Greenhouse gases are the gases that are responsible for global warming & climate change. By absorbing the heat radiating from the earth and transmitting it back to earth, these gases heat up the lower atmosphere and earth’s surface.
All talk of greenhouse gases is focussed only on CO2.
So, is CO2 the only greenhouse gas?
Not at all!
CO2 is one of the many greenhouse gases that reach the atmosphere. Some of the other prominent greenhouse gases include methane, nitrous oxide, ozone and fluorinated gases – sulfur hexafluoride, hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs).
In fact, you will be surprised, even water vapour is a gas that can cause the greenhouse effect! n fact, water vapour constitutes the largest segment amongst the greenhouse gases.
So, why the heck is the world after CO2?
The main reason has to do with the amount of residence time that CO2 has in the atmosphere.
Putting it simply: CO2 sticks around for a long, long time.
CO2 remains in the atmosphere longer than the other major heat-trapping gases emitted.
It takes about a decade for methane (CH4) emissions to leave the atmosphere (it actually converts into…CO2!) and about a century for nitrous oxide (N2O).
In the case of CO2, most of what we emit today will stay on for about a hundred years; about 20 percent will still exist in the atmosphere approximately 800 years from now!
This literally means that the heat-trapping CO2 we release today from our cars and power plants are setting the climate our children and grandchildren will inherit.
CO2’s long life in the atmosphere provides the clearest possible rationale for reducing our CO2 emissions without delay.
What about water vapor?
Water vapor is the most abundant heat-trapping gas, but rarely discussed when considering human-induced climate change. The principal reason is that water vapor has a short cycle in the atmosphere (a few days) before it is incorporated into weather events and falls to Earth, so it cannot build up in the atmosphere in the same way as CO2 does.
What about CFCs?
Chlorofluorocarbons (CFCs) are indeed as harmful as a greenhouse gas, but are now largely regulated in production and release to the atmosphere by international agreements. As a result, these are not expected to create as much harm as CO2 in the context of climate change/global warming.
So, there are other culprits, but CO2 is the greenhouse villain we should be most worried about.
For those who wish to understand the effect of greenhouse gases in a more vivid and memorable way, I would recommend a reading of Al Gore’s popular book An Inconvenient Truth. While there are a number of sources that explain green house gases and their effects, I found Al Gore’s book to be one of the more lucid ones.