Ailleurs dans le monde...

[iceberg]

LA NINA !!

 

(Apr. 22, 2008) Boosted by the influence of a larger climate event in the Pacific, one of the strongest La Niñas in many years is slowly weakening but continues to blanket the Pacific Ocean near the equator, as shown by new sea-level height data collected by the U.S.-French Jason oceanographic satellite.

 

This La Niña, which has persisted for the past year, is indicated by the blue area in the center of the image along the equator. Blue indicates lower than normal sea level (cold water). The data were gathered in early April.

 

The image also shows that this La Niña is occurring within the context of a larger climate event, the early stages of a cool phase of the basin-wide Pacific Decadal Oscillation. The Pacific Decadal Oscillation is a long-term fluctuation of the Pacific Ocean that waxes and wanes between cool and warm phases approximately every five to 20 years. In the cool phase, higher than normal sea-surface heights caused by warm water form a horseshoe pattern that connects the north, west and southern Pacific, with cool water in the middle. During most of the 1980s and 1990s, the Pacific was locked in the oscillation's warm phase, during which these warm and cool regions are reversed.

A La Niña is essentially the opposite of an El Niño. During El Niño, trade winds weaken and warm water occupies the entire tropical Pacific Ocean. Heavy rains tied to the warm water move into the central Pacific Ocean and cause drought in Indonesia and Australia while altering the path of the atmospheric jet stream over North and South America. During La Niña, trade winds are stronger than normal. Cold water that usually sits along the coast of South America is pushed to the middle of the equatorial Pacific. A La Niña changes global weather patterns and is associated with less moisture in the air, and less rain along the coasts of North and South America.

 

This multi-year Pacific Decadal Oscillation 'cool' trend can intensify La Niña or diminish El Niño impacts around the Pacific basin," said Bill Patzert, an oceanographer and climatologist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The persistence of this large-scale pattern tells us there is much more than an isolated La Niña occurring in the Pacific Ocean."

 

Sea surface temperature satellite data from the National Oceanic and Atmospheric Administration also clearly show a cool Pacific Decadal Oscillation pattern, as seen at: http://www.cdc.noaa.gov/map/images/sst/sst.anom.gif . The shift in the Pacific Decadal Oscillation, with its widespread Pacific Ocean temperature changes, will have significant implications for global climate. It can affect Pacific and Atlantic hurricane activity, droughts and flooding around the Pacific basin, marine ecosystems and global land temperature patterns.

 

The comings and goings of El Niño, La Niña and the Pacific Decadal Oscillation are part of a longer, ongoing change in global climate, said Josh Willis, a JPL oceanographer and climate scientist. Sea level rise and global warming due to increases in greenhouse gases can be strongly affected by large natural climate phenomenon such as the Pacific Decadal Oscillation and the El Nino-Southern Oscillation. In fact, said Willis, these natural climate phenomena can sometimes hide global warming caused by human activities. Or they can have the opposite effect of accentuating it.

[Regg001]

Modération

 

Ice and any of you posting, don't forget to include the links and/or the source of the article (or any document, photo, etc.) . It is important to respect any rights associated with documents anyone cut/paste here.

 

Et pour tous, il est important de toujours mentionner la source des articles (ou images) que vous copiez/collez afin de respecter les droits d'auteur de ces éléments.

 

Merci.

[iceberg]

WASHINGTON - Human beings may have had a brush with extinction 70,000 years ago, an extensive genetic study suggests. The human population at that time was reduced to small isolated groups in Africa, apparently because of drought, according to an analysis released Thursday.

 

The report notes that a separate study by researchers at Stanford University estimated the number of early humans may have shrunk as low as 2,000 before numbers began to expand again in the early Stone Age.

 

"This study illustrates the extraordinary power of genetics to reveal insights into some of the key events in our species' history," Spencer Wells, National Geographic Society explorer in residence, said in a statement. "Tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA."

 

Wells is director of the Genographic Project, launched in 2005 to study anthropology using genetics. The report was published in the American Journal of Human Genetics.

 

Previous studies using mitochondrial DNA which is passed down through mothers have traced modern humans to a single "mitochondrial Eve," who lived in Africa about 200,000 years ago.

 

The migrations of humans out of Africa to populate the rest of the world appear to have begun about 60,000 years ago, but little has been known about humans between Eve and that dispersal.

 

The new study looks at the mitochondrial DNA of the Khoi and San people in South Africa which appear to have diverged from other people between 90,000 and 150,000 years ago.

 

The researchers led by Doron Behar of Rambam Medical Center in Haifa, Israel and Saharon Rosset of IBM T.J. Watson Research Center in Yorktown Heights, N.Y., and Tel Aviv University concluded that humans separated into small populations prior to the Stone Age, when they came back together and began to increase in numbers and spread to other areas.

 

Eastern Africa experienced a series of severe droughts between 135,000 and 90,000 years ago and the researchers said this climatological shift may have contributed to the population changes, dividing into small, isolated groups which developed independently.

 

Paleontologist Meave Leakey, a Genographic adviser, commented: "Who would have thought that as recently as 70,000 years ago, extremes of climate had reduced our population to such small numbers that we were on the very edge of extinction."

 

Today more than 6.6 billion people inhabit the globe, according to the U.S. Census Bureau.

 

The research was funded by the National Geographic Society, IBM, the Waitt Family Foundation, the Seaver Family Foundation, Family Tree DNA and Arizona Research Labs.

[iceberg]

WELLINGTON (AFP) - New Zealand's largest glacier is shrinking fast due to climate change and will eventually disappear altogether, scientists said Thursday.

 

The 23-kilometre (14.3 mile) long glacier in the South Island's Southern Alps is likely to shrink at a rate of between 500 and 820 metres a year, said Martin Brook, a physical geography lecturer at Massey University.

 

"In the last 10 years the glacier has receded a hell of a lot," Brook said on the university website.

 

"It's just too warm for a glacier to be sustained at such a low altitude -- 730 metres above sea level -- so it melts rapidly and it is going to disappear altogether."

 

The rapid melting has seen a lake seven kilometres long and two kilometres wide form at the base of the glacier. Thirty-five years ago, the lake did not exist.

 

"The last major survey was in the 1990s and since then the glacier has retreated back 180 metres a year on average," Brook said.

 

The lake at the foot of the glacier is speeding up the melting as more ice is submerged under the surface of the water.

 

A study last year by the National Institute of Water and Atmospheric Research found the volume of ice in the Southern Alps had shrunk almost 11 percent in the past 30 years.

 

More than 90 percent of this loss was due to the melting of the 12 largest glaciers in the mountain range due to rising temperatures, the university report said

Modifié le 25 avril 2008 par iceberg

[iceberg]

MARS WEATHER !!! BRR

 

25 APRIL 2008.

 

Today... High winds will lift some scattered dust storms, otherwise mostly sunny. Dust storms may continue throughout the week, causing eye and skin irritation. South wind becoming East to 30 km/hr.

 

Tonight...isolated evening dust then clearing. Lows in the upper -70s to lower -60s. Northwest wind 30 to 40 km/hr diminishing.

 

Saturday...mostly sunny. Highs in the mid -40s. Northwest wind to 40 km/hr.

 

 

 

Extended forecast...

 

Sunday through Thursday...dry with a warming trend. Lows in the -60s. Highs in the lower to mid -30s.

 

forecasts are provided by the Interplanetary Weather Service

 

 

jaime cette prévisions de mars.....

 

http://astro.sci.uop.edu/~harlow/weather/mars.html

Modifié le 25 avril 2008 par iceberg

[iceberg]

Glaciers Reveal Martian Climate Has Been Recently Active

 

Brown University researchers have found compelling evidence of thick, recurring glaciers on Mars, a discovery that suggests that the Red Planet's climate was much more dynamic than previously believed - and could change again. Results are published on the cover of Geology magazine.

 

The prevailing thinking is that Mars is a planet whose active climate has been confined to the distant past. About 3.5 billion years ago, the Red Planet had extensive flowing water and then fell quiet - deadly quiet. It didn't seem the climate had changed much since.

 

Now, in a research article that graces the May cover of Geology, scientists at Brown University think Mars' climate has been much more dynamic than previously believed. After examining stunning high-resolution images taken last year by the Mars Reconnaissance Orbiter, the researchers have documented for the first time that ice packs at least 1 kilometer (0.6 miles) thick and perhaps 2.5 kilometers (1.6 miles) thick existed along Mars' mid-latitude belt as recently as 100 million years ago. In addition, the team believes other images tell them that glaciers flowed in localized areas in the last 10 to 100 million years - akin to the day before yesterday in Mars' geological timeline.

 

This evidence of recent activity means the Martian climate may change again and could bolster speculation about whether the Red Planet can, or did, support life.

 

"We've gone from seeing Mars as a dead planet for three-plus billion years to one that has been alive in recent times," said Jay Dickson, a research analyst in the Department of Geological Sciences at Brown and lead author of the Geology paper. "[The finding] has changed our perspective from a planet that has been dry and dead to one that is icy and active."

 

In fact, Dickson and his co-authors, James Head, a planetary geologist and the Louis and Elizabeth Scherck Distinguished Professor at Brown, and David Marchant, an associate professor in the Department of Earth Sciences at Boston University, believe the images show that Mars has gone through multiple Ice Ages - episodes in its recent past in which the planet's mid-latitudes were covered by glaciers that disappeared with changes in the Red Planet's obliquity, which changes the climate by altering the amount of sunlight falling on different areas.

 

Dickson and the other researchers focused on an area called Protonilus Mensae-Coloe Fossae. The region is located in Mars's mid-latitude and is marked by splotches of mesas, massifs and steep-walled valleys that separate the lowlands in the north from the highlands in the south.

 

The team looked in particular at a box canyon set in a low-lying plain. Images show the canyon has moraines - deposits of rocks that mark the limits of a glacier's advance or the path of its retreat. The rock deposit lines appear to show a glacier that flowed up the box canyon, which "physically cannot happen," Dickson said.

 

Instead, the team deduced the ice in the surrounding plain grew higher than the canyon's walls and then flowed downward onto the top of the canyon, which had become the lowest point on the ice-laden terrain. The team calculated the ice pack must have been one kilometer thick by past measurements of height between the plain and the lip of the canyon. Based on the ice flow patterns, the ice pack could have reached 2.5 kilometers at peak thickness during a period known as the late Amazonian, the authors said.

 

The finding could have implications for the life-on-Mars argument by strengthening the case for liquid water. Ice can melt two ways: by temperature or by pressure. As currently understood, the Martian climate is dominated by sublimation, the process by which solid substances are transformed directly to vapor. But ice packs can exert such strong pressure at the base to produce liquid water, which makes the thickness of past glaciers on its surface so intriguing.

 

Dickson also looked at a lobe across the valley from the box canyon site. There, he saw a clear, semi-circular moraine that had spilled from an ancient tributary on to the surrounding plain. The lobe is superimposed on a past ice deposit and appears to be evidence of more recent glaciation. Although geologists can't date either event, the landscape appears to show at least two periods in which glaciation occurred, bolstering their theory that the Martian climate has undergone past Ice Ages.

 

Read an online version of the paper.

 

NASA and the National Science Foundation funded the work.

[Regg001]

Encore de l'action du côté USA avec 14 rapports de tornade avant hier et 10 pour hier. Ce matin l'action est surtout au nord mais va redémarrer jusqu'au Texas dès que le soleil va se pointer. C'est tout un système avec d'un côté de la neige et une météo hivernale et de l'autre des températures d'été très chaudes. La recette pour faire sauter la marmite.

 

Aussi une superbe photo d'un immense Water Spout (tornade au dessus de l'eau) qui a eu lieu au Delaware le 20 avril . J'en avais jamais vu d'aussi gros que ça.

 

Source Accuweather - Photo Neil B.

http://photo.accuweather.com/photogallery/500/a987793a5.jpg

Modifié le 25 avril 2008 par Regg001

[Regg001]

Selon plusieurs discussions il ne s'agirait pas d'un water spout mais d'un phénomène très rare d'un roll cloud qui se serait rendu jusqu'au sol (!)

 

Personnellement j'ai jamais entendu ou vu ça, mais la nature nous épates constamment. Toujours est-il que , c'est une tab-ar-nouche de belle photo quand même.

 

Blog Jesse Farrel - Accuweather

After speaking with several leading storm chasers, I no longer hold out much hope that this was a tornado or waterspout, though they couldn't specifically explain what it was either. I have spoken to Neil, who took the photo below (also featured on the WGMD site). Neil is a boat captain with many years under his belt, and this formation was new to him. He has seen many waterspouts but none like this. He says the object formed slowly from the top down and appeared to "hit" the water or suddenly start sucking it up. For this reason I think it may have been the thunderstorm updraft or downdraft. I will explain more on this week's Friday Featured Fotos. Neil's photo, which is the best view of the event, is below.

Modifié le 25 avril 2008 par Regg001

[iceberg]

DELAY IN GLOBAL WARMING !!

 

A new study by German researchers indicates that there will be a respite from global warming through the year 2015 before worldwide temperatures resume the upward trend predicted by most of the worlds climate experts.

Climatologists from the Max Planck Institute for Meteorology in Hamburg and the Leibniz Institute of Marine Sciences in Kiel say that a natural variation in ocean currents will cancel out the effects of manmade greenhouse gases.

 

They made that prediction based on what they believe is an impending change in the Gulf Stream the ocean conveyor belt that carries warm surface waters from the tropical Atlantic to the northern Atlantic before returning cooler water southward in the oceans deep.

 

Northern Europe and North America should benefit the most from the delayed warming.

 

Just to make things clear, we are not stating that anthropogenic (man-made) climate change wont be as bad as previously thought, said professor Mojib Latif.

 

What we are saying is that on top of the warming trend, there is a long-periodic oscillation that will probably lead to a lower temperature increase than we would expect from the current trend during the next years.

 

FROM API

Modifié le 4 mai 2008 par iceberg

[colapster89]

NASA Says Climate Shifting

to Cooler Temperatures

(This is a major admission by NASA)

By Phil Brennan

_____________________________ 

.

1 May 08 The allegedly warming earth is in for about 30 years of cooling according to NASA, one of the leading global warming theory advocates.

 

NASA has confirmed that a developing natural climate pattern will likely result in much colder temperatures, according to Marc Shepherd, writing in the April 30 American Thinker. He adds that NASA was also quick to point out that such natural phenomena should not confuse the issue of manmade greenhouse gas induced global warming which apparently will be going on behind the scenes while our teeth are chattering from a decade and a half long cold spell.

 

"A cool-water anomaly known as La Niña occupied the tropical Pacific Ocean throughout 2007 and early 2008. In April 2008, scientists at NASA's Jet Propulsion Laboratory announced that while the La Niña was weakening, the Pacific decadal Oscillation a larger-scale, Slower-cycling ocean pattern had shifted to its cool phase."

 

Notes Shepherd "This shift in the PDO, which could last for 20 or 30 years, can have significant implications for global climate."

 

Warns meteorologist Anthony Watts: "Look out California agriculture. The wine industry, fruits and nut growers will be hit with a shorter growing season and more threats of frost, among other things."

 

Watts warns that California's agriculture, which experienced "unprecedented growth" during the past warm phase, may now be in serious trouble as things cool down:

 

Notes Shepherd "Recently lower global temps, likely caused by the late start of Solar Cycle 24, already have some greenhouse gassers nervous - particularly amid speculation of a possible impending 'little ice age.'

 

"But surely," he says, "a 30 year protracted naturally-explainable cooling period concurrent with rising atmospheric CO2 levels would forever cool the public's receptiveness to global warming alarmism. No problem our ever panicking friends at NASA have that angle covered, too."

 

Says NASA: "Natural, large-scale climate patterns like the PDO and El Niño-La Niña are superimposed on global warming caused by increasing concentrations of greenhouse gases and landscape changes like deforestation. According to Josh Willis, JPL oceanographer and climate scientist, These natural climate phenomena can sometimes hide global warming caused by human activities. Or they can have the opposite effect of accentuating it.'"

 

In other words, CO2 is secretly warming the planet. Or not.

 

Considering how strongly NASAs James Hansen has been pushing

global warming,, this is a major admission. I wonder how long it will

take for NASA to admit that we could even possibly, maybe,

conceivably, be headed into an ice age

 

See entire article by Phillip Brennan:

http://www.newsmax.com/newsfront/NASA_Clim...5/01/92541.html

[colapster89]

je vais vous sortir un article que j'avais lu sur le PDO (Pacific decadal oscillation)

 

http://earthobservatory.nasa.gov/Newsroom/...p3?img_id=18012

 

** Modération: Merci d'utiliser la fonction d'édition des messages ***

Modifié le 4 mai 2008 par cpweather

[dann17]

Intéressant ! Merci Colapster...

 

Mais, me semble que ce sont des perspectives un peu hâtives et optimistes... même s'ils précisent que cela ne pourrait avoir pour effet que de cacher voire changer les effets dûs à la hausse du CO2...

[colapster89]

l'homme est-il vraiment responsable du réchauffement ou est-ce un cycle?

Modifié le 4 mai 2008 par colapster89

[beachcp31]

Les preuves sont quand même indéniables (voir dernier rapport du GIEC) que l'homme modifie le climat sensiblement avec son activité, et que l'apport en gaz à effet de serre contribue au réchauffement climatique, en interaction avec les cycles naturels.

Sinon ce serait dénigrer le travail de tous les scientifiques signataires du document du GIEC. Faudra avoir des arguments solides :

http://www.ipcc.ch/ipccreports/assessments-reports.htm

 

Certains affirment que le réchauffement avait fait une pause car le mois de Janvier 2008 était plus froid. Ce qu'il ne faut pas oublier, c'est que cette affirmation n'était basée que sur la comparaison avec Janvier 2007!!! Cela ne montre en effet que la variabilité naturelle du climat d'une année à l'autre :

http://www.metoffice.gov.uk/research/hadle...ariability.html

 

De même, un document qui donne des informations sur les questions qu'on se pose le plus :

http://www.metoffice.gov.uk/corporate/pressoffice/myths/

 

Et au sujet du site web iceagenow.com, c'est un site qui manipule l'information et qui contient des faussetés :

http://mc-computing.com/qs/Global_Warming/Junk_Science.html

http://www.mindfully.org/Air/2005/Bellamy-...ence10may05.htm

 

Christian Pagé

[dann17]

Je suis malheureusement entièrement d'accord avec Christian ! Je dis "malheureusement", car comme bcp de monde, j'aimerais que ce dérèglement progressif mais inévitable du climat à cause des activités humaines ne soit qu'une illusion.

Seulement voilà, en effet, il est un peu facile de contrer les arguments d'au moins 95% de la communauté scientifique concernée par ce sujet en avançant des théories sorties d'on ne sait où. Je ne dis pas ça pour toi Collapster. Mais pour ceux qui pondent ces théories sorties du chapeau comme par magie !

 

Il y a de toutes façons des certitudes concernant l'évolution déjà produite : le réchauffement a déjà commencé, et son évolution n'est pas linéaire car il y a une inflexion vers le haut des températures. Et ceci est analysé sur plusieurs dizaines d'années, par seulement en comparant 2 années de suite, ce qui est tout sauf scientifique...

[iceberg]

Interesting Changes in the Pacific

Wednesday, May 07, 2008

There has been some talk in the media about this change going on in the Pacific Ocean and how it will slow global warming. That may be a bit of a stretch, but the changes could certainly have an impact on the long-term weather pattern in western Canada, especially British Columbia.

 

What am I talking about? I am talking about the Pacific Decadal Oscillation (PDO). The PDO is a long-term pattern similar to the much shorter term El Nino/La Nina (ENSO phases), in which there is a fairly distinct pattern of sea surface heights in the North Pacific Ocean over a 5 to as much as 30 year period. There are still a lot of unknowns about the PDO, especially since the phrase was only coined just 12 years ago. According to one paper (Gershunov and Barnett 1998), ENSO teleconnections with North American climate show a strong dependence on the phase of the PDO. If the PDO is in the cool phase for a long period of time then there will likely be a decrease in El Nino events, while La Nina would be more common.

 

Anyway, according to NASA'S Jet Propulsion Lab, the PDO appears to have shifted into the "cool" phase. Most of past two decades have seen the PDO in the "warm" phase. This link shows the classic warm and cool phase sea surface temperature anomaly patterns over the Pacific. It also shows a graph of the PDO index since 1900.

 

Here is the latest sea-surface anomaly chart for the globe........

 

 

 

Note: the large area of above-normal sea surface water temperatures (higher heights) extending from southeastern Asia to north of Hawaii and the distinct area of cooler-than-normal water (lower than normal sea-surface heights) extending from the Gulf of Alaska to the West Coast of the U.S. and down into the central equatorial Pacific. Now if you look back at the link I posted, you can see that the cool phase example on the right matches fairly well with what is going on.

 

Obviously, a couple of questions that come to mind are.....

 

What will the impact be for Canada? I do not personally have a lot of experience with the PDO, but from what I have read it seems to suggest that the cool phase of the PDO would create an above-average northwestern North American snow pack in the spring, which we have seen. With that, you also get a greater spring time flood risk. Precipitation during the cold months from October to March across northwestern North America is above-average with below-normal temperatures. I assume northwestern North America includes the Alaska panhandle and British Columbia down to the pacific Northwest of the U.S.

 

Not a lot is known about the influence farther to the east across central and eastern Canada. But, this past winter could be one example, especially being a La Nina winter.

 

The second question is how long would PDO phase last. No one really knows, as you can see by the chart I linked to earlier there was a short "cool" phase around 1999-2003, but a much longer one from the late 40s to the mid 70s.

 

No doubt this is interesting stuff. Brett Anderson ACCU WEATHER.

Modifié le 7 mai 2008 par iceberg

[iceberg]

South Pole Weekly Climate Summary for 26 Apr - 02 May, 2008

 

Weekly Climate Summary for 26 April 2008 through 02 May 2008 UTC

South Pole Station, Antarctica

 

Temperature:

Average temp... -52.8°C / -63.0°F

Maximum temp... -33.5°C / -28.3°F on day 26

Minimum temp... -61.6°C / -78.9°F on day 29

 

Wind:

Average wind speed.......... 8.2 mph or 7.1 knots

Prevailing wind direction... Grid East

Maximum wind speed.......... 17 mph or 15 knots on day 28

Maximum wind direction...... Grid Northeast

Average vectored wind....... 047 degrees at 6.5 knots

 

Station Pressure:

Average pressure... 690.4 mb

Highest pressure... 700.6 mb on day 26

Lowest pressure.... 684.4 mb on day 1

 

Physio-altitude:

Average physio-alt = 10238 ft/ 3121 m

Highest physio-alt = 10463 ft/ 3189 m on day 1

Lowest physio-alt = 9861 ft/ 3006 m on day 26

 

Sky Cover:

Average cloud cover (8ths)... 3

Days clear................... 5

Days partly cloudy........... 1

Days cloudy.................. 1

 

Sunshine:

Sunrise on 20 September 2008

Average hours per day... 0.0

Percent of possible..... 0

 

Visibility:

0 days with visibility of 1/4 mile or less.

 

Balloon flight data:

Number of soundings for the week..... 7

Average height of soundings.......... 59.2 mb, or 18881 meters

Highest sounding..................... 28.1 mb, or 22837 meters

on day 28/00Z flight

 

0 soundings were missed.

 

**RECORDS**

[dann17]

Interesting Changes in the Pacific

Wednesday, May 07, 2008

There has been some talk in the media about this change going on in the Pacific Ocean and how it will slow global warming. That may be a bit of a stretch, but the changes could certainly have an impact on the long-term weather pattern in western Canada, especially British Columbia.

 

What am I talking about? I am talking about the Pacific Decadal Oscillation (PDO). The PDO is a long-term pattern similar to the much shorter term El Nino/La Nina (ENSO phases), in which there is a fairly distinct pattern of sea surface heights in the North Pacific Ocean over a 5 to as much as 30 year period. There are still a lot of unknowns about the PDO, especially since the phrase was only coined just 12 years ago. According to one paper (Gershunov and Barnett 1998), ENSO teleconnections with North American climate show a strong dependence on the phase of the PDO. If the PDO is in the cool phase for a long period of time then there will likely be a decrease in El Nino events, while La Nina would be more common.

 

Anyway, according to NASA'S Jet Propulsion Lab, the PDO appears to have shifted into the "cool" phase. Most of past two decades have seen the PDO in the "warm" phase. This link shows the classic warm and cool phase sea surface temperature anomaly patterns over the Pacific. It also shows a graph of the PDO index since 1900.

 

Here is the latest sea-surface anomaly chart for the globe........

 

 

 

Note: the large area of above-normal sea surface water temperatures (higher heights) extending from southeastern Asia to north of Hawaii and the distinct area of cooler-than-normal water (lower than normal sea-surface heights) extending from the Gulf of Alaska to the West Coast of the U.S. and down into the central equatorial Pacific. Now if you look back at the link I posted, you can see that the cool phase example on the right matches fairly well with what is going on.

 

Obviously, a couple of questions that come to mind are.....

 

What will the impact be for Canada? I do not personally have a lot of experience with the PDO, but from what I have read it seems to suggest that the cool phase of the PDO would create an above-average northwestern North American snow pack in the spring, which we have seen. With that, you also get a greater spring time flood risk. Precipitation during the cold months from October to March across northwestern North America is above-average with below-normal temperatures. I assume northwestern North America includes the Alaska panhandle and British Columbia down to the pacific Northwest of the U.S.

 

Not a lot is known about the influence farther to the east across central and eastern Canada. But, this past winter could be one example, especially being a La Nina winter.

 

The second question is how long would PDO phase last. No one really knows, as you can see by the chart I linked to earlier there was a short "cool" phase around 1999-2003, but a much longer one from the late 40s to the mid 70s.

 

No doubt this is interesting stuff. Brett Anderson ACCU WEATHER.

Very interesting Iceberg, thanks a lot !

Unfortunately, we don't have the see surface temperature of the 40's to 70's... in order to compare with today's temperatures.

But nevertheless, this explaination given by Brett could be not far away from the truth ! And it's true that, when you look to the average temperatures in Montréal from 1880 till today, you see some periodic oscilliations. And those periods seem to be 20 or 30 years long...

 

Très intéressant Icebreg, merci !

Mais ce qui est dommage, c'est que nous ne disposons pas des données de températures de surface de l'océan de 1940 à 1970, afin de les comparer avec celles d'aujourd'hui.

Mais néanmoins, l'explication donnée par Brett est peut-être proche de la réalité. Et, en effet, losque vous regardez l'évolution des températures moyennes de Montréal (par exemple) de 1880 à aujourd'hui, on constate des oscilliations periodiques, avec une période de 20 à 30ans...

[dann17]

Juste une petite parenthèse : cet après midi, il faisait 13°C sur l'Ile d'Ouessant à la limite entre la Manche (English Channel) et l'océan Atlantique (mer d'Iroise), mais au même moment il faisait près de 27°C à Dunkerke dans l'extrême nord de la France, là aussi au bord de la mer (mer du Nord)...! Méchante différence, et surtout impressionnant 27°C pour Dunkerke en début mai !

[iceberg]

Climate Models Overheat Antarctica, New Study Finds

(May 8, 2008) Computer analyses of global climate have consistently overstated warming in Antarctica, concludes new research by scientists at the National Center for Atmospheric Research (NCAR) and Ohio State University. The study can help scientists improve computer models and determine if Earth's southernmost continent will warm significantly this century, a major research question because of Antarctica's potential impact on global sea-level rise.

 

 

"We can now compare computer simulations with observations of actual climate trends in Antarctica," says NCAR scientist Andrew Monaghan, the lead author of the study. "This is showing us that, over the past century, most of Antarctica has not undergone the fairly dramatic warming that has affected the rest of the globe. The challenges of studying climate in this remote environment make it difficult to say what the future holds for Antarctica's climate."

 

The study marks the first time that scientists have been able to compare records of the past 50 to 100 years of Antarctic climate with simulations run on computer models. Researchers have used atmospheric observations to confirm that computer models are accurately simulating climate for the other six continents. The models, which are mathematical representations of Earth's climate system, are a primary method for scientists to project future climate.

 

Antarctica's climate is of worldwide interest, in part because of the enormous water locked up in its ice sheets. If those vast ice sheets were to begin to melt, sea level could rise across the globe and inundate low-lying coastal areas. Yet, whereas climate models accurately simulate the last century of warming for the rest of the world, they have unique challenges simulating Antarctic climate because of limited information about the continent's harsh weather patterns.

 

The study was published on April 5 in Geophysical Research Letters. It was funded by the National Science Foundation, NCAR's primary sponsor, and the Department of Energy.

 

The authors compared recently constructed temperature data sets from Antarctica, based on data from ice cores and ground weather stations, to 20th century simulations from computer models used by scientists to simulate global climate. While the observed Antarctic temperatures rose by about 0.4 degrees Fahrenheit (0.2 degrees Celsius) over the past century, the climate models simulated increases in Antarctic temperatures during the same period of 1.4 degrees F (0.75 degrees C).

 

The error appeared to be caused by models overestimating the amount of water vapor in the Antarctic atmosphere, the new study concludes. The reason may have to do with the cold Antarctic atmosphere handling moisture differently than the atmosphere over warmer regions.

 

A chilling ozone hole

 

Part of the reason that Antarctica has barely warmed has to do with the ozone hole over the continent. The lack of ozone is chilling the middle and upper atmosphere, altering wind patterns in a way that keeps comparatively warm air from reaching the surface. Unlike the rest of the continent, the Antarctic Peninsula has warmed by several degrees, in part because the winds there are drawing in warmer air from the north. The models generally capture these wind changes, although sometimes incompletely.

 

The study delivered a mixed verdict on Antarctica's potential impact on sea-level rise. The Intergovernmental Panel on Climate Change, which operates under the auspices of the United Nations, has estimated that sea-level rise could amount to 7 to 23 inches (18-59 centimeters) this century, in part because of melting glaciers worldwide. The Geophysical Research Letters paper suggests that warming in Antarctica over the next century could offset that by about 2 inches if the continent warms by 5.4 degrees F (3 degrees C), as computer models have indicated. The reason is that the warmer air over Antarctica would hold more moisture and generate more snowfall, thereby locking up additional water in the continent's ice sheets.

 

But the authors caution that model projections of future Antarctic climate may be unreliable.

 

"The research clearly shows that you can actually slow down sea-level rise when you increase temperatures over Antarctica because snowfall increases, but warmer temperatures also have the potential to speed up sea-level rise due to enhanced melting along the edges of Antarctica," says Monaghan, who did some of his research at Ohio State University before coming to NCAR. "Over the next century, whether the ice sheet grows from increased snowfall or shrinks due to more melt will depend on how much temperatures increase in Antarctica, and potentially on erosion at the ice sheet edge by the warmer ocean and rising sea level."

 

"The current generation of climate models has improved over previous generations, but still leaves Antarctic surface temperature projections for the 21st century with a high degree of uncertainty," adds co-author and NCAR scientist David Schneider. "On a positive note, this study points out that water vapor appears to be the key cause of the problematic Antarctic temperature trends in the models, which will guide scientists as they work to improve the climate simulations."

 

The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under primary sponsorship by the National Science Foundation (NSF). Opinions, findings, conclusions, or recommendations expressed in this document are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, NASA, or other funding agencies.

UPI

[dann17]

Distribution des températures très inhabituelles en Europe en ce moment même :

 

figurez-vous que l'endroit le plus chaud actuellement en Europe se trouve être en Belgique et aux Pays-Bas, autrement dit des pays du nord de l'Europe, et au bord de la mer du Nord en plus ! Il fait donc jusqu'à 28°C en Belgique (et 27°C à Antwerpen, à Amsterdam, pour ne citer que ces villes) !!!

Il fait aussi 26°C en Angleterre à Londres et à Norwich (à 300km au nord de Londres !!)...

Et encore plus surprenant : 26°C à Nortodden et Lillehammer (à 200km au nord de Oslo, Norvège !!!!!) et tout de même 25°C à Stockholm (Suède)...

 

En contrepartie, il ne fait cet après midi que 9°C petits degrés à Madrid (centre de l'Espagne), et seulement 13°C à Barcelone (sur le Costa Brava méditerrannéenne espagnole) !!

[jules76]

Bonsoir a tous,

Je suis Normand (France) et ma station météo ma indiquer 36°C aujourd'hui, d'habitude on as ces températures en Avril et le mois de Mai est plus calme, il y a 3 semaine de ça on as reçu 40Cm de neige et aujourd'hui on se croirai en été .

 

Bien sur c'est exceptionnel pour la saison, et pour revenir a l'hiver ça fait deux ans que on as pas eu d'hiver correcte .

 

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Modifié le 13 mai 2008 par cpweather

[Tyrone]

***MODÉRATION***

 

Réponse effacé pour propos non-appropriés

Modifié le 12 mai 2008 par stefano

[beachcp31]

Jules,

 

De toute évidence, votre station météorologique n'est pas aux normes car il n'a pas fait plus de 25 C en Normandie. De plus, il n'y a pas eu 40 cm de neige non plus de tout l'hiver.

[Tyrone]

Jules,

 

De toute évidence, votre station météorologique n'est pas aux normes car il n'a pas fait plus de 25 C en Normandie. De plus, il n'y a pas eu 40 cm de neige non plus de tout l'hiver.

Si on me laisse m'exprimer... Jules est un membre du forum IC de France, ****MODÉRATION******

 

 

Bref...

Modifié le 13 mai 2008 par stefano