My 4th grade level Science class on Global Warming!
Ok class this is the first of many lessons on global warming. I'd like everyone to pay attention here and save your questions for the end of the class?
Does anyone know what makes the Earth warm?
That's right Sinch it's the sun!
Does anyone know what the Geenhouse effect is?
Well the Greenhouse effect is a bunch of different gases in our atmosphere that act like a blanket to keep the Earth warm. Light form the sun penetrates the blanket pretty well and warms the Earth below. The Earth eventually radiates that heat back up and a lot of that heat gets caught in the blanket.
Is this a good thing or a bad thing?
Wrong devoish, this is in fact a very good thing because without the Greenhouse effect, the Earth would be 60 degrees colder than it is now! A lot of our planet would be unlivable without the Greenhouse effect.
Ok so lately there has been a group led by Al Gore, (Inventor of the internet) Kenneth Lay (Who hasn't been as active from his prison cell), Goldman Sachs (Upstanding financial intitution with no ties to the government) and Blythe Masters (Inventor of the very popular Credit Default Swaps.) This group is stating that there is an emergency of a massive scale and a problem with Greenhouse effect! They say that the mean old businesses are pumping too much Carbon gas into the atmosphere and it is causing the blanket to get thicker and cause the Earth to get hotter. This would be a very bad thing if true so we should investigate...
First we should see if we are in fact getting hotter, and we are. Temperature records show that since a very cold period called the "Little Ice Age we have been consistently getting warmer. But since we should be expected to get warmer after a cold period, we should check and see if we have ever been as hot as we are now and in fact we have been this hot many, many, times. The last time was about the same time that Columbus set sail for the new world and we are not quite as hot as we were back then.
Ok so the above information doesn't seem to support anything to worry about yet, but we should be dilligent! Lets look for a link between Carbon and warming.
Fortunately the "Inventor of the Internet" wrote a book called an Inconvienient Truth" (On sale at your local bookstore for $19.95) In that book he did show a rise in Carbon level along with the rise in temperature. Finally we are getting somewhere class! Unfortunately what "Mr Locked-box" didn't mention was that the increase in Carbon lagged the increase in temperature. So it appears that the extra Carbon is a result of the warmer temperature and not the other way around. How could this be? We'll get to this in a moment class.
Next, let's try to isolate Carbon as a culprit. The first question we should ask is that if this is most Carbon we've had in the atmosphere before. It's not even close in this dept! We currently have 380 ppm of Carbon in the atmosphere and back in the time of the Dinosuars (Jurassic Period) it was at 1800 ppm. Before that in the Cambrian period it was at a whopping 7000 ppm! there was even an Ice Age known as the Ordovician period where Carbon levels were at 4400 ppm. In an Ice Age!
Ok, well that isn't much help. It seems like Carbon makes up a very tiny amount of the atmosphere at the moment. Lets see if we can find out how much heat it can absorb. Fortunately we can measure this exactly! If you take visible light and shine it through CO2 you can measure what's called it's absorbtion spectrum. Everything has an absorbtion spectrum. This measures the frequencies that the CO2 absorbs and therefore the heat it can absorb. CO2 absorbs the following 3 narrow bands of wavelengths of 2.7, 4.3 and 15 microns respectively. Added together, (and I'm being generous here.), that means that Carbon could absorb about 8% of all the IR spectrum of light passing through it. Ok so we have something that is only 0.038% of the atmosphere that can absorb only 8% of the heat passing through it. This doesn't sound like it has the potential to damage to me. But that's all for today class!
In the next class we are going to explain the Greenhouse effect further and get into the reason that Carbon is more of an effect of warming than it is a cause.