Newsgroup: it.politica.internazionale
Titolo: Global Warming: An Exclusive Look at James Hansen’s Scary New Math

Non considero OT questo argomento, per il semplice fatto che ritengo che 
la politica, a livello planetario, dovrebbe seriamente iniziare ad 
assumersi la responsabilità dei cambiamenti climatici in atto e a 
governare quelle attività umane che contribuiscono a determinare questo 
fenomeno.
 
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Global Warming: An Exclusive Look at James Hansen’s Scary New Math
A new analysis by the NASA climatologist for the first time ties 
specific weather events to human-induced climate change
By Paul Tullis | May 10, 2012 | +
 
How can NASA physicist and climatologist James E. Hansen, writing in the 
New York Times today, “say with high confidence” that recent heat waves 
in Texas and  Russia “were not natural events” but actually “caused by 
human-induced climate change”?
 
It wasn’t all that long ago that respected MIT atmospheric scientist 
Kerry Emanuel flatly refuted the notion that you can pinpoint global 
warming as the cause of an extreme weather event. “It’s statistical 
nonsense,” he told PBS.
 
In 2005, Emanuel reported that hurricane intensity, which is fed by 
warmth, had increased some 80 percent during the previous 50 years, a 
period during which temperatures had increased more dramatically than 
any time in at least 500 years. Nonetheless, he asserted, that didn’t 
mean Hurricane Katrina, the sixth strongest Atlantic storm on record, 
had been brought on by climate change.
 
Even with a multitude of extreme weather events in recent years — 
tornadoes in New York City, blizzards in Washington, D.C., 15,000 
warm-temperature records shattered across the U.S. in March — each 
consistent with computer models of a warming world, Emanuel and many 
other noted scientists have been unwilling to attribute any one event to 
global warming. There’s just too much variability in the weather, these 
experts say, and their dedication to data has helped prop open the door 
for “denialists” to sow doubt about the reality of our warming world.
 
But Hansen’s shot across the bow this morning indicates that the 
unwillingness to point fingers may be changing. According to a 
peer-reviewed paper Hansen has submitted to a leading scientific journal 
and made available to Time.com prior to publication, scientists can now 
state “with a high degree of confidence” that some extremely high 
temperatures are in fact caused by global warming, simply because they 
occur much more frequently than they used to. (A preliminary draft of 
the article is available here.)
 
Hansen’s reasoning has to do with math. Statisticians employ standard 
deviation to measure variability; it’s the calculation pollsters use to 
determine margin of error, and it’s especially valuable when looking at 
the weather. Perfect distribution of standard deviation is graphed as 
the familiar bell curve; about two-thirds of the time, data points fall 
in the middle of the bell — or within one standard deviation of the mean.
 
Hansen, with co-authors Reto Ruedy, also of NASA, and Makiko Sato, of 
Columbia University, has crunched decades’ worth of readings from more 
than 1,000 weather stations around the world as well as satellite 
observations and measurements from Antarctic research stations. The aim: 
to figure out how often temperatures varied from the mean — and how far 
they varied — during two periods.
 
In the paper, which Time.com confirmed has been peer-reviewed, the 
authors show that extreme outliers of more than three standard 
deviations above the mean temperature covered between six and thirteen 
percent of the globe during the years 2003 to 2008. If they were 
normally distributed and similar to the climactic record, that should 
have been just a 0.1-to-0.2 percent frequency of an extreme heat event. 
(That’s about exactly as often as a perfect bell curve predicts they 
would occur.) Hansen dubs this difference a “three-sigma anomaly,” for 
the Greek-letter symbol for standard deviation. And in the world of 
statistics, these anomalies represent a stunning 10-fold increase in 
extreme weather events.
 
Hansen says the heat wave that struck Texas and Oklahoma last summer and 
the Moscow heat wave of 2010 (which caused 11,000 deaths in the city) 
are examples of three-sigma anomalies. In a paper published last year in 
the Proceedings of the National Academy of Sciences, Stefan Rahmstorf 
and Dim Coumou of the Potsdam Institute for Climate Impact Research, in 
Germany, wrote that it was 80 percent probable that the Moscow heat wave 
had been caused by global warming.
 
“These three-sigma anomalies,” Hansen says, “we can now say are due to 
global warming.” But what about the extreme cold snaps climate-change 
deniers keep pointing to? Even with global warming, Hansen told Time.com 
in an email, there “is still a broad bell curve. In fact, it has become 
broader, which means there will still be times when a season is colder 
than average. When that happens [people] should not say, ‘What happened 
to global warming?’ It will still be there — they are just looking at 
natural variability.”
 
Back in 1988, when Hansen was among the first and most credible 
scientists to sound the alarm about global warming, he, Ruedy and 
several co-authors came up with the concept of “climate dice.” Imagine 
dice with two sides red (for hot), two sides blue (for cold) and two 
sides white (average temperatures). If you roll the dice, you’re equally 
likely to get any result. With continued emissions of greenhouse gas, 
however, the authors predicted that by the early 21st century, four of 
the sides would be red.
 
“The climate dice are loaded now, just as we said back in the 1980s that 
they would be,” Hansen wrote to Time.com. “People should be able to 
recognize the change, especially the increasingly extreme events. Don’t 
be surprised if there are more examples this summer.”
 
http://ecocentric.blogs.time.com/2012/05/10/global-warming-an-exclusive-look-at-james-hansens-scary-new-math/?xid=rss-topstories&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+time%2Ftopstories+%28TIME%3A+Top+Stories%29
 
-- 
Sostieni Rete ECO
 
http://rete-eco.it/it/sostienici.html
 
 

 svicolare, Pippone.
 
Ma di che parli, fesso stralunato?  Vogliamo parlare di quando mi 
accusasti di essere amico di Gheddafi?
Ma abbi almeno la dignità di non nasconderti dietro pretesti libertari e 
umanitari, strafesso.


 umanitari, strafesso.
 
Canezza nel Cirque
 
 
-- 
“Until the wolf shall lay with lamb, we’d better be the wolves.”
–Ehud Barak

 Canezza nel Cirque
 
Devo ammettere che anche Persio ha i suoi momenti: la definizione di 
"strafesso" per amalric è ficcante.
 
PP
 


Purtroppo per Persio è uno specchietto.
 
 
-- 
Io non gufo l'Inter. Le spacco le corna.