Why is carbon dioxide the key greenhouse gas that is monitored when there are other greenhouse gases in the atmosphere?

Answer 1

Carbon dioxide is not as abundant as water vapour, but in one important way it is a more important greenhouse gas because it is substantially responsible for the enhanced greenhouse effect that causes global warming and climate change. Carbon dioxide differs from water vapour in that human activities can increase its atmospheric concentration. When we burn fossil fuels such as coal, oil and natural gas, we add to the atmospheric concentration of carbon dioxide. This has been going on since the beginning of the Industrial Age, and the level of carbon dioxide in the atmosphere has increased in that time by more than 35 per cent, from the long-term range of 260-280 parts per million (ppm) to the present level of over 380 ppm.

As the atmospheric concentration of carbon dioxide increases, it traps more heat in the atmosphere and adds to global warming.

Answer 2

The important naturally occurring greenhouse gases are water vapour, carbon dioxide, methane and ozone. Carbon dioxide is considered to be the most important greenhouse gas for the enhanced greenhouse effect responsible for global warming, followed by methane.

The emphasis is on carbon dioxide because human activities, such as burning fossils (coal, oil and natural gas) are increasing the atmospheric cocetration of this gas at an alarming rate. Since the start of the Industrial Age, atmospheric carbon dioxide levels have increased by over 35 per cent, from the long-term range of 260-280 parts per million (ppm) to the present level of over 380 ppm. It is this rise that climate scinetists say is driving global warming.

Methane levels have also risen as a result of human activity, but have tended to level out in recent years. While we need to reduce methane emissions, the emphasis is on carbon dioxide simply because this is the greenhouse gas that presents the greatest danger.

Humans have no direct control over atmospheric concentrations of water vapour, although it can act as an enhancer for any global warming. Any additional atmospheric water vapour will only remain in the atmosphere for a few days before precipitating and restoring the previous balance. However, as average global temperatures rise, the atmosphere is able to hold more water vapour, which in turn can add to the enhanced greenhouse effect, raing temperatures further.

Ozone is present in the stratosphere and has actually been depleted in the recent past by human use of CFC gases, but there is no anthropogenic process likely to add to stratospheric ozone concentration. Ozone in the lower atmosphere generally does not last long enough to be of importance. Not only is ozone a greenhouse gas, it also protects us from damaging ultraviolet radiation from the sun, so its presence is important to us. The manufacture of CFC gases for industrial use has now been banned, and the ozone layer is gradually returning to normal.

Answer 3

Greenhouse gases need three atoms to vibrate and turn the infrared light into heat in the atmosphere. Oxygen (O2) has only two atoms per molecule, whereas carbon dioxide (CO2) and other greenhouse gases have three atoms or more.

Answer 4

Carbon dioxide is the primary greenhouse gas monitored because it is the most abundant and long-lasting in the atmosphere, contributing significantly to global warming. Other greenhouse gases, like methane and nitrous oxide, are also monitored, but carbon dioxide is the focus due to its widespread sources and influence on the Earth's climate system.