The Greenhouse Effect

I'm sure many of you have heard of the greenhouse effect or/and greenhouse gases. In this post I will give you a description of both and why understanding them is important. The greenhouse effect is a natural occurring process that has warmed the Earth for millions of years. Without the greenhouse effect, the earth’s surface would be around 30°C cooler.

The name greenhouse effect comes from … well, a greenhouse. A greenhouse is a house made of glass panels and is used to grow plants usually in the winter by allowing them to grow in a warm climate. The glass panels of the greenhouse let in light but keeps heat from escaping. Earth works in much the same way. But instead of glass panels, earth has greenhouse gases to trap heat in.

Greenhouse gases are a natural component of the atmosphere. Think of the atmosphere as the greenhouse’s frame and the greenhouse gases as the glass panels. Some greenhouse gases occur naturally in the atmosphere and the rest due to human activity. Greenhouse gases include water vapor, methane, carbon dioxide, nitrous oxide, and ozone.

The greenhouse effect is essential for humans to live on earth but issues arise when the greenhouse effect becomes stronger. As it becomes stronger the more consequences take place on earth. It gets stronger when more greenhouses gasses are built up in the atmosphere. These atmospheric gases have risen to levels higher than at any time in the last 420,000 years due to human activity. This has caused and will continue to cause earth to warm up higher than it naturally would, producing undesirable events to our lives.

Below is how the greenhouse effect works. Below that is how greenhouse gases are produced by humans.


(1) Solar radiation from the Sun passes through earth's atmosphere (The stuff that gives you a suntan or sunburn).

(2) Some solar radiation is blocked from entering earth and is sent back into space. Also, some of the solar radiation that makes its way to earth is reflected by earth's surface to space.

(3) The remaining solar radiation that was not reflected into space is solar energy that is absorbed by earth. This energy is what warms our earth's surface causing heat. This heat then in turn causes emissions of infrared radiation. Just think of infrared radiation as heat itself.

(4) Infrared radiation rises to the atmosphere. Some of the radiation is then absorbed and reemitted back to earth in all directions through greenhouse gas molecules. This in turn causes further warming to earth and part of the atmosphere (Troposphere). This cycle causes the surface to gain more heat and infrared radiation is then emitted starting the process again.

(5) Every time infrared radiation is emitted to the atmosphere, some of the radiation passes through the atmosphere and is lost in space.

Greenhouse Gasses
During the past two decades, about three-quarters of human-made carbon dioxide emissions were from burning fossil fuels such as oil, gas and coal. These fossil fuels are used to power our cars, heat our homes and run our factories. Deforestation is another producer and contributor to an increase in carbon dioxide. Trees burnt down release carbon dioxide. But if left uncut or burnt, trees would absorb carbon dioxide and release oxygen instead.

Methane which accounts for 9 percent of total emissions comes from landfills, coal mines, agriculture and many other sources. Methane has doubled in levels since 1750 and will double once again in 2050. Methane is released in the air through live stock, coal mining, drilling for oil, landfills and other sources.

Nitrous Oxide (aka laughing gas) is released naturally by the world’s oceans. It is also released into the atmosphere through fertilizers, sewage treatment plants, automobile exhaust and other sources.

Other typical greenhouse gases come from aerosol cans, refrigerators and air conditioners.

Conclusion
As we continue to emit carbon dioxide, methane and other greenhouse gases, our world as we know it will change. It has already started to change. Polar ice caps that act as one large mirror to solar radiation (see step 2 in the above diagram) are melting and increasing sea levels causing more severe floods. As the ice caps melt, the more solar radiation is absorbed by earth, in turn causes other ice caps to melt faster in a vicious cycle. The warmer temperature also causes heat waves that kill ecosystems, animals and people who are not used to or prepared for it.

As you have read this post, I hope you have thought of ways that you can reduce some of these greenhouse gases in your everyday life. In a future post, I will list ways everyone can reduce energy consumption and greenhouse gases.

References
Greenhouse effect. (2006, December 5). In Wikipedia, The Free Encyclopedia. Retrieved December 10, 2006, from http://en.wikipedia.org/w/index.php?title=Greenhouse_effect&oldid=92323608

"Greenhouse Effect," Microsoft® Encarta® Online Encyclopedia 2006 http://encarta.msn.com © 1997-2006 Microsoft Corporation. All Rights Reserved.

Greenhouse Gases, Climate Change, and Energy (2004, April 2). In EIA Brochures. Retrieved December 10, 2006, from http://www.eia.doe.gov/oiaf/1605/ggccebro/chapter1.html

Greenhouse Effect. (2006). In Envirolink. Retrieved December 10, 2006, from http://www.envirolink.org/topics.html?topic=Greenhouse20Effect&topicsku=2002116191249&topictype=subtopic