23/12/10

THAT SNOW OUTSIDE IS WHAT GLOBAL WARMING LOOKS LIKE






Unusually cold winters may make you think scientists have got it all wrong. But the data reveal a chilling truth
guardian.co.uk, Monday 20 December 2010 20.30 GMT


A zebra stands in its snow-covered pen at Whipsnade Zoo, north of London on December 20, 2010 Photograph: Max Nash/AFP/Getty Images 


There were two silent calls, followed by a message left on my voicemail. She had a soft, gentle voice and a mid-Wales accent. "You are a liar, Mr Monbiot. You and James Hansen and all your lying colleagues. I'm going to make you pay back the money my son gave to your causes. It's minus 18C and my pipes have frozen. You liar. Is this your global warming?" She's not going to like the answer, and nor are you. It may be yes.
There is now strong evidence to suggest that the unusually cold winters of the last two years in the UK are the result of heating elsewhere. With the help of the severe weather analyst John Mason and the Climate Science Rapid Response Team, I've been through as much of the scientific literature as I can lay hands on (see my website for the references). Here's what seems to be happening.
The global temperature maps published by Nasa present a striking picture. Last month's shows a deep blue splodge over Iceland, Spitsbergen, Scandanavia and the UK, and another over the western US and eastern Pacific. Temperatures in these regions were between 0.5C and 4C colder than the November average from 1951 and 1980. But on either side of these cool blue pools are raging fires of orange, red and maroon: the temperatures in western Greenland, northern Canada and Siberia were between 2C and 10C higher than usual. Nasa's Arctic oscillations map for 3-10 December shows that parts of Baffin Island and central Greenland were 15C warmer than the average for 2002-9. There was a similar pattern last winter. These anomalies appear to be connected.
The weather we get in UK winters, for example, is strongly linked to the contrasting pressure between the Icelandic low and the Azores high. When there's a big pressure difference the winds come in from the south-west, bringing mild damp weather from the Atlantic. When there's a smaller gradient, air is often able to flow down from the Arctic. High pressure in the icy north last winter, according to the US National Oceanic and Atmospheric Administration, blocked the usual pattern and "allowed cold air from the Arctic to penetrate all the way into Europe, eastern China, and Washington DC". Nasa reports that the same thing is happening this winter.
Sea ice in the Arctic has two main effects on the weather. Because it's white, it bounces back heat from the sun, preventing it from entering the sea. It also creates a barrier between the water and the atmosphere, reducing the amount of heat that escapes from the sea into the air. In the autumns of 2009 and 2010 the coverage of Arctic sea ice was much lower than the long-term average: the second smallest, last month, of any recorded November. The open sea, being darker, absorbed more heat from the sun in the warmer, light months. As it remained clear for longer than usual it also bled more heat into the Arctic atmosphere. This caused higher air pressures, reducing the gradient between the Iceland low and the Azores high.
So why wasn't this predicted by climate scientists? Actually it was, and we missed it. Obsessed by possible changes to ocean circulation (the Gulf Stream grinding to a halt), we overlooked the effects on atmospheric circulation. A link between summer sea ice in the Arctic and winter temperatures in the northern hemisphere was first proposed in 1914. Close mapping of the relationship dates back to 1990, and has been strengthened by detailed modelling since 2006.
Will this become the pattern? It's not yet clear. Vladimir Petoukhov of the Potsdam Institute says that the effects of shrinking sea ice "could triple the probability of cold winter extremes in Europe and northern Asia". James Hansen of Nasa counters that seven of the last 10 European winters were warmer than average. There are plenty of other variables: we can't predict the depth of British winters solely by the extent of sea ice.
I can already hear the howls of execration: now you're claiming that this cooling is the result of warming! Well, yes, it could be. A global warming trend doesn't mean that every region becomes warmer every month. That's what averages are for: they put local events in context. The denial of man-made climate change mutated first into a denial of science in general and then into a denial of basic arithmetic. If it's snowing in Britain, a thousand websites and quite a few newspapers tell us, the planet can't be warming.
According to Nasa's datasets, the world has just experienced the warmest January to November period since the global record began, 131 years ago; 2010 looks likely to be either the hottest or the equal hottest year. This November was the warmest on record.
Sod all that, my correspondents insist: just look out of the window. No explanation of the numbers, no description of the North Atlantic oscillation or the Arctic dipole, no reminder of current temperatures in other parts of the world, can compete with the observation that there's a foot of snow outside. We are simple, earthy creatures, governed by our senses. What we see and taste and feel overrides analysis. The cold has reason in a deathly grip.

18/12/10

COLD WINTER IN A WORLD OF WARMING?

REAL CLIMATE

rasmus @ 14 December 2010

Last June, during the International Polar Year conference, James Overland suggested that there are more cold and snowy winters to come. He argued that the exceptionally cold snowy 2009-2010 winter in Europe had a connection with the loss of sea-ice in the Arctic. The cold winters were associated with a persistent ‘blocking event’, bringing in cold air over Europe from the north and the east.

Last year’s cold winter over northern Europe was also associated with an extreme situation associated with the
North Atlantic Oscillation (NAO), with the second lowest value for the NAO-index on record (see figure below).
I admit, last winter felt quite cold, but still it wasn’t so cold when put into longer historical perspective. This is because I remember the most recent winters more vividly than those of my childhood – which would be considered to be really frosty by today’s standards. But such recollections can be very subjective, and more objective measurements show that the winters in Europe have in general become warmer in the long run, as explained in the German blog called ‘Wissenlogs’. If there were no trend, then such a low NAO-index as last year’s would normally be associated with even colder conditions over Europe than those observed during the previous winter. 

  
NAO-index for December-March, which the winter 2009-2010 being associated with the second lowest value on record.


In a more recent press-release, Vladimir Petoukhov and Vladimir Semenov, argue that Global Warming could cool down winter temperatures over Europe, and a reduced sea-ice extent could increase the chance of getting cold winters. Also they propose that cold winters are associated with the atmospheric circulation (see schematic below), and their press-release was based on a paper in Journal of Geophysical Research (JGR), which may seem to have a serendipitous timing with the cold spell over Europe during the last weeks. However, the original manuscript was submitted in november 2009 (before the statement made by James Overland) and accepted in May 2010. One could regard the paper more as a ‘prediction’ rather than an ‘explanation’.
Scematic illustration of proposed effect. Courtesy of PIK.
Although Petoukhov and Semenov’s findings sound plausible, I don’t think they are as straight-foward as they initially seem in terms of their implications for this winter either. For one thing, it is impossible to prove that one single event is due to a change in the long-term, as we pointed out for the case of hurricanes (The 2010 hurricane season this year, by the way, was quite active).
I think it is important too keep in mind that the Petoukhov and Semenov study is based on a global atmosphere model that simulated a non-linear response to the loss of sea-ice in the Barents-Kara seas: intially warm winters, followed by cold, and then warm winters, as the sea-ice extent is gradually reduced. 

NCEP/NCAR reanalysis: surface temperature anomaly wrt 1961-1990.

 
One interesting question is how the Barents-Kara sea-ice affects the winter temperatures over the northern continents. By removing the sea-ice, the atmosphere above feels a stronger heating from the ocean, resulting in anomalous warm conditions over the Barent-Kara seas. The local warming gives rise to altered temperature profiles (temperature gradients) along the vertical and horizontal dimensions.
Changes in the temperature profiles, in turn, affect the circulation, triggering a development of a local blocking structure when the sea-ice extent is reduced from 80% to 40%. But Petoukhov and Semenov also found that it brings a different response when the sea-ice is reduced from 100% to 80% or from 40% to1%, and hence a non-linear response. The most intriguing side to this study was the changing character of the atmospheric response to the sea-ice reduction: from a local cyclonic to anti-cyclonic, and back to cyclonic pattern again. These cyclonic and anti-cyclonic patterns bear some resemblance to the positive and negative NAO phases.

They also show a different response in surface air temperature (SAT) during December, January, and February. From their Figure 2, it is not immidiately obvious from that figure that a sea-ice reduction leads to lower SAT during January. This is, however, very much in line with similar analysis that I have carried out with colleagues and struggeled to find a consistent response (albeit we looked at the summer season).
But Petoukhov and Semenov provide theoretical support for their observations, and argue that the non-linear response can be explained in terms of ‘convectional-frictional’ and ‘baro-clinic-frictional’ mechanisms. The former includes warming over the areas where sea-ice disappear, and changes in the vertical temperatur gradients, stability, and hence friction, while the latter involves a change in the surface friction force associated with temperature changes over distances.
I think that the scientific community will need some time to confirm this link, and there are some
important caveats: For one thing, the spatial model resolution (the size between the boxes in the grid mesh, through which the models represent the world) has an influence on their ability to represent blocking frequency.
Hazeleger et al. Has observed that “… different horizontal resolutions … confirm the resolution-dependence found in NWP [Numerical Weather Prediction]”. The atmospheric model used by Petoukhov and Semenov has a fairly coarse spatial resolution (2.8 degrees x2.8 degrees), and it is legitimate to question whether it can reproduce the
frequencies of blocking events realistically, and whether that has a bearing for the conclusions.
But also the fact that the sea-surface temperatures (SSTs) were fixed in these experiments may affect the conclusions. Balmaseda et al. found that the atmospheric response to changes in sea-ice conditions may depend on the background SSTs, at least for the summer months. They also compared results from a coupled ocean-atmosphere model with the results from an atmosphere model for which the SSTs were given. Their unexpected finding was that the atmospheric response in these two cases were very different.
In fact, global atmospheric and climate models are better at describing the large picture than more regional and local characteristics. There is a limit to what they are able to describe in terms of local regional details, and it it reasonable to ask whether the response to changes in regional sea-ice cover is beyond the limitation of the global model. If different models give different answers, then it is likely that the response is not robust.
Another interesting question is whether the sea-ice the is whole story. Not long ago, there were some suggestions of a link between low solar activity and cold winters (this correlation, however, is so weak that you would never notice without statistical analysis. Also see comment here). Do these factors affect the circulation patterns over the North Atlantic? The sunspots tend to vary on a time scale of 10-12 years, but the NAO-index suggests that few of the extreme low values were repeated over two subsequent years. In other words, the NAO doesn’t show the same persistence as the sunspots. It will be interesting to see if this winter will break with previous patterns – if it does, that could be interpreted as a support of Petoukhov and Semenov hypothesis.
It is nevertheless no contradiction between a global warming and cold winters in regions like Europe. Rather, recent analysis suggest that the global mean temperature is marching towards higher values (see figure below), and Petoukhov and Semenov argue that the cold winter should be an expected consequence of a global warming.


EUROPA BAJO LA NIEVE

La Reppublica
Dopo l'incubo, la A1 torna normale
ma è polemica sulla gestione dell'emergenza
Automobilisti bloccati per tutta la notte sul tratto toscano dell'autostrada a causa della neve e del ghiaccio. Il ministro dei Trasporti convoca per lunedi Autostrade, Fs, Anas e Protezione Civile. Disagi anche per i treni, poi la circolazione è ripresa
ROMA - L'emergenza è superata, i disagi rimangono, ma intanto monta la polemica per la paralisi che da  venerdì fino al pomeriggio di oggi ha colpito il sistema dei trasporti in Toscana. L'autostrada A1 è stata riaperta dopo uno stop di quasi 24 ore e un lungo inferno per gli automobilisti fermi, nella notte, al gelo, senza soccorsi. Il Comune di Firenze e la Regione Toscana non escludono proprie responsabilità nella gestione dell'emergenza, ma mettono sotto accusa Autostrade, Ferrovie e Anas. In serata chiusa per ghiaccio la Firenze-Siena.

Proprio i vertici delle tre società, insieme alla Protezione civile, sono stati convocati d'urgenza dal ministro dei Trasporti Altiero Matteoli per fare chiarezza su quanto accaduto. La riunione si terrà lunedì pomeriggio, servirà per fare il punto sull'emergenza maltempo e "si verificheranno l'origine e le ragioni dei disagi per l'utenza". E adesso è allarme ghiaccio: il Centro di monitoraggio meteo-idrologico della Regione Toscana ha diffuso un nuovo avviso fino alle 16 di domenica. Il gelo dovrebbe colpire soprattutto le zone interne centro-settentrionali della regione e, localmente, le zone collinari fra Siena e Grosseto.

I fatti. Venerdì è iniziato con la neve che imbiancava la costa della Toscana, sulle zone interne le precipitazioni nevose sono iniziate in tarda mattinata con un'intensità che nessuno si aspettava. La mobilità regionale è  andata in tilt. Già dalla mattina si è bloccato il servizio ferroviario sull'asse tirrenico, poi è toccato alla stazione di Santa Maria Novella, snodo centrale del trasporto su ferro per l'intero paese. Dopo le ferrovie è toccato alle strade, al mattino si è bloccata la Fi-Pi-Li nel tratto vicino Pisa. Bloccati gli aeroporti di Pisa e di Firenze, decine di voli cancellati e qualche centinaio di passeggeri rimasti a terra. La sorte peggiore è quella toccata agli automobilisti. In centinaia sono rimasti bloccati da neve e ghiaccio (e da altri mezzi slittati sul fondo stradale e finiti di traverso sulla carreggiata) soprattutto nel tratto fiorentino dell'A1 e hanno dovuto sopportare un'intera notte al gelo nelle proprie vetture, mentre da Firenze e Arezzo i vigili del fuoco provavano a portare soccorsi ma con grande difficoltà.

La A1 liberata nel pomeriggio. L'autostrada è stata sbloccata solo nel pomeriggio di oggi. "E' ripresa la circolazione del traffico sul tratto Incisa-Valdarno" è scritto in una nota della Protezione civile che hasancito la fine dell'emergenza "per la quale le Amministrazioni territoriali avevano richiesto un intervento della Protezione Civile Nazionale". "La gestione" torna ora "alle strutture ordinariamente competenti" prosegue la nota, che successivamente invita le stesse strutture a mantenere alto lo stato di allerta "alla luce del quadro meteorologico che si prevede per le prossime ore". Quanto agli aeroporti, quello di Firenze è stato riaperto alle 17 mentre per quello di Pisa la riapertura è stata rimandata alla mattina di domenica. Dopo la riapertura al traffico ferroviario della stazione di Firenze Santa Maria Novella, avvenuta alle 9.30, nel corso della mattinata la circolazione dei treni è tornata alla normalità sull'intera rete.

La Protezione civile si difende. Per quel che riguarda il disastro della A1, la Protezione civile si difende. "I disagi e le nevicate erano state da noi ampiamente segnalate con una dettagliatissima circolare a tutti gli enti. Se fossero state seguite non ci saremmo trovati in questa situazione" accusa il capo dipartimento Franco Gabrielli, aggiungendo che "c'è stato un sistematico disinteresse degli italiani che si sono messi in auto senza attrezzature adeguate".

De Telegraaf

za 18 dec 2010, 09:15
Britten vrezen meer problemen door sneeuw
LONDEN -  De Britse politie heeft de inwoners opgeroepen dit weekeinde niet te gaan reizen als het niet strikt noodzakelijk is. Volgens de autoriteiten is het al een chaos op de weg en in het openbaar vervoer en dreigen er nog grotere problemen, omdat meer sneeuw wordt verwacht.


Dat heeft de BBC zaterdag gemeld. In de nacht van vrijdag op zaterdag viel in het noordwesten van Engeland circa 20 centimeter sneeuw. Op tal van wegen ontstonden verkeersproblemen. Op de M6 in Lancashire strandden honderden vrachtwagenchauffeurs in de sneeuw. In het zuiden van Wales zijn verscheidene wegen gesloten.
Meteorologen voorspellen meer sneeuwval voor Schotland, Ierland en delen van Engeland. Vliegmaatschappijen Easyjet en British Airways hebben een aantal voor zaterdagmorgen geplande vluchten van en naar Gatwick Airport in Londen geschrapt.
Op Gatwick is in de nacht van vrijdag op zaterdag een temperatuur van 11 graden onder nul gemeten. In het graafschap Buckinghamshire in het zuidoosten van Engeland was het 13 graden onder nul.
De autoriteiten in Noord-Ierland repten vrijdag van de meest barre winterse omstandigheden van de afgelopen vijfentwintig jaar. Zeker zevenhonderd scholen bleven dicht. In Wales bleven ruim achthonderd scholen gesloten en in Schotland circa vijfhonderd.
Ook België ondervindt veel overlast van het wintserse weer. De Vlaamse zender VRT meldde zaterdag dat het in de nacht van vrijdag op zaterdag flink heeft gesneeuwd in de provincies Antwerpen, Oost- Vlaanderen en Vlaams-Brabant. Veel secundaire wegen en snelwegen zijn moeilijk begaanbaar.

The Independent


The Big Freeze

Winter blast brings Britain to a standstill

PA
Saturday, 18 December 2010

No traffic on the M61 in Lancashire as heavy snow shuts part of the motorway

 Millions of Britons faced travel misery today with planes grounded, rail services cancelled and roads rendered impassable on what is traditionally the busiest weekend before Christmas.
Plunging temperatures and heavy snow saw large swathes of the country grind to a standstill, as London's Gatwick Airport closed its runway and British Airways cancelled flights at Heathrow.
Overnight blizzards and plummeting temperatures buckled a huge chunk of the nation's road and rail networks, as the latest blast of wintery weather showed little sign of easing.

Related articles

This weekend is expected to be the busiest for retailers and commuters in the run-up to December 25 but many are expected to face chaos as the transport network bears the brunt of the big freeze.
Air passengers have already faced disruption at Exeter, London City, Aberdeen and Cardiff airports, while Belfast City was closed last night, with flights expected to resume at 11am.
Southampton Airport was closed until 12pm and flights to certain destinations from Birmingham were also grounded.
Delays and cancellations were expected at Belfast International while a spokesman for Heathrow said the airport was open but would be "challenged" today.
"Heathrow is fully operational but we are expecting more snow and planning for the worst," he said.
"BA passengers must stay at home as all BA flights are cancelled. At this time there are no significant delays at other terminals.
"All passengers must check with airlines before setting off as the situation will worsen."
A Gatwick airport said efforts were now under way to clear the snow.
"We've had heavy snowfall solidly now for the past hour and it continues to fall," a spokesman said.
"We're now out there ploughing, sweeping and brushing the snow away and will continue to do that until it's safe to resume operations."
Officials advised all passengers to check their flight status before travel.
There was also widespread chaos on major roads and motorways.
Hundreds of motorists were left stranded on the M6 in Greater Manchester as the North West of England was hit with reported deluges of up to 25cm of snow.
Meanwhile, parts of the south were also blanketed and as much as a foot of the white stuff is expected to fall on parts of the South East and the Midlands today.
Forecasters expect the mercury will struggle to break freezing in the next 24 hours, after overnight temperatures dropped as low as minus 13C in Chesham, Buckinghamshire, with Gatwick producing a reading of minus 11C.
A fleet of 47 snow ploughs, tractors and other vehicles were deployed in a frantic effort to clear the snow from the runway at Gatwick as it continued to fall.
Some 150 staff were drafted in to carry out the operation in an attempt to clear the ground and create safe conditions for take-offs.
But as soon as a patch was cleared, it was almost instantly covered again by another coating.
Regulations require the airport to suspend flights if snow lies thicker than 3cm on the ground.
And the heavy snowfall was expected to continue for at least another hour.
Extra ground staff were working in the terminal to deal with frustrated and disappointed passengers facing long waits.
Free internet access was provided to help would-be travellers book alternative flights and attempt to rescue their holiday plans.
The airport spokesman said: "When you get a situation like this the welfare of the passengers is of the utmost priority.
"We've told them to expect delays and cancellations throughout."
Almost 600 flights were scheduled to operate from Gatwick today, with at least 138 cancelled by mid-morning.
British Airways grounded all its flights out of Heathrow until at least 5pm this afternoon, despite the airport's operator saying it is "fully operational".
A spokeswoman from the airline said: "The weather at Heathrow now is quite appalling."
"We knew that severe weather conditions were expected, so rather than asking passengers to travel down from Scotland, for example, just to have their flight cancelled, we think it's better to tell all our customers that flights are cancelled.
"We need to give our customers some certainty."
She said the airline regretted inconveniencing passengers, but insisted it was the correct decision.
"This costs British Airways a huge amount of money, so this is not a decision we take lightly," she said.
"There's a backlog from yesterday and that has an impact on today's customers.
"The main thing is we don't want customers turning up today to get stranded and not be able to get out by car or by plane.
She said the airline is providing people with food and drinks, and putting people up in rooms.
Warnings were also issued to communities in Hampshire and the Isle of Wight, with snow depths reaching up to 12cm in some areas.
Temperatures on the Isle of Wight are due to plunge to -10 in rural parts, presenting black ice hazards to drivers.
Christmas shoppers were told to stick to main roads, which have been gritted as a priority along with trunk roads, motorways and town and city centres.
Festive party-goers out in the towns and cities this weekend were encouraged to put on warm clothing as the mercury drops overnight.
Salting lorries from Hampshire County Council have been running round-the-clock since 6pm last night on the priority one routes.
More than 1,000 salt bins have been placed in communities to enable residents to help themselves to keep pavements and roads safe.
All major and most minor roads in the two counties were passable with care but there are fears that slush will freeze later, Hampshire Police said.
In the North West, one of the worst affected regions, police and highways officers were providing food and water to stranded drivers.
Commuter Stephen Derbyshire said he was stuck for five hours on the M6 in Greater Manchester, which has now reopened. He was forced to complete the last two hours of his journey on foot.
"It is absolute mayhem," he told BBC Radio Five Live.
Drivers were advised to avoid parts of the M6 and M61 in Lancashire following a number of road traffic collisions due to snow and ice. The M58 and M57 were also affected by the weather.
Yesterday, nearly a quarter of all train services experienced delays and a similar picture was expected today with operators in the south, including Southeastern, South West Trains and Southern Railway, running reduced services.
Wintry conditions were also causing delays in Scotland but new transport minister Keith Brown said a multi-agency response was under way to keep the north east and Highlands and Islands moving in the face of severe winter weather.
The country's major airports were open but experiencing delays and cancellations because of the knock-on effect on heavy snowfall in the south-east of England.
But the cold weather was good news for some. Many of Scotland's mountain sports resorts were reporting good conditions to take to the slopes.
Severe weather warnings of heavy snow and widespread icy roads are in place in London and the South East, the South West, the Midlands, the North West and Yorkshire and Humber. Wales, northern Scotland and Northern Ireland - which had experienced its heaviest snow for 25 years - were also issued with severe warnings.
Mark Seltzer, a forecaster for the Met Office, predicted this could be the coldest December on record, with a current average temperature of minus 0.7C - five degrees below the long-term average.
"A lot of snow has fallen across the north-west of England overnight but it should ease off during the day," he added.
"A lot of snow also fell in the South West overnight and it will progressively move into the South East and parts of the Midlands and East Anglia throughout the day. There could be local accumulations of 20-25cm.
"Temperatures will struggle to get over freezing and although the snow should ease off tonight, it will return to eastern areas on Sunday."
Yesterday, a man injured in a car crash near Eastbourne, in East Sussex, died after the ambulance he was being taken to hospital in left a country road in poor weather conditions and careered into a bush.
Elsewhere, two pedestrians died after being hit by a Range Rover in Glasgow; a 17-year-old boy was killed when his car ploughed off the road in Bilsington, Kent; a woman in her 60s, thought to be from the Inverness area, was killed in a three-vehicle pile-up in Huntly, Aberdeenshire; and a 19-year-old man was stabbed in the neck in Sheffield after asking a group of teenagers to stop throwing snowballs.
Thames Water reported a "near four-fold" increase in burst pipes caused by the sub-zero temperatures.
Transport Secretary Philip Hammond yesterday met RAC Foundation chairman David Quarmby to receive his audit on how well Britain was prepared for poor weather conditions. The report is due to be published next week.
Transport minister Norman Baker has written to local authorities reminding them of earlier independent recommendations to reduce the amount of salt they spread on roads in an attempt to conserve stocks.
Disgruntled passengers stuck at airport terminals tweeted their irritation on the microblogging site Twitter.
Corine Wood, waiting at Gatwick Airport, wrote: "Our north terminal bound shuttle is stuck in the snow. SAVE US!"
A passenger at Heathrow going by the name of Fridalust asked: "How come British Airways flights have been cancelled but 'most other flights' are ok!? What's the difference between them?"
And Lara Brill tweeted: "They always seem very surprised and unprepared when it snows, which is foolish."
Gatwick Airport said the runway would be shut until at least 3pm.
The AA had attended around 4,000 breakdowns across the UK by 10.30am, with calls peaking at 1,200 every hour - around twice the normal rate. By the end of the day, it expects to attend around 18,000 call-outs, compared to around 9,000 on an average Saturday.
A spokesman said the southern half of the country was the worst affected, with drivers suffering most problems within the M25 and in the Home Counties. Call-outs were also high in Somerset and Newcastle.
Extra AA patrols and 'storm-chasing' Land Rover crews were working across the country to help motorists in trouble.
Darron Burness, head of AA special operations, said driving conditions were "extremely difficult" in some regions.
"One of the biggest problems is that large amounts of snow are falling very quickly on to frozen surfaces, making driving hazardous," he added.
"Around the western side of the M25, three to four inches of snow has fallen in two hours.
"Some may have no choice but to travel, although with road conditions unlikely to improve much over the weekend, drivers should exercise a lot of caution and be prepared for some long delays in places."
Dozens of football fixtures fell victim to the weather, as snow blanketed pitches and the icy conditions made getting to grounds too treacherous for fans.
In the North West, Wigan's clash against Aston Villa at the DW Stadium, as well as Liverpool's match versus Fulham at Anfield were cancelled.
Cardiff's home tie against Burnley and Portsmouth's game at Fratton Park with Scunthorpe were called off in the Championship.
In Scotland, Premier League games between Rangers and St Mirren, Aberdeen and Motherwell, St Johnstone and Dundee Utd, and Hamilton and Celtic were cancelled.
Over 20 more lower league matches were cancelled in England, as well as around eight non-league clashes. About a dozen lower league games in Scotland were also called off.
Racing meets around the country were also forced to be abandoned, as well as many other sporting fixtures.
Birmingham's Premier League fixture at home to Newcastle was also postponed due to snow and freezing conditions, the Midlands club confirmed.
Birmingham Airport suspended all of its flights until at least 1pm while it clears snow from the runway.
A spokesman warned that flights expected to leave the airport this afternoon may be cancelled or delayed because of the adverse conditions.
West Midlands Ambulance Service said yesterday was its busiest day since regional records began, even beating the last three consecutive New Years Eve/Days.
A spokeswoman said it provided 3,941 responses throughout the West Midlands region, approximately 120 more responses compared to last year's New Years Eve/Day, which is traditionally the busiest time for the ambulance service.
A West Midlands Ambulance Service spokeswoman said: "A large number of these calls were to reports of breathing problems, road traffic collisions and slips, trips and falls, which have come about due to the sudden onset of cold weather.
"With the wintry weather set to stay over the next couple of days, the public is being urged to take extra precautions to try to avoid any unnecessary accidents."
Up to 15cm of snow is expected to hit London today while weathermen suggested around 20cm could fall in parts of North Wales, the Midlands and south east England.
Lindsay Dovey, a forecaster with MeteoGroup, the weather division of the Press Association, said temperatures dropped to minus 15.5C in Aviemore, Scotland, this morning.
"There has been a band of snow that is stretching from North Wales right across to the far south east of England, pivoting northwards over London," she said.
"It is going to be around for a while, probably for most of the day, but will hopefully die out tonight when conditions are going to improve."
The mercury could plunge to minus 20C in parts of Scotland, she said.


2/12/10

Der wetter.com Schneechaosblog am 2.12.2010



www.wetter.com

Heute gebietsweise SCHNEEFALL, in Verbindung mit dem lebhaften und böigen Wind besteht weiter Gefahr von SCHNEEVERWEHUNGEN. Im Norden und in der Mitte weht eisiger Nordostwind mit WINDBÖEN, vereinzelt auch mit STÜRMISCHEN BÖEN, in höheren Lagen sowie an der Küste mit STURMBÖEN, teilweise SCHWERE STURMBÖEN. Verbreitet gibt es GLÄTTE, meist durch Schnee oder gefrorene Nässe. Vor allem im Osten und Nordosten sowie in der Mitte herrscht lokal STRENGER FROST um -10°C, in der Nacht zu Freitag lokal bis -20°C.
Das Bodentief KATARINA zieht heute weiter nordwärts über das westliche Polen hinweg zur Ostsee, wobei es im Norden und Nordosten noch zu mäßigen Schneefällen kommt, die sich am Nachmittag und Abend dann vornehmlich auf die küstennahen Gebiete konzentrieren.
Dabei besteht das Risiko, dass sich – ähnlich wie am Dienstag – linienhaft organisierte quasistationäre Schneeschauerstreifen bilden, die von der Ostsee landeinwärts ziehen. Das könnte, lokal begrenzt, erneut eine Unwettersituation mit ergiebigen Schneefällen zur Folge haben. Hier sind dieSchneehöhen.
Die Situation auf den Autobahnen ist weiter angespannt, zudem weht in Schleswig Holstein und an der Nordsee anfangs noch ein stürmischer Nordostwind. Im großen Rest Deutschlands gestaltet sich der Wetterablauf ruhiger bei leichtem bis mäßigem Dauerfrost und gebietsweise leichtem Schneefall. Unter Beachtung der für Anfang Dezember extrem niedrigen 850hPa-Niveau-Temperaturen im Nordosten Deutschlands (unter -15°C) dürften die Temperaturen dort auch tagsüber lokal im strengen Frostbereich verbleiben.
10:56 Uhr: Zugausfälle zwischen Hamburg und Kopenhagen
Die ICE-Linie von Hamburg ins dänische Kopenhagen ist am Donnerstagvormittag wegen Schneeverwehungen unterbrochen worden. Die Züge entfallen in Deutschland ersatzlos, wie die Deutsche Bahn mitteilte. Ein Schienenersatzverkehr könne nicht angeboten werden, da die Straßen nicht passierbar seien. Eine Prognose für die Streckenfreigabe war den Angaben zufolge zunächst nicht möglich.
Witterungsbedingte Einschränkungen im Zugverkehr aufgrund starker Schneeverwehungen gibt es in Schleswig-Holstein auf der Strecke Lübeck-Puttgarden und Eckernförde-Flensburg. Auch in diesen Bereichen gebe es keinen Ersatzverkehr mit Bussen, hieß es weiter.
Auf der Strecke Kiel-Flensburg wird Reisenden in beiden Richtungen die Fahrt über Neumünster empfohlen. Die Züge pendeln derzeit nur zwischen Kiel und Eckernförde.
Aufgrund von Weichenstörung im Kieler Hauptbahnhof kam es am Donnerstagvormittag zu Verspätungen und Zugausfällen. Auf der Strecke Lübeck-Bad Kleinen fiel seit dem frühen Morgen jeder zweite Zug aus, so dass die Regionalbahn nur einen Zweistundentakt fuhr. Es sollten die Züge ab Lübeck-Hauptbahnhof zu den ungeraden Abfahrtzeiten ausfallen. Es wurden keine Busse als Ersatz eingesetzt. Die aktuellen Verkehrsmeldungen der Deutschen Bahn!
10:51 Uhr: Zahlreiche Schulen bleiben wegen heftiger Schneefälle geschlossen
Zahlreiche Schulen in Bayern sind am Donnerstag wegen der heftigen Schneefälle geschlossen geblieben. Nach Angaben des Kultusministeriums waren acht Landkreise und Städte im Nordosten des Freistaats betroffen. Im Einzelnen fiel der Unterricht in Regensburg Land und Stadt, Tirschenreuth, Hof Stadt und Land, Cham, Schwandorf und Kelheim aus.
10:48 Uhr: Wintersturm verursacht Verkehrschaos auf Rügen – Polizei rät von Autofahrten in Vorpommern ab
Der heftige Wintersturm hat auch auf der Insel Rügen zu einem Verkehrschaos geführt. Besonders im Norden der Insel sei der Autoverkehr stellenweise zum Erliegen gekommen, sagte ein Polizeisprecher. Der Busverkehr wurde eingestellt, für einige Schüler falle der Unterricht aus. Auch in Nordvorpommern gehe stellenweise nichts mehr.
Die Zufahrt zum Fährhafen Sassnitz in Mukran versperrten inzwischen bis zu eineinhalb Meter hohe Schneewehen. Mehrere Lkw seien steckengeblieben. Einsatzfahrzeuge des Technischen Hilfswerks (THW) seien angefordert worden, um die Lastwagen zu bergen.
Der Winterräumdienst auf Rügen ist seit den Nachtstunden pausenlos im Einsatz. Bei Windböen bis Stärke 8 seien die Straßen aber immer schon eine halbe Stunde später wieder zu, sagte ein Mitarbeiter. Für die Freihaltung der 270 Kilometer Bundes- und Landesstraßen stehen auf Rügen zwei Schneefräsen, eine Schneeschleuder und 17 Räumfahrzeuge zur Verfügung. Zudem halten private Anbieter und Landwirte Räumtechnik bereit.
Die Polizei rät inzwischen Autofahrern, auf nicht unbedingt erforderliche Fahrten am Donnerstag zu verzichten. Auch auf dem Festland seien zahlreiche Straßen durch steckengebliebene Fahrzeuge blockiert, sagte der Sprecher der Polizeidirektion Stralsund, Uwe Werner. «Auf dem Rügenzubringer herrscht so heftiges Schneetreiben, dass die Sicht nahezu Null ist». Es habe inzwischen auch mehrere Unfälle mit Blechschäden gegeben. Die Rügenbrücke sei gegenwärtig frei.
Wegen des Sturms und Hochwassers hat am Donnerstag die Weiße Flotte den Fährverkehr zur Insel Hiddensee eingestellt. Überfahrten von Stralsund und Schaprode könnten derzeit nicht angeboten werden, sagte eine Reedereisprecherin. Weil sich im Bodden erstes Eis gebildet habe, sei inzwischen auch der Verkehr mit kleinen Wassertaxis nicht mehr möglich.
9:58 Uhr: 65 Unfälle nach Schneefall in Berlin
Witterungsbedingt ist es am Donnerstagmorgen zu zahlreichen Unfällen auf Berlins Straßen gekommen. Bis 8.00 Uhr erfasste die Polizei 65 Unfälle nach den ersten heftigen Schneefällen in diesem Winter. Alleine zwischen 7.00 Uhr und 8.00 Uhr ereigneten sich einer Sprecherin zufolge 28 Unfälle. Welche Schäden dabei entstanden und ob Personen zu Schaden kamen, konnte sie zunächst nicht sagen. Die Zahl der Unfälle sei angesichts des Schneefalls aber normal. Sie rief Autofahrer dazu auf, vorsichtig zu fahren und den Sicherheitsabstand einzuhalten.
Vor 9:17 Uhr

Consecuencias del calentamiento global sobre la circulación oceánica


Los Océanos

Saber más

Consecuencias del calentamiento global sobre la circulación oceánica

Es muy probable que el calentamiento global tenga serios efectos sobre los océanos. Sabemos que el dióxixo de carbono se disuelve más fácilmente en agua fría que en agua caliente, por lo que, de entrada, un calentamiento general disminuirá la capacidad del océano para captar dióxido de carbono de la atmósfera y facorecerá el efecto invernadero. El aumento de temperaturas también aumentará el flujo de agua dulce en los océanos en latitudes altas, los modelos sugieren que esto se debe al aumento de lluvias en latitudes medias y altas y el deshielo de los casquetes polares. Además las temperaturas cálidas provocan la expansión del agua, lo que, unido con el agua del deshielo, provocará un aumento del nivel del mar que provocará serias inundaciones.
La circulación del océano es muy sensible a la cantidad de agua dulce que entra en el sistema. El agua dulce controla la densidad del agua salada y por lo tanto la capacidad del agua de hundirse al enfriarse. Si el agua es demasiado dulce, el enfriamiento no la hará lo suficientemente densa como para que se hunda hasta el fondo oceánico. Si el agua no se hunde en las altas latitudes, el viento será la única fuerza de movimiento de la corriente del golfo y la circulación global se verá frenada. 
Tenemos algunas evidencias de que la corriente termohalina ha dejado de funcionar en algunos momentos en el pasado. El calentamiento posterior a la última glaciación hace 15000 años derritió los casquetes polares que cubrían Norte América y aumentó el aporte de agua dulce al Atlántico Norte. Esto redujo la salinidad del agua, impidiendo su hundimiento y frenando la formación de aguas profundas. Existe evidencia de que esto produjo la parada de la corriente termohalina, frenó la corriente del Golfo y con ello el transporte de calor hacia el Norte de Europa. Así se interrumpió el calentamiento del final de la última glaciación.
El estudio de las capas los casquetes polares y los sedimentos del fondo oceánico muestran que la temperatura en el Noroeste de Europa descendió unos 5ºC en sólo unas décadas, devolviendo a la región del Atlántico Norte a las condiciones glaciares. Esta etapa de la historia se conoce como el periodo frío Dryas reciente. También tenemos evidencia de que la circulación oceánica está cambiando ahora debido al calentamiento global. Las observaciones muestran que el Atlántico Norte está disminuyendo la salinidad de forma constante durante los últimos 40 años.


1.  Hace unos 13000 años terminó la última glaciación y la TIerra se volvió más cálida. Este calentamiento aumentó el flujo de agua dulce en el Océano Atlántico al derretirse los hielos. La circulación oceánica se frenó y la región del Atlántico Norte se volvió fría otra vez. Los aportes de agua dulce frenaron una vez que todo el hielo se había derretido y la circulación oceánica se reanudó. Esto produjo un rápido (en términos geológicos) aumento de la temperatura ya que el agua templada de los trópicos pudo volver fluir hasta las costas del Norte de Europa. Imagen cedida por R. Alley and the CLIVAR project. Pincha sobre la imagen para verla mejor (12 KB).


Intentar predecir el impacto del calentamiento global requiere el uso de modelos de ordenador extremadamente complejos que siempre incluyen presunciones sobre condiciones futuras que no pueden ser comprobadas adecuadamente. El resultado son modelos con predicciones muy diferentes. Lagunos predicen que el calentamiento global llevará a un debilitamiento de la corriente termohalina durante este siglo pero que no se frenará completamente, otros en cambio predicen esta parada, producida por el deshielo y aportes de agua dulce a los océanos. Por ello es difícil predecir cómo será el clima en caso de que la circulación oceánica cambiase.



2. Nueve modelos de predicción estiman resultados completamente diferentes para el cambio producido en la circulación oceánica como consecuencia del calentamiento global. Algunos modelos prevén un cambio mínimo en la formación de aguas profundas a altas latitudes y por lo tanto un cambio mínimo de la circulación termohalina. Otros, sin embargo, estiman que el calentamiento global reducirá enormemente la formación de aguas profundas. la unidad de medida que se utiliza es el Sverdrup (Sv) que mide el volumen de agua que se mueve por unidad de tiempo. 1 Sv es un millón de metros cúbicos de agua movíendose en un segundo. El peor caso estimado significaría un descenso de 15 Sv en el flujo de las aguas superficiales hacia el fondo en el Atlántico Norte para el año 2100, reduciendo así enormemente la circulación termohalina. Figura cedida por el proyecto CLIVAR. Pincha en la imagen para verla mejor (25 KB).

Los modelos complejos estiman un enfriamiento de unos 2ºC sobre la mayor parte de Europa como consecuencia de la reducción del transporte de calor desde el Caribe al debilitarse la corriente del Golfo.


3. Esta imagen muestra como las temperaturas del aire también cambiarán en caso de que la corriente termohalina cambie o simplemente pare. La mayoría de los modelos utilizados sugieren que las temperaturas en el Norte de Europa descenderán al disminuir el aporte de calor que supone la corriente del Golfo desde las latitudes tropicales. Imagen cedida por Michael Vellinga y Richard Wood del proyecto CLIVAR.  Pincha en la imagen para verla mejor (11 KB).

El impacto del calentamiento inducido por los gases de efecto invernadero debe ser añadido a todo esto para conseguir una buena predicción del clima. Se prevé un aumento generalizado de las temperaturas en el mundo, sin embargo, la mayoría de los modelos coinciden en que sobre Europa, las temperaturas no cambiarían o cambiarían muy poco debido al colapso de la circulación termohalina. Además de este ligero calentamiento también se prevé un clima más húmedo y tormentoso, aunque prever dónde y cuándo serán estas tormentas es más complicado. Así que todavía necesitamos mejores observaciones y modelos más realistas para reducir la incertidumbre de lo que pasará en el futuro con nuestro clima.

Sobre esta página:
autor: Lucinda Spokes - Environmental Sciences, University of East Anglia, Norwich - U.K.
1. Revisión científica: Prof. Grant Bigg - Department of Geography, University of Sheffield, Sheffield - U.K.
2.
Revisión educativa:

Última actualización: 2003-10-01