The Day After Tomorrow: A Scientific Critique

The 2004 film The Day After Tomorrow, in which global warming leads to a new ice age, has been vigorously criticized by climate scientists. Why is this? What mistakes in the film led Dr. Andrew Weaver, Canada’s top climate modeller, to claim that “the science-fiction movie The Day After Tomorrow creatively violates every known law of thermodynamics”? What prompted Dr. Gavin Schmidt, NASA climatologist, to say thatThe Day After Tomorrow was so appallingly bad, it was that that prompted me to become a more public scientist”? What could an innocent blockbuster movie have done to deserve such harsh criticisms?

A New Ice Age?

The Day After Tomorrow opens with a new scientific discovery by paleoclimatologist Jack Hall, played by Dennis Quaid. After a particularly harrowing trip to gather Antarctic ice cores, he discovers evidence of a previously unknown climate shift that occurred ten thousand years ago. Since the film is set in the early 2000s, and ice cores yielding hundreds of thousands of years of climate data have been studied extensively since the 1960s, it seems implausible that such a recent and dramatic global climatic event would have gone previously unnoticed by scientists. However, this misstep is excusable, because a brand new discovery is a vital element of many science fiction films.

Jack goes on to describe this ancient climate shift. As the world was coming out of the last glacial period, he explains, melting ice sheets added so much freshwater to the Atlantic Ocean that certain ocean circulation patterns shut down. Since thermohaline circulation is a major source of heat for the surfaces of continents, the globe was plunged back into an ice age. Jack’s portrayal of the event is surprisingly accurate: a sudden change in climate did occur around ten thousand years ago, and was most likely caused by the mechanisms he describes. To scientists, it is known as the Younger Dryas.

The world’s ascent out of the last ice age was not smooth and gradual; rather, it was punctuated by jumps in temperature coupled with abrupt returns to glacial conditions. The Younger Dryas – named after a species of flower whose pollen was preserved in ice cores during the event – was the last period of sudden cooling before the interglacial fully took over. Ice core data worldwide indicates a relatively rapid drop in global temperatures around eleven thousand years ago. The glacial conditions lasted for approximately a millennium until deglaciation resumed.

The leading hypothesis for the cause of the Younger Dryas involves a sudden influx of freshwater from the melting Laurentide Ice Sheet in North America into the Atlantic Ocean. This disruption to North Atlantic circulation likely caused North Atlantic deep water formation, a process which supplies vast amounts of heat to northern Europe, to shut down. Substantial regional cooling allowed the glaciers of Europe to expand. The ice reflected sunlight, which triggered further cooling through the ice-albedo feedback. However, the orbital changes which control glacial cycles eventually overpowered this feedback. Warming resumed, and the current interglacial period began.

While Jack Hall’s discussion of the Younger Dryas is broadly accurate, his projections for the future are far-fetched. He asserts that, since the most recent example of large-scale warming triggered glacial conditions, the global warming event currently underway will also cause an ice age. At a United Nations conference, he claims that this outcome is virtually certain and “only a matter of time”. Because it happened in the past, he reasons, it will definitely happen now. Jack seems to forget that every climate event is unique: while looking to the past can be useful to understand today’s climate system, it does not provide a perfect analogue upon which we can base predictions. Differences in continental arrangement, initial energy balance, and global ice cover, to name a few factors, guarantee that no two climate changes will develop identically.

Additionally, Jack’s statements regarding the plausibility of an imminent thermohaline shutdown due to global warming fly in the face of current scientific understanding. As the world continues to warm, and the Greenland ice sheet continues to melt, the North Atlantic circulation will probably slow down due to the added freshwater. The resulting cooling influence on parts of Europe will probably still be overwhelmed by warming due to greenhouse gases. However, a complete shutdown of North Atlantic deep water formation is extremely unlikely within this century. It’s unclear whether an eventual shutdown is even possible, largely because there is less land ice available to melt than there was during the Younger Dryas. If such an event did occur, it would take centuries and still would not cause an ice age – instead, it would simply cancel out some of the greenhouse warming that had already occurred. Cooling influences simply decrease the global energy balance by a certain amount from its initial value; they do not shift the climate into a predetermined state regardless of where it started.

Nevertheless, The Day After Tomorrow goes on to depict a complete shutdown of Atlantic thermohaline circulation in a matter of days, followed by a sudden descent into a global ice age that is spurred by physically impossible meteorological phenomena.

The Storm

Many questions about the Ice Ages remain, but the scientific community is fairly confident that the regular cycles of glacial and interglacial periods that occurred throughout the past three million years were initiated by changes in the Earth’s orbit and amplified by carbon cycle feedbacks. Although these orbital changes have been present since the Earth’s formation, they can only lead to an ice age if sufficient land mass is present at high latitudes, as has been the case in recent times. When a glacial period begins, changes in the spatial and temporal distribution of sunlight favour the growth of glaciers in the Northern Hemisphere. These glaciers reflect sunlight, which alters the energy balance of the planet. The resulting cooling decreases atmospheric concentrations of greenhouse gases, through mechanisms such as absorption by cold ocean waters and expansion of permafrost, which causes more cooling. When this complex web of feedbacks stabilizes, over tens of thousands of years, the average global temperature is several degrees lower and glaciers cover much of the Northern Hemisphere land mass.

The ice age in The Day After Tomorrow has a more outlandish origin. Following the thermohaline shutdown, a network of massive hurricane-shaped snowstorms, covering entire continents, deposits enough snow to reflect sunlight and create an ice age in a matter of days. As if that weren’t enough, the air at the eye of each storm is cold enough to freeze people instantly, placing the characters in mortal danger. Jack’s friend Terry Rapson, a climatologist from the UK, explains that cold air from the top of the troposphere is descending so quickly in the eye of each storm that it does not warm up as expected. He estimates that the air must be -150°F (approximately -100°C) or colder, since it is instantly freezing the fuel lines in helicopters.

There are two main problems with this description of the storm. Firstly, the tropopause (the highest and coldest part of the troposphere) averages -60°C, and nowhere does it reach -100°C. Secondly, the eye of a hurricane – and presumably of the hurricane-shaped snowstorms – has the lowest pressure of anywhere in the storm. This fundamental characteristic indicates that air should be rising in the eye of each snowstorm, not sinking down from the tropopause.

Later in the film, NASA scientist Janet Tokada is monitoring the storms using satellite data. She notes that temperature is decreasing within the storm “at a rate of 10 degrees per second”. Whether the measurement is in Fahrenheit or Celsius, this rate of change is implausible. In under a minute (which is likely less time than the satellite reading takes) the air would reach absolute zero, a hypothetical temperature at which all motion stops.

In conclusion, there are many problems with the storm system as presented in the film, only a few of which have been summarized here. One can rest assured that such a frightening meteorological phenomenon could not happen in the real world.

Sea Level Rise

Before the snowstorms begin, extreme weather events – from hurricanes to tornadoes to giant hailstones – ravage the globe. Thrown in with these disasters is rapid sea level rise. While global warming will raise sea levels, the changes are expected to be extremely gradual. Most recent estimates project a rise of 1-2 metres by 2100 and tens of metres in the centuries following. In contrast, The Day After Tomorrow shows the ocean rising by “25 feet in a matter of seconds” along the Atlantic coast of North America. This event is not due to a tsunami, nor the storm surge of a hurricane; it is assumed to be the result of the Greenland ice sheet melting.

As the film continues and an ice age begins, the sea level should fall. The reasons for this change are twofold: first, a drop in global temperatures causes ocean water to contract; second, glacier growth over the Northern Hemisphere locks up a great deal of ice that would otherwise be present as liquid water in the ocean. However, when astronauts are viewing the Earth from space near the end of the film, the coastlines of each continent are the same as today. They have not been altered by either the 25-foot rise due to warming or the even larger fall that cooling necessitates. Since no extra water was added to the Earth from space, maintaining sea level in this manner is physically impossible.

Climate Modelling

Since the Second World War, ever-increasing computer power has allowed climate scientists to develop mathematical models of the climate system. Since there aren’t multiple Earths on which to perform controlled climatic experiments, the scientific community has settled for virtual planets instead. When calibrated, tested, and used with caution, these global climate models can produce valuable projections of climate change over the next few centuries. Throughout The Day After Tomorrow, Jack and his colleagues rely on such models to predict how the storm system will develop. However, the film’s representation of climate modelling is inaccurate in many respects.

Firstly, Jack is attempting to predict the development of the storm over the next few months, which is impossible to model accurately using today’s technology. Weather models, which project initial atmospheric conditions into the future, are only reliable for a week or two: after this time, the chaotic nature of weather causes small rounding errors to completely change the outcome of the prediction. On the other hand, climate models are concerned with average values and boundary conditions over decades, which are not affected by the principles of chaos theory. Put another way, weather modelling is like predicting the outcome of a single dice roll based on how the dice was thrown; climate modelling is like predicting the net outcome of one hundred dice rolls based on how the dice is weighted. Jack’s inquiry, though, falls right between the two: he is predicting the exact behaviour of a weather system over a relatively long time scale. Until computers become vastly more precise and powerful, this exercise is completely unreliable.

Furthermore, the characters make seemingly arbitrary distinctions between “forecast models”, “paleoclimate models”, and “grid models”. In the real world, climate models are categorized by complexity, not by purpose. For example, GCMs (General Circulation Models) represent the most processes and typically have the highest resolutions, while EMICs (Earth System Models of Intermediate Complexity) include more approximations and run at lower resolutions. All types of climate models can be used for projections (a preferred term to “forecasts” because the outcomes of global warming are dependent on emissions scenarios), but are only given credence if they can accurately simulate paleoclimatic events such as glacial cycles. All models include a “grid”, which refers to the network of three-dimensional cells used to split the virtual Earth’s surface, atmosphere, and ocean into discrete blocks.

Nevertheless, Jack gets to work converting his “paleoclimate model” to a “forecast model” so he can predict the path of the storm. It is likely that this conversion involves building a new high-resolution grid and adding dozens of new climatic processes to the model, a task which would take months to years of work by a large team of scientists. However, Jack appears to have superhuman programming abilities: he writes all the code by himself in 24 hours!

When he has finished, he decides to get some rest until the simulation has finished running. In the real world, this would take at least a week, but Jack’s colleagues wake him up after just a few hours. Evidently, their lab has access to computing resources more powerful than anything known to science today. Then, Jack’s colleagues hand him “the results” on a single sheet of paper. Real climate model output comes in the form of terabytes of data tables, which can be converted to digital maps, animations, and time plots using special software. Jack’s model appeared to simply spit out a few numbers, and what these numbers may have referred to is beyond comprehension.

If The Day After Tomorrow was set several hundred years in the future, the modelling skill of climate scientists and the computer power available to them might be plausible. Indeed, it would be very exciting to be able to build, run, and analyse models as quickly and with as much accuracy as Jack and his colleagues can. Unfortunately, in the present day, the field of climate modelling works quite differently.

Conclusions

The list of serious scientific errors in The Day After Tomorrow is unacceptably long. The film depicts a sudden shutdown of thermohaline circulation due to global warming, an event that climate scientists say is extremely unlikely, and greatly exaggerates both the severity and the rate of the resulting cooling. When a new ice age begins in a matter of days, it isn’t caused by the well-known mechanisms that triggered glacial periods in the past – rather, massive storms with physically impossible characteristics radically alter atmospheric conditions. The melting Greenland ice sheet causes the oceans to rise at an inconceivable rate, but when the ice age begins, sea level does not fall as the laws of physics dictate it should. Finally, the film depicts the endeavour of science, particularly the field of climate modelling, in a curious and inaccurate manner.

It would not have been very difficult or expensive for the film’s writing team to hire a climatologist as a science advisor – in fact, given that the plot revolves around global warming, it seems strange that they did not do so. One can only hope that future blockbuster movies about climate change will be more rigorous with regards to scientific accuracy.

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26 thoughts on “The Day After Tomorrow: A Scientific Critique

  1. This is an excellent critique and reads very true to what little I know about historical climate change (having only a lay interest in the topic). Have you considered emailing this critique to the editor of the movie review section in the local newspaper?

    • Precisely. There aren’t many captivating stories with a several generations time line (actually there are a few, but nothing to be called ‘action’).

      I have to admit though, that I once watched and kind of enjoyed TDAT on the telly after coming home from work, tired. Tired is a requirement, it helps suspend disbelief :-)

    • I dunno, Dana, I think some of the recent ‘think tank’ antics would provide plenty of material. So long as the ‘action’ was more of the spy film intrigue type (a la Bourne or Bond) and less of the ridiculously accelerated natural processes type…

  2. These inconvenient facts in the science were lost on the population in general, though it did give people a shock and cause some of them to think.
    If it galvanized Gavin and other climatologists into being more publicly active, then as far as I’m concerned it was the mission’s first phase accomplished!

    The opening scene in the antarctic was truly spectacular, but I had to suspend belief to enjoy the rest of the film.

    Trouble is that the reality is presently too slow and boring for Hollywood… What layperson would want to spend 100 years glued to the screen watching a glacier melt? :-)

    The real excitement should get going in the next couple of decades, and I really don’t believe enough of humanity ‘gets it’ to be able to turn down the thermostat in time.

    By then, I should think that Hollywood would have some more exciting and believable scenarios to develop, perhaps watched in “sail-in” cinemas…

  3. New poster here

    I’m a scientist, but in another specialty (cell biology) – I am interested in AGW personally more than professionally.

    I have long been intrigued by the Younger Dryas and the Lake Agassiz drainage explanation for it, and so was tempted to give the film a pass when I saw it (I thought it downright erudite for Hollywood to use such a mechanism as a plot line).

    However, when I saw it, I quickly saw the problems that Kate so ably pointed out in her post – my favorite was the stratospheric downdraft freezing the helicopter fuel line (wouldn’t that produce a Foehn-like effect rather than such catastrophic freezing?).

    In the films defense (yes, I know it is indefensible), Hollywood does this on a regular basis. Silly has always ruled there! The following is relevant to the experiences of a current college student (it reveals my age, certainly). This post took me back briefly to 1980…..

    I was a second year college student when Star Wars first came out, and I saw it with a bunch of my (bio major) pals. We had high standards – I remember snorting when they showed a bunch of guys in shirt sleeves in an airlock, and refused to suspend disbelief for the rest of the film.

    Since then I have become more tolerant – so I didn’t subject TDAT to the same comprehensive critique that I gave to Star Wars 20+ years earlier.

    Never forget that the competition is shows like I Dream of Jeannie, Mr Ed, My Favorite Martian and Mork and Mindy………..(all old, yes, but the new ones are no better).

    Garth H.

  4. This is totally off topic, but I thought you might like to know how highly some people regard you and what you have done with this blog.

    “Your question reminds me of a young lady whose blog I found by accident a few years ago. She was a high school student interested in global warming. Now she’s a college student studying to be a climate scientist. And she’s a class act. You could visit her blog and ask the same question — I’ll bet she would have excellent advice to offer. It’s here:

    https://climatesight.org/

    Her name is Kate, and she’s one of my heroes. Maybe soon, you will be too.”

    tamino — 3 May 2012 @ 4:32 PM – http://www.realclimate.org/?comments_popup=11654#comment-234771

    FYI, “tamino” is the nome de plume of a professional statistician who has worked a lot on climatology – see http://tamino.wordpress.com/. If he thinks highly of you, you’re doing a lot of things right – congrats! And thanks for continuing this blog.

    Back to the topic at hand – “It would not have been very difficult or expensive for the film’s writing team to hire a climatologist as a science advisor – in fact, given that the plot revolves around global warming, it seems strange that they did not do so.” They didn’t need to – most of the audience doesn’t know or care if the picture is technically accurate.

    This is part of the problem with communication to the general public – If you point out that giant storms are low pressure cells and have updrafts, and downdrafts generate heating of the atmosphere(like Foehn winds as Garth noted) and clear weather, they won’t get it, and may not believe you. We’re lucky that most people understand that high altitudes are colder, but maybe only 10% of the population understands ‘adiabatic lapse rate” or “latent heat”. If part of the plot involved fueling the helicopters with gasoline, and it resulted in a spectacular fiery explosion, they would accept that, because gas tanks on cars blow up all the time in movies – and practically never in real life; and most people are unaware that modern gas turbine engines will run unmodified on jet fuel(which is a high grade kerosine) or heating oil, or gasoline, or vegetable oil, or diesel. Most people don’t know how much of what they think they know is wrong, and colored by their social and political beliefs. Unfortunately, they are just as likely to accept it when Rush Limbaugh says “volcanoes emit 100 times the CO2 as humans” as they are to accept that AGW spawned storms will blow icy stratospheric winds to the surface.

  5. Just wanted to point out that water expands when it freezes, the only substance we know of, and that should make the ice rise up along the shoreline, assuming the oceans froze. However, that’s unlikely. Good article,nonetheless.

  6. Actually, there is sinking motion in the eye of a hurricane. The low pressure in the center of hurricane is due to diabatic heating of the air column in the mid levels of the storm from convection about the center.

    The eye forms when higher momentum air from the low levels advects upward into lower momentum air. The air aloft has lower momentum because there is a weaker height gradient in a warm core system such as a hurricane. This causes the eywall to slope outward with height due to the conservation of angular momentum. The upward motion in the convection surrounding the eyewall leads to divergent airflow all around the eyewall and thus some weak convergence over the center of the storm. This causes the air aloft to sink slowly in the center, warming and drying the air through adiabatic compression.

    The fact that air sinking from the troposphere to the surface warms compressionally due to the increase in pressure is the real error in this part of the movie. Fast sinking air will warm as much as slowly sinking air since the air is increasing its pressure by the same amount as it moves from tropopause to the surface.

    So even if the air temperature at the tropopause was -100C and the tropopause was at an air pressure of 200 hPa, the air temperature at the surface would still warm to 1C.

  7. While I’d agree the film in question is a pile of unscientific junk – disaster porn of the 2012 type – there is a serious note about abrupt climate change. Sometimes it would appear – over extensive regions at least – that some climate change events can happy truly abruptly.

    One can’t extrapolate too far from past events – but my understanding is recent research suggested the onset of glacial conditions could have occurred within as little as months (and a few years at the outer limit).

    http://www.sciencedaily.com/releases/2009/11/091130112421.htm

    I would imagine that once there was significant snow and ice cover this would have tended to reinforce the effect – a cooling positive feedback driven by albedo increase. Today albedo is decreasing increasingly rapidly in the Arctic as sea ice and land snowpack retreats earlier each year.

    How fast does it need to be to count as “abrupt” climate change?

    • I might be mistaken but the film opens with them drilling an Antartic oceanic ice shelf – those things break up every year and therefore don’t contain thousands of years of data.

  8. I think you missed the point, which was not scientific, but political. This was not about accurate science, but anthropogenic claptrap meant to mislead a gullible public with chicken little “we gotta do something, anything, right now or we’re all going to die” scare tactics to advance a specific political agenda. This movie may have been made in 2004, but they’re still at it. Thanks for being a voice of scientific reason, even if only a few of are listening.

  9. It’s hard to find the definitive data online (since websites can be “updated” ala Orwell’s 1984), but I distinctly remember the narrative changing from “global warming” to “climate change” about the same time this movie came out. I remember thinking how convenient that Hollywood had a movie ready just in time for this narrative change. It was like they were either, a) highly prescient, or b) in on the story very early on.

  10. “At high latitudes the tropopause and lower stratosphere temperature can plunge to ~ -85°C…” -121F
    Although, I agree there is no way the earth would cool as quickly as the movie suggests. For earth to bleed off that much energy the entire sun would need to dim.
    From your work cited page:
    http://www.atoptics.co.uk/highsky/htrop.htm

  11. Well it is a movie, it is Hollywood and we all know they drive the underlying message they want to sell. The point of this movie was demonize fossil fuel use, depict protesters concerned about global warning as a few nuts chanting stop global warming, in New Delhi in a snowstorm (lol), and to sex up the science of the global warming industry to allow for hero’s to step in such as the US government climate or science agencies in NASA, NOAA etc. then forgiving Latin American debt to allow safe passage and sanctuary to their population. The same population who previously would prefer to bomb the shit out of them because they are brown, as they do most populations around the world who have something they want or who don’t stick to the capitalist US dollar script of finances and finance created “wealth” (making money out of thin air backed by nothing of value and asking people to pay back more than is in the pot to be able to do that, creating more debt and so on and so on). For escapism and to enjoy this movie for the effects and the cute Emmy Rossum, do as one commentator did, watch it when tired after a long day.

  12. Hollywood has its own set of rules and physics, if you want an accurate movie, you’ll have to make it yourself, and if you want to reach a wide audience, you’ll also have to make it entertaining. You can do both, if you want. You’ve noted that Hollywood often does just one of the two. Bemoaning it is good for starting a discussion but like change in how we treat or pollute the environment, you have to make a start with active participation and maybe a lead. Reclaim the science channels, and maybe a studio, make that entertaining think piece or make peace with the Hollywood way.

    The movie did get me to look up the real and false things it presented, so unlike a bad SyFy movie where the brain checks out, it did engage a lot of people, and hopefully to the right info.

  13. The movie borrows from the mammoth quick frozen in Siberia theories. In order to freeze such large animals there would have had to have been a very sudden and very large drop in temperature.

  14. I had watched this movie today in my Geography class, and my teacher could not stress this enough: “This is a dramatisation, so things that could take decades happen in a matter of hours.”

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