The article fail to explain how CO2 is a “greenhouse gas”. Water vapor is not a “greenhouse gas” either .. In fact there’s no such thing as “greenhouse gases”. Temperature is dictated, or given, as a function of mass, pressure and gravity regardless of the type of air molecules present and the concentration or ratio / mixture. Example Venus, 96% CO2., ref.: http://claesjohnson.blogspot.no/2015/02/venus-vs-earth-atmospheric-mass.html
Guest essay by Andy May
This version corrects an error in the average concentration of water vapor in the atmosphere.
The Earth’s dry atmosphere is 78% nitrogen, 21% oxygen and 0.9% argon. These are not greenhouse gases and they total 99.9%, leaving little space for the greenhouse gases methane, carbon dioxide and water vapor. The amount of water vapor in the atmosphere varies a lot with altitude and temperature. At low altitude and high temperatures (greater than 30°C or 86°F), over the ocean, it can reach 4.3% or more of the atmosphere and is less dense than dry air, causing it to rise. It will rise until the temperature is low enough for it to condense to a liquid or solid state and form clouds, rain or snow.
The amount of water vapor in the air drops to very close to zero when temperatures are below -10.0°C. Thus, the average volume of water vapor in the total atmosphere is variable and usually between 1% and 2%. So, excluding nitrogen, oxygen, water vapor and argon, we are left with 0.1% for everything else. Water vapor is a powerful radiative greenhouse gas and where the concentration is high, over the tropical oceans, it has a large radiative greenhouse effect. But, over land and in the cooler high latitudes, there is not enough of it to have a significant effect.
Carbon dioxide makes up 0.04% of the Earth’s atmosphere and is more evenly distributed than water vapor. Nearly all of the radiative greenhouse effect in dryer areas is due to carbon dioxide, with a small contribution from methane. Methane makes up about 0.00018% of the atmosphere on average, it is distributed unevenly like water vapor. Over swampy areas with a lot of vegetation or over farms it can be high. Over most of the Earth it is essentially zero. Methane is very reactive and is removed from the atmosphere quickly after it is released.
Carbon dioxide, water vapor and methane are the main radiative greenhouse trace gases in the atmosphere. There are some other trace gases, like neon, krypton and xenon, but they are not greenhouse gases. The IPCC (WG1 AR5) likes to add N2O (nitrous oxide or laughing gas) to the greenhouse list. It is a gas emitted from oceans, soils, fertilizer and burning biomass. It is present in the atmosphere in very low concentrations (0.000032%) and is very reactive. It is a rocket fuel and a race car gasoline additive, after all. This volatility results in a very short atmospheric lifetime, so it is hard to understand how it could have much of a greenhouse effect. The gas is so safe it is approved as a food additive and as a propellant for whipped cream! Further, even the IPCC admits on page 468 of WG1 AR5, the added nitrogen increases natural CO2 sinks (basically increases plant growth) so the net effect of nitrous oxide may be to reduce the greenhouse effect. This post will focus on CO2.
Carbon dioxide is emitted when animals and some microbes breathe, from the oceans (which contain 93% of the carbon dioxide on Earth) and when plants or fossil fuels are burned. In the 1990’s fossil fuel emissions were about 3% of the carbon dioxide entering the atmosphere according to the EPA. About half of the fossil fuel emissions were absorbed by the environment. Mostly the CO2 emissions were absorbed by the oceans, land plants, and marine algae. Additional carbon dioxide in the atmosphere is a powerful fertilizer, for a dramatic illustration of the effect, see this short youtube video. Figure 1 shows the impact of additional carbon dioxide on pine trees under controlled conditions. The four CO2 levels tested are, from left to right, 385 ppm, 535 ppm, 685 ppm, and 835 ppm.