At this time we all have heard of the evils of carbon dioxide (CO2) in the atmosphere. According to many sources, the CO2 blocks infrared radiation from leaving the earth for outer space, making the earth warm up.
Atmosphere levels of CO2 are around 300 parts per million. Less publicity is given to the 22000 parts per million of water vapor in the atmosphere. Water vapor is also a green house gas, as strong an infrared absorber as CO2. And there is better than 70 times as much water vapor in the air as there is CO2.
With 70% of the earth's surface covered by water, we are going to have a lot of water vapor in the air. Dry air will absorb as much water vapor as it likes, as it blows across the oceans. With the concentration of water vapor 70 times or more that of CO2, why do we worry about CO2? Even if man made CO2 was reduced to zero, the water vapor is still there, trapping heat, and warming the world.
Of the 300 PPM of CO2, much of it comes from natural causes like volcanoes and cannot be abated, no matter how drastic the restrictions on fuel burning become. A reduction of 100 PPM of CO2 (from 300 to 200 PPM) is the optimistic best that can be expected. It won't do anything for water vapor. So, today we have 22300 PPM of CO2 and water vapor. After drastic reductions in fuel use we get down to 22200 PPM. Is that going to save the world?
Few global warming enthusiasts talk much about water vapor.