Is this global warming? (brief history of Category 5 hurricanes.)

[jobycom]

All this is from Wikipedia,of course.

First, keep in mind that our ability to detect and monitor storms has increased dramatically over the last fifty years. In 1900, the Galveston hurricane (not a Cat5) was unknown until it hit land. It may have been a Cat 5 off the coast and weakened to a 4. We don't know.

Before 1950, five storms were measured as Category 5s in the Atlantic/Gulf region. Most of these were measured as they hit land somewhere. Only one hit the US as a Cat 5, and it is considered the most powerful (1938 Florida Keys hurricane) because of it's low barometric pressure--lowest on record.

After 1950, after we became better at measuring them at sea, and eventually to track them by satelite and create storm models, 21 were measured at Category 5. Seven made landfall, two in the US. One of these was never measured as a Cat 5 (Andrew), it was only categorized that way based on property damage.

A quick overview. The most active hurricane season had 21 storms, in 1933 (much before that and measurement was spotty). in 1995 there were 19, in 1969 there were 18. We've had 17, which puts this as the fourth busiest year. That will increase, we may become the busiest on record.

In 1950 there were 8 hurricanes Cat 3 or higher. In several years there have been six, including this year, with Rita. This may still increase, given conditions.

In two years, 1960 and 61, there were two Cat 5s each year, four total in two years. None made landfall as Cat 5s.

From 1958 to 1971 there were 8 Cat 5s. One hit the US (Camille). Then there was a lull, with only three in the 70s, 3 in the 80s (including Gilbert, which hit Mexico as a Cat 5 with the lowest pressure on record), and 2 in the 90s--although Andrew was never measured as a Cat 5, and only classified that way based on property damage.

We've had three Cat 5s in three years, though none has made landfall. Looks like we will have a fourth, making four in three years--second to the 1960-61 spurt.

This may become the worst season on record, since we've been able to measure storms. Katrina was huge, and though I haven't seen records for size of storm, ranks really high (usually highest) based on the memories of anyone I've heard talk about it.

So this year may turn out to be the worst ever, but so far it is not a runaway season. We've seen busier periods, stronger storms on land and sea, and stronger groupings of strong storms.

So far, in other words, this year isn't clearly abnormal. It's heading that way. And a couple of seasons like this would be abnormal.

I'm not a scientist, so I don't know one way or the other whether global warming is an issue here. I have been an historian, and can say that the globe warms and cools in centuries long cycles all the time. We've had ice ages, we've had hot centuries. The rise and fall of nations can be charted along with this weather changes. Rome fell during a cooling trend, as barbarian hordes from northern Europe moved south in search of farmlands, and as Roman fields became colder and less fertile. Europe has risen and fallen with these trends, with warming periods preceding the Carolingian and the 12th century flourishes, and cooling periods marking the dark ages and the Viking invasions.

Global warming is a reality, don't get me wrong. We need to halt it, develop plans to deal with the damage, etc. But there could be normal factors at work, too, in this hurricane season.

My concern is that if we keep claiming this hurricane season proves global warming, without scientific evidence, and then we go five seasons with minor activity, we look like Chicken Little and people may start to doubt the science.

Just my two cents. Tell me how ridiculous I am.

[Modem Butterfly]

1. Excellent analysis.

Recommended.

[Toots]

2. People have been sent to the electric chair with less evidence

The retreat of the arctic ice cap has global ramifications, and given the complexity of the climate, and its sensitivity to even small changes (such as the eruption of Pinatubo as just one example) it is difficult for scientists to given unqualified predictions of just what the effects on the global climate will be in response to these changes taking place in the arctic. Both the atmospheric currents and the ocean currents can be expected to change, and this is already some research would suggests that the changes in the arctic affect such weather events as rainfall in far away Africa.

It surprises me that there are those who say, 'I don't believe in Global warming.' The graph of global temperature increase shows a particularly sharp increase beginning in the 1970s (it is beginning to display the characteristics of an exponential curve, with a period of gradual increase, followed by a sharp upward turn in the graph). Global warming is a fact, and if people remain ignorant of this fact it can only be due to propaganda which originates with special interest groups. The amount of CO2 in the atmosphere has increased by one third during the fossil fuel age, and I find it remarkable that there are those who would suggest that an increase in greenhouse gas of this magnitude could not possibly result in a change in the global climate. For example, they will try to suggest that this change is 'part of the natural variability of the climate' or they will blame it on 'an increase in the sun's energy level'. How could the amount of greenhouse gas increase by a third, and global warming occur, and yet still their is all this disputation concerning the cause of the warming that is occuring?

Global warming is not controversial science (or at least it should not be) and similarly the cause of the warming (increased greenhouse gases) should not be controversial, and probably would not be, if it were not for the fact that a multi-trillion dollar industry fuels and funds the controversy. What is controversial is what the effects of this ongoing global warming will be. No one can say for certain what the new climate of the planet will be like, since climate is extremely complex, as well as being extremely sensitive. Climate change is a gamble, and the unfortunate thing is that like in all gambling, if anyone suffers a loss, there is no way to begin again

[jobycom]

3. Never said it didn't

Okay, global warming is happening, and there is strong evidence to suggest that it is at least in part due to CO2. I agree, no part of my post said otherwise.

But people are saying Katrina and Rita are the results of global warming. Historical evidence, so far, does not bear out that anything unusual is happening now. Well, maybe unusual, but not unheard of. We could have five more years of weak hurricane seasons. If we link Katrina and Rita and the 2005 season to global warming, and the next few years turn out to be duds, BushCo and his ilk will point to that as proof that we were wrong on the hurricanes, and thus wrong on all global warming.

The science is there, just as the science is there to prove evolution and that tax cuts targeted to the wealthy cause recessions. People don't understand science, they understand the mindless buzzwords of politicians. The science isn't political, but the response to it is.

[Viking12]

4. An excellent analysis available at RealClimate.org

Hurricanes and Global Warming - Is There a Connection?

by Stefan Rahmstorf, Michael Mann, Rasmus Benestad, Gavin Schmidt, and William Connolley (note from Viking12, these atuhors are all working climate scientists)

On Monday August 29, Hurricane Katrina ravaged New Orleans, Louisiana and Missisippi, leaving a trail of destruction in her wake. It will be some time until the full toll of this hurricane can be assessed, but the devastating human and environmental impacts are already obvious.

Katrina was the most feared of all meteorological events, a major hurricane making landfall in a highly-populated low-lying region. In the wake of this devastation, many have questioned whether global warming may have contributed to this disaster. Could New Orleans be the first major U.S. city ravaged by human-caused climate change?

The correct answer--the one we have indeed provided in previous posts (Storms & Global Warming II, Some recent updates and Storms and Climate Change) --is that there is no way to prove that Katrina either was, or was not, affected by global warming. For a single event, regardless of how extreme, such attribution is fundamentally impossible. We only have one Earth, and it will follow only one of an infinite number of possible weather sequences. It is impossible to know whether or not this event would have taken place if we had not increased the concentration of greenhouse gases in the atmosphere as much as we have. Weather events will always result from a combination of deterministic factors (including greenhouse gas forcing or slow natural climate cycles) and stochastic factors (pure chance).

Due to this semi-random nature of weather, it is wrong to blame any one event such as Katrina specifically on global warming - and of course it is just as indefensible to blame Katrina on a long-term natural cycle in the climate.

-more-

http://www.realclimate.org/index.php?p=181

[jobycom]

6. Well, yeah, I'd have said all that if I could have!!

:-) Great link, thanks.

I have two disagreements with them. Obviously not on their scientific evidence, I don't know enough, and it verifies what common sense should indicate, anyway. My two points: first, our ability to measure hurricanes has improved so much that it's not safe to compare, say, the 1930s hurricane seasons with the 2005 one, especially using the fine tuned results they use. 1933 had more hurricanes, and since our ability to measure them was not as great as our ability now, we don't know that some of those storms may have been stronger at their peaks, when no one was measuring them. Thus, we can't be sure that hurricane PDI wasn't as powerful in, say, the 20s, or even the 1800s.

Second, they talk about the AMO, which is an oscillation in hurricane activity marked in decades. Global warming and cooling can be mapped out over centuries, making it likely that past centuries would have seen wild swings over the current one and half that we've been measuring storms in the Gulf. We have no real way of knowing, for instance, that 1705 didn't see four Cat 5 hurricanes with lower pressure and higher winds than we are seeing now.

For the record, the authors may not even disagree with my two points, and their discussion doesn't rely on them to prove that something is happening, and that it could be caused in part at least by human impact on the environment.

None of it fully matters. Global warming is an obvious threat. Human activity is certainly making it worse, and may be entirely responsible. That's all measurable and determinable. We should be doing what we can to reduce our impact on the climate, and to reduce the effects of a phenomonum that, even if we corrected the cause of, will continue for decades to disrupt world agricultural and flood patterns.

[Lisa]

10. it would be great to get proxy data for earlier periods

Written historical records of damage, say -- or natural ones in tree rings (storm damage?) or sediment cores. I know some people who are working on this kind of thing.

But, as you say, the further back you go, the harder it is to find records that are complete and consistent (let alone cover a large area). One would need to monitor continent-sized areas in order to see significant trends (some of the latest extreme event studies are almost global in scope). And if you're looking at fluctuations which are decades long, you're lucky to get even one cycle that's well-documented. (I did some work on the PDO, which is a decadal oscillation in the Pacific rather than the Atlantic -- and that was the situation we were up against.)

We can say that an increasing number of powerful storms is consistent with theory and computer models ... but singling out individual events is as risky as trying to explain the score of, say, a particular baseball game -- without having actually seen the game unfolding, and knowing only as much about each player as shows up on the trading cards.

[crispini]

5. Very sensible thread.

Nominated.

[DemCam]

7. I agree and thank you

There have been cyclical studies of hurricanes...though I have no link...that fits with the deadly 1960-61 seasons...i.e. 30 to 40 years.

We need to err on the side of caution for global warming theories but keep a vigilant monitor on fossil fuel use and emissions standards for several reasons...dependence and diminishing supples as well as known pollution disasters globally from their use.

[Beausoleil]

8. GW is real

And I think you can make a case that GW is causing average ocean temperature to increase, rising ocean levels and rising average global temperature, whether GW is natural or a result of human activity or both. All three of these factors may be causing more rapid strengthening, higher storm surges and longer hurricane seasons. But I don't see how the human component can be discounted.

[jobycom]

9. Read the whole thread. I never said it wasn't. There's even a link

to a good article upthread a bit.