Climate and the statistics of extremes

Jan 18, 2012
© blackwarrior57

(PhysOrg.com) -- Swiss mathematicians have shown that the risk of extreme climate events is largely underestimated. They are developing a model for better understanding the impact of climate change.

Remember the 2003 ? According to the standard weather models, it was impossible. Mathematicians from EPFL’s Chair of Statistics, however, say that there was a five in ten thousand chance for the event to occur. That’s a pretty slight chance, but not completely negligible. To reach this result, they developed a model that specifically deals with extreme weather events. Thanks to this tool, which takes into account various parameters such as , the researchers are already able to more precisely predict the risk of extreme phenomena for the upcoming decades.

Weather stations and probability

“The problem of extremes is that there are so few events, by definition,” explains EPFL mathematician Anthony Davison. “It’s thus necessary to create specific models that are different from those that use innumerable mean values.” The researchers used MeteoSuisse data to simulate a thousand summers, using probabilities and their model of extremes. They were able to determine the risk of elevated temperatures for a given period. To arrive at conclusive results, their model groups weather stations into pairs so their measurements can be correlated.

Combining the stations into pairs for the simulation requires a huge number of calculations. The number of combinatorial operations can quickly escalate. “For example, to simulate heavy rainfall, we were limited to ten weather stations, which already represented several days’ worth of calculations on a high-speed computer network,” Davison explains. In spite of this, the research is already leading to extreme events analyses that are more realistic than those arrived at using traditional models.

Six times more likely in 2050

For several years now, the scientists have noted that the increase in extreme events associated with climate change appears to be having much more of an impact on society than the increase in mean temperatures. Natural disasters are accompanied by a significant human and economic cost. In the case of exceptional heat waves, the found that, based on global warming predictions, the probability of an event at least as severe as the 2003 heat wave will be six times greater in 2050 than it was in 2003.

The specialists are also developing models for other extreme weather events, such as rain, snow, and ice. The challenge is to improve them in terms of precision. “Eventually, we would like to be able to integrate more calculation points in order to better cover the territory. We also need to optimize our models to include dynamic phenomena, which require even more operations,” Davison says.

Explore further: Canada to push Arctic claim in Europe

More information: Geostatistics of extremes, Davison and Gholamrezaee, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences (2012) vol. 468 (2138) pp. 581-608. dx.doi.org/10.1098/rspa.2011.0412

Provided by Ecole Polytechnique Federale de Lausanne

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User comments : 20

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GSwift7
1.5 / 5 (8) Jan 18, 2012
For several years now, the scientists have noted that the increase in extreme events associated with climate change appears to be having much more of an impact on society than the increase in mean temperatures


Faulty base assumptions lead to faulty conclusions. GIGO. The US NCDC has made repeated statements in regard to this. You can find them on their web page. They have an FAQ section.

http://www.ncdc.n...dex.html
GSwift7
1.5 / 5 (8) Jan 18, 2012
It doesn't look to me like we are seeing a global warming signal in extreme events. Here's the official stats from NOAA from around 1900 to current. Looks like the rate dropped in the middle 20th century, and it's returning to 'normal' now. Why would anyone look at that graph and assume it's going to continue an upward trend?

http://www.ncdc.n...ei/01-12

Oh, and if you see that slight increase in the linear trend, that isn't a statistically significant trend compared to the standard deviation.
Sean_W
1.8 / 5 (4) Jan 18, 2012
It's worse than we thought.
ODesign
1 / 5 (4) Jan 18, 2012
I believe I read somewhere that a warming global environment exhibits increased extremes, but global cooling is a comparatively stable transition without major fluctuations.
kochevnik
3.9 / 5 (17) Jan 18, 2012
Open systems are defined by extremes where there is free energy.
Howhot
4.6 / 5 (18) Jan 18, 2012
It looks like weasel has popped for the Anti-Global-Climate-Change crowd. The AGCC's will never get it right.
gregor1
1.4 / 5 (20) Jan 19, 2012
There's an "Anti-Global-Climate-Change crowd" now? Are they the same as The "Climate change denier" crowd that also don't exist? As far as I'm aware the debate is simply about the extent of human influence on climate change and that such terms of vilification are invented by trolls to stifle that debate. I'm not aware of anyone who thinks the climate doesn't change.
ryggesogn2
1.2 / 5 (18) Jan 19, 2012
Natural disasters are accompanied by a significant human and economic cost.

Economic inflation, population and communication all contribute.

In the 30s, most people were smart enough NOT to live on a coastline prone to hurricanes.
Peak high temperatures occurred in the 30s along with extreme drought.
In today's 24/7 news cycle what was once considered normal, like -30F winter temps are now extreme. Wooses.
ryggesogn2
1.2 / 5 (18) Jan 19, 2012
1936:
"February brought record snow levels. After the snow came the cold. In North Dakota, the temperature never rose above zero for 18 consecutive days. The month's mean temperature was 11 below. In St. Louis, it was only 12. The Arkansas River froze at Little Rock for the first time in memory. "
"in July, came the heat, rolling up slowly from the Southwest, as if the door to the Mojave furnace had swung open. A massive high pressure system off the Pacific coast pumped the hot air into the nation's midsection. On July Fourth, as crowds frolicked on the beaches in Chicago and New York, it was already 98 degrees in North Dakota. Two days later, it would reach 121 in the town of Steele. The temperature swing of 182 degrees, from the Feb. 15 mark of 60 below, would be unprecedented in U.S. Weather Bureau annals. "
"On a muggy April 5, a band of twisters careened through Tupelo, Miss., rural Alabama and Gainesville, Ga., killing 419. No tornado system since has taken such a death toll. "
ryggesogn2
1.2 / 5 (17) Jan 19, 2012
(cont)
"Friday was the first time in history that three consecutive 100 degree days had been recorded in Detroit. It reached 101."
"The weather mechanics that produced the intense heat and drought of the '30s are still a puzzle to climatologists. There have been other such cycles since then, but never one so widespread or so intense. Or so deadly. "
This story appeared in The Detroit News on July 6, 1986.
http://apps.detne...p?id=134
rubberman
2.6 / 5 (5) Jan 20, 2012
It's worse than we thought.


Yup.
Howhot
4.7 / 5 (14) Jan 20, 2012
There's an "Anti-Global-Climate-Change crowd" now? Are they the same as The "Climate change denier" crowd that also don't exist?

OH! I wrote that tongue-in-cheek, but I can roll with that. So there was a "climate-change denier" crowd. Wow, they must be a bunch of asses and feel like fools now that climate change is well established fact.
ryggesogn2
1.2 / 5 (18) Jan 20, 2012
Climate has been changing for billions of years.
What's new?
rubberman
2 / 5 (3) Jan 23, 2012
Climate has been changing for billions of years.
What's new?


Us.
Howhot
5 / 5 (2) Jan 24, 2012
R2, you couldn't box yourself out of environmental issue if landed in your kitchen sink. Climate change is you. It's all about you conserva-lib.
ryggesogn2
1 / 5 (5) Jan 25, 2012
Climate has been changing for billions of years.
What's new?


Us.


What caused the millions of years of climate change before 'us'?
You AGWites are quite full of yourselves. But that is a symptom of socialism, hubris, arrogance in BELIEVING you know what is best for everyone and quite willing to use force to impose your beliefs.
Howhot
4.5 / 5 (2) Jan 26, 2012
Your right-wing-nut is showing R2. The UN has been working on establishing a re-education camp for AGW deniers like you. It's a nice camp, first they take you to a glacier (or whats left of one) so you can see how socialist a rock is where there should be 20ft of ice.

Haven't you ever noticed how many times us AGW progressives (and there are a lot of us) are right all of the time. It's not fake science causing that. Its just that you are WRONG.
In fact, your kind of fringe crazy man.
MarkyMark
not rated yet Jan 26, 2012


What caused the millions of years of climate change before 'us'?

Heh you are such a moron!
Howhot
5 / 5 (1) Jan 28, 2012
What caused the millions of years of climate change before 'us'?


I don't know, where you around at that time?

I mean, what was the weather like on Titan millions of years ago, or Mars if you would like to think there were once oceans there. Its wide open isn't it?

Well not so much. At least on the blue marble we can look a fossils, rocks and sediments to get a handle on what was happening back then. That give one a powerful tool for investigation, like what cause the temperature to spike here and not there.

The problem today is we live in technologically advanced societies that can not take extreme changes. Your mother is not going to want to 105 degree summers and spend a fortune on air conditioning. You want to be able to raise a good corn crop, but you can't even get the corn to sprout because of a spring drought.

It doens't need to be "millions of year", just a decade or two before the human race cries "Uncle, Uncle, Uncle"
ryggesogn2
1 / 5 (3) Jan 28, 2012
we live in technologically advanced societies that can not take extreme changes.

It is our technological advancement that has enable societies to adapt to extreme change.
If some societies can't adapt, technology can't be blamed.

Just over 100 years ago, no one could live in Las Vegas, not Mormons or aborigines. Now, thanks to technology, over a million live in Clark County.