Global warming denialists claim that carbon dioxide (CO2) is nothing more than a beneficial trace gas that plants need to make food, and thus the increase in it over the past few decades is nothing to worry about. Let’s look at all the relevant facts:
- CO2 makes up about 380 ppm (parts per million) in the atmosphere.
- CO2 is essential for plants to do photosynthesis.
- CO2 is opaque to infrared radiation, thus making it a greenhouse gas.
- CO2 makes up most of the atmosphere of Venus, which has the worst greenhouse effect.
- CO2 is 1.5 times heavier than air in general, thus it would tend to be lower in the atmosphere than the nitrogen and oxygen that makes up most of it.
- In one cubic meter of Earth’s atmosphere at ground level the number of molecules is about ten to the 23rd power. (That’s 1 followed by 23 zero’s !!!)
Let’s do some basic math. Ten to the 23rd power divided by a million (ten to the 6th power) is ten to the 17th power. So if CO2 is indeed 380 ppm, that means there are 38 times ten to the 18th power molecules of CO2 in one cubic meter of air, or 38,000,000,000,000,000,000.
The troposphere, the lowest layer of the atmosphere where most of its weather occures, has an average depth of about 17 km (10 miles) in the middle latitudes. A kilometer is 1000 meters. So when we multiply (38 times ten to the 18th power) by (17 times ten to the 3rd power), we get about 65 times ten to the 22nd power. Obviously, the actual amount of CO2 in a column of air 17 km tall, one meter wide and one meter long would be less, due to CO2 concentrating more in the lower levels as noted before, but this is enough to show that CO2′s designation as a “trace gas” means in no way that it cannot have a profound influence on climate. It can because the actual number of CO2 molecules is so great. Only the inability of some people to grasp huge numbers makes them think that any gas that has less than 1% of the atmosphere is therefore insignificant. So it stands to reason that ANY increase in CO2 also leads to an increase in atmospheric temperatures.
Another thing to consider is how serious the greenhouse effect of Earth’s atmosphere really is. Without it, Earth’s average temperature would be about -18 degrees C, which is about 32 degrees C different from Earth’s actual average temperature (14 degrees C). Again, people who are not scientifically trained have difficulty grasping this, since they think of temperatures below “room temperture” (18 to 24 degrees C) as being cold. But in fact, it is quite warm compared to most of the universe. The cosmic microwave background (CMB) radiation, a leftover remnant of the Big Bang, is about 2.7 degrees above absolute zero, which is itself about −273 degrees C. Thus an object recieving radiation from no other source would still have a temperature of -270.45 degrees C. The Earth recieves radiation from the Sun that by itself adds about 252 degrees C to its temperature. That’s a LOT of heat! The greenhouse effect adds only about 1/8th more heat to Earth. But that is still enough to make the difference between a frigid, lifeless planet and one with oceans filled with life.
Still another thing to consider is that it can take only one degree difference in average temperature over several decades to turn a glacier into iceless land or open water. When water ice reaches its melting point, it ALL turns into liquid, thus the loss of a glacier at a certain location would mean a profound difference there. Imagine what the melting and disappearance of an entire polar ice cap would be! It might take decades or even centuries for the polar ice caps to melt as a result of global warming, but unless it is reversed, the melting is inevitable!