Saturday 2 September 2017

1 in 500

Hurricane Harvey is a 1 in 500 year flood, according to some sources. Well, that's comforting - it means it most likely won't happen again for 500 years. Harvey dumped 40 inches of rain on Texas and has caused (so far) 51 confirmed deaths. Economic loss estimates range from $10 billion to $160 billion.

Do you remember Tropical Storm Allison, in 2001? That was a 1 in 500 year flood.
40 inches of rain, 55 dead,  $9 billion damage

Hurricane Ike; 2008, 195 killed, 145 mph winds, $37.6 billion damage.

Hurricane Rita, 2005. 16 inches rain, 180 mph winds. 97-125 killed, $12 billion damage.

I don't think you need to be a statistician to deduce that four such deadly storms in 16 years means that we should be talking about a once in four year event, not once in 500.

Because if it only happens once in 500 years, there's not a good reason to take significant action.  But if huge storms like this happen every four years, maybe it's worth spending a bit to put up defences. 

Because climate change couldn't possibly be part of the problem, whereby warmer ocean water increases the amount of moisture that a storm can carry, and Americans believe that climate change is a Chinese hoax.

Fortunately, none of this affects us here in England.


  1. Your link brings up this source: "according to researchers at the University of Wisconsin’s Space Science and Engineering Center" who say it is once in 1000 years and that "there is nothing in the historical record that rivals the devastation". These guys are at least as believable as the "scientists" who make claims about global warming based on computer models, which are just glorified spreadsheets. We know how prone those are to input and operator errors, especially as their early predictions have not panned out and keep having to be "adjusted".

  2. Yes. My entire essay is pointing out that this is not a "1 in 500" year disaster, more like a one in four year disaster.