Good and Bad Science as Presented in the Movie
Introduction and Background Information
Global Warming is a familiar topic that shows up frequently news headlines,
is taught in science classes and explored in depth in science magazines.
Documented scientific evidence exists that earth is warming and that, in fact, it has warmed 1° Fahrenheit (0.56° Celsius) in the last decade, mostly due to an increase in atmospheric carbon dioxide caused by the burning of fossil fuels. While one degree may not seem all that significant the fact is that such an increase has had an impact on global sea levels due to the melting of Arctic, Antarctic and Greenland Ice. The Antarctic Larsen Ice Sheet has collapsed. Ironically the collapse of the Larsen Ice Shelf actually occurred after it had been written into the movie. Greenland's ice sheet is predicted to melt if global temperatures rise by 5.4° Fahrenheit (3° Celsius), resulting in a sea level rise of 23 feet (7 meters).
One species-related effect of global warming was exposed in a recent MSNBC news article dated Oct 23, 2006. It stated that "Dead Zones" have increased by one third in just two years, bringing the number from 149 to 200. Dead Zones are areas of the world's oceans where blooms of tiny plants known as phytoplankton, along with the bacteria that consume them, have depleted the oxygen that fish rely upon for their very existence. Not only are fish species becoming less plentiful as food but they are also in danger of extinction. The causes are the dumping of pollutants into waterways and also the burning of fossil fuels which releases greenhouse gases.1 Carbon dioxide alone has increased about 30 percent in the last century. Greenhouse gases that become trapped in the Earth's atmosphere act like a blanket, preventing outgoing terrestrial radiation from escaping back into space. Average air temperatures rise and the secondary effect is an increase water temperatures. Fish that cannot adapt quickly to warmer water become stressed and large scale fishkill is inevitable. However, the algae and bacteria that cause the eutrophication of oceans thrive quite well in warmer waters.
By 2050, rising temperatures could drive more than a million terrestrial plants and animals into extinction.2 Nearly everyday there is a news headline with a discovery of another negative impact that global warming is having on our planet and on living organisms.
If global temperatures continue to increase many or all of the following concerns can and will become a reality:
- Heat stress
- Widespread disease
In fact, the year 2005 set the all-time greenhouse gas record and levels continue to spiral upward.3 Scientific data shows that present-day changes, caused by increased temperatures, include the following:
If fossil fuel emissions continue at present or even higher rates, computer
generated climate models predict an additional warming of about 2-10 °F over
the next 100 years would be possible.
While there are those who debunk Global Warming believing Earth's temperature rise to be a natural, inter-glacial, phenomenon, most scientists tend to agree that a state of warming does exist and that humans are responsible for this temperature increase due to the addition of greenhouse gases into the atmosphere over a short period of time.
Then the movie The Day After Tomorrow comes along causing people to question, "Is this what will happen to our Earth's climate?" "Will these changes and catastrophic events occur and will they happen soon?" While the movie is based on a few sound scientific facts, the key fictional aspects of the film revolve around 2 adjectives: exaggerated and abrupt.
The plot of The Day After Tomorrow, inspired by The Coming Global Superstorm, a book written in 1999 by At Bell and Whitley Strieberis, is based on the following scenario: Earth is in a state of Global Warming but soon temperatures are about to drastically change. The Gulf Stream (North Atlantic drift), referred to in the movie as the "ocean conveyor belt", is disrupted and abruptly stops flowing due to the melting of the polar ice caps and an influx of large volumes of fresh water into the oceans. Since the Gulf Stream brings warm water from the tropics past the North American continent, then continues in a circular pattern across the Atlantic towards Western Europe, the climates of these continents are influenced by this warm water current. The disruption in the Gulf Stream circulation pattern results in a severe global deep freeze which sets the stage for the fictional drama in the film.
Abrupt Climate Change
When scientists speak about abrupt climate change they mean within five or
ten years up to a century. For on-screen drama, events was compressed to a couple
of days to weeks and, put simply, Ice Ages do not occur, nor do they retreat,
overnight. Climate change has happened a couple of times over the last 13,000
years but, unlike in the movie, never in a few days time.
A complete shut down of the Gulf Stream is possible and is believed to have happened in the geologic past however, it is not expected to occur within the 21st century. It would require a 9°F (5°C) average global temperature increase to create all the conditions necessary for a complete stoppage of this ocean current.
Can Global Warming lead to Global Cooling?
Yes it can, but not over several days as depicted in the movie. Over geologic
time Earth has gone through several ice ages followed by inter-glacial warming
periods. One possible cause of major periods of glaciation is a change in the
tilt of Earth's axis causing a corresponding change in the intensity and location
of sun insolation.
Shorter periods of much cooler temperatures have also occurred due to:
Scientists are well aware of the delicate balance between 'cloud cover, aerosols, solar radiation and greenhouse gases' and resulting climatic changes. It is absolutely possible that a state of global warming could lead to much colder temperatures for North America and Western Europe, however the timeframe for such an event would not be days or weeks but rather decades and the deep freeze would probably not reach Ice Age proportions.
Two distinct factors that can lead
to a state of cooling after a period of global warming are:
A change in Thermohaline Circulation and a change in Cloud Cover and Aerosols.
Oceanic Circulation Patterns - Thermohaline Circulation
|As depicted in the movie, a disruption to the pattern of circulation in the Gulf Stream is a possibility that is based on sound scientific concerns. The climates of North America and Europe are influenced by the Gulf Stream, a warm ocean current seen boxed in red on the illustration to the left. An interruption in this pattern of flow, either a decrease in the temperature of the Gulf Stream or a cessation of flow altogether would result in dramatic lowering of average temperatures for both continents. The melting of Arctic sea ice and resulting disturbance of the Gulf Stream ocean current, could bring colder weather to Europe and North America and a rise in temperature for the southern hemisphere.|
The unknown factor is how much of this Northern Hemisphere cooling would be
offset by simultaneous atmospheric global warming.
The Gulf Stream acts like a conveyor belt, moving in a circular pattern; a convection current driven by the density difference between warm, tropical salt water versus the colder water found at northern latitudes. An ocean current is like a river flowing through the ocean, at all times maintaining its integrity as one single body of water traveling on a distinct course.
As the Gulf Stream flows from equatorial regions, along the east coast of North America, two things happen. First, the warm current loses heat to the air, modifying coastal land temperatures. Second, because the Gulf Stream has lost heat, the current is now colder and so the water in current sinks. As the water sinks it flows back towards the tropics close to the ocean bottom.
Why is the melting of glacial ice such a problem for the Gulf Stream? Fresh water is less dense than salt water therefore, when a large volume of fresh water mixes with a salt water current, it may no longer be dense enough to sink. This would slow down, if not stop, the Gulf Stream from continuing its present course, the end result being that temperatures, normally modified by its path, would drastically change...for the colder.
In the past retreating glaciers dumped enough water into oceans to cause the North Atlantic branch of the Gulf Stream current to stop. This occurred around 8,200 and 12,700 years ago and both times the climate cooled.
Exactly how much fresh water is necessary to totally shut down the Gulf Stream is uncertain.
Experts say, "Watch the ice!" Continued melting of glacial ice is the most important telltale sign that Global Warming is taking place.
Cloud Cover and Aerosols
Higher temperatures increase the amount of cloud cover due to an increase in
higher evaporation rates of surface water.
Initially, the clouds will assist in trapping heat re-radiating from Earth's surface, adding to the global warming process and the continued rise in temperatures.
However, cloud cover actually works against global warming. Clouds tend to block and reflect back into space any incoming solar radiation, increasing Earth's albedo. After some time, global warming is no longer the main issue; instead global cooling conditions are a threat. How long the cooling will take after the initial warming is uncertain. Some models suggest approximately 50-100 years, but cooling could come much sooner.
Another critical factor in both the formation of thicker, denser clouds and the blocking of sun insolation is aerosols; small particulates such as ash, soot, skin cells, sea salt, sulfates, pollutants and dust. Some of these particulates are natural in origin. Since the industrial revolution however, humans have introduced an excessive amount of pollutants into the air through the burning of fossil fuels. It has been estimated that cloud cover may have increased up to 5% solely based on aerosol emissions contributed by humans.
Airborne aerosols are condenstion nuclei for cloud formation, causing water vapor to condense into more, but smaller, cloud droplets resulting in the thicker cloud cover seen over the past few decades. Ironically, though there is more cloud cover, there is less rain because the water droplets are too small and lightweight to fall.
In addition, aerosols tend to block and reflect sun energy even when they not part of a cloud formation.
Can Global Warming and Global Cooling
Result in Significant Changes in Weather Patterns?
Yes but once again, not as abruptly, nor to the exaggerated degree as seen in the movie. The next 6 sections deal with specific events in the film, exposing the good and the bad science for each meteorological disaster.
Tornadoes Hit Los Angeles
has never experienced a tornado higher than an
F1 on the F1 to F5 Fujita Scale nor have any fatalities occurred as a result
of one. Generally speaking, there is a recent increase in the
frequency of tornadoes in the United States. However, it must be pointed out
that technology used to detect and record tornadoes has significantly improved
along with an increase in more stations capable of analyzing tornadic activity.
Such a technological advance will inevitably detect the smaller, weaker and less damaging tornadoes that decades ago may have gone unrecorded. On the Fujita Scale there has actually been a decline in the more severe tornadoes, those ranking F3 through F5.
The erratic behavior of storms generated in a globally warmed climate cannot at this time be predicted with respect to exactly which locations will bear the brunt of increased violent weather activity. Therefore, references made in the film with respect to tornadoes in Los Angeles neither depart from a possible reality nor are they supported by historical fact or computer-generated models of future weather patterns.
Scientists do admit that more violent weather will occur with rising temperatures. This is due to the fact that an increase in evaporation rates provides the atmosphere with more water vapor, the essential fuel for storm activity.
Massive Storm in New Delhi and a Southward Advancing Ice Age
While it is true that some areas would experience significant drops in temperature due to a change in ocean current circulation, global warming will not necessarily bring about a worldwide Ice Age. Greenhouse gases trap heat and many locations on Earth will experience an increase in temperatures. Also, at this point in time, the Northern Hemisphere is receiving more incoming solar radiation than it did during the last ice Age 20,000 years ago.
Hurricanes and Global Warming
There has been a steady increase in Atlantic hurricane activity since 1995 and according to Kevin Trenberth and Dennis Shea of the National Center for Atmospheric Research (NCAR), "Global warming accounted for around half of the extra hurricane-fueling warmth in the waters of the tropical North Atlantic in 2005, while natural cycles were only a minor factor".5 Hurricane seasons are forecast to be more active as global temperatures continue to rise. Fueling the 2005 hurricanes were ocean surface water temperatures 1.7° F above the 1901-1970 average with global warming accounting for approximately 0.8° F of this temperature increase.
Super Cell Hurricanes in the Movie
In The Day After Tomorrow several Super Cell Storms present immediate threats to mankind. Bringing freezing, sub-zero temperatures across massive continents, all life in the path of these cyclones will perish immediately. The very formation of these super cells is one of the movie's most significant departures from scientific fact.
Sub Zero Freezing Temperatures and Super Cell Storms
As freezing air descends it warms and then rises. However in the movie this
law of physics is dismissed by one of the main characters, scientist Jack
Hall, when he states that the air in the center of the super cell is "simply
descending too quickly".
Apparently, this super cell is an area of such extreme low pressure that cold
air from the troposphere, (-150°F to -101°C) is rapidly sucked downward towards
Earth's surface, instantly freezing everything it comes in contact with. The
very concept defies Ideal Gas Laws.
When molecules of air descend they warm adiabatically due to compression. There are more air molecules concentrated closer to Earth's surface due to gravitational force. More air molecules means more molecular contact and collisions and this generates heat; a kinetic temperature, if you will, in proportion to the increase in kinetic energy.
Manhattan is Flooded by a Gigantic Tsunami
Actually, in the movie, the flooding of Manhattan is caused by a 300 foot "wind-driven
storm surge". An actual tsunami that could produce an oncoming wave of the
magnitude seen in the film would be caused by an underwater earthquake, a
landslide or a direct meteorite impact over the ocean. In reality winds speeds
would have to equal two times the speed of sound, or 1200 mph, in order to
create a storm surge and wave in proportion to the one that inundated Manhattan.
The force of the onslaught of water against buildings would immediately implode all submerged windows along with sections of wall leaving behind complete devastation with very little left standing, including the Statue of Liberty. After the rush of water receded there would be no survivors left seeking shelter in the library.
Also interesting is the fact that the huge wave approached Manhattan from the east where the borough of Queens is located. The Atlantic Ocean is located south of Manhattan. The nearest body of open ocean found due east of Manhattan is 120 miles away off the east end of Long Island.
So, enjoy the movie!
The Day After Tomorrow has fantastic special effects,
an interesting story line and some tense moments.
But, know the science!
Students and teachers may want to consider the following essays as a supporting
activity when students watch The Day After Tomorrow. Teachers may
find them helpful if the film will be shown in the classroom setting.
Students might consider doing one or more essays for extra science credit. Be sure to check with your instructor first.
1. Present arguments for and against a present state of Global Warming.
You can find many links to informative articles on this page: Earth Issues: Global Warming.
2. Presenting only documented scientific facts, research the effects that Global Warming will have on our planet. Include not only climate changes but also the effects that a rise in temperature will have on ice, sea levels, drought and weather patterns in general.
Some of the links that appear in the References and Credits section at the bottom of this document will assist you in your research.
3. CO2 Sequestration has been proposed as a possible natural intervention in the continued atmospheric accumulation of this greenhouse gas. It has also been proposed that humans might be able to sequester CO2 at depths within Earth's crust.
Research CO2 Sequestration, focusing on the following:
You can begin your research by exploring the following web pages:
Science and fiction of 'Day After Tomorrow' - Scroll down and open the interactive animation.
Here is the above MSNBC interactive link alone: MSNBC CO2 Sequestation Interactive
Geotimes - March 2003 - Storing Carbon in Earth
Oceans Found to Absorb Half of All Man-Made Carbon Dioxide
The Carbon Cycle What Goes Around Comes Around by John Arthur Harrison, Ph.D., Visionlearning
4. In the movie The Day After Tomorrow, the effects of Global Warming are exaggerated and fictionalized for dramatic purposes.
First, explore some of the fictional aspects of the film pointing out specific scientific errors, exaggerations and impossibilities presented to the viewing public.
Second, state whether anything in the movie was actually factual.
Third, considering the overabundance of fictionalized data in the movie, in your opinion do you see a positive effect the film might have on the attitudes of the viewing public?
Explain your answer.
You may find some ideas towards the bottom of this web page: "Day After Tomorrow" Ice Age "Impossible," Researcher Says
5. "Global Warming can ultimately lead to a state of Global Cooling." Explain how this could occur.
Supplementing what you have read in this document, you may want to consult the following web sites as you begin to explore this concept:
A Chilling Possibility
The Science of Abrupt Climate Change
References and Credits
At the completion of this document in November of 2006, all of the above reference links were active and fully functional. They will, however, not be maintained.
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