Un riscaldamento poco globale: al Polo Sud il ghiaccio è a livelli record

Un riscaldamento poco globale: al Polo Sud il ghiaccio è a livelli record
La temperatura ai poli sta cambiando. Ma non come si crede comunemente. Anche perché la stampa "ufficiale" si guarda bene dal raccontare tutta la storia. Il New York Times, nelle sue pagine scientifiche, nei giorni scorsi ha pubblicato un tipico articolo sull'argomento (1). E' lo stesso quotidiano liberal che i corrispondenti dagli States di Repubblica e Corriere citano e copiano ogni volta che possono, premettendo che si tratta dell'"autorevole" New York Times.

L'articolo, nella pagina web, è lungo 40 righe. Il titolo, le prime 38 righe e la foto dal satellite sono dedicati a quanto sta succedendo in Artide. «Mentre il monitoraggio satellitare del ghiaccio polare è stato fatto solo a partire dal 1979, molti esperti che hanno studiato le registrazioni fatte dalla Russia e dall'Alaska, che risalgono a diverse decadi precedenti, sostengono che l'arretramento del ghiaccio quest'anno non ha probabilmente uguali durante il Ventesimo secolo, incluso il periodo caldo degli anni Trenta». Il che, per inciso, non vuole dire molto: nella cosiddetta estate medievale, tra il 1100 e il 1300, è assai probabile che il ghiaccio al Polo Nord fosse assai inferiore rispetto a quello attuale, visto che - ad esempio - fu proprio in quel periodo che la Groenlandia, complici le alte temperature, potè essere colonizzata. E allora i Suv non c'erano.

Fin qui, comunque, niente di nuovo. Soliti dati noti a tutti, interpretati apposta per puntellare le tesi più allarmiste. La notizia, quella vera, è nelle ultime 2 righe dell'articolo. Ben nascosta. Riguarda la faccia opposta della Terra, il Polo Sud. Dove sta avvenendo questo:
«Il ghiaccio attorno all'Antartide ultimamente ha visto una insolita espansione invernale, e questa settimana ha raggiunto livelli record».
Tutto vero. Il ghiaccio in Antartide è ai livelli massimi dal 1979. Qui, sul sito che l'Università dell'Illinois ha dedicato alla criosfera (2), il grafico (3) che misura il fenomeno, e qui, su Icecap, uno studio dei dati (in sintesi).

L'importante, come sempre, è che non si sappia in giro, e che venga divulgata col megafono solo la metà più allarmante delle notizie. Si sapesse in giro che il riscaldamento dei mari e lo scioglimento dei ghiacci sono tutt'altro che globali, e che anzi ci sono zone importanti del Paese in cui succede l'esatto opposto, gli ecotastrofisti ci rimarrebbero male, e sarebbero costretti a inventarsi una lunga serie di nuove ipotesi ad hoc per spiegare l'ennesima incongruenza dei loro modelli.

http://aconservativemind.blogspot.com/2007/09/un-riscaldamento-poco-globale-al-polo.html

(1)Scientists Report Severe Retreat of Arctic Ice
By ANDREW C. REVKIN
Published: September 21, 2007
FAIRBANKS, Alaska, Sept. 20 — The cap of floating sea ice on the Arctic Ocean, which retreats under summer’s warmth, this year shrank more than one million square miles — or six Californias — below the average minimum area reached in recent decades, scientists reported Thursday.

NASA, via Associated Press
A satellite image from last Saturday shows shrinking ice opening Canada’s Northwest Passage. Scientists said on Thursday that this year’s ice retreat was probably unmatched in the 20th century.
The minimum ice area for this year, 1.59 million square miles, appeared to be reached Sunday. The ice is now spreading again under the influence of the deep Arctic chill that settles in as the sun drops below the horizon at the North Pole for six months, starting Friday.
The findings were reported by the National Snow and Ice Data Center in Boulder, Colo., and posted online at www.nsidc.org.
While satellite tracking of polar sea ice has been done only since 1979, several ice experts who have studied Russian and Alaskan records going back many decades said the ice retreat this year was probably unmatched in the 20th century, including during a warm period in the 1930s. “I do not think that there was anything like we observe today” in the 1930s or 1940s, said Igor Polyakov, an ice expert at the University of Alaska, Fairbanks.
The ice retreat has been particularly striking this year. The Alaskan side of the Arctic Ocean has stretches of thousands of square miles of open water; the fabled Northwest Passage through the islands of northern Canada was free of ice for weeks; and the sea route between the Atlantic and Pacific Oceans north of Russia was nearly clear a week ago, with one small clot of ice around a group of Siberian islands.
Mark Serreze, a senior researcher at the snow and ice center, said it was increasingly clear that climate change from the buildup of greenhouse gases was playing a role in the Arctic warming, which is seen not only in the floating ice but also in melting terrestrial ice sheets, thawing tundra and warming seawater.
“We understand the physics behind what’s going on,” Dr. Serreze said. “You can always find some aspect of natural variability that can explain some things. But now it seems patterns that used to help you don’t help as much anymore, and the ones that hurt you hurt you more.”
“You can’t dismiss this as natural variability,” he said. “We’re starting to see the system respond to global warming.”
Still, he and other scientists acknowledged that both poles were extraordinarily complicated systems of ice, water and land, and that the mix of human and natural influences was not easy to clarify.
Sea ice around Antarctica has seen unusual winter expansions recently, and this week is near a record high.
http://www.nytimes.com/2007/09/21/science/21arctic.html?_r=2&oref=slogin&oref=slogin

(2) http://arctic.atmos.uiuc.edu/cryosphere/
A NEW RECORD FOR ANTARCTIC ICE EXTENT?

While the news focus has been on the lowest ice extent since satellite monitoring began in 1979 for the Arctic, the Southern Hemisphere (Antarctica) has quietly set a new record for most ice extent since 1979.

This can be seen on the graphic below from the University of Illinois site (Chapman) which is updated daily. The areal coverage is the highest in the satellite record (which began in 1979), just beating out 1995, 2001, 2006 and 2007.



This winter has been an especially harsh one in the Southern Hemisphere with cold and snow records set in Australia, South America and Africa. We will have recap on this hard winter shortly.
Since 1979, the trend has been up over the satellite record for the total Antarctic ice extent.

Though there was a flurry of media interest in 2002 when the Larsen Ice sheet broke up and the ice extent declined rapidly, it was very temporary.

That break up which caused a big temporary decline in the southern ice extent was not due to greenhouse warming but a big spike of solar activity, which caused significant warming of low and middle latitudes, a shrinking or the polar vortices in both hemispheres and actually even a temporary break-down for the first time ever of the southern vortex. This caused an increase in the winds and currents leading to the ice break-up. As the sun quieted, the ice quickly returned and has resumed its slow increase.

While the Antarctic Peninsula area has warmed in recent years and ice near it diminished during the Southern Hemisphere summer, the interior of Antarctica has been colder and ice elsewhere has been more extensive and longer lasting, which explains the increase in total extent. This dichotomy was shown clearly in this blog posted recently by the World Climate Report.

Note the average winter temperatures over the South Pole is about a degree colder than in 1957 and the coldest winter on record was 2004. This past winter was less cold with the equivalent of what we call high latitude blocking in the northern hemisphere forcing cold air to middle latitudes. This explains the cold extremes in Australia, South America and Africa.

The Southern and Northern Hemisphere have been out of sync, with little warming noted in the oceans or land in the Southern Hemisphere during the recent warming period in the Northern Hemisphere.

(3) http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.area.south.jpg