Why do human-made greenhouse gases matter when water vapor is the most potent greenhouse gas?
The Earth’s surface temperature would be about 34°C (61°F) colder than it is now if it were not for the natural heat trapping effect of greenhouse gases like carbon dioxide, methane, nitrous oxide, and water vapor. Indeed, water vapor is the most abundant and important of these naturally occurring greenhouse gases. In addition to its direct effect as a greenhouse gas, clouds formed from atmospheric water vapor also affect the heat balance of the Earth by reflecting sunlight (a cooling effect), and trapping infrared radiation (a heating effect). However, just because water vapor is the most important gas in creating the natural greenhouse effect does not mean that human- made greenhouse gases are unimportant. Over the past ten thousand years, the amounts of the various greenhouse gases in the Earth’s atmosphere remained relatively stable until a few centuries ago, when the concentrations of many of these gases began to increase due to industrialization, increasing demand for energy, ris
