Anyone notice the comments for this article on WP? There appears to be a poster called "The burning bush" who is commenting with lengthy comments about every 6 minutes. All of the the comments from that user are sceptical of man made climate change. Washington post does not appear to let you sort by anything other than "newest"... which means that this commenter's posts are always the top comment. That's concerning!
Houston is experiencing its third ‘500-year’ flood in 3 years
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Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#82This article reminds me of Nate Silver's book [1] which has a far more scientific and in depth look on the failure/success of these types of predictive statistics.
The chapters on the many attempts (or many failed hopes) in predicting earthquakes was particularly interesting, including many times the media has bought into hyped up new charlatans who say they finally figured it out but which ultimately failed to survive under basic statistical scrutiny.
It also has a useful soft introduction to Bayesian statistics and other useful concepts from the field of prediction that I hope more journalists read about. As this seems to be a very common theme in reporting.
Even this journalist couldn't help themselves with this line (combined with some scary looking charts described with an alarmist tone farther down):
> Was there some miscalculation of how frequently these massive flooding events occur? Or, most alarmingly, is something else happening that suggests these catastrophic weather events are becoming much more common?
The failure to mention the effects of El Nino/El Nina seems like a big oversight in this article, especially when we're just coming out of a particularly strong one. Climate stats are an easy one to get wrong - or to shape into any narrative - especially when timeframes and location are easy things to be viewed too narrowly.
[1] https://www.amazon.com/Signal-Noise-Many-Predictions-Fail-bu...
Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#83Cue discussion on the works of Tabeb, and what a horrible job humans do at predicting the frequency of rare events.
Parent means Nassim Nicholas Taleb http://www.fooledbyrandomness.com/ And yes, basically we don't understand the actual probability of a "500-year storm", so our 0.2% chance per year is unreliable at best, more likely misleading. Just like Europeans didn't know the actual probability of a black swan until they found them in Australia.
I think the idea of a black swan is something which you don't even imagine before you encounter it, ie: nobody would even think about computing the probability of a black swan (bird) existing.
Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#84While the article obliquely makes reference to this, I wonder if this is somewhat similar to the "birthday" problem in statistics. Any given person has ~1 in 365 chance of being born on a particular day. Yet, if you have 30 people in a room, there is a greater than 50 percent chance that at least one PAIR has the same birthday. Given the hundreds of cities (thousands?) in the US that may be affected by a flood, it's…
The "Birthday Problem" has a simple explanation. Something like nearly 45% of people are born in the Summer months. Ensure that you get people of different ages and your chances of finding someone with similar/same birthday goes up enormously.
No, the birthday problem still works if you consider that the probability of being born on a particular day is uniform.
It's related to the fact that the probability of two people in a room having a birthday is more closely related to the number of pairs of people in the room (which in turn grows as O(n^2)), than to the number of people in the room.
A detailed proof/explanation can be looked up easily with Google, if you have a bit of mathematical maturity.
Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#85Earlier quoted context omitted.
There is no way to credibly make this kind of claim. We don't have the data to quantify the recurrence rate of low-probablity events like this, nor can we be sure the the underpinning mechanism isn't changing with time.
If we have a baseline of 500 year flood level at 0.2% and it's well over that then yes there is a basis for making this claim. I wouldn't make this claim though...
> If we have a baseline of 500 year flood level at 0.2%
That's exactly the point. We don't have that baseline, despite acting as if we do. We would need data going back 5,000 years to do that.
Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#86Howdy! I work in cleantech, and I guess it's that time again for a what-can-you-do-about-it post :) To start, here's my favorite climate change joke: "They say we won't act until it's too late... Luckily, it's too late!" ==So what can you do about it?== The biggest thing that is most relevant to the HN audience is that you can work at a new energy technology company! Our industries are out of the R&D stage and are cu…
While energy is definitely a huge part of the problem, preventing things specifically like Houston's flooding seems like more an issue of infrastructure and emergency readiness.
And dealing with the aftermath seems like it's a space for organizations dealing logistics, drone fleets (e.g., for mapping, finding survivors and communicating with them, delivery to inaccessible areas), etc..
Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#87Earlier quoted context omitted.
"Fort Bend County Judge Robert Hebert stated that Hurricane Harvey is more like a 800-year event" 500 years, 800 years ... even 1000 years - none of those are timetables that planning for city ^H^H^H^H region the size of Houston should be operating on. A city that large, that populous and with that much economic activity that is crucial to the world should be using risk models to 10k year events. This is not unpreced…
Sounds like the city fell asleep at the wheel, or rolled the dice and didn't want to pay for proper drainage. Now the citizens get to pay. Sounds like the Judge is preparing the country for the fact that nothing will still be done about it.
There was an article from 2016 also on HN today about the risk. Three different experts were quoted saying something along the lines "nothing will be done now, we need to wait for the big flood and 2-4 years after we will build a wall".
The "wall" (actually a more complex thing) was projected to cost 8 bil. A bad flood like the one from today was projected to cost 70+, but people were hoping that we have around 10-20 years to prepare
Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#88While the article obliquely makes reference to this, I wonder if this is somewhat similar to the "birthday" problem in statistics. Any given person has ~1 in 365 chance of being born on a particular day. Yet, if you have 30 people in a room, there is a greater than 50 percent chance that at least one PAIR has the same birthday. Given the hundreds of cities (thousands?) in the US that may be affected by a flood, it's…
From what I understand of the article, the "1 in 500 years" measure is based on the estimated probability of a flood on a given year in a local area. So the probability of a "1 in 500 year" flood in Houston is independent of the probability of a "1 in 500 year" flood for another city.
My understanding is that by definition, a 500 year flood has a probability of 1/500 per year. But I live at the top of a hill in the Midwest, so a 500 year flood in my locale has a much different severity than a 500 year flood in Houston.
Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#89Earlier quoted context omitted.
I understand your argument, but you can't compare floods to the birthday problem. Unlike randomly-sampled people's birthdays, floods in US cities are not independent random variables. For instance, chances of 500-year floods in two Texas cities is not 1 out of 500*500 in a year. If they're geographically similar and physically close, it should be closer to 1 out of 500.
In 2 Texas cities, sure, but in every U.S. city? There are going to be several that end up getting a few 500-year floods... and several others that don't flood as expected in several 1000 years.
In many US cities. Recall that during hurricane sandy, pretty much any landfill or low lying area was flooded in the NY metro area.
That means dozens of cities and towns with 7% of the US population.
Re: Houston is experiencing its third ‘500-year’ flood in 3 years
#90The elephant in the room has been mentioned somewhere else these days: severe lack of planning and crumbling infrastructures. Remarkably how ne of the few non-partisan issues on the table goes under the radar time and time again. Tongue in cheek, we might think only polemic issue get the attention of the public. There is also the notion of national pride. We built our infrastructural base earlier than pretty much any…
Which other city in the US can handle 40 or 50 inches of rain, and 15 trillion gallons of water, within a one week timespan? That's as much rain as most US cities get in a year.
This is not the fault of poor planning or poor infrastructure in Houston. It's freak weather event that shouldn't just be given partisan rhetoric.