I can’t claim to understand the dynamics of hurricane formation or large weather systems in general. So all I can use is basic reasoning :
The news articles on it talk about how layers of warm water near the ocean surface tend to strengthen hurricanes. The warmer and deeper the water layer, the stronger the storm.
Well, if CO2 and methane in the upper atmosphere are reducing how much IR can radiate back off the earth, that water layer will get warmer. Simple and obvious. And therefore the large, super-hurricanes will be more common.
You hear about climate change being blamed for ice storms and any old extreme weather event - I can’t claim to understand the reasoning there.
But is the case basically closed that these massive hurricanes are definitely caused by global warming, the warming is from extra CO2 and methane in the upper atmosphere, and because of that warming, they are going to be happening extremely often from now on - maybe every year, now? I mean, if that’s the case, maybe the city planners in Houston, New Orleans, Miami, and so on need to plan on a new strategy…
It was a sarcastic way of saying that global climate change will increase the severity of such storms. Houston has had three ‘one in 500 years’ floods in the past three years.
Of course a ‘once in 500 years’ event has a 0.2% chance of occurring every year. but that doesn’t mean the event cannot occur more often.
In a word, no. That is, it’s acknowledged that warm sea surface temperatures are a critical factor in hurricane energies, but in anything as incredibly complex as the climate system, it’s impossible and really makes no sense to attribute any particular event or two to climate change. Part of the problem is that numerous other factors including random ones can help or hinder hurricane formation, and furthermore, the same climate change that warms the oceans and lower atmosphere can also create disruptive forces that help to break up hurricanes.
So causative correlation can only be established statistically over long periods of time and supported by modeling and theory. Part of the problem right now is that strong correlations between SSTs and hurricane energies exist primarily in the North Atlantic area and not elsewhere. Further complicating the issue is that there’s a pretty strong correlation between SST differentials in the Atlantic basin versus elsewhere, as opposed to absolute sea surface temperatures.
The general expectation is that hurricane energies in this part of the world will continue to increase, but this hasn’t been well quantified and the confidence level at this point isn’t extremely high. Hurricane researchers like Emanuel Kerry, who pioneered the use of the hurricane Power Dissipation Index as a measure of energy, is among many who believe that PDIs will continue to increase as the oceans warm further. There is far less confidence about the frequency of hurricanes. Conversely, confidence is quite high in the increased incidence of extreme weather in general, and on long-term regional climate changes.
I believe it’s the most severe hurricane ever recorded in the Atlantic (outside the Gulf and Caribbean) and only the second tropical storm that maintained more than 185 mph winds for more than 24 hours.
Irma is in fact the strongest hurricane ever recorded in the Atlantic basin, and the second strongest on record, exceeded only by Wilma in 2005. I guess that’s pretty “super”!
ETA: Ninja’d by Colibri. I’m gonna need a faster keyboard!
There seems to be a bit of “fake news” concerning these superlatives assigned to Irma … generally the news is that Irma is the “strongest” storm ever recorded in the Atlantic, as measured by top wind speed … but that’s a fabrication, Hurricane Allan (1980) holds that record at 190 mph, 4 are tied for second at 185 mph (including Irma) … another measure of hurricanes is “intensity” and that’s minimum central pressure … Irma is tied for 12th most intense Atlantic hurricane at 914 mb … all data is from Wikipedia “List of Category 5 Atlantic hurricanes” …
“Super-hurricane” is not a recognized scientific term … it’s media hype … officially, tropical cyclones with top winds 110 mph or greater are called Major Hurricanes in the North Atlantic and Northeast Pacific Ocean Basins …
I think wolfpup’s excellent rundown of what we can say today in his post #8 about how climate change effects hurricane intensity and frequency is spot-on correct … although I’d hedge more towards “maybe, we just don’t know” … we have to be careful looking at year-to-year differences as these tend to be widely disparate … far better to look at 50-year averages and we only have 50 years of good data (meaning since the Age of Satellites) … we do know that three Major Hurricanes made landfall in the USA in 2005, so two in one year isn’t unusual or unnatural … and Category 5 Hurricanes anywhere in the North Atlantic is about a “three year” event …
One thing is incontrovertible is that sea level rise exacerbates the flooding. But me, I am satisfied that these frequent “500 year” storms are strong evidence of the effects of climate change. But if you want to call it a Chinese hoax, go ahead. We never get hurricanes in Montreal and warmer weather can only improve our climate (except, to be sure, for ice storms).
I thought the whole “500 year storm” thing is people completely misunderstanding statistics and probability.
IIRC it was something akin to “We only call it a 500 year storm because we only have spotty records going back to 500 years, so we don’t know how often these things actually come up”
I saw a list of the most severe Atlantic hurricanes in history recently. What impressed me was that 1/3 of them were in the last 15 years, with almost 1 per year in the last 3-4 years. That seemed to be compelling evidence.
But of course, it wouldn’t convince a climate change denier.
I don’t know if there’s any evidence that could.
It’s not so much fake news as they are using a definition of “Atlantic hurricane” that’s not standard and not telling people about it. That is, they are distinguishing Atlantic hurricanes from those in the Caribbean and Gulf of Mexico. This is an artificial distinction, since those in the latter two bodies of water always start off as tropical storms in the Atlantic. For example, Allen started off way over near the Cape Verde Islands and tracked directly across the ocean, but didn’t reach Category 5 until it was in the Caribbean.
“500 year storm” is an estimate using statistics of the probability of an unlikely event occurring. I am not sure what figure of merit is used to characterize a storm’s “strength”, so let’s assume we are talking about a “500 year flood” (which is actually what is being discussed in Houston).
See the Wikipedia page for 100-year flood for a more detailed explanation (100-year floods are used to determine who lives in a “flood plain” and will be obligated to purchase flood insurance by their lender). Basically you look at the historical record to collect the annual maximum flood level in a given location. You fit a probability distribution to this collection of data ; I am not sure what distribution is used for floods, but if you assume a normal distribution (unlikely since you can’t have a negative flood) calculating the mean and variance based on measured data is pretty straightforward. You now have a model giving you the probability of a particular flood level being reached in a one year period. To find the 100-year flood you would calculate from the fitted distribution the flood level which corresponds to a 1% probability (1/100). To find the 500-year, calculate the flood level which has a 0.2% probability.
Since the data used to estimate the probability distribution is limited, there is considerable uncertainty in the calculations to the point where the “500 year” level basically comes down to “a shitload more water than we ever though we’d see”.
