Another one-in-100-year event?

 

I'M ALREADY SEEING IDIOTS bleating, after today's rain here in Auckland, that "one once-in-a-hundred year weather event in a year is unfortunate; two in a few months is beginning to look like a trend. Of course, we know what that trend is called [he says]: climate change... Twice in one year should be a warning. We need to ... address the cause, rather than just blithely dragging out feet to apocalypse."

Statistically, this is just flat wrong.

It's a common error, mostly made by those who don't understand statistics. But for the record, here's a meteorologist in Texas explaining it: 

You may have ... heard the phrase “a 100-year flood,” especially around hurricane season. Perhaps you heard this phrase two years in a row or even two months in a row!
    What does this mean? In the weather world, it’s about probability of the event happening, not the timing. It does NOT mean that a 100-year flood should only happen once in a hundred years.
    As with “once in a hundred years,” it’s a statistical way of describing a weather event has a 1% chance of happening in any given year.
    Now you know!

Clear enough? A once-in-a-hundred year event is equivalent to saying there's a 1% chance of that event happening somewhere in any given year.

Still and all, as a more local fellow adds explanatorily:

Many people are surprised by the feeling that one-in-100-year events seem to happen much more often than they might expect. Although a 1% probability might sound pretty rare and unlikely, it is actually more common than you might think. There are two reasons for this.
    First, for a given location (such as where you live), a one-in-100-year event would be expected to occur on average once in 100 years. However, across all of Australia you would expect the one-in-100-year event to be exceeded somewhere far more often than once in a century!
    In much the same way, you might have a one in a million chance of winning the lottery, but the chance someone wins the lottery is obviously much higher.
    Second, while a one-in-100-year flood event might have a 1% chance of occurring in a given year (hence it’s referred to as a “1% flood”), the chance is much higher when looking at longer time periods. For example, if you have a house designed to withstand a 1% flood, this means over the course of 70 years there’s a roughly 50% chance the house would be flooded at some point during this time! Not the best odds.
    Incidents like these 1% annual exceedance probability events are often referred to as “flood planning levels” or “design events”, because they are commonly used for a range of urban planning and engineering design applications. Yet this presupposes we can work out exactly what the 1% event is, which sounds simpler than it is in practice.

Got all that? 

So when you hear idiots like the above bleating that too many one-in-100-year events too soon is just too much, just remember that's not true, statistically.

THE CONCLUSION THAT THE idiot draws from his statistical error is dead wrong too, by the way: dead wrong scientifically this time.

Dead wrong because -- even if you accept the climate scare, and were to accept the claims that human industry as a whole are causing these events -- then there is not a thing we in New Zealand could do that would cause a blind bit of difference to that. The entirety of New Zealand could slip into the sea, and all of us with it, and the world's carbon emissions would diminish by so little as to be unnoticeable.

So his claim of causality has just too much distance between his alleged cause (you and I driving our utes today) and tomorrow's alleged apocalypse  -- let alone today's rain in Auckland. Too distant, and too inconsequential.

And I'll bet some of those utes are becoming damned useful about now.

You may see now why the idiot stopped taking comments on his blog.

PS: And for those who've been inquiring: yes, me and mine are fine. Thanks for asking.