Global Warming in a Nutshell
Occasionally it's good to step back from the details of global warming science and offer non-technical visitors a "Global Warming 101" perspective, sort of like The Big Picture, but starting from the very beginning and touching on many aspects of this broad topic. This article was revised and re-posted from Larry's website. The figures supplement the main text with key data, but they are mostly independent and reading the figures is not necessary for understanding the text, and vice versa.
The Greenhouse Effect
The Earth is a giant rock, hurtling through space in its orbit around the sun. It would be a frozen lifeless rock like the moon if not for the thin layer of atmosphere that traps solar energy and insulates the Earth's surface, like a transparent blanket.
The way the atmosphere traps solar energy is called (somewhat inaccurately) the Greenhouse Effect, because the effect is similar to a greenhouse or a closed car heating up in the sun. Sunlight comes in through a transparent window and is absorbed by whatever it hits, heating up the interior. Some of that heat is trapped inside, partly because glass is less transparent to heat than it is to light, and the temperature increases.
In the atmosphere, sunlight is absorbed by the Earth's surface or rooftops or whatever, and that energy is radiated as heat (infrared energy) back toward space. Most of that heat doesn't make it to space, because it gets absorbed by certain gases in the atmosphere, mainly water vapor, carbon dioxide, and methane.
Normally this is a good thing, because without the heat trapped in the atmosphere by "greenhouse gases", our planet would be frozen. But it turns out that too much of a good thing is a bad thing. If extra carbon dioxide that is not part of the natural carbon cycle is added to the atmosphere, then extra heat is trapped that would otherwise escape to space, and the atmosphere gets warmer.
So in a nutshell, Global Warming is an increase in the Earth's overall average temperature caused by adding extra carbon dioxide and other greenhouse gases to the atmosphere that absorb and trap heat.
Article continues at ENN affiliate, Global Warming is Real
Earth image via Shutterstock