How Global Warming Could Cause an Ice Age
Or：What scientific knowledge do we learn from the movie, “The Day After Tomorrow”？ Wang Yao-Wei （Daniel）
March 10, 2006
What is global warming? This is a very popular issue all over the world. In order to learn more about global warming, we should go through what makes the earth warm and how warming affects the earth. The first thing we need to be familiar with is the greenhouse effect. It plays an important part in controlling the earth temperature. Thus, we need to know how the greenhouse effect is to know how it could affect the earth. Global warming and greenhouse effect：
The greenhouse effects is caused when surface and atmosphere absorb the sun’s short-wave radiation then release it as long-wave radiation to the atmosphere and the surface. That means the greenhouse effect gases are in the air and they affect the radiation. Because of the greenhouse effect gases, the atmosphere absorbs the infrared radiation and reflects them to the surface. So at the surface, the surface absorbs the infrared radiation and emits it back to the atmosphere. According to this kind of process, the amount of the radiation that the atmosphere absorbs is more than it releases. Hence, the earth becomes warmer. We could be experiencing this “greenhouse effect.” The percentage of greenhouse effect gases only totals 1%. They include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbon (CFC), water (H2O) and ozone (O3). Carbon dioxide is released into the atmosphere by using the fossil fuels, this kind of greenhouse effect gas enters into the atmosphere in a big number. And carbon dioxide will absorb the radiation reflected from the surface. Next we will talk about the two most important issues that are occurred by the greenhouse effect. The first one is the changing of the climate. Global warming is the main cause. From their article, Titus, et. al. (1987). They said that the greenhouse effect will make the earth’s temperature rise. They also said the rates of climate change are about 15 to 40 times faster than ever before. On average, the earth’s temperature will raise 3℃ every hundred years. To put it simply, the climate that we know now would be very different in the future. It will become warmer in the summer and colder in the winter. The second thing is the rising sea level. Common sense, tell us that because of the global warming, the ice from the South Pole and North Pole will melt. And this is definitely occurring right now. The increasing temperature of both poles may melt the ice from the lands and the mountains and make the sea level rise about 0.2 to 1.4 meters. Many cities will be flooded by the rising sea level. Now that we have some basic scientific knowledge about global warming and how it affects the, now we can consider the scenario presented in the movie “The Day After tomorrow”. Do we still have the day after tomorrow? This is what I want to talk about in the next paragraph. In the movie “The Day After Tomorrow”, we see that the land was covered by ice and the earth enters the next ice age early. I want to focus on this part’s, how global warming could cause an ice age. Will the climate change so fast that human beings cannot predict？We will know after talking about this. The movie mentioned that the big climate change is due to the extreme variation of the North Atlantic Ocean current. And this is the question. How can the ocean current affect the climate? It should be global warming, right？ In fact, it is global warming. But global warming is the background of the climate change. So I could tell that the ocean currents have their own direction to flow. Although the surface of the sea we see is clam, there are lots of differences under the seas. The flow of the water depends on its mass. Its density, temperature, and concentration will influence the ocean currents. The ocean currents play an important part to modulate the heat energy on the surface. For example, the lower latitude ocean currents will bring the warmer water to the higher latitude areas. That means the ocean current control the heat balance and they may affect the climate. So the greenhouse effect is one part of global warming and it makes the South Pole ice melt. And we know that ocean current may change the climate. Now we have to connect two things and make it relate to the movie. A large volume of fresh water goes into the sea and dilutes the salt water concentration of the sea because of the melting of the icebergs. So the melting water affects the ocean current and destroys the balance of the heat on the surface. Because the heat balance doesn’t exist anymore, the climate changes rapidly and causes an ice age. This is what the movie says. From ancient climate research, the last ice age ended about 12,000 years ago. In fact, the earth has the same scenario like the movie about 12,000 years ago. On the ending of the last ice age, the earth’s temperature was getting warmer and warmer. But at that time, the scientists found that the earth was suddenly thrust into an ice age. This accidental episode was called “Younger Dryas” event. Why was the recovering temperature disturbed by the “Younger Dryas” event? Scientists believe that it was because of the ocean circulation. The warm water is brought from tropics to the two poles of the earth and the colder water was brought form the poles to the tropics by ocean current. We could have an example from Parrott, J.K. (2004). “ When the warm water moves to the north, its temperature become lower and the mass of water starts to sink. On the other side, the salt-free sea ice is formed and make it original ocean current has higher salt component. This process was called thermohaline circulation.” Because the melting ices cut down the transportation of the heat, the decreasing concentration of salt water stops the global thermohaline circulation. It reduces the heat transportation and makes the earth enter an ice age again. We could use this point of view to explain the phenomena from the movie. But think clearly, these incidences were recorded from the ancient climate records. We could say that they still have some useful lessons to be learned. We are still trying to analyze these data and figure out when these events will happen. But after understanding these mechanisms, scientists must face the hard scientific facts. Briefly, except the earth’s climate have the natural processes and conditions to force to an ice age. The human’s behaviors, like industry revolution still impact on our weather. From the movie “The Day After Tomorrow” that the climate changes to freeze rapidly and the lands are covered by the ice. The human impact on the earth is detriment to the earth’s climate. But from the “Do warming oceans portend an ice age?” there is a sentence that it shows that “"I don't believe the Earth can plummet into an ice age today, but human-caused global warming has the ability to affect climate in ways we haven't seen before and do it very quickly," concludes from “Do warming ocean portend an ice age?” (2004). That means it is safe to say that the global warming will not lead to the onset of a new ice age, said from Weaver, A. J., & Hillaire-Marcel, C. (2004). No matter what our future will be, we have to preserve and protect our own earth as best as we can. We could reduce the pollutions of the global warming gases and improve energy efficiency. Finding and using renewable energy resources and unclear energy. There are different ways to lower the pollutants that are man made. But we should realize a very important thing is that we only have one earth.
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