But could the climate crash 'the day after tomorrow'?

MARK PEPLOW

A 50-metre high tsunami engulfs Manhattan. Helicopters plummet from the sky when their fuel freezes solid in the mother of all blizzards. Monster hailstones rain down on Tokyo.

These are all scenes from The Day After Tomorrow, a US$125 million eco-disaster film showing in cinemas worldwide from 28 May. The film is already causing a stir as some scientists question its premise, and environmental groups such as Greenpeace use the apocalyptic vision of climate change to promote their cause.

The plot is simple enough. The Atlantic Ocean is being diluted as Arctic ice melts, owing to global warming. This dilution turns off the vital ocean current, known as thermohaline circulation, that normally carries warm water from the equator deep into the northern hemisphere by means of the Gulf Stream.

So far, so modelled; the Hadley Centre in Exeter, part of the UK's Met Office, has run computer simulations to study the demise of this aquatic conveyor belt. Their model showed that without warm water from the Gulf Stream, western Europe would be about 5 °C cooler after just a few decades. Many climatologists believe that a similar shut-down happened at the end of the last ice age, roughly 13,000 years ago, when meltwater from an enormous glacier poured into the north Atlantic.

As well as translating this scenario to the United States, The Day After Tomorrow takes this idea a few stages further. First, the ocean cools down by 13 °C as the thermohaline circulation ceases. This creates three enormous hurricanes that drag cold air down from the upper atmosphere. Anyone who ventures outside is instantly frozen solid by the chilly draught, which also disables the hapless helicopters. Within a week, the entire Northern Hemisphere is covered in ice.

While the movie's producers acknowledge that details in the film are exaggerated, they emphasise that human activity could trigger a sudden ice age. "We pushed the time period in which an ice age could occur for dramatic purposes," says producer Mark Gordon, "but the theory that global warming could cause an abrupt climate shift is gaining mainstream attention."

Few scientists would quibble with artistic licence, but many question the basic premise that global warming could trigger a sudden, cataclysmic climate change. "The evidence to date suggests that the big turn off is very unlikely. You would have to warm the Earth by many, many degrees to put enough fresh water into the Atlantic," says David Viner, a climatologist at the University of East Anglia in Norwich. Human activity will definitely produce a gradual global warming rather than sudden global cooling, he says, although he concedes that "localized extreme weather events such as golf ball-sized hailstones are definitely on the rise in our warming world." Abrupt global cooling is more likely to be caused by a volcanic eruption or meteorite impact that throws dust into the atmosphere, blocking the Sun's rays, he suggests.

"We are seeing some slowing of the thermohaline circulation, but my hunch is that we are not going to see a dramatic climate change because of it," agrees Julian Hunt, a climate model expert at University College London. Losing Arctic ice during the summer would just weaken the current rather than shutting it down altogether, he says, and nobody predicts that Arctic ice will be lost during the winter.

Hunt adds that although global warming may weaken ocean currents, it also tends to strengthen winds that push warm water into higher latitudes. This could counteract any cooling effects.

The director and co-writer Roland Emmerich, who also made Independence Day, still wants his film to be taken seriously as a climate scenario. "My secret dream is that this film will move politicians to act," he told Spiegel Online earlier this month.

Not so secret, perhaps. In one scene, the head of the National Oceanic and Atmospheric Administration reprimands the stubborn vice-president of the United States. "You did not want to know about the science when it could have made a difference," he chides. Emmerich clearly loves making the vice-president eat humble pie when he later thanks Mexico for taking in US refugees.

The film may in fact gain some political influence. Former vice-president Al Gore is planning an environmental rally to tie in with the film première, for example. "It will not be as sudden and dramatic as the Hollywood film, but the Earth's environment is currently sustaining severe and potentially irreparable damage," says Gore.

“I hope the film will help raise awareness of the human influence on climate change," despite its sometimes questionable science, says Viner.

"This film has certainly added a new dimension to the public engagement with this issue in a way that climate scientists could never do," says Ian Curtis, who develops methods for communicating climatology at Oxford University's Environmental Change Institute.

But Viner believes that the film's impact will ultimately depend on its quality. "Look at Waterworld: that was supposed to be about climate change. But it was crap, and everyone ignored it," he says.

At a preview screening yesterday, the audience's reaction to the hammier sections of the film's dialogue did not augur well. Their derisive laughter may scupper Emmerich's ambitions for political leverage.

Back