Super-typhoon Soudelor and a need for new hurricane & typhoon metrics

Super typhoon Soudelor is hitting sustained wind speeds of up to 178 miles per hour! That totally blows the Beaufort scale out of the water, and also leaves the Saffir-Simpson scale well behind, too.

There are two reasons why these scales are not too useful:

1. They all have maximum values,
2. The maximum values are tied with technologically based assumptions and purposes.

The Beaufort scale maxes out at "Hurricane force" winds that are anything of 72.9 mph or greater, and this maximum was set based on the technological limitations of shipping, for which the scale was developed. The idea was that anything greater than a category 12 was effectively as dangerous to ships as the winds at 72.9 mph, and so there was no reason for ship captains to worry about categories larger than 12.

The Saffir-Simpson scale maxes out at "Category 5 hurricane" winds that are anything of 157 mph or greater, and this maximum was set based on the technological limitations of building construction in the 1950s US. The idea was that anything greater than a Category 5 was effectively going to blow apart any building, and so there was no reason for having higher categories (despite an increasing number of buildings with the capacity to withstand 157mph and higher winds).

It's that "or greater" part that really is troubling to me. Why? Because it means that a hurricane with sustained winds of 157 mph is classified as a "Category 5" hurricane... right along with a super typhoon like Soudelor, which is reaching wind speeds of almost 180 mph.

Back in 2011, I noted that the scale for the Saffir-Simpson scale was somewhat linear, up to Category 5; but if we took that linear scale and extended it, we would be able to include a Category 6 (and even Category 7) type of storm:

Category 1: <95mph
Category 2: 96-110mph
Category 3: 111-130mph
Category 4: 131-150mph
Category 5: 151-175mph
Category 6: 176-205mph
Category 7: 206-235mph

Under this extended classification, Super typhoon Soudelor is a Category 6; one of only a few in recorded history, but potentially one of a growing number in a future with global warming.

Similarly, the Beaufort scale can be extended beyond the category 12. The Beaufort Scale progresses along an x-squared rate (Excel comes up with the equation: y = 0.4952x^2 + 5.2857x + 0.0382), giving us:

Beaufort Number
0: <7mph
1: 0.8-3.4mph
2: 3.5-7.4mph
3: 7.5-12.2mph
4: 12.3-17.8mph
5: 17.9-24.1mph
6: 24.2-31.0mph
7: 31.1-38.4mph
8: 38.5-46.4mph
9: 46.5-54.7mph
10: 54.8-63.6mph

11: 63.7-72.9mph
12: 73.0-83.7mph
13: 83.8-94.7mph
14: 94.8-106.3mph
15: 106.4-118.5mph
16: 118.6-131.3mph
17: 131.4-144.8mph
18: 144.9-158.8mph
19: 158.9-173.5mph
20: 173.6-188.8mph

Under this classification, Super typhoon Soudelor has a Beaufort number of 20! This is very different from just classifying it as a 12, solely because 12 arbitrarily is the largest value on the Beaufort scale.


Why worry?
Back in 2011, I wrote up a short extension of a 2005 paper in Nature, that indicated that the total number of hurricanes has been remaining the same, but that the strength of the hurricanes has been growing stronger. This means that there are a lower number of Category 1, 2, and 3 hurricanes now than in the past, but the number of Category 4 and 5 hurricanes has increased:

What is being measured here is storm intensity by proxy of hurricane Category. However, such a measure will not show the entire picture if Category 5 remains anything over 157mph, since this open-ended category definition would mask the rising intensity of hurricanes that is shown in the graph.

While this might seem an academic point, another way to think about this is to ask why the Richter scale doesn't have a maximum value? After all, if the Saffir-Simpson scale was built around the idea that structures wouldn't be able to sustain a force of a Category 5 hurricane, then why shouldn't the Richter scale max out at 7.0? And if the idea that the Richter scale should max out at an arbitrary number (like 7.0) sounds ludicrous, then why accept the idea that Category 5 in Saffir-Simpson (and Category 12 in Beaufort) are the maximum of the scale?

Especially in a future where the numbers of increasingly intensive hurricanes is only going to increase as the numbers of "lesser" hurricanes decrease?

On sectorial water use and obfuscation via statistics

So a friend of mine posted this picture on their Facebook wall, and its message seemed well-intentioned but also so very problematic.

Let me first state that I do think that California must make hard decisions about water restrictions and water use, and I don't think that the current forms of water restrictions and bans are anywhere approaching what would be an equitable diminution in water use (and never mind the problems that California's system of water laws, interstate compacts, and inter-watershed irrigation systems play in creating further problems in the legal, political, and water management worlds). However, I don't know whether this image presents a useful comparison on all fronts. Furthermore, the presentation is arguably deceptive, since the compared units are not the same, with toilets (presumably being the one thing that the viewer is supposed to be sympathetic toward, since it is placed last) being based on a very low metric of gallons/flush of one toilet, and all the rest (presumably the ones the viewer is supposed to feel antagonistically toward, since they are often held up as being "enemies" of water use) being based on really large sector-wide annual figures.

This simplistic switch of metrics undermines the presumed argument of the image on two fronts. First is the casual deception: why present sector-wide annual figures for the "bad" water uses, and personal, single-use figures for the "good" water use? This presentation does not present an easy-to-grasp comparison between water uses at the State level. (There is also the problem of using words like "million" and "trillion" to describe the amount of water used, since it is so easy for people to lose the differential scales between hundred, thousand, million, billion, and trillion, but those sorts of distinctions are better covered in places such as this visualization of what $1 trillion looks like.) In order to place the water used in Californian toilets in direct comparison with the others, we must first convert the value of 1.6 gallons/flush into a figure of gallons/year throughout California. When we do this, we find that toilet-flush water use in California is at least:

1.6 gallons/flush (x 5 flushes/person/day)
= 8 gallons/person/day (x 38,800,000 Californians)
= 310,400,000 gallons/day in California (x 365 days/year)
= 113,296,000,000 gallons/year

(I write "at least" 113,296,000,000 gallons/year, since I am using the figures for household toilets and only 5 flushes/day, even though the average is somewhat higher. This number doesn't include, of course, water use statistics for public toilets, urinals, port-a-jons, etc.)

Now let's list all the water uses presented in the picture in increasing gallons/year:

70,000,000 gallons/year (fracking)
400,000,000 gallons/year (Nestlé bottled water)
113,296,000,000 gallons/year (toilet flushes)
1,100,000,000,000 gallons/year (almond farms)

When we look at toilet flushes in this perspective, it is clear that it is 1,618 times greater than the reported value for fracking. Furthermore, it is 283 times greater than the reported value for Nestlé bottled water. Indeed, when presented in this way, California toilet-water use can be presented as being far more profligate than either fracking or Nestlé bottled water, and by a LONG shot, simply because California has SO many people, and almost 60% of that population (22,680,000 in 2010) lives in sunny, drought-ridden SoCal. This places domestic water use (which includes baths/showers, toilets, dishwashing, lawn irrigation, carwashing, etc) far ahead of most industrial water uses... save agriculture

Indeed, when compared to the reported value of almond farms, toilet-water use is a mere 10%. However, there's a problem with the number presented in the graphic for almond farms. Specifically, the number of 1.1 trillion gallons/year is 1.6 times greater than the value reported by Hanson out of UCDavis, whose figure of roughly 2.1 milion AF/year works out to roughly 680 billion gallons/year (compared to this number, toilet flush water use is roughly 16%).

Let's look, though, at water used to grow alfalfa, which is, according to Hanson, the largest agricultural water use in the State. Accordling to Hanson, alfalfa grown in California uses roughly 5.2 million AF/year, or roughly 1.7 trillion gallons/year (which is about 2.5 times greater than the amount he reports for almond and pistachio irrigation). The second-largest agricultural water use (reported by Hansen) is for forages, which uses roughly 3.3 million AF/year, or roughly 1.1 trillion gallons/year.

So we can see that -- from an argument based around comparative water uses alone -- the merits of placing fracking and Nestlé bottled water fall flat, since toilet-flush water use far outstrips both of these two uses combined. It would have been a better argument to put up alfalfa farms and forage farms. However, it's almond growers that have been in the news, and not alfalfa or forage, which is likely why it is almond growers that are shown (even though they are not the largest agricultural water users, and even though they have a far more valuable crop than either alfalfa or forage crop farms).

Now, one could still use the water use figures presented in the graphic to make associated arguments, but I was unable to find a single argument that held true against the fracking, Nestlé, and almond farms while preserving toilet flushing. For example, one argument for water conservation that is often made against fracking regards removing water from the hydrological cycle completely, and it's true that one could make the argument that water used in fracking is effectively "lost" to the immediate hydrological cycle (since fracking wastewater is often deepwell injected) and therefore cannot be used for drinking or any other use, but that argument doesn't hold for almond farming or bottled water, since both return their water to the immediate hydrological cycle (primarily as groundwater recharge, evapotranspiration, and biomass decay in the case of almond farms and as urine that is flushed down a toilet in the case of bottled water). So the argument that it's about removing water from the hydrological cycle use is not valid across cases.

Another common argument against fracking, irrigation, and bottled water is that these uses are consumptive uses. In the case of fracking, this is undoubtedly true (as laid out above), and water used in agriculture is often also considered to be consumptive. However, the charge of consumptive use can also leveled at most of California's toilet water flushes, since much of the State's water is pumped from watersheds in Northern California and the Colorado River, creating consumptive water use pressures in those areas.

The only real argument that comes to mind is that it is unfair for the government to impose water restrictions upon flesh-and-blood citizens but not impose water restrictions upon corporate "citizens." However, such an argument isn't a water volume argument, but a water rights argument, especially in how Californian water rights are not egalitarian, with a large part of this argument lying in the problems associated with California's water rights laws. Most individual Californian citizens do not own any water rights, let alone water rights that predate 1914. The date of 1914 forms the demarcation date between so-called "junior" and "senior" water rights, and those holding junior water rights will have their rights to water curtailed before those of senior water rights holders. Such a system of rights is based on a "first in place, first in right" principle, with a strong incentive for the right to be held by a non-human entity (such as a corporation, water district, or the like), since the death of an individual could lead to the "death" of that right. From an equity perspective, such distributions of water rights is inherently inequitable, since it creates structural inequalities that become evermore entrenched as the value of water increases (making the purchase or transfer of water rights less likely to occur). During times when water availability is high, such a structurally unequal distribution of water rarely impacts large swathes of citizens. In cases of drought, though, such inequalities emerge. But regardless of the structural inequalities that California's water rights system imposes upon its citizens, the percecption of unfairness in who gets the restrictions is not due to water volumes (as the graphic implies), but due to water policy and water law.

One "good" note though (if only from a perspective of masochistic schadenfreude), is that if the drought continues, it is likely that even those holding senior rights (which includes many major agricultural water users) will have their water withdrawals restricted.

In sum, while bottled water and fracking are often seen as problematic for various social, public health, and environmental reasons, the comparative water consumption in these two sectors doesn't hold a candle to the total sector-wide water consumption of toilets. Furthermore, hiding the scales of water use between different water uses in the way presented in the graphic is deceptive, and such deception can foster mistrust of the messenger or supporter of the message. In other words, in order to make the graphic less deceptive and more salient to a message associated with different types of water use, it needs more than just a simple comparison of water volumes.

Of course, this additional nuance can create problems when trying to disseminate a message...

Just what is nature anyway?

The concept of "nature" is pernicious in how slippery it is - how unable one is to pin it down with a definite definition. Much like how Justice Potter Stewart defined obscenity, nature is something that falls more into the category of, "I know it when I see it."

The definition is more liberal than the dictionary one of: "the natural world as it exists without human beings or civilization," since people like to "get out into nature," and that area doesn't become "not-nature" whilst they are out in it. However - to most - a city park isn't (really) "nature" - although it can be natural.

It seems that - for many Americans - "nature" is somewhere close(ish) to the idea of "the natural world... without human beings...", but with certain allowances. (Especially since I'd imagine that no one - if they sit down and think about it - can really say that there is any place on earth that does not truly "exist without human beings." Indeed, many things can be considered to be "very natural" and even "nature" that are actually deliberate human (and human civilization) constructions. Indeed, New York City's Central Park is - to many - both a "park" and "nature." And - for a more personal example - the University of Michigan's Saginaw Forest is - to many of its visitors - a natural area (even though it's actually a highly artificial forestry farm that has many direct and indirect human impacts).

Presently, there is a question about whether the City of Ann Arbor should put in an art installation at the recently constructed Cascades on the Huron River.

View Larger Map

People's comments from the Facebook story are illuminating in how they perceive this obviously completely artificial, man-made structure:

• "Keep it natural. If I want to see art ill go downtown to the museum."
• "Bad idea. Nature is beautiful art without modification"
• "Lets keep it natural art, plant some really pretty flowers."
• "I don't think that this us a place for it. Keep it in its natural state."
• "Leave it natural"
• "good grief. The "Artists" have more than enough venue in A2, leave Mother Nature's gallery alone."
• "Humans, especially the ones in charge feel a deep seeded need to destroy everything good and beautiful in the world. The only art that should go there are the skulls of the people who first suggested putting art in."
• "Let nature be natural"

On the AnnArbor.com site's comments section, there were far fewer people making direct comparisons of the Cascades to being nature. These were the closest, though:

• "Idiotic waste of the taxpayer's money! Art does not belong in what should be a Natural Area."
• "How about something architectural?" 
• "Isn't the natural setting art enough ?" 
• "Ugh. I really don't want to see some cheesy, non-local art awkwardly perched atop some rocks as I go through the cascades. The rocks and plants are already beautiful. This is a really undesirable idea, as most other commenters will surely agree."

There were a few comments on both the Facebook page and the AnnArbor.com story that indicated that the Cascades are actually constructed and not-natural, but compared to the number of comments that indicated the Cascades a natural, they were few and far between.

So, are the Cascades natural? I'd say that it definitely doesn't match the dictionary definition. However, the reconstructed river channel that was built as a bypass around Argo Dam is definitely more natural than a stormwater canal. And as the plantings in the Cascades grow in and the channel settles into its new configuration, it will continue to become increasingly naturalized.

At what point, though does a naturalized artificial landscape become "nature"? I'd argue that it will never become the nature of the dictionary definition. (And - arguably - it was never that type of nature once the first human being entered the area, thousands of years ago.) Indeed, I'd argue that the objective definition given by the dictionary is completely artificial and conceptual (and also associated with a rather ... problematic ... management and policy history in which native peoples and multi-generational families were evicted from "natural areas" in order to try and reconstruct this definition of "nature"). Indeed, since it is so completely artificial and conceptual, it cannot actually be found anywhere on Earth, and that's why - perhaps - people eschew the purist dictionary definition and instead opt for following the completely subjective definition of, "I know it when I see it."

Misunderstanding Flood Frequency and Climate Change

Apparently, some people still have problems understanding what the difference is between "climate" and "weather" - or in this case the impact of a changing climate on flooding (which is an outcome of severe weather). The high rains that hit the Calgary, Alberta region of Canada were caused by what The Weather Network described as an "atmospheric river"caused by a major meander in the Jet Stream. This sort of major meander in the Jet Stream is what caused Alaska to shatter high-temperature records, and could be linked to what is now causing a massive heat wave in much of the western US. This meandering of the Jet Stream is the reason why the UK is having such a soggy summer. And why, exactly, is the Jet Stream meandering so much? If only we had an explanation for it that makes sense of it in scientific terms. Oh, wait, we do, and it's called climate change (aka global warming).



See? Climate change is causing increased warming in higher latitudes. Warmer air in the higher latitudes means that the energy gradient compared to lower latitudes diminishes, which means that the Jet Stream meanders more. This is what the theory predicts, and this is what we actually see.

But - apparently - many people don't understand this. Many in the initial piece really wanted to bludgeon others with the contention that - since the Bow River had flooded in the past to the same magnitude (and even greater amount) - the current flooding has absolutely nothing to do with climate change. This is problematic on two fronts. The first is that the evidence of why the Bow River flooded (the "atmospheric river" caused by a major meander in the Jet Stream, which is exactly in line with what our models of climate change would predict to become more common). The second is that the justification for the argument (that we can use historic data and historic probabilities of flooding to predict the likelihood of future flooding) fly out the window when we recognize that global warming will alter the underlying processes governing flooding.

There was one particular commentator - Luke - who was more than a bit of an arrogant twit. Unfortunately, it looks like he deleted all of his comments from the page. (I'm making the assumption that he did it himself, because none of the other obviously-wrong-and-just-as-arrogant statements have not been removed.) Still, Luke's comments showed an obvious misunderstanding of flood frequency and the link between floods and global warming (outlined above). The basic contention by Luke was that the recent flooding in Calgary was nothing strange, and that - in fact - the name of the river indicates that flooding is a normal part of the river's course, citing this story, and specifically this passage:

The Bow River gets its name from the Peigan name “Makhabn” which means the “river where the bow reeds grow.” And a good place for reeds to grow is a flood plain.

To Luke, the fact that bow reeds grow on flood plains (and - apparently - that the term "flood plain" has the word "flood" in it) must have meant that the recent massive flooding wasn't really that big of a deal. To that contention, I wrote:

Perhaps you ought to look up what a floodplain is, and what the flooding frequency of a floodplain.

Or you can just keep believing that you aren't seeing the truth of your constructed reality being washed away. But that's your choice.

I prefer to side with reality. Call me biased in that way.

His response was to point me to another comment that he made about the size of the ten biggest floods recorded on the Bow River in Calgary. However, if you knew what a flood plain is, you would know that flood plains are not flooded only when there are historically huge floods. Indeed, flood plains are flooded far more frequently than once every 100 years or so. It's why they're called "flood plains", instead of just "plains." Indeed, I decided to even give Luke a link to an easy-to-read explanation from the USGS (yeah, I know, Calgary is in Canada, and the USGS is a US governmental agency, but the hydrology of rivers doesn't change at the border). (The portion in Courier is a blockquote from his comment, to which I was responding.)

Had you bothered to look at the table I posted below, you'd know exactly what the frequency is. But, evidently, all you've got is a big mouth.

Umm... Actually, all you're doing is showing the extent of your naivete about these issues. What you provided is the historical maximum floods. I actually did see that table. However, these incredibly large floods are not the only ones that inundate floodplains, and pointing to only this table indicates to me that you don't actually know what a flood plain is.

(To recap: Your original contention is that the name of the place - river where the bow reads grow - indicates that this is a flood plain, and that flood plains are known for ... flooding, and so what we just saw in Calgary ain't that big a deal. And then when I asked you if you actually know what the flooding rate of a flood plain is, you pointed me to a table that shows only the largest floods, which - if you know anything about flood plains - doesn't even come close to the numbers of floods that inundate a flood plain, which indicates your ignorace of what a flood plain actually is.)

Here is some reading material about what a flood plain actually is, and what the flooding frequency of a floodplain is. (I'll give you a big hint about where to find the answer: paragraph three, which begins with the words "Bank-full discharge..."

http://nevada.usgs.gov/crfld/floodfreq_desc.htm

Of course, these floods are several magnitudes smaller than the one that hit the city, but the point is that you can have flood plain inundation - and therefore have a great place to grow bow reeds - with river discharge rates far below the one that you're trying to show as being no big deal.

Still, I applaud your efforts to try and understand something that either beyond your comprehension or actually operates in a way that runs counter to your presuppositions. My advice to you is to keep working at it, eventually you might come to recognize that you're wrong, which might then allow you to actually learn something correct.

Good luck!

After this point, Luke decided to cut his losses and say that I won... but without actually recognizing why his position was wrong. I really wish that I had his wording, since it's patently clear that Luke was just trying to find a way to get out of having to argue against someone who slung his arrogance back in his face, along with a ready understanding of the very facts that he was trying to use to bludgeon his opponents. Of course, his weasel-worded "concession" comment tried to have it both ways; saying that I won the debate but that he was right on the facts. However, there was a problem... A: there was no "debate", and B: the whole point of my comments were that he was wrong on the facts. (Did I mention that he was an arrogant-twit?) So, since he crowned me the victor, I felt that it was important to explain to him why his concession was actually just annoying:

Wow. Apparently you don't understand simple hydrology (or you are incapable of taking 10 minutes to read some easy-to-digest science from people who do and written for people who don't).

I'm not going to waste time even trying to explain more to you, since you have twice shown an unwillingness to actually make the slightest modicum of effort to understand why your statements are just grossly and laughably wrong.

To this, he gave the completely bizarre (and equally weasel-worded) response that amounted to, "But I said you won. Why don't you just accept that you won and move on?" And I decided not to respond further, since - as I wrote - he wasn't worth my time.

Things were left there for a day, and now, another commentator felt that I was too harsh on Luke, and insinuated that some of the positions I outlined were wrong:

Your arrogance overshadows everything you've said. The point is that the big floods in Calgary were 125 years ago when 1/100th as many buildings were on the Bow River's flood plains. So this flood was both normal, and predictable. That may not follow the climate alarm industry's script, but it is observed fact. BTW, the Bow River's floodplains mostly grow cottonwoods.

I do recognize that I'm acerbic. And I also recognize when others are being acerbic. If someone wishes to be acerbic, I'm more than happy to oblige them, but what am I supposed to do with this comment? I mean, there is nothing there that actually is written to confront or try to refute any factual piece that I wrote (other than the observation about the current plant ecology, which I didn't introduce in the first place) while simultaneously implying that none of it is valid because I wrote arrogantly to an arrogant person or to bring up points that are only tangentially related to things that I wrote and to point out that the reference to the plant ecology of the Bow River (which I didn't introduce, but was actually responding to) was incorrect. Well, I decided to spend about 30 minutes to write the following exhaustive reply to each of the points that this commentator raised (many of which I didn't discuss at all in the first place, but whatevs):

As with kindness, respect, or sincerity, I return arrogance, like for like, pound for pound, and Luke was dishing his arrogance out like there was no tomorrow. From the above, though, you'll note that neither Luke nor I really minded (or at least commented that we minded) on the heights of arrogance that we were using to talk with each other. I enter each interaction with the understanding of how - based on the evidence - the other person/people are already conducting themselves in the forum, and apply the Golden Rule: they are treating others with arrogance, which means that it is apparently how they wish to be treated. (After all, if they didn't wish to be responded to with arrogance and derision, they shouldn't have done it in the first place, right?) However, those are issues of interactive game theory and socialization, which (although an interesting topic) isn't the one covered by this article, nor by Luke.

To the substantive points you make, you are right: there are more buildings in Calgary now than there were 125 years ago, but this has nothing to do with regional flood frequency. But if I am missing some connection between flood frequency and the different number of buildings in Calgary, I would be happy for you to explain that link to me. The only major impact of building construction to flood frequency is the extent to which the land-cover changed, although landcover change creates local impacts, and the flooding wasn't only occurring within Calgary, which means that land-cover change wasn't the significant driver of this flooding event. But again, if I'm wrong on the facts here, please let me know.

As for the growth of cottonwoods vs. bow reeds, I was not making any claim about the actual biodiversity in the region, only responding to the claim by Luke that the large floods are somehow normal, because the name cites bow reeds, and bow reeds grow in floodplains, and - as evidence of flooding - Luke points only to extreme flooding events instead of a natural frequency of flood-plain inundation. Still, this doesn't change the general point of linking the comment to the flood-plain inundation rate and not the historical maximum flood rates, because although I am not a plant ecologist, the species of cottonwood I am familiar with tend to grow in/near floodplains and (especially in more arid regions) rely heavily on the periodicity of flood-plain inundation. Therefore, whether it's bow reeds of cottonwoods, it's the flood-plain inundation frequency (and not the historical maximum flood volumes and rates of flooding) that are more important in understanding those local ecosystem dynamics. (Although, to be fair, extreme floods do have a significant effect in shaping certain constraints to ecosystem structure, but the temporal scale of their impacts are at a completely different scale than the flood-plain inundation rates, which are far more important for year-to-year survival and propagation. This is the case for most flood-plain ecosystems, and I'm assuming that those in Alberta are no different in these broad-brushstrokes.)

Also, I agree with your point that the flood was predictable, and - in that sense - as normal as any large and predictable flood would be in the course of the history of a location. I am hesitant, though, to say that it's "normal," since the idea of "normal" is different when speaking about flood frequency and speaking in a day-to-day context. To most people, the idea of "normal" tends to be in the "happens regularly within a time frame that I happen to expect it to occur within (which usually extends to a maximum of "my life so far")". Therefore, while a 100-year flood, 500-year flood, or 1000-year flood occurring at some time in the history of a river system is "normal" in the grand-scheme of things, to most people, that particular event wouldn't be seen as "normal", since it didn't happen in their lifetimes (and if it did, then it wouldn't be "normal" since multi-century events "shouldn't" happen more than once in their lifetimes, even though - statistically - they could, and would be perfectly "normal" from a flood-frequency perspective).

Finally, to shift the discussion to where I infer that you're implying that I'm "follow[ing] the climate alarm industry's script", let's step away from the label-placing and automatic assumptions and speak about how climate change will affect the reliability of current flood frequency statistics. Flood frequency is based on a statistical probability based on past events, and this is fine, so long as current climate is adequately described by past climate. In general, though, climate change is expected to significantly alter flood frequencies in many places. Therefore, methodologically speaking, a future with altered climate makes using flood frequencies that were established on historic data methodologically troubling at best (and - if a region's climate has changed dramatically - it makes them completely useless).

Again, if I get anything wrong here, please do let me know. I'd be happy to have a discussion with you about them and to correct my knowledge and expectations.

I won't hold my breath to see if there's a response.