In this episode, No. 4 of our carbon series, we get to the heart of the matter.
If there's a growing concentration of CO2 in our atmosphere, (and there is) why does that make the planet warmer?
In our cartoon and in the slideshow below, you see the CO2 molecule getting hit by the heat energy from bouncing light. And instead of breaking up, it just gets excited (the chemical equivalent of getting warmer). That's essentially the chemical explanation for global warming.
As we've said all week, carbon's atomic structure, which gives it a tight grip on the oxygen atoms — fancifully called "Carbon In Love" in our cartoon — is the chemistry behind our climbing global temperatures.
Just To Review
To say this one more time (in case that went by a little fast), ordinarily, the Earth is warmed by the sun. When sunshine (or solar radiation) hits the Earth's surface, some of it is transformed into infrared light and reflected, or bounced, back into space. Think about sunshine glinting off a lake or snow or a white beach. As you can see in this slideshow from the University of California, San Diego ...
... if there are now extra quantities of carbon dioxide or other "greenhouse gases" gathered in the Earth's atmosphere, the extra gas can trap some of that infrared light, warming up those molecules and refracting that warmth around the earth.
Some say we are just getting more solar radiation from the sun — and indeed there are sunshine cycles — but the increase in carbon dioxide is almost certainly contributing.
As to why there is more CO2 in the atmosphere, well that's what people are arguing about. My own sense — which you may or may not share — is that the disappearance of trees in many parts of the world and all those new coal-burning, oil-burning, natural gas-burning plants plus factories, cars and appliances are certainly a significant cause. Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.