which gas is most abundant in earth's current atmosphere
By far, the most abundant gas in the Earth's atmosphere is nitrogen, which accounts for about 78% of the mass of dry air. Oxygen is the next most abundant gas, present at levels of 20 to 21%. Although humid air seems like it contains a lot of water, the maximum amount of water vapor that air can hold is only about 4%. Abundance of Gases in the Atmosphere. This table lists the eleven most abundant gases in the lower portion of Earth's atmosphere (up to 25 km). While the percentage of nitrogen and oxygen are fairly stable, the amount of greenhouse gases changes and depends on location. Water vapor is extremely variable.