What is the greenhouse effect?

Our atmosphere is just a thin layer of gas, but it and its greenhouse effect make life on Earth possible – and could destroy life as we know it.
Greenhouse gases trap some of the sun\'s energy within our atmosphere and increase the temperature .../ Credits: Shutterstock

The sun is the Earth’s primary energy source, a burning star so hot that we can feel its heat from over 150 million kilometers away.

About one third of this solar energy is reflected back into the universe by shimmering glaciers, water and other bright surfaces. Two thirds, however, is absorbed by the Earth, thus warming land, oceans, and the atmosphere.

Much of this heat radiates back out into space, but some of it is stored in the atmosphere. This process is called the greenhouse effect. Without it, the Earth’s average temperature would be a chilly -18 degrees Celsius, despite the sun’s constant energy supply.

In a world like this, life on Earth would probably have never emerged from the sea. Thanks to the greenhouse effect, however, we enjoy a comfortable average temperature of 14 degrees Celsius.

So, how does it work?

Radiator in space

Only about half of all solar energy that reaches the Earth is infrared radiation, which causes warming. The other half only translates into heat once it hits Earth and is reflected back into space as infrared radiation.

This transformation of solar radiation into infrared radiation is crucial, because infrared radiation can be absorbed by the atmosphere. Like a radiator in the middle of a room, our atmosphere radiates this heat in all directions.How is this radiation absorbed?

Sunrays enter a greenhouse, heat up the ground, which, in turn, heats up the air inside the greenhouse. The glass roof and walls trap that warm air and temperatures increase.

Earth has no glass walls, but it does have the atmosphere, and within the atmosphere it has greenhouse gases.

Ninety-eight percent of the Earth’s atmosphere is made up of nitrogen, oxygen, and argon. But they do not absorb much infrared radiation, and don't contribute to the greenhouse effect.

Greenhouse gases like water vapour, carbon dioxide, ozone, methane, nitrous oxide, and chlorofluorocarbons do absorb heat, and thus increase atmospheric temperatures.

Studies indicate that until some 2.7 billion years ago, there was so much carbon dioxide (CO2) and methane in our atmosphere that average temperatures on Earth were as high as 70 degrees Celsius.

But bacteria and plants slowly turned CO2 into oxygen and the concentration of CO2 in our current atmosphere dropped to just about 0.038 percent or 383 parts per million (ppm).

Minuscule changes, global impact

Slight changes in the amounts of carbon dioxide in the atmosphere are already changing the way our planetary heating system works.

Measurements of carbon dioxide amounts from Mauna Loa Observatory in Hawaii show that CO2 has increased from about 313ppm in 1960 to as high as 400ppm in 2013.

That means for every million particles in our atmosphere, there are now 62 CO2 particles more than in 1960. Even if this does not seem like much, scientists say this increase—most probably caused by human activities—is mainly responsible for rising global temperatures throughout the last decades.

Even if the term “greenhouse effect” is somewhat of a misnomer, it still might be a useful handle from which the public can grasp an otherwise intricate natural process.

Most people can relate to how hot and stuffy a greenhouse can get. Now that the Earth has started to heat up, we realize that our own global greenhouse has no window that we can open to catch some fresh air.

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Comments (92)

lankeswar: 29.02.2012, 10:25

essay was simple &good. if you extended & gone deep through subject it will be so good.

dev dongol: 17.01.2012, 07:10

Dear Will Haas
Please consult elementary level science to learn about principle and methods of heat transmission, green house making, insulation green house gases etc. Our atmosphere is not closed but open to cosmos so gases cannot behave as GHG and insulator, the air of our atmosphere is continuously transmitting heat (by convection method only, not conduction) to the space and man has no control over it. The sun is heating the earth continuously; now it is getting warmer because we have disturbed the very effective cooling system of nature, the rain cycle. Details in the blog: devbahadurdongol.blogspot.com

Will Haas: 11.01.2012, 09:09

In a green house as in the earth's atmosphere the primary transfer of heat from the surface to the air is through conduction and convection. This means that Nitrogen and Oxygen are really the primary green house gasses. I use such a convection system to heat my house. The atmosphere acts as a thermal insulator and along with the heat capacity properties of the earth the oceans and the atmosphere the earth is kept warm.

dev dongol: 04.12.2011, 14:56

Considering the fluid properties of gases, physical properties of our climatic atmosphere and heat transmision principle, it is impossible to happen as shown in the diagram above.

dev dongol: 04.12.2011, 14:50

Dear Yoggi ji,

IPCC, KYOTO protocol, UNFCCC, COP17 etc are ALL MISLEADING the world by accusing the gases for GW / CC. There is not a single scientific explanation to prove the claim is correct. They are the scientists without science? Gases are actually helping the earth to cool down by convection method of heat transmission. So, dear Yoggi ji if you wish details of causes and solutions to CC please visit devbahadurdongol.blogspot.com

yoggi: 04.12.2011, 12:55

but how is carbon dioxide responsible for global warming?

dev dongol: 12.10.2011, 02:16

Dear shradha maharaj Ji,

If you don’t mind I humbly request you for some of your scientific research works on GW and CC – blog url or any other link will do. If possible please make me available through email, I shall be grateful to you.

For solutions to CC and Power crisis please visit my blog, url is: devbahadurdongol.blogspot.com
My email address is in the blog also: dev.dangol@yahoo.co.uk

Please clarify these following words, I don’t think you are abusing someone else, are you?
Insparational, valuble, dought

Best Regards,

Dr. Dev

shradha maharaj: 11.10.2011, 18:16

i for one have researched the topic of global warming for a long time and i must say it has both been an insparational but vile task. for every article someone has composed there has always been some tom, dick or harry out there who always challenge that person...............well, I can truly say that out of all this reseach, i have found nothing scientifically valuble only this: stupid people in the world will always be sure that they are right even though they are not, but the intellegent ones will always dought themselves even when they know they are right.

dev dongol: 23.09.2011, 07:53

Please read my comment below and consult elementary science teacher if necessary. Any fluid like CO2 when heated goes up, does not stay at the lower region or where it is heated, but releases heat in the colder surroundings - heat transmission principle and covection method of heat teransfer. So called green house gases are just imaginary, can't exist in nature.Nitrogen gas is about 2700 times more than CO2 and O2 is about 700 times more than CO2, don't they and other gases trap heat? Earth is heated and gases are cooling the earth by convection method which is not enough so nature has another effective cooling system - the rain cycle which mankind has disturbed too much.

Scientific reason for Ozone loss? if not millions of jet flights. Ozone is O2 and jet needs O2 to burn the fuel.
Higher altitude is colder because the atmosphere is thinner, thinner the colder. Vacuum space is coldest and can absorb any amount of heat.

For solutions to CC and Power crisis please visit my blog, url is: devbahadurdongol.blogspot.com

If any body wants summary please email me. email address is in the blog also: dev.dangol@yahoo.co.uk


Michael Grimm (editor): 22.09.2011, 18:24

@Twallib, thank you very much for your comment. To learn more about how greenhouse gases behave in the atmosphere you may want to check our animation on the lifespan of 3 greenhouse gases:

BTW one of the alleged greenhouse effects is not warming of the upper regions of the atmosphere but exactly the opposite: upper regions of the atmosphere are cooling because these gases trapp heat in lower regions.

There are indications that emissions from cars and industrial plants could contribute to a cooling of high-altitude atmospheric layers. As greenhouse gases such as CO2 dam up heat radiation from the Earth in the lower atmosphere, the high altitudes tend to cool. This could be a reason for recent ozone loss over the Arctic:

Stay around for more information and new findings on climate change, global warming especially as we approach COP 17 in Durban.

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