- Global Warming Conference -
-UN Conference on Global Warming-
0:06:20 - The main part of the movie kicks off with the "UN Conference on Global Warming, New Delhi". The UN Conferences on Global Warming do actually take place where countries across the globe discuss, what else, global warming. In real life, the conferences initially started in 1992 with the United Nations Framework Convention on Climate Change (UNFCCC) which was a treaty where countries got together and vowed to make a difference in climate change (UNFCCC.int). Following that, the UN set up an annual Conferences on the Parties (COP) about Global Warming. The COP started in 1995 in Berlin and continues to run up through today (as of 2013 when this is being written). In 2002 the conference was held in New Delhi (COP 8), as depicted in the movie (UNFCCC.int). The conference took place from October 23rd - November 1st. I find this amazing that they actually went to that level of detail to get this right.
- Climate Shift 10,000 Years Ago -
0:06:21 - Jack Hall, which is the main character of the story (Quaid), goes on to talk at the conference about a "cataclysmic climate shift that occurred around 10,000 years ago". 10,000 years ago is the time when the Pleistocene epoch (the "Ice Age") approximately ended (it is actually dated to 11,700 years ago) and the Holocene (the age of humans) began. Generally, the climate has been fairly stable over the last 10,000 years in what is considered a "warm period" following an ice age (Nature). This stable period actually began around 10,000 years ago following a series of abrupt oscillations in the climate from 80,000 to 18,000 years ago (see Figure to left). As in the movie, these numbers are based on data obtained in ice cores, but this time they are mostly from Greenland. It has also been suggested recently that the climate was shifted about 10,000 years ago due to the extinction of the mammoths, in part due to humans, which changed the vegetation across the northern regions, which would have caused the warming of these northern regions like Siberia (Live Science).
There is also an event that took place around 10,700 years ago termed the Younger Dryas, which seems to be a direct result of polar melting. This polar melting caused to temperature of Southern Greenland to rise by 7°C in about 50 years (Dansgaard et al., 1989). This event ushered in the warming that is known from 10,000 years onward. However you slice it, it appears that a shift in the climate did take place 10,000 years ago, as recorded in the ice cores. Although the shift seems to be more towards balance than out of balance.
The problem though is that Jack goes on to state that what was detected in the ice cores, in the movie, was a concentration of natural green house gases that resulted in a smaller ice age that lasted 200 years. I have found no evidence of such an ice age. As mentioned in the previous paragraphs, I have found just the opposite, that 10,000 years ago was the beginning of stability in the climate. The ice age ended around 11,700 years ago and the glaciers took about 2,000 years to melt. That melting is what is visible as the strong uptick in the graph (to the left) before the final leveling out. This even led to climates being warmer and drier than they are today from 9,000 to 5,000 years ago (snu.ac.kr). So other than getting the timing right, the movie completely made up the "cataclysmic" event.
- Warming Leads to Cooling -
0:06:43 - The next part is basically the explanation for the entire movie. It is stated that global warming can trigger a cooling trend, i.e., increased temperatures can lead to an ice age. Having taken Glacial Geology I have learned (previous to the movie coming out) that this is actually correct, no matter how convoluted it may sound. The reason for this is that the temperature of the Earth is maintained by the Gulf Stream and it's northern extension, the North Atlantic Current, along with the rest of the global oceanic circulation currents. These "streams" are bodies of water within the ocean that have different temperature and chemical properties than the surrounding oceanic water. This causes countries like the UK and Norway to generally have warmer climates than their counterparts along the same latitude (Miami.edu). The result of an increasing temperature of the Earth (both as a result of global climate change, and its subset global warming) is that the ice sheets in Greenland are melting. The melting of the ice sheets releases a large amount of cold, fresh water into the northern Atlantic. Due to the low salt content the freshwater floats on top of the saltwater. If you look at the map (figure to the right), you can see that the warm Gulf of Mexico waters are carried up to the coast of England on the surface (red lines) then drop to the bottom of the ocean (blue lines) and circulate south along the coast of the Americas. The sudden influx of cold, fresh water into the North Atlantic could potentially cause the North Atlantic Current, which is salt water, to get cut off. This would shut down the conveyor belt of oceanic water mixing globally as we know it. Eventually it would get restarted, although likely in a different but similar pattern, but the immediate effect would be to cut if off completely. Without the warmer water being circulated to the poles, the entire Earth's temperature would begin to drop. So, the basic premise of the movie is correct, a warming trend could lead to another ice age.
The main problem with this part of the movie though, is the map that they use (pictured left, arrows added to show direction of the movement as emphasized in the movie). It is a much simplified version of the already simplified figure above and to the right. The current they show of the Gulf Stream is actually running along the coast of Africa and Europe instead of from the Gulf of Mexico to England.
0:07:10 - The timeline of all of this occurring is also brought up in the movie which is a major flaw of the movie itself. Hall is asked when he thought this could happen and acting like a scientist he gives his best estimate, which could be any time really, anything from 100 years to 1,000 years. he stipulates though that something needs to be done today to help curb future catastrophes. Although, the timeline mentioned by Hall is feasible, this could take place over the course of the next few thousand years, the timeline of the movie takes a different course and is much sped up from that that is predicted.
0:32:23 - The North Atlantic Current is said to rely on the delicate balance between salt and fresh water. The movie then goes on to state that the current has reached a "critical desalinization point" due to the amount of fresh water dumped into the ocean by the melting of the polar ice, i.e. the Greenland Ice Sheet. What is meant by this "desalinization point"? Restating a little of what I said before, the way that the water circulation works in the North Atlantic is that warm water is carried north from the Gulf of Mexico. As it reaches the northern latitudes it then sinks. The heavier water is rich in salt, making it denser. Fresh water from rainwater and the melting of ice and snow, like from glaciers, is less dense than saltwater and therefore will actually float on top of seawater until enough mixing has taken place. This happens at all river deltas where fresh and salt water meet. What the movie is predicting is that the fresh water content has reached a maximum where suddenly the current is no longer dropping down into the ocean, cutting off oceanic circulation for the entire planet, or at least rerouting it, cutting off the warmer waters to the north.
This scenario is a distinct possibility. The melting of the ice caps could have a significant impact on the planet, plunging us into a colder climate due to the melting of the polar ice caps (NASA). The problem though, is that if this were to happen it would take decades at the least to feel any significant impacts. The global temperature is not going to drop to freezing overnight, which is literally what the movie is stating. The globe is such a large place that it takes a large time for anything to change. Think of a truck versus a car driving down the highway. The larger the vehicle the more time it takes to alter its course.
- The Kyoto Accord -
0:07:10 - The Kyoto Accord is the next thing brought up in the movie. A controversial international treaty among nations that was started in 1997 and officially adopted in 2005. The purpose of the treaty was to legally bind countries to alter their greenhouse gas emissions (UNFCCC.int). The main controversy was that the United States would not back the treaty due to the harm it would place on the economy by putting an unwanted demand on industry (Newsmax.com) and that it did not include China and other fast growing developing countries, which were responsible for a large percentage of the global greenhouse gases (USAToday). Since the US is one of the largest producer of greenhouse gas emissions, this was seen as a possible failure of the document, although it has gone through without US backing. The depiction of the delegate from the United States shown in the movie is supposed to represent George W. Bush's rejection of the Accord due to the reasons that are mentioned in the movie.