Hail stones the size of tennis balls are knocking people out in Japan. Shortly afterwards it is snowing in India. But that is only the beginning. The fuel in the helicopters sent to rescue the royal family in Balmoral freezes in flight and within days all those living north of Washington have been abandoned by the US military as beyond help of evacuation. Meanwhile, those from the southern states plead for refugee status in Mexico as they flee to the border to escape the cold.
This is a Hollywood blockbuster, which in the tradition of the disaster movie plays ruthlessly on the irrational fears of the average American. It also has unexpectedly strong political content, and a scanty relationship with scientific fact.
But yesterday The Day After Tomorrow won praise from both the British research establishment and the environment movement.
The new film, which opens across Britain next week, bizarrely plunges the earth into a new ice age as a result of global warming. While concentrating on New York it incidentally freezes the royal family to death in their Scottish retreat.
Among the film's unexpected fans after a sneak preview are the government's chief scientific adviser, Sir David King, and Geoff Jenkins, head of the Hadley Centre for Climate Change, who both regard the film's stunning special effects as good fun and welcome the blockbuster as raising public awareness and debate about a vital issue.
Sir David, who recently stirred political debate on both sides of the Atlantic by saying that global warming was a greater threat than terrorism, said the beginning of the film was particularly realistic - both scientifically and politically.
The political content of the film, in which the US administration is seen to rubbish scientific theories of global warming and paying a heavy price for it, is a double surprise because the film comes from Rupert Murdoch's 20th Century Fox studio, and has been billed by environmental groups as a strongly anti-Bush movie in an election year. The realism Sir David praised was where the film's hero, Jack Hall, a climate scientist played by Dennis Quaid, seeks to convince a high-powered but sceptical audience including the US vice president, that the Gulf Stream is weakening because of climate change.
The Cheney lookalike rejects the idea of global warming being a threat, and says the US economy is more fragile than the climate.
It is then that the film's grip on science begins to ease. Special effects go into overdrive with super-tornadoes in Los Angeles - one of America's recurring horror fantasies.
New York suffers in just six days the kind of weather-related disasters that could be expected over 100 years of the most severe climate change.
But Dr Jenkins said: "It is a blockbuster movie. Let us not be too po-faced, they need a return on their money."
Millions of people are wiped out in the film which Dr King said was also justifiable poetic licence, pointing out that 21,000 people died in Europe last summer because of a heatwave linked to climate change. "There was little attribution to the cause, man-made climate change, and little public response, although it was a very extreme event."
Although fact and fiction are tangled, the main scientific information in the film is that the Gulf Stream, which warms the UK climate by about 5C, is slowing down and then suddenly stops.
The fact that the Gulf Stream is slowing down is an established fact but how fast this is happening and how long it will take is still a matter of scientific uncertainty.
Dr Meric Srokosz, from the Southampton Oceanographic Centre, who has just been given £20m by the government to find out more about this potentially frightening phenomenon, said it had happened twice in the last 12,000 years over a decade and not the six days depicted in the film.
Temperatures had plunged as a result but not as disastrously. He was trying to find out if the chances of it happening again were 1 in 10, 1 in 100 or 1 in 1,000.
He rejected suggestions that the hype of the film would damage the cause of cli mate scientists and play into the hands of sceptics. He worked on the basis that "any publicity is good publicity for the climate cause" - mainly because there had not been enough.
The scientists assembled yesterday to comment on the film and explain the "real science" said that without the Gulf Stream Britain could be as cool as Newfoundland or Nova Scotia.
In the movie, the Gulf Stream - also known as the Atlantic Conveyor - switches off, to precipitate blizzards, hailstones, ice storms, and widespread instant hypothermia.
In real life, as far as anybody knows, any such switch-off would take a decade, and lower the average temperature of central England by 3 C to 4 C.
This would be pretty uncomfortable. The difference between the so-called medieval warm period in the 13th century, when grapes flourished in England, and the Little Ice Age in the 18th and 19th centuries, when the Thames froze over, was no more than 1 C to 2 C, on average.
Some scientists were not so enthusiastic about the bending of science. "It breaks the laws of physics. What is proposed as climate change is the opposite of what we think will happen. It's a parable that doesn't do anything for me," said Professor Mike Hulme, director of the Tyndall centre for climate change research, University of East Anglia.
Dr Jenkins came to the film's defence: "Certainly the basic process of the shutdown of the Gulf Stream could in principle happen in the same way that it happened before.
"So I think it would be arrogant of us to say: we don't need to look at this. We do need to be concerned about the stability of the ocean circulation and why that could change in the future."
But for Bill Maguire, head of the London-based Benfield Hazards Centre, the value of Hollywood raising the issue only goes so far: "Abrupt climate change is a serious business and evidence is accumulating for global warming triggering huge changes to ocean circulation. But the total destruction of LA by tornadoes? I think not."
Could it really happen?
· A vast iceberg drops off the Antarctic ice shelf
Realistic. Bigger bergs are already breaking off
· The British royal family freezes to death in Balmoral
Unlikely, but the castle is notoriously underheated
· Los Angeles is destroyed by tornadoes
We don't think so, say climate scientists
· A 100ft tidal wave engulfs New York
The Big Apple going under is a disaster-movie staple. Unlikely in a global warming scenario
· Three vast, hurricane storms cover the northern hemisphere
Impossible over land, say scientists
· Temperatures plummet 10 degrees Celsius a second, freezing people solid
Beyond the laws of physics
· The southern US states are evacuated
A tall order in three days
· The US president dies of cold, and his successor apologises for global warming
Hard to imagine, even after George Bush made his half-apology this week
· US writes off Latin American debt to allow Americans to flee across the Mexican border
Campaigners have been trying to persuade Washington to forgive more third world debt for years, with only limited success. Raised the loudest laughs from the audience
· Europe is covered by 15ft of snow, writing off the entire continent
The UK goes first in an entirely US-centric disaster show. Some thanks for our special relationship