How the Ocean is Regulating Global Warming

Greenhouse gases are not the only factors involved in global warming. The ocean plays a large part in the Earth's climate. Global warming can affect many aspects of our weather from the amount of precipitation to disasters such as hurricanes. It is important to understand both how global warming works and what the ocean's role in global warming is.

Global warming means different things to different people. For the purpose of this paper, "global warming is the observed increase in the average temperature of the Earth's atmosphere and oceans in recent decades." Although the average temperature may change due to natural factors, global warming in recent decades is believed to be connected to human activity. Burning fossil fuels, clearing land, agriculture, and many other human activities contribute to the increase of carbon dioxide into the atmosphere along with other greenhouse gases. Greenhouse gases allow solar radiation to pass through the atmosphere, but prevent most of the outgoing radiation from escaping. While this process is essential to our survival, it can also be harmful. An increase in global temperatures has lead to a rising sea level, changes in the amount of precipitation, floods, droughts, heat waves, tornados, and hurricanes. A few of the consequences of our actions pertaining to global warming include glacier retreat, species extinction, lower agricultural yields, and an increase in disease vectors.

The ocean plays many roles in global warming. The ocean can store energy as heat. Some of this heat is released as heat into the atmosphere and other energy is released as water vapor. The ocean covers over 70% of the Earth's surface and is over 97% of the surface water. Being so large, the ocean has high temperature inertia. That is, the ocean is very resistant to change and is not going to change temperature quickly. However, that does not mean that we do not have to be careful about our greenhouse gas emissions. Even a minor change in the temperature of the ocean can have dramatic consequences.

As the ocean covers the majority of the planet, most incoming heat comes into contact with the ocean. A portion of the incoming heat bounces off the ocean rather than going into it. This warms the atmosphere directly. Heat can also travel into the ocean and later rise up into the atmosphere to raise the Earth's temperature. This is what creates temperature gradients and winds. Winds push against the surface of the ocean and create horizontal currents. Vertical currents however, are controlled by salinity. Warm fresh water flows upward, while cold and salty water is denser and therefore sinks. Warm surface water is transported near the poles so that heat is more easily released into outer space. Enormous amounts of heat are transported in the ocean.

Oceans help to regulate heat so that areas near the oceans have moderate climates. Global climate modelers estimate that in the 20th century the ocean has reduced the expected surface warming due to rising greenhouse levels by about half. However, some scientists question the stability of the ocean circulation pattern. Rising temperatures, rising levels of greenhouse gases, and fresh water runoff from melting glaciers may adversely affect the ocean circulation pattern. Fresh water runoff affects the salinity of the ocean. The density of the surface water is lessened and the freezing point becomes higher. With the freezing point raising, it is possible to have more surface ice. This surface ice at the poles inhibits the release of heat back into the atmosphere and into outer space.

The ocean not only helps control temperature with its current system, it also helps to control greenhouse gases. The ocean can be both a source and a sink for greenhouse gases. The most abundant greenhouse gas on our planet is water vapor. Much of the heat that escapes from the ocean is released as water vapor. This can contribute to warming the planet. However, water vapor can also form clouds, which have a cooling affect. While water vapor is important, this cycle has been going on for a long time. Carbon dioxide may be the most important greenhouse gas due to its link with human activities. People are adding more carbon dioxide into the atmosphere. Currently, the majority of the carbon in the world is found in the ocean. The upper levels of the ocean contain lower levels of carbon than the deeper levels of the ocean. If this were to be reversed however, the ocean would become a source rather than a sink for carbon dioxide. Human activities may be able to disrupt this carbon dioxide sink. Many greenhouse gas concentrations have increased due to human activity and because we can control our activities, this is where the focus is generally brought in global warming discussions. "Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%." We cannot expect the ocean to control increasing greenhouse gas concentrations infinitely.

Currently, we are seeing a warmer atmosphere due to global warming. A warmer atmosphere can also translate into warmer oceans. Warmer oceans fuel disasters such as hurricanes. The Gulf of Mexico was 5 degrees Fahrenheit warmer during Hurricane Katrina. When ocean temperatures rise, so does the amount of water vapor in the air. Since 1970, the average ocean temperature has gone up one Fahrenheit degree. The average temperature of our atmosphere has also gone up one Fahrenheit degree. Globally, there has been no real increase in the frequency of hurricanes. However, people tend to live by the coasts more often nowadays, and when a whole city is wiped out it is viewed as more of a disaster. If no one lived in these areas, we would not be as concerned. Even though there has not been an actual increase in the frequency of hurricanes, there has been an increase in the intensity of hurricanes. We are seeing less level one, two, or three hurricanes. More level four and five hurricanes are appearing. To understand why global warming contributes to hurricanes having a greater intensity, we must understand how hurricanes work. Low pressure areas first draw in air from high pressure areas. Moist air is then warmed by the ocean. "If strong atmospheric winds don't break this cycle, the storm becomes a hurricane when spiraling air speeds reach 74 mi/h (119 km/h), forming a vortex of rain-laden clouds that circle a calm eye." If the ocean were not warm enough, a hurricane would not have formed. "For a hurricane to form, ocean water has to be at least 80 F (27 C) to a depth of 150 ft." If the increase in atmospheric temperatures continues, the temperature of the ocean will also continue to increase, and with increasing temperatures of the ocean we can expect to see more intense hurricanes in the future.

The ocean plays a very important role in global warming. Due to the ocean's resistance to change, temperatures have not increased as much as they would have otherwise. The ocean transports an enormous amount of heat so that it can escape the atmosphere at the poles. In addition, the ocean helps to protect the atmosphere from having an even greater amount of carbon dioxide accumulate. However, global warming has caused our ocean to become warmer. Slight changes produce drastic consequences, as we have seen with the recent hurricanes. Despite the changes in the intensity of our weather patterns due to the warmer ocean, we would see a far greater consequences if the ocean was not protecting us from ourselves.