The plot seems a little too chilling for some experts.

But they are still happy to see a public spotlight put on the problem with the 125 million dollar movie, directed by Roland Emmerich of "Independence Day" fame, which hits screens on Friday.

"Whether its premise is valid or not, or possible or not, the very fact it's about climate change could help to spur debate and dialogue," said Gretchen Cook-Anderson a spokeswoman for the US National Aeronautics and Space Administration (NASA).

"In the event that the movie is popular beyond American borders, it will be an opportunity to spur dialogue, to inform people and educate people about climate changes."

Emmerlich made his name with aliens bringing the near destruction of the world in effects-laden "Independence Day".

The cause of the trouble is nearer to home in "The Day After Tomorrow" which tells how global warming could cause climate change, a new ice age and all the disasters that would entail.

The warming Earth melts the polar ice caps, which yield fresh water. Fresh water is lighter than the salt water of the seas, and forms a lid over it. That lid slows and stops the oceans' natural circulation, beginning in the warm tropics toward the colder, northern latitudes.

Dennis Quaid plays a climatologist who warns of the looming disaster and then has to cope with it faster than even he expected as tornadoes, hurricanes, earthquakes, tidal waves, floods lash the planet.

The Houses of Parliament in London and the Eiffel Tower in Paris are both buried in ice and snow.

Ten thousand years ago, the Earth saw a mini-ice age called the Younger-Dryas period, according to David Adamec, a scientist and scriptwriter consulted for the film.

"The premise of the movie is that if you interrupt that heat being transported to the poles, all of a sudden you set up an imbalance in motion which brings on an ice age," said Adamec, an oceanographer at Goddard Space Center outside Washington.

"It takes place catastrophically over the course of a few days."

But this is Hollywood.

"Even the Younger Dryas period happened over decades and decades," said Adamec, who read the script before shooting began.

"I looked at the screenwriter and said, 'you know, it's not realistic.' He said: 'Yes, I know -- it's a movie'."

In one part, a storm brings air temperatures of minus 100 to minus 120 degrees Celsius (minus 148 to minus 184 degrees Fahrenheit) that flash-freezes people where they stand.

"Well, that can't happen" Adamec said.

"When air descends from the upper altitude, it's compressed, so it warms up, like in a bicycle pump when you compress air you can feel that it's warm. That's ignored in the movie," he said.

Adamec, like other experts and activists who favor lowering greenhouse gas emissions, still welcomed the attention the film is drawing.

"If it gets people interested in the problem, that's great. That way, individual people make a more informed decision about where they want their government and policy to go."

The world premier in New York will be accompanied by a demonstration in favor of protecting the environment to be attended by former vice president Al Gore.

Gore said, "Millions of people will be coming out of theaters on Memorial Day weekend asking the question: 'Could this really happen?' I think we need to answer that question."

The director said the film has even larger pretensions.

"The threat of global climate change is the only problem big enough to force all the countries of the world to stop fighting and work together to save the planet," Emmerich said.

Whether that's another impossible idea, only time will tell.

SPACE.WIRE