If carbon dioxide is heavier than air, how does it become a greenhouse gas?

Answer 1

shakespear (answerer 2) is quite wrong.

Although the atmosphere contains about a dozen different gases of different densities, the proportions of all these gases are virtually constant with height, right up to a height of about 100 km. This lower part of the atmosphere is sometimes called the 'heterosphere'.

It is only above 100 km that the lighter gases begin to predominate. All the climate impact takes place well below that height.

Answer 2

It becomes a green house gas because the government says it is. There are too many variables, too little evidence, and too little actual change in the environment to say that mankind is somehow effecting climate or that CO2 in particular is the culprit. CO2 is an innocuous gas that is used by plants to survive. It's what we exhale for goodness sake. The simple fact that it is heavier than air should illustrate that it will settle to the surface of the Earth and be "metabolized."

Answer 3

There is incredibly little carbon dioxide in the air - about 360 parts per million (0.04%). Its next to nothing. Even 3% of CO2 in air causes no more than breathlessness. So we are well over 100 times off health risk limits.

Answer 4

CO2 does not allow light and the heat energy to reflect back out into space. It traps the energy under the atmosphere and keeps it at the surface of the Earth. This is how it acts like a "green house." The warm air currents cannot pass their energy to the upper atmosphere where the heat can radiate back out into space.

Answer 5

carbon dioxide being heavier settles to the lower level and traps the terrestrial heat radiated from the earth's surface.
therefore it is a better greenhouse gas.