do not exactly understand how the interaction works you are still justified in thinking that something significant is happening."
That presupposes that there is something significantly "un-normal" about recent hurricane activity, which is certainly not supported by the data. Even if we could detect some anomalous pattern it would be highly unscientific, rocket or otherwise, to attribute it to any one factor, say increased atmospheric CO2, with out rigorously verified evidence that supported a falsifiable hypothesis. Nothing of the sort exists.
What does exist is a political framework all too ready to attribute any and all negative observations to global warming. It is no accident that Chris' column appears in "The Daily Green".
Caring attitudes.
Prudent decisions.
Mature behaviors.
It's been my experience and observation that healthy, functional human cultures arise from graceful interactions among healthy, mature individuals. Healthy, functional cultures integrate new information with grace and ease when healthy individuals consistently, repeatedly demonstrate the caring attitudes and prudent decisions that comprise mature human behaviors.
Sparring with word games -- especially when they become a consistently repeated pattern of combative behavior -- seems to me to serve only to disrupt the functions that maintain a culture's healthy operation.
If our children and grandchildren are to live in a healthy, functional human society, it will happen because we set a healthy, mature, sustainable precedent for them -- by our behavior now.
I commend Chris and Sheril for consistently demonstrating that they care about the future of the world around them by choosing to write about the processes of prudent decision-making. And I commend comment participants, such as Fred, who consistently demonstrate a pattern of mature interactions with other participants.
But I am not impressed -- nor will I ever be persuaded -- by a consistently repeated pattern of combative behavior. Occasionally I may acknowledge such behavior for the sole purpose of reinforcing the social boundary necessary to quarantine a culturally unhealthy meme. But other than that, I will continue to discount and disregard any attempt to influence me if it relies upon a pattern of unhealthy behavior. Such attempts to persuade me have not worked in the past, they don't work in the present, and there is no evidence to suggest that they will ever work in the future.
Folks who seek to influence me -- and to influence people like me -- might benefit by learning from that hint.
Two responses to etbnc, who compliments me, which of course, I appreciate.
etbnc states: "But I am not impressed -- nor will I ever be persuaded -- by a consistently repeated pattern of combative behavior."
I'm a lot like you in that respect, etbnc, but it's hard to like a political candidate, given present techniques of battle. I'm wondering how you are responding to the current scuffles on the Democratic side. (I don't care much about the Republicans, especially since the establishment seems to have launched a media campaign against nice-fella-but-Creationist Pastor Huckabee.)
I guess I judge most harshly those who deliberately stir up trouble and judge most positively those who recognize the tactic and try to respond in a way that both makes a point and turns down the heat.
I like Obama in that way. Edwards uses his lawyering skills to do that as well, but it makes him seem less genuine.
On this blog, I have come to see Lance as a person who has the capability to raise important questions and challenges but usually in too combative a way. I don't even mind his sarcasm until it turns personal, which has happened frequently.
In this thread, I opted out of our exchange simply because we were tussling over trivia and I was satisfied I had made my point. Lance responded and I decided not to bother going further.
etbnc,
Your sentiments about the persuasion of mature behavior were compelling. I also disdain over-heated rhetoric for its own sake. Also, personal attacks should always be eschewed in any civil discourse. This blog is somewhat less rancorous than others here at Scienceblogs (Deltoid comes to mind) and for that Chris and Sheril are to be commended.
Sometimes, however, direct language is required. That language should always be civil and precise. If I have failed to meet your standards in this regard my apologies.
I find another form of communication untenable, the disingenuous behavior of hidden agendas. While you may find my comments a bit brusque and "combative" I think you will agree that I present my ideas in terms that make my intentions and motivations quite clear.
I have serious differences of opinion with Chris and Sheril on the subject of the science of catastrophic global warming and the prescribed policy "remedies". When I feel they are selectively presenting evidence to further a political agenda I am compelled to respond.
Open political discourse is of course a vital part of any free society, but it should not be presented as unbiased "science reporting". As a scientist I insist that the distinction should be made clearly and openly. To do less is a disservice to both science and journalism.
Chris and Sheril's caring and thoughtful intentions do not give them license to blur these boundaries.
From 1950 to 2000, the average number of Atlantic (sub)tropical storms per year was about 9.5 . Now we have a number of people discussing the 15th storm of the season, and nonetheless describing the season with words such as 'average', 'uneventful', and so on. This is how much recent hurricane seasons, such as those of 2003 (16 (sub)tropical storms) 2004 (15 (sub)tropical storms) and 2005 (28 (sub)tropical storms ) have shifted the baseline; even those who purportedly believe there is no trend in Atlantic hurricane activity describe activity exceeding historical averages by over 50% as 'average', or 'uneventful'.
llewelly,
Perhaps you should have a look at the link in my first post, to the Summary Statement of the 6th International Workshop on Tropical Cyclones and Climate Change from the World Meteorological Organization before making your unsupported assertions.
Your remarks are far outside of what even Chris would "highlight" in a review of the science. If my insistance that people stick to the science is viewed as "combative" then I'm afarid I have little recourse. Perhaps if I through in a few friendly emoticons...
As usual, Lance, you are reading not what I wrote, but what you wished to respond to. My post contains no particular assertion about any link between global warming and hurricane trends - instead, it asserts that (a) the 2008 season is unusual compared to the 1950 - 2000 historical record, yet (b) people here are describing it as 'average' or 'uneventful'. This, I believe, has more to do with undue focus on a few extreme seasons than with global warming.
Excuse me, in my previous post, I intended to refer to the 2007 Atlantic hurricane season - not, of course, the 2008 season.