Hurricane Sandy a 1-in-700-Year Event Says NASA Study

Rebecka writes "Hurricane Sandy, which pelted multiple states in Oct. and created billions of dollars in damage, was a freak occurrence and not an indication of future weather patterns, according to NASA's Goddard Institute for Space Studies via LiveScience. The study (abstract), which calculated a statistical analysis of the storm's trajectory and monitored climate changes' influences on hurricane tracks, claims that the tropical storm was merely a 1-in-700-year event. 'The particular shape of Sandy's trajectory is very peculiar, and that's very rare, on the order of once every 700 years,' said senior scientist at NASA and study co-author, Timothy Hall. According to Hall, the extreme flooding associated with the storm was also due to the storm's trajectory which was described as being 'near perpendicular.' The storm's unusual track was found to have been caused by a high tides associated with a full moon and high pressure that forced the storm to move off the coast of the Western North Atlantic."

Re:The problem with Probability...

[alen]

Sandy hit at high tide and a full moon
the gravity of the moon raised the water a few feet which is why the storm surge caused all the flooding

we had a more powerful storm hit NYC the year before and it did a lot less damage because it didn't hit at high tide. very minor flooding.

for another hurricane to do as much damage as Sandy, it has to hit the around the 22nd of the month and make landfall close to 8pm

Re:So what happens ...

[gstoddart]

even events like hurricanes, where there is no scientific consensus on the matter - are as big a problem as the "I don't believe in global warming" crowd.

Well, the problem with that statement is that except for the "I do not believe in global warming" crowd, there's an awful lot of scientific [nasa.gov] consensus [ca.gov] on the topic.

Re:The problem with Probability...

[vux984]

False. 0.5^1000 == 0.5^1000 no matter how many trials there are

Your right of course. But he's saying the longer you flip a coin, the more likely you will see an occurrence of 1000 heads in a row, and this is true.

Lets look at a smaller set 2 heads in a row:

The odds when flipping a coin twice is 0.5^2. or 1 in 4.
The odds when flipping a coin twice more is again 1 in 4.
repeat ad nauseum, which is your argument.

His observation is that if you flip it 3 times, the odds of two heads coming up in a row increases, and it does. It's now 3 in 8 which is greater than 1 in 4. If you flip it 4 times... its up to 8 in 16 (or 50%), 5 times, and your odds get to 19/32 which is almost 60%, 6 times 51/64 (almost 80%).

That doesn't change the odds of a superstorm happening next year, or next week. Its still a 1 in 700 year probability. But the thing about statistically unlikely things is not only that they can happen, but that they DO happen, and over a long enough period unlikely things are nearly inevitable.

The NASA paper bears no resemblance to the summary

[petaflop]

The NASA paper does not say that Sandy was not influenced by climate change. What they actually calculate is that Sandy-like hurricanes occur once in 700 years under pre-industrial conditions. Here is one of many relevant quotes:

The fact that our calculations show Sandy’s track to be so rare under long-term average climate conditions lends support to a climate-change influence. On the other hand, the most recent climate model simulations project reductions in blocking frequency in a warmer climate [Dunn-Sigouin and Son, 2012]. Global high-resolution models suggest that tropical cyclone frequency will decrease globally, while mean intensity will increase. There is growing consensus that the most intense events will increase in frequency, but there is high uncertainty, especially in individual basins [Knutson et al., 2010]. On the other hand, further sea level rise is almost certain, with a meter or more expected in the next century [Nicholls and Cazenave, 2010]. This will exacerbate TC-induced flooding even if the storms themselves do not change.

Someone should have RTFA.

Re:The problem with Probability...

[hackertourist]

it has to hit the around the 22nd of the month and make landfall close to 8pm

That would be valid only for this month, as the tides don't follow a monthly cycle but a ~ 28-day cycle.

Re:The problem with Probability...

[bobbutts]

Check out IKE (Integrated Kinetic Energy). It is a valuable metric for quantifying potential for storm surge. Sandy was freakishly high on this scale.

This article
Superstorm Sandy packed more total energy than Hurricane Katrina at landfall [washingtonpost.com]
does a good job explaining.

Long story short, discount Saffir-Simpson categories and look at IKE when you want to discuss surge.

Re:Last 700 years: yes, future: not so much

[Anonymous Coward]

Le sigh.

From a recent WMO report [wmo.int] titled "2001-2010, A Decade of Climate Extremes":

Every year of the decade except 2008 was among the 10 warmest years on record.

The 2001-2010 decade was the second wettest since 1901. Globally, 2010 was the wettest year since the start of instrumental records.

According to the U.S. National Oceanic and Atmospheric Administration, 2001-2010 was the most active decade since 1855 in terms of tropical cyclone activity in the North Atlantic Basin.

According to the 2011 Global Assessment Report, the average population exposed to flooding every year increased by 114% globally between 1970 and 2010, a period in which the world’s population increased by 87% from 3.7 billion to 6.9 billion. The number of people exposed to severe storms almost tripled in cyclone-prone areas, increasing by 192%, in the same period.

But apart from that, no new records.

To quote Bill Hicks: “Go back to bed, America, your government has figured out how it all transpired. Go back to bed America, your government is in control. Here, here's American Gladiators. Watch this, shut up, go back to bed America, here is American Gladiators, here is 56 channels of it! Watch these pituitary retards bang their fucking skulls together and congratulate you on the living in the land of freedom. Here you go America - you are free to do what well tell you! You are free to do what we tell you!”