Episode Three: Breaking Carbon Bonds
To get to the heart of the global warming story, the very heart of it, it turns out that the scientific explanation hangs on the behavior of one very particular atom — carbon.
The more you know about carbon, the more you'll know about global warming. In a five-part cartoon series, NPR's Robert Krulwich explains the chemistry behind this special atom. Here, episode 3:
OK, so you've already met the Carbon Atom. In episodes 1 and 2, we watched it bond with other atoms inside living creatures, large and small. When a carbon atom grabs on to a neighbor, it grabs tightly. There's energy in those bonds. Now let's get the energy out, starting with how about a carrot?
Yes, there are carbon atoms, energetically bonded, in a carrot. So how do I get that energy out? Simple. I eat the carrot. And when I do, the digestive juices in my stomach break the carbon bonds inside and release the energy in the form of calories. We call it digesting. But chemists would call this "bond breaking."
You may not realize it, but we do this all the time. We don't eat trees, of course; we can't digest wood. But we still can break its carbon bonds by setting a log on fire. Burning is a very common way of releasing the energy in carbon bonds. When you spark an engine, you are breaking bonds. In fact, one could argue that civilization started when this happened: when cave people felt cold, they got themselves some thermal energy — heat — by burning wood. Since then, we've been burning more and more carbon, not just from trees and vegetables, but from ancient life.
In episode 2, we watched primitive life forms die, fall to the bottom of the sea, and get all squished with the carbon inside still intact. That carbon is still there, millions of years later, with the energy still inside, which is why we call it "fossil" fuel. We can pull that oil, coal and natural gas out of the ground, set it on fire, and use the energy to power our cars and appliances, our factories and cities. Everybody's doing it, both the "industrialized" or well-off nations, and the "developing" countries.
And because most of our energy comes from fossil fuels, the more energy we consume, the more carbon we use.
But curiously, not every rich nation is hooked on carbon. Both France and Denmark, for example, broke their carbon addictions. France gets a whopping 80 percent of its energy from nuclear power, and Denmark gets about 20 percent from, of all things, the wind. All over the globe, nations are testing solar, hydroelectric and hydrogen power. But those sources tend to be more expensive than fossil fuels, and so carbon remains the favorite.
In fact, the rest of the world prefers carbon so strongly that within the next 10 years, developing countries are expected to burn more of it than the already-industrialized countries do.
Which creates a bit of a problem: When we dig up all that ancient carbon hiding below the Earth, when we break all those carbon bonds, we release a lot more carbon into our atmosphere. And carbon, as we've shown, doesn't like being alone. It is designed to bond with other atoms. So when we break carbon bonds, carbon seeks a new mate. Stay tuned, for episode 4, which we call Carbon in Love, next week.
Special thanks to Dan Nocera, chemistry professor, Massachusetts Institute of Technology, and NPR's Anil Mundra for research and design.