Sunday, July 02, 2017

From the ACS (American Chemical Society), founded in 1876, it is among the most trusted source of chemical organizations.

It’s true that water vapor (click here) is the largest contributor to the Earth’s greenhouse effect. On average, it probably accounts for about 60% of the warming effect. However, water vapor does not control the Earth’s temperature, but is instead controlled by the temperature. This is because the temperature of the surrounding atmosphere limits the maximum amount of water vapor the atmosphere can contain. If a volume of air contains its maximum amount of water vapor and the temperature is decreased, some of the water vapor will condense to form liquid water. This is why clouds form as warm air containing water vapor rises and cools at higher altitudes where the water condenses to the tiny droplets that make up clouds.

While it would be easy to simply call water vapor a greenhouse gas, it is only marginally so because it mitigates heat and does not cause it as other greenhouse gases do.

The greenhouse effect that has maintained the Earth’s temperature at a level warm enough for human civilization to develop over the past several millennia is controlled by non-condensable gases, mainly carbon dioxide, CO2, with smaller contributions from methane, CH4, nitrous oxide, N2O, and ozone, O3. Since the middle of the 20th century, small amounts of man-made gases, mostly chlorine- and fluorine-containing solvents and refrigerants, have been added to the mix. Because these gases are not condensable at atmospheric temperatures and pressures, the atmosphere can pack in much more of these gases . Thus, CO2 (as well as CH4, N2O, and O3) has been building up in the atmosphere since the Industrial Revolution when we began burning large amounts of fossil fuel....