The greenhouse effect is pretty uncontroversial. It’s basic physics. And it’s why we can live on this planet.
In short, the greenhouse effect is the process by which light energy from the sun, upon passing through the atmosphere and reflecting off the earth, is partially blocked from leaving the atmosphere again. This is what warms the earth.
The basic principle is shown here.
For a quick reminder about what the greenhouse effect is, you can check out this animated diagram.
And if you want a little bit more detailed information, here is another good source.
Now if you really want something to sink your teeth into, try this slightly more technical and expansive site.
Scientific understanding of the basic physics of the greenhouse effect has been building for over 200 years. Contrary to what some seem to think, the greenhouse effect was not invented by Al Gore in 2006 when his movie, An Inconvenient Truth, was released. In fact, it was first named in 1827 by Joseph Fourier, who was a mathematician in Napoleon’s army (though I’m not really sure why Napoleon had a mathematician in his army). In any case, Fourier came up with the idea that outgoing infrared energy would be blocked by gases in the atmosphere, more or less analogous to a pane of glass in a greenhouse. This was built on the work of Sir William Herschel, who besides discovering the planet Uranus and writing symphonies had discovered in 1800 that energy can be transported by invisible infrared radiation.
In 1859 a British physicist named John Tyndall identified three main greenhouse gases – carbon dioxide (CO2), methane (CH4), and water vapor (H2O). He discovered that these gases absorb light energy, convert it to heat, and reradiate the heat away as infrared light.
Then in 1896 a Swedish scientist named Svante Arrhenius calculated that doubling the carbon dioxide concentration in the atmosphere would increase the temperature of the Earth by about 4-6°C on average (roughly 7-11°F). Despite having to make thousands of calculations by hand and the lack of measurement instruments at the time, Arrhenius’ estimate isn’t too far off from the more up-to-date estimates of 2-4.5°C (about 3.6-8°F). This increase in global warming due to the doubling of CO2 has come to be known as “climate sensitivity,” that is, how sensitive is climate to the increase in CO2 and other greenhouse gases. Still another guy, actually a dashing young Englishman named Guy, as in Guy Stewart Callendar, came around in 1938 to estimate this climate sensitivity to be about 2°C (about 3.6°F).
Wow, so it seems that the greenhouse effect is well known and built on knowledge that goes back to the work of scientists over two centuries ago. Knowledge that has expanded as technology has enhanced our ability to measure what we couldn’t measure and calculate by computer what Arrhenius and others could do only by hand. It wasn’t something Al Gore made up at all. There is, in fact, a whole body of science behind this simple concept.
As I noted at the beginning of this article, the greenhouse effect is why this planet supports life. Without it we would be like either Venus or Mars, either too hot or too cold. It is scientific fact that increasing greenhouse gases cause an increase in atmospheric temperature. Without this greenhouse effect, the surface temperature of the Earth would be much, much colder than it is! And that wouldn’t be good at all, at least for us humans and most other plants and animals.
For those who are into the mathematical proofs of such things, you can read “Proof of the Atmospheric Greenhouse Effect, ” a paper published in 2008 by physicist Arthur Smith.
That’s enough for today. In future posts I’ll take a look at the relative contributions of the various greenhouse gases, as well as other “forcings” that impact climate.
This post is part of a series in The Truth About Global Warming, located at climatetruth.gather.com, which is dedicated to explaining what we know, and what we don’t know, about climate change. Feel free to join the group and set settings to receive new articles when they are posted. The group includes an archive of past posts.
I also have set up a separate group called “Exposing Climate Denialism – A Guide to Tactics and Tall Tales,” located at climatelies.gather.com for those who want to read about some of the intentional disinformation used by climate denialists to confuse the public about the state of climate science. Feel free to join the group and set settings to receive new articles when they are posted. The group also includes an archive of past posts.