Greenhouse Effect

What Does That Mean?

A greenhouse is a glass building that allows sunlight to enter but traps heat inside. Therefore, the building stays warm even when it is cold outside. Gases in the Earth's atmosphere also lets in light & trap the heat, which is where the term “greenhouse effect" comes in. The greenhouse effect works in a similar way as an actual greenhouse would, which is why the name stuck (1).

Chemical Process - Alkanes

Alkanes are often used as fuels such as in internal combustion engines and household heating mostly because they releease huge amounts of energy when they burn. Alkanes goes through combustion, which means that the reactions of combustion are highly exothermic. This is because of the large amount of energy released in forming the double bonds in CO2 and the bonds in H2O.

Alkanes burn in the presence of excess oxygen to produce carbon dioxide and water:

C3H8(g) + 5O2(g) --> 3CO2(g)

However, when oxygen supply is limited, carbon monoxide and water is produced:

2C3H8(g) + 7O2(g) --> 6CO(g) + 8H2O(g)

In conditions when oxygen is extremely limited, carbon will also be produced:

C3H8(g) + 2O2(g) --> 3C(s) + 4H2O(g)

The products of all the above reactions have a serious impact on the environment, which is why the burning of these and other fossil fuels on a very large scale is now widely recognized as a global problem. CO2 and H2O are both called greenhouse gases. Rising levels of CO2 are being largely implicated in the significant increase in average world temperatures (2).

Basic Understanding of the Greenhouse Effect

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Natural Process of the Greenhouse Effect

The natural process of the greenhouse effect is when the Sun's energy is absorbed by certain gases present in the atmosphere. This happens after it is reflected from the Earth's surface. When the Sun's energy reaches the Earth, around 51% of it is absorbed by the surface and the rest is either absorbed/reflected back to space. After reaching certain temperatures, the Earth releases heat and is then absorbed by particular gases. This energy is then released in all directions, warming the earth's surface and atmosphere (3).

The temperature of the Earth is maintained by a steady state balance between radiation received from the sun & energy leaving the Earth. The "natural" source for the greenhouse effect comes from carbon dioxide given by plants and animals. Clouds and water vapor are also contributors. An influence to this greenhouse effect could include the increase in temperatures. Another example could include the melting of polar ice caps and glaciers.

What is the greenhouse effect? | Global Ideas

Understanding the Natural Process More

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Anthropogenic Process of the Greenhouse Effect

There comes an anthropegenic process for the greenhouse effect. The source of this is through the burning of fossil fuels. Fossil fuels have been steadily increasing over the last 150 years. All of the chemicals that come from fossil fuels are in our atmosphere right now. Our main contribitor is Carbon Dioxide with other contributors such as Methane (CH4), CFC's, Ozone(O3), and Nitrous Oxide, and Water Vapor. These all add on to the anthropogenic process of the greenhouse effect.

After these gases are added to the atmosphere, they do not stay in one area. As air moves around the world, greenhouse gases become globally mixed. This means that the concentration of a greenhouse gas such as carbon dioxide is roughly the same no matter where you measure it. Even though some countries produce more greenhouse gases than others, emissions from every country contribute to the problem. That's one reason why climate change requires global action (1).

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Good or Bad ?

Scientists have known about the greenhouse effect since 1824, when Joseph Fourier calculated that the Earth would be much colder if it had no atmosphere. This greenhouse effect is what keeps the Earth's climate livable. Without it, the Earth's surface would be an average of about 60 degrees Fahrenheit cooler. In 1895, the Swedish chemist Svante Arrhenius discovered that humans could enhance the greenhouse effect by making carbon dioxide, a greenhouse gas. He kicked off 100 years of climate research that has given us a sophisticated understanding of global warming (4).

The Earth's surface temperature would be around 33 °C cooler than usual if there was no greenhouse effect. Our planet would be much like Mars, too cold for life. But if there are too many greenhouse gases can cause the temperature to increase out of control and our planet would be much like Venus's, too hot for life to ever form. The greenhouse effect is useful because trapping some of the energy keeps the temperatures on our planet mild and suitable for living things.

Greenhouse gases have just the right molecular structure to absorb infrared radiation that the Earth emits. It re-emits most of that infrared energy in all directions which spreads the heat back to our lands & oceans, also warming the atmosphere to its comfortable average temperature of 15°C (60°F). The greenhouse gases act somewhat as an actual greenhouse that helps plants grow. They let sunlight through on its way in from space, but intercept some of the infrared light on its way back out. The greenhouse effect, in ways, can be a good thing.

Although Earth’s average temperature fluctuates naturally, the current rapid rise in temperatures—global warming—is potentially harmful to life on Earth. The summer of 2003 was the hottest since 1500 and was responsible for 11,000 deaths in France alone. The National Science Foundation predicts that at the current rate of production of greenhouse gases, killer heat waves will be longer and more frequent (5). Climate scientists know how the natural greenhouse effect works on Earth and other planets. That is why they worry about what is happening as humans change the balance of greenhouse gases, for example by burning fossil fuels that release more CO2 to the air than what is released naturally (6).

Human activity will always cause an increase in the amount of greenhouse gases in the atmosphere. Carbon dioxide from the burning of fossil fuels (coal, oil, and natural gas) will always be the increase from humans. The extra greenhouse gas may be trapping too much heat, abnormally raising Earth’s temperatures.

Need More Understanding?

The Greenhouse Effect